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Sample records for regional paddy field

  1. Methane flux measurements from paddy fields in the tropical Indian region

    NASA Astrophysics Data System (ADS)

    Lal, Shyam; Venkataramani, S.; Subbaraya, B. H.

    Methane flux measurements have been made from paddy fields in the Thanjavur region in southern India from September 1991 to January 1992. This is a major rice growing area having plenty of river and rain water. A perspex chamber was used to cover the plants. Samples from this chamber were collected using a metal bellows pump in small sample bottles. The methane flux values estimated from the analysis of these samples are mostly in the range of 15-25 mg m -2h -1. These preliminary results, from natural fields, give higher flux values than estimates from some other regions in India, as well as average values for the mid-latitude region, but values lower than from China.

  2. Paddy field, groundwater and land subsidence

    SciTech Connect

    Wen, L.J.

    1995-12-31

    Through many years of research and technical interchange both at home and abroad, it is commonly recognized that paddy fields possess the functions of micro-climate adjustment, flood detection and prevention, soil and water conservation, river-flow stabilization, soil salinization prevention, water purification, groundwater recharge, rural area beautification and environmental protection which are all beneficial to the public. In recent years, the global environmental problems have become a series concern throughout the world. These include the broken ozone layer, green house effects, acid rain, land desertion, tropical rain forest disappearing etc. Among them, rain forest disappearing draws great attention. Both rain forests and paddy fields are in tropical areas. They have similar functions and are disappearing because of economic pressure. This paper describes the special functions of paddy fields on water purification, ground water recharge and prevention of land subsidence, and reiterates groundwater utilization and land subsidence prevention measures. In view of the importance of groundwater resources, paddy fields, which can not be replaced by any other artificial groundwater recharge facilities, should not be reduced in acreage, nor can they be left idle. Paddy fields shall be properly maintained and managed in order to strengthen their special functions in the years to come even under heavy pressure from foreign countries.

  3. Persistence behaviour of pretilachlor in puddled paddy fields under subtropical humid climate.

    PubMed

    Kaur, Paawan; Kaur, Pervinder; Bhullar, M S

    2015-08-01

    The paper delineates the field trials conducted to investigate the persistence behaviour and dissipation kinetics of pretilachlor in puddled paddy fields under subtropical humid climatic region. Matrix solid phase dispersion (MSPD) method was used for extraction of the pretilachlor from paddy grain and paddy soil samples collected from the experimental field. Pretilachlor residues were quantified using high-performance liquid chromatography (HPLC) with UV/Vis detector at 210 nm. The average recoveries of pretilachlor extracted from matrix ranged from 80.3 to 103.3% with standard deviation less than 10% and sensitivity of 0.01 ?g g(-1). The dissipation rate of pretilachlor in paddy field soil and paddy field water followed first-order kinetics with decrease in pretilachlor residues as a function of time. Faster dissipation of pretilachlor was observed in paddy field water than in paddy field soil with half life of 1.89-2.97 days and 7.52-9.58 days, respectively. At harvest, the residues of pretilachlor in the paddy soil and paddy crop samples were below the detection limit. PMID:26205285

  4. Effect of paddy-upland rotation on methanogenic archaeal community structure in paddy field soil.

    PubMed

    Liu, Dongyan; Ishikawa, Hiroki; Nishida, Mizuhiko; Tsuchiya, Kazunari; Takahashi, Tomoki; Kimura, Makoto; Asakawa, Susumu

    2015-01-01

    Methanogenic archaea are strict anaerobes and demand highly reduced conditions to produce methane in paddy field soil. However, methanogenic archaea survive well under upland and aerated conditions in paddy fields and exhibit stable community. In the present study, methanogenic archaeal community was investigated in fields where paddy rice (Oryza sativa L.) under flooded conditions was rotated with soybean (Glycine max [L.] Merr.) under upland conditions at different rotation histories, by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and real-time quantitative PCR methods targeting 16S rRNA and mcrA genes, respectively. Soil samples collected from the fields before flooding or seeding, during crop cultivation and after harvest of crops were analyzed. The abundance of the methanogenic archaeal populations decreased to about one-tenth in the rotational plots than in the consecutive paddy (control) plots. The composition of the methanogenic archaeal community also changed. Most members of the methanogenic archaea consisting of the orders Methanosarcinales, Methanocellales, Methanomicrobiales, and Methanobacteriales existed autochthonously in both the control and rotational plots, while some were strongly affected in the rotational plots, with fatal effect to some members belonging to the Methanosarcinales. This study revealed that the upland conversion for one or longer than 1 year in the rotational system affected the methanogenic archaeal community structure and was fatal to some members of methanogenic archaea in paddy field soil. PMID:25113614

  5. Spatial landuse planning using land evaluation and dynamic system to define sustainable area of paddy field: Case study in Karawang Regency, West Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Widiatmaka, Widiatmaka; Ambarwulan, Wiwin; Firmansyah, Irman; Munibah, Khursatul; Santoso, Paulus B. K.

    2015-04-01

    Indonesia is the country with the 4th largest population in the worlds; the population reached more than 237 million people. With rice as the staple food for more than 95 percent of the population, there is an important role of paddy field in Indonesian food security. Actually, paddy field in Java has produced 52,6% of the total rice production in Indonesia, showing the very high dependence of Indonesia on food production from paddy fields in Java island. Karawang Regency is one of the regions in West Java Province that contribute to the national food supply, due to its high soil fertility and its high extent of paddy field. Dynamics of land use change in this region are high because of its proximity to urban area; this dynamics has led to paddy field conversion to industry and residential landuse, which in turn change the regional rice production capacity. Decreasing paddy field landuse in this region could be serve as an example case of the general phenomena which occurred in Javanese rice production region. The objective of this study were: (i) to identify the suitable area for paddy field, (ii) to modelize the decreasing of paddy field in socio-economic context of the region, and (iii) to plan the spatial priority area of paddy field protection according to model prediction. A land evaluation for paddy was completed after a soil survey, while IKONOS imagery was analyzed to delineate paddy fields. Dynamic system model of paddy field land use is built, and then based on the model built, the land area of paddy field untill 2040 in some scenarios was developped. The research results showed that the land suitability class for paddy fields in Karawang Regency ranged from very suitable (S1) to marginally suitable (S3), with various land characteristics as limiting factors. The model predicts that if the situation of paddy field land use change continues in its business as usual path, paddy field area that would exist in the region in 2040 will stay half of the recent area. Based on the model, the scenario were developed for the protection of priority area. With such scenario, paddy field remains close to the value predicted oficially. Spatial information then can play a role by presenting the scenario spatially. Combining spatial information with land suitability, priority areas of paddy field protection can be delineated. Policies that followed also then be compiled, including the location of protection. Key-words: Land evaluation, food security, spatial information

  6. Depth distribution of radiocesium in Fukushima paddy fields three years after the accident

    NASA Astrophysics Data System (ADS)

    Lepage, Hugo; Laceby, J. Patrick; Evrard, Olivier; Onda, Yuichi; Lefvre, Irne; Ayrault, Sophie

    2015-04-01

    Rice paddy fields located in the vicinity of the Fukushima Dai-Ichi Nuclear Power Plant (FDNPP) were contaminated by radioactive fallout from the March 2011 accident. Although many studies have investigated the fate of radiocesium in soil in the months following the accident, the potential migration of radiocesium in rice paddy fields requires further examination after major typhoons occurred in this region in 2011 and 2013. Further investigations are also required because paddy fields are typically comprised of Andosols, a soil type in which radiocesium has been known to potentially migrate deeper in the depth profile. To investigate the depth migration of radiocesium we collected soil cores in 10 paddy fields located less than 20 km from the FDNPP in November 2013. The maximum depth penetration of 137Cs was attributed to field maintenance (e.g. grass cutting) (97% of 137Cs in the upper 5-cm) and farming operations (tillage/cultivation - 83% of 137Cs in the upper 5-cm). The low migration observed in undisturbed paddy fields could be attributed to the presence of phyllosilicates that were detected by X-ray diffraction in Andosols. As radiocesium is mainly located in the uppermost soil layers, we recommend the rapid removal of these upper layers (e.g. the top 5 cm) to reduce radiocesium export during erosive events such as the major typhoons known to impact the region. Further research is required to thoroughly understand the impacts of erosion on the transfer and migration of radiocesium throughout the Fukushima Prefecture.

  7. Phosphine in paddy fields and the effects of environmental factors.

    PubMed

    Niu, Xiaojun; Wei, Aishu; Li, Yadong; Mi, Lina; Yang, Zhiquan; Song, Xiaofei

    2013-11-01

    Ambient levels of phosphine (PH3) in the air, phosphine emission fluxes from paddy fields and rice plants, and the distribution of matrix-bound phosphine (MBP) in paddy soils were investigated throughout the growing stages of rice. The relationships between MBP and environmental factors were analyzed to identify the principal factors determining the distribution of MBP. The phosphine ambient levels ranged from 2.3680.6060 ng m(-3) to 24.836.529 ng m(-3) and averaged 14.254.547 ng m(-3). The highest phosphine emission flux was 22.543.897 ng (m(2)h)(-1), the lowest flux was 7.644.83 ng (m(2)h)(-1), and the average flux was 14.174.977 ng (m(2)h)(-1). Rice plants transport a significant portion of the phosphine emitted from the paddy fields. The highest contribution rate of rice plants to the phosphine emission fluxes reached 73.73% and the average contribution was 43.00%. The average MBP content of 111.6 ng kg(-1)fluctuated significantly in different stages of rice growth and initially increased then decreased with increasing depth. The peak MBP content in each growth stage occurred approximately 10 cm under the surface of paddy soils. Pearson correlation analyses and stepwise multiple regression analysis showed that soil temperature (Ts), acid phosphatase (ACP) and total phosphorus (TP) were the principal environmental factors, with correlative rankings of Ts>ACP>TP. PMID:23876504

  8. Evaluating health of paddy rice field ecosystem with remote sensing and GIS in Lower Yangtze River Plain, China

    NASA Astrophysics Data System (ADS)

    Li, Jingjing; Qin, Zhihao; Li, Wenjuan; Lin, Lu

    2008-10-01

    A paddy rice ecosystem is a farming system composed of paddy, animals, microbes and other environmental factors in specific time and space, with particular temporal and spatial dynamics. Since paddy rice is a main grain crop to feed above half of population in China, the performance of paddy rice ecosystem is highly concerned to yield level of paddy and food supply safety in China. Therefore, monitoring the performance of paddy rice ecosystem is very important to obtain the required information for evaluation of ecosystem health. In the study we intend to develop an approach to monitor the ecosystem performance spatially and dynamically in a regional scale using MODIS remote sensing data and GIS spatial mapping. On the basis of key factors governing the paddy rice ecosystem, we accordingly develop the following three indicators for the evaluation: Crop growing index (CGI), environmental Index (EI), and pests-diseases index (PDI). Then, we integrated the three indicators into a model with different weight coefficients to calculate Comprehensive ecosystem health index (CEHI) to evaluate the performance and functioning of paddy rice ecosystem in a regional scale. CGI indicates the health status of paddy rice calculated from the normalizing enhanced vegetation Index (EVI) retrieved from MODIS data. EI is estimated from temperature Index (TI) and precipitation Index (PI) indicating heat and water stress on the rice field. PDI reflects the damage brought by pests and diseases, which can be estimated using the information obtained from governmental websites. Applying the approach to Lower Yangtze River Plain, we monitor and evaluate the performance of paddy rice ecosystem in various stages of rice growing period in 2006. The results indicated that the performance of the ecosystem was generally very encouraging. During booting stage and heading and blooming stage, the health level was the highest in Anhui province, which is the main paddy rice producer in the region. During stage of yellow ripeness, Jiangsu province had the lowest level of performance. Yield level of paddy rice in 2006 confirms that the applicability of the proposed approach for a rapid evaluation and monitoring of agricultural ecosystem performance in Lower Yangtze River Plain. As a result, the new approach could supply scientific basis for relevant departments taking policies and measures to make sure stable development of paddy yield.

  9. Urbanization dramatically altered the water balances of a paddy field dominated basin in Southern China

    NASA Astrophysics Data System (ADS)

    Hao, L.; Sun, G.; Liu, Y.; Wan, J.; Qin, M.; Qian, H.; Liu, C.; John, R.; Fan, P.; Chen, J.

    2015-02-01

    Rice paddy fields provide important ecosystem services (e.g., food production, water retention, carbon sequestration) to a large population globally. However, these benefits are declining as a result of rapid environmental and socioeconomic transformations characterized by population growth, urbanization, and climate change in many Asian countries. This case study examined the responses of streamflow and watershed water balances to the decline of rice paddy fields due to urbanization in the Qinhuai River Basin in southern China where massive industrialization has occurred in the region during the past three decades. We found that streamflow increased by 58% and evapotranspiration (ET) decreased by 23% during 1986-2013 as a result of an increase in urban areas of three folds and reduction of rice paddy field by 27%. Both highflows and lowflows increased significantly by about 28% from 2002 to 2013. The increases in streamflow were consistent with the decreases in ET and leaf area index monitored by independent remote sensing MODIS data. The reduction in ET and increase in streamflow was attributed to the large cropland conversion that overwhelmed the effects of regional climate warming and climate variability. Converting traditional rice paddy fields to urban use dramatically altered land surface conditions from a water-dominated to a human-dominated landscape, and thus was considered as one of the extreme types of contemporary hydrologic disturbances. The ongoing large-scale urbanization in the rice paddy-dominated regions in the humid southern China, and East Asia, will likely elevate stormflow volume, aggravate flood risks, and intensify urban heat island effects. Understanding the linkage between land use change and changes in hydrological processes is essential for better management of urbanizing watersheds.

  10. Runoff and degradation of aerially applied dinotefuran in paddy fields and river.

    PubMed

    Yokoyama, Sayako; Ito, Masataka; Nagasawa, Shunsuke; Morohashi, Masayuki; Ohno, Masaki; Todate, Yukitaka; Kose, Tomohiro; Kawata, Kuniaki

    2015-06-01

    Variation, run-off and degradation characteristics of the insecticide dinotefuran, (EZ)-(RS)-1-methyl-2-nitro-3-(tetrahydro-3-furyl-methyl)guanidine, in water and soil from two paddy fields after aerial application was investigated as well as in river water. Maximum concentrations of dinotefuran were 290 and 720 g/L in the two paddy waters, 25 and 28 g/kg dry in the two paddy soils, and 10 g/L in the river water. Runoff ratios of dinotefuran from the paddy fields were calculated as 14%-41%. Mean half-lives of dinotefuran were 5.4 days in the paddy water and 12 days in the paddy soil. Results obtained in this study are important for the evaluation of the actual behavior of dinotefuran in paddy fields and rivers. PMID:25917847

  11. Spatial distribution and temporal variability of arsenic in irrigated rice fields in Bangladesh. 2. Paddy soil.

    PubMed

    Dittmar, Jessica; Voegelin, Andreas; Roberts, Linda C; Hug, Stephan J; Saha, Ganesh C; Ali, M Ashraf; Badruzzaman, A Borhan M; Kretzschmar, Ruben

    2007-09-01

    Arsenic-rich groundwater from shallow tube wells is widely used for the irrigation of boro rice in Bangladesh and West Bengal. In the long term this may lead to the accumulation of As in paddy soils and potentially have adverse effects on rice yield and quality. In the companion article in this issue, we have shown that As input into paddy fields with irrigation water is laterally heterogeneous. To assess the potential for As accumulation in soil, we investigated the lateral and vertical distribution of As in rice field soils near Sreenagar (Munshiganj, Bangladesh) and its changes over a 1 year cycle of irrigation and monsoon flooding. At the study site, 18 paddy fields are irrigated with water from a shallow tube well containing 397 +/- 7 microg L(-1) As. The analysis of soil samples collected before irrigation in December 2004 showed that soil As concentrations in paddy fields did not depend on the length of the irrigation channel between well and field inlet. Within individual fields, however, soil As contents decreased with increasing distance to the water inlet, leading to highly variable topsoil As contents (11-35 mg kg(-1), 0-10 cm). Soil As contents after irrigation (May 2005) showed that most As input occurred close to the water inlet and that most As was retained in the top few centimeters of soil. After monsoon flooding (December 2005), topsoil As contents were again close to levels measured before irrigation. Thus, As input during irrigation was at least partly counteracted by As mobilization during monsoon flooding. However, the persisting lateral As distribution suggests net arsenic accumulation over the past 15 years. More pronounced As accumulation may occur in regions with several rice crops per year, less intense monsoon flooding, or different irrigation schemes. The high lateral and vertical heterogeneity of soil As contents must be taken into account in future studies related to As accumulation in paddy soils and potential As transfer into rice. PMID:17937268

  12. Mobility and Bioavailability of Technetium in Rice Paddy Fields

    SciTech Connect

    Uchida, S.; Tagami, K.

    2003-02-24

    Field observations and radiotracer experiments were carried out to investigate the behavior of 99Tc in paddy fields. The concentrations of global fallout 99Tc in soil collected from paddy fields in Japan were 6-88 milli-bequerels per kilogram (mBq/kg)-dry and activity ratios of 99Tc to 137Cs ranged from 1.1 x 10-3 to 7.0 x 10-3 with an average of (4.8 {+-} 2.1) x 10-3. (The theoretical activity ratio from nuclear fission yield is presently calculated as 3.3 x 10-4 with correction for radioactive decay.) This result implies that there was a tendency for 99Tc to accumulate in rice paddy fields. To understand the mechanisms of the accumulation, a sequential extraction method was applied over a 6-month period to waterlogged soils contaminated with TcO4-. From the results, it was clear that the TcO4- in soil under waterlogged conditions was readily changed to other insoluble physicochemical forms, such as TcO2, TcS2 and organically bound forms.

  13. Heavy metals accumulation in parts of paddy Oryza sativa L. grown in paddy field adjacent to ultrabasic soil

    NASA Astrophysics Data System (ADS)

    Hadif, Waqeed Mahdi; Rahim, Sahibin Abd; Sahid, Ismail; Bhuiyan, Atiqur Rahman; Ibrahim, Izyanti

    2015-09-01

    The present study was carried out to evaluate the accumulation and translocation of heavy metals from soil around the root zone to various parts of the paddy plant, namely the roots, stems, leaves and rice grains. This study was conducted in 2014 in paddy field adjacent to ultrabasic soil (field 1 and 2) located in Ranau, Sabah and one field (Field 3) taken as control located at the UKM experimental plot in peninsular of Malaysia. The plant species used in the present investigation is Paddy Batu. The heavy metals studied were Chromium (Cr), Iron (Fe) and Nickel (Ni). Heavy metals in soil and plant were extracted by wet digestion method. Heavy metals present in paddy plants and soils extract were measured using the ICP-MS. Heavy metals concentrations in the plant parts in descending order is the root > leaves > stem > rice grain. Lower concentration of all heavy metals in soils and plant parts was shown by the control site (Field 3) in UKM Bangi. Higher concentration of heavy metals occurred in the roots compared to other above ground parts (stem, leaves, and grains) of the paddy plant in all of the paddy field. The bioaccumulation factor (BAF) of heavy metals in all locations were recorded in descending order as Ni > Cr > Fe, the BAF values for all metals in the rice grains were low, whereas the BAF values were recorded high for Ni in all locations. The results also showed that Fe was the most predominant metal ion in the roots, followed by Ni then Cr.

  14. Residual Rate and Escape Route Preference of Juvenile Carassius auratus grandoculis Reared in Paddy Fields

    NASA Astrophysics Data System (ADS)

    Maehata, Masayoshi; Ohtsuka, Taisuke; Mizuno, Toshiaki; Kanao, Shigefumi

    Gathering paddy-reared juvenile fish (0-year fish) at the paddy's drain outlet at the time of the mid-summer drainage often results in many unharvested fish being left behind. To devise ways of reducing this wastage as much as possible, we performed two experiments during the irrigation season in modernized, consolidated paddy fields as follows. Experiment I: an investigation into the numbers of juvenile Carassius auratus grandoculis that succeeded in leaving a paddy field through the drain outlet. Experiment II: an investigation into their preferred route of escape from the paddy, either via the drain outlet or the water inlet, when both were available. In Experiment I, more than 39.1% of the number of fish that escaped from the paddy were still left behind in the paddy more than three days after the mid-summer drainage had begun. In Experiment II, most of the juveniles, i.e., 99.8% of the fish that escaped from the paddy, left from the water inlet. These results suggest that greater efficiency in reducing the numbers of unharvested juvenile fish in paddy culture may be achieved by first capturing fish at the drain outlet with the irrigation water shut off, and then partially refilling the paddy while using traps or other gear to catch the remaining fish that are attracted towards the water inlet.

  15. Urbanization dramatically altered the water balances of a paddy field-dominated basin in southern China

    NASA Astrophysics Data System (ADS)

    Hao, L.; Sun, G.; Liu, Y.; Wan, J.; Qin, M.; Qian, H.; Liu, C.; Zheng, J.; John, R.; Fan, P.; Chen, J.

    2015-07-01

    Rice paddy fields provide important ecosystem services (e.g., food production, water retention, carbon sequestration) to a large population globally. However, these benefits are diminishing as a result of rapid environmental and socioeconomic transformations, characterized by population growth, urbanization, and climate change in many Asian countries. This case study examined the responses of stream flow and watershed water balances to the decline of rice paddy fields due to urbanization in the Qinhuai River basin in southern China, where massive industrialization has occurred during the past 3 decades. We found that stream flow increased by 58 % and evapotranspiration (ET) decreased by 23 % during 1986-2013 as a result of a three-fold increase in urban areas and a reduction of rice paddy fields by 27 %. Both high flows and low flows increased significantly by about 28 % from 2002 to 2013. The increases in stream flow were consistent with the decreases in ET and leaf area index monitored by independent remote sensing MODIS (Moderate Resolution Imaging Spectroradiometer) data. Attribution analysis, based on two empirical models, indicated that land-use/land-cover change contributed about 82-108 % of the observed increase in stream flow from 353 ± 287 mm yr-1 during 1986-2002 to 556 ± 145 during 2003-2013. We concluded that the reduction in ET was largely attributed to the conversion of cropland to urban use. The effects of land-use change overwhelmed the effects of regional climate warming and climate variability. Converting traditional rice paddy fields to urban use dramatically altered land surface conditions from an artificial wetland-dominated landscape to an urban land-use- dominated one, and thus was considered an extreme type of contemporary hydrologic disturbance. The ongoing large-scale urbanization of the rice paddy-dominated regions, in humid southern China and East Asia, will likely elevate storm-flow volume, aggravate flood risks, and intensify urban heat island effects. Understanding the connection between land-use/land-cover change and changes in hydrological processes is essential for better management of urbanizing watersheds in the rice paddy-dominated landscape.

  16. Nitrous oxide emissions in nonflooding period from fallow paddy fields.

    PubMed

    Huang, Shuhui; Pant, Hari K; Lu, Jun

    2008-01-01

    The study was conducted to investigate the N2O emissions and dissolved N2O in the leachate during the nonflooding period in nongrowing paddy fields. Three kinds of paddy soils were repacked to soil columns and were supersaturated with water initially and dried gradually in a greenhouse to attain the N2O emissions flux during the incubation. Soils with the texture of silty clay-loam (Q and H) produced cracks during the drying of soil, but soil with the texture of silty loam (X) did not form the cracks. Cracked soils had similar amount of N2O emissions, and the mean N2O flux was 1,280.9 and 1,133.3 microg/(m2 x h) from Q and H soil, respectively, during the incubation; whereas the mean N2O flux from noncracked X soil was 426.3 microg/(m2 x h), i.e., significantly different from cracked soils. From cracked soils, the diurnal N2O emissions reached two peaks at 14:00 and 2:00, but such emissions peaked only at 2:00 from noncracked soil. The dissolved N2O concentrations in leachates from noncracked soil columns were greater than those from the cracked soil columns, and it indicated that the preferential flow might not affect the amounts of dissolved N2O in leachates during soil cracking. Supersaturated dissolved N2O in the leachate was potential source of N2O emissions. Fallow paddy fields have big risks of N2O emissions during nonflooding periods. PMID:19202873

  17. [Residue dynamics of flubendiamide in paddy field].

    PubMed

    Wang, Dian-Dian; Song, Ning-Hui; Wu, Wen-Zhu; You, Zong-Zheng; He, Jian; Shi, Li-Li

    2013-02-01

    Residue dynamics and terminal residue of flubendiamide 19.8% suspension concentrate (SC) in rice and field environment were measured by ultra performance liquid chromatography (UPLC). As flubendiamide and its metabolite were applied at a range of concentrations from 0.05 to 1.0 mg.kg-1, average recoveries of them in soil, water, rice straw, rice grain and rice hull samples ranged from 78.2% to 104.8%, with variation coefficients of 1.1% -4.4%. One-year and three-area results showed that the half-life of gradation for flubendiamide was 9. 8 to 17.3 d in water, 10. 8 to 22.4 d in soil, and 7.6 to 17.3 d in rice plants, respectively. Residues of metabolite NNI-des-iodo in water were detected, but not in soil or rice plants. When flubendiamide was applied at the recommended dose, its residue in rice grain on the 10th day after application was lower than 0.5 mg.kg-1, the maximum residue limit allowed by US for agricultural chemical residues in rice. PMID:23668149

  18. Field investigation to assess nutrient emission from paddy field to surface water in river catchment

    NASA Astrophysics Data System (ADS)

    Kogure, Kanami; Aichi, Masaatsu; Zessner, Matthias

    2015-04-01

    In order to maintain good river environment, it is remarkably important to understand and to control nutrient behavior such as Nitrogen and Phosphorus. Our former research dealing with nutrient emission analysis in the Tone River basin area in Japan, in addition to urban and industrial waste water, nutrient emission from agricultural activity is dominant pollution source into the river system. Japanese style agriculture produces large amount of rice and paddy field occupies large areas in Japanese river basin areas. While paddy field can deteriorate river water quality by outflow of fertilizer, it is also suggested that paddy field has water purification function. As we carried out investigation in the Tone River Basin area, data were obtained which dissolved nitrogen concentration is lower in discharging water from paddy field than inflowing water into the field. Regarding to nutrient emission impact from paddy field, sufficient data are required to discuss quantitatively seasonal change of material behavior including flooding season and dry season, difference of climate condition, soil type, and rice species, to evaluate year round comprehensive impact from paddy field to the river system. In this research, field survey in paddy field and data collection relating rice production were carried out as a preliminary investigation to assess how Japanese style paddy field contributes year round on surface water quality. Study sites are three paddy fields located in upper reach of the Tone River basin area. The fields are flooded from June to September. In 2014, field investigations were carried out three times in flooding period and twice in dry period. To understand characteristics of each paddy field and seasonal tendency accompanying weather of agricultural event, short term investigations were conducted and we prepare for further long term investigation. Each study site has irrigation water inflow and outflow. Two sites have tile drainage system under the field and TD water can be sampled for infiltrating water measurement. We installed monitoring wells to measure ground water level and water quality. Inflow, outflow, flooding water, infiltrating water, and ground water were measured and sampled. Regarding to parameters, temperature, pH, EC, DO and COD, main ions were measured to understand characteristic of water quality and transformation processes. Inorganic forms of nitrogen and phosphorus were also measured, as behavior and balance of nitrogen and phosphorus are focused on. We observed following points by taking data of water quality; seasonal trend, changes occurred according to agricultural events like irrigation and fertilization. Nitrogen in ground water tends to high in June due to fertilizer. It is thought because farmers fertilize the filed before transplanting at the beginning of flooding season. Regarding to dissolved inorganic nitrogen, higher concentrations were observed in inflow water than in flooding water and outflow water. Though it needs discussion in loads as well as flow measurement, this suggests that nutrients are absorbed in paddy field and less nutrients are emitted after irrigation water passing through paddy field. Based on this research we are planning continuous investigation to assess environmental impact from paddy field.

  19. [Effects of different rice farming systems on paddy field weed community].

    PubMed

    Zhang, Dan; Min, Qing-Wen; Cheng, Sheng-Kui; Yang, Hai-Long; He, Lu; Jiao, Wen-Jun; Liu, Shan

    2010-06-01

    Taking the paddy fields planted with glutinous rice and hybrid rice in the traditional agricultural region in Congjiang County of Guizhou Province as the case, and by using semi-experiment combined with random sampling investigation, this paper studied the characteristics of weed community in the paddy fields under rice monoculture (R), rice-fish culture (R-F), and rice-fish-duck culture (R-F-D). Under the three rice farming systems, glutinous rice had higher capability in inhibiting weeds, compared with hybrid rice. Farming system R-F-D decreased the weed density significantly, with the control effect on Monochoia vaginalis and Rotala indica being 100%. The overall weed-inhibiting effect of R-F-D was significantly higher than that of the other farming systems. Under R-F-D, the species richness and Shannon diversity index of weed community decreased markedly, while the Pielou evenness index increased, indicating that the species composition of weed community changed greatly, and the occurrence of native dominant weed species decreased. It was concluded that R-F-D was a feasible farming system for the control of paddy field weed community. PMID:20873641

  20. Genetic Structure of Loach Population in Yatsu Paddy Field

    NASA Astrophysics Data System (ADS)

    Koizumi, Noriyuki; Takemura, Takeshi; Mori, Atsushi; Okushima, Shuji

    Using repeated sequences of microsatellite DNA, we investigated genetic variation and spatial structure of the loach Misgurnus anguillicaudatus population in drainage canals including a main stream in the Shitada River basin composed of Yatsu paddy fields, Chiba Prefecture. Loach population samples of nine to 48 individuals were collected from 54 sampling sites in eight canals and the main stream, and genotype data in eight microsatellite loci were obtained for each sample in the genetic analysis. The average number of alleles per locus was 3.9 to 9.0, and the average observed and expected heterozygosities were 0.444-0.647 and 0.463-0.628, respectively, across samples. All samples seemed to be random mating, which conformed to the Hardy-Weinberg equilibrium. Values of the fixation index FST, were estimated to range between 0-0.161 among all samples, and a part of these values were significant. The pattern of genetic differentiation between samples with principal component analysis indicated that samples in three distinct canals appeared to differentiate, suggesting that the genetic spatial structure of the loach population in Yatsu paddy fields must be complex.

  1. Evaluating Attitudes towards Changes in Rural Landscape by Grazing Cattle on Abandoned Paddy Fields

    NASA Astrophysics Data System (ADS)

    Yasuhito, Kitai; Toshihiro, Hattori; Hiroshi, Takahashi

    The appearance of cattle grazing abandoned paddy fields can be used to evaluate attitudes towards this land-use change. The semantic differential (SD) method was used families of a university student to evaluate and compare attitudes towards five types of rural landscape: pasture, pasture grazed by cattle, rice paddy field, abandoned paddy field converted to pasture and abandoned paddy field converted to pasture grazed by cattle. Cattle grazing abandoned paddy fields were determined to have a positive effect on the landscape. However, all grazing cattle created a negative attitude because of the unclean appearance of the landscape. Grazing cattle at high stocking rates in small areas could create a negative attitude because of the oppressive appearance of the landscape. The acceptance of grazing cattle was lower if the animals ware newly introduced to the landscape.

  2. Investigation of Spatial Distribution of Radiocesium in a Paddy Field as a Potential Sink

    PubMed Central

    Tanaka, Kazuya; Iwatani, Hokuto; Takahashi, Yoshio; Sakaguchi, Aya; Yoshimura, Kazuya; Onda, Yuichi

    2013-01-01

    Surface soils, under various land uses, were contaminated by radionuclides that were released by the Fukushima Daiichi Nuclear Power Plant accident. Because paddy fields are one of the main land uses in Japan, we investigated the spatial distribution of radiocesium and the influence of irrigation water in a paddy field during cultivation. Soil core samples collected at a paddy field in Fukushima showed that plowing had disturbed the original depth distribution of radiocesium. The horizontal distribution of radiocesium did not show any evidence for significant influence of radiocesium from irrigation water, and its accumulation within the paddy field, since the original amount of radiocesium was much larger than was added into the paddy field by irrigation water. However, it is possible that rainfall significantly increases the loading of radiocesium. PMID:24260481

  3. Seasonal analysis of precipitation, drought and Vegetation index in Indonesian paddy field based on remote sensing data

    NASA Astrophysics Data System (ADS)

    Darmawan, S.; Takeuchi, W.; Shofiyati, R.; Sari, D. K.; Wikantika, K.

    2014-06-01

    Paddy field is important agriculture crop in Indonesia. Rice is a food staple for 237,6 million Indonesian people. Paddy field growth is strongly influenced by water, but the amount of precipitation is unpredictable. Annual and interannual climate variability in Indonesia is unusual. In recent years remote sensing data has been used for measurement and monitoring of precipitation, drought and Vegetation index such as Global Satellite Mapping of Precipitation (GSMaP), Multi-purpose Transmission SATellite (MTSAT) and Moderate Resolution Imaging Spectroradiometer (MODIS). The objective of this research is to investigate seasonal variability of precipitation, drought and Vegetation index in Indonesian paddy field based on remote sensing data. The methodology consists of collecting of enhanced vegetation index (EVI) from MODIS data, mosaicking of image, collecting of region of interest of paddy field, collecting of precipitation and drought index based on Keetch Bryam Drought Index (KBDI) from GSMaP and MTSAT, and seasonal analysis. The result of this research has showed seasonal variability of precipitation, KBDI and EVI on Indonesia paddy field from 2007 until 2012. Precipitation begins from January until May and October until December, and KBDI begins to increase from June and peak in September only in South Sumatera precipitation almost in all month. Seasonal analysis has showed precipitation and KBDI affect on EVI that can indicate variety phenology of Indonesian paddy field. Peak of EVI occurs before peak of KBDI occurs and increasing of KBDI followed by decreasing of EVI. In 2010 all province got higher precipitation and smaller KBDI so EVI has three peaks such as in West Java that can indicated increasing of rice production.

  4. Estimation of nighttime ecosystem respiration over a paddy field in China

    NASA Astrophysics Data System (ADS)

    Hossen, M. S.; Hiyama, T.; Tanaka, H.

    2010-02-01

    Accurate estimation of terrestrial ecosystem respiration is crucial for developing regional- to global-scale carbon budget databases. This study evaluated nighttime ecosystem respiration under low turbulence conditions at a paddy field in China during the 2004 growing season. Data from turbulent flux with storage change and alternatively from CO2 concentration profiles measured from the surface to 32 m height were investigated and compared. Conditions were separated into windy and calm using a friction velocity (u∗) threshold. On calm nights, the vertical gradient of CO2 concentration was higher near the canopy level and decreased with height. No differences were detected in terms of quantity and seasonality between the eddy covariance-observed nighttime ecosystem respiration (Re) and the alternatively calculated Re under calm conditions. Nighttime underestimation of paddy ecosystem respiration was low, even under calm conditions. Under stable atmospheric conditions, nighttime "loss" of CO2 flux may result mainly from CO2 being stored in air below the sensor height, and CO2 drainage loss could be small because advection is small. Because the addition of measurement-height storage change is preferable for reducing nighttime underestimation, u∗ filtering and low turbulence data elimination are not required for the paddy ecosystem. Alternatively, under low turbulence conditions, nighttime flux can be calculated from concentration profiles, but actual measurement of the nocturnal boundary layer height is very important. For gap-filling of nighttime CO2 flux data for a paddy ecosystem, development of multiple regression functions based on the crop biomass/leaf area index in association with field water status is preferable to a single regression function using air/soil temperature.

  5. Temporal changes of radiocesium in irrigated paddy fields and its accumulation in rice plants in Fukushima.

    PubMed

    Yang, Baolu; Onda, Yuichi; Wakiyama, Yoshifumi; Yoshimura, Kazuya; Sekimoto, Hitoshi; Ha, Yiming

    2016-01-01

    About half of the total paddy field area, which is the dominant agricultural land in Fukushima Prefecture, was contaminated by radiocesium released by the Fukushima Daiichi Nuclear Power Plant accident. In this study, we investigated the temporal changes of radiocesium in soil, irrigation water, and rice plant in two adjacent rice paddies, with and without surface-soil-removal, in Fukushima Prefecture for over three years (2012-2014) after the nuclear accident. Our results showed that radiocesium migrated into 24-28 cm soil layers and that the activity concentration of radiocesium in paddy soils showed a significant reduction in 2014. The newly added radiocesium to paddies through irrigation water contributed only a maximum value of 0.15% and 0.75% of the total amount present in control and decontaminated paddies, respectively, throughout the study period. The radiocesium activity concentration in suspended sediment in irrigation water exponentially decreased, and the effective half-lives (Teff) for (137)Cs and (134)Cs were 1.3 and 0.9 years, respectively. Additionally, the average suspended sediment concentration in irrigation water increased between 2012 and 2014, suggesting that enhanced soil erosion had occurred in the surrounding environment. Radiocesium accumulation in rice plant also decreased with time in both paddies. However, the concentration ratio of radiocesium for rice plant in the decontaminated paddy increased compared with control paddy, despite approximately 96% of fallout radiocesium removed in paddy soil. Further analysis is required to clarify the reasons of high concentration ratio of radiocesium for rice plant in the decontaminated paddy. PMID:26561453

  6. [Water requirement of paddy field under different soil water conditions].

    PubMed

    Wang, Xiaoying; Wen, Dazhong; Liang, Wenju

    2003-06-01

    Field experiment with three irrigation treatments, i.e., continuous flooding irrigation (CSF), moisture condition irrigation (MTC), and intermittent irrigation (IT) were installed to study the water requirement of paddy fields. The results showed that in field experiment, the evapotranspiration(ET) was 889.1, 635.9 and 775.9 mm, and the evapotranspiration rate was 6.9, 4.9 and 6.0 mm.d-1 for CSF, MTC and IT, respectively during the entire growing season. MTC and IT were less than CSF by 28.5 and 12.7%. Under sufficient water supply, the evapotranspiration calculation by Penman formula was less than that from field experiment by 29.3%, during stages from returning green to milk. The biomass was 16438.22, 15887.94 and 15757.88 kg.hm-2, and the grain yield was 8014.01, 7828.91 and 7853.93 kg.hm-2 for CSF, MTC and IT, respectively. No significant differences were found among three treatments. The water use efficiency (WUE) was 9.01, 12.31 and 10.12 kg.hm-2.mm-1 for CSF, MTC and IT, respectively. The WUE of MTC and IT were higher than that of CSF by 26.8 and 11.0%, showing that MTC was a comparatively water-saving irrigation treatment. PMID:12973998

  7. Preliminary study of phosphorus runoff and drainage from a paddy field in the Taihu Basin.

    PubMed

    Zuo, Qiang; Lu, C A; Zhang, W L

    2003-02-01

    An investigation into phosphorus runoff and drainage from a paddy field was carried out at Changshu Agricultural Ecological Station of CAS during the year 2000. According to the preliminary study, some results indicated: (1) Total phosphorus (TP) content of regular irrigation water was 19 times higher than TP content of P0 (zero rate of P fertilization) stand water. This indicates that paddy fields are a potential source of phosphorus pollution by runoff and drainage into the Taihu Lake Basin (TLB); (2) During the first 10 days after phosphate fertilizer application, the TP concentration of stand water in the paddy field was very high, therefore this was the high risk period for Taihu Lake phosphorus contamination; (3) Four mathematical models of P losses from a paddy field in the TLB are developed. These are based on data for the year 2000, but they will be improved as more data is acquired in future years. PMID:12688477

  8. Methane and nitrous oxide emissions from paddy field as affected by water-saving irrigation

    NASA Astrophysics Data System (ADS)

    Yang, Shihong; Peng, Shizhang; Xu, Junzeng; Luo, Yufeng; Li, Daoxi

    Water-saving practices for rice production has become one of the major agricultural policies in China due to the severe water scarcity. However, greenhouse gases emissions from paddy field may be changed with water-saving practices. In the two-year field experiment at Thaihu Lake Basin of China, CH4 and N2O fluxes from paddy field under controlled irrigation and continuous flooding irrigation were monitored using closed chambers. Total CH4 emission from paddy field under controlled irrigation during the rice-growing period were 2.47 and 1.88 g m-2 in 2006 and 2007, respectively, reduced by 79.1% on average compared with continuous flooding irrigation. The CH4 emission from paddy field was further concentrated in the initial and middle tillering stages of rice growth under controlled irrigation for 2 years. The N2O emission from paddy field under controlled irrigation was mostly larger than those from flooding irrigation during the rice-growing period. Total N2O emission from paddy field under controlled irrigation during the rice-growing period was 106 mg m-2, increased by 10.6% compared with those from flooding irrigation. Carbon dioxide equivalents of CH4 and N2O emissions from paddy field during the rice-growing period under controlled irrigation were 788 kg CO2 ha-1, reduced by 61.4% compared with those from flooding irrigation. It can be concluded that controlled irrigation is an effective technique for mitigating the carbon dioxide equivalents of CH4 and N2O emissions from paddy field.

  9. Geochemical Transformation of Cadmium (Cd) from Creek to Paddy Fields in W Thailand

    NASA Astrophysics Data System (ADS)

    Kosolsaksakul, Peerapat; Graham, Margaret; Farmer, John

    2013-04-01

    Extensive Cd contamination of paddy soils in Tak Province, western Thailand, a consequence of Zn mining activities, was first established in 2005 and medical studies showed that the health of local communities was being impaired. Mae Tao, Tak Province, comprising many paddy fields and irrigation canals, has been selected for this study of the geochemical transformation of Cd from the contamination source in the mountainous region to the east of the study site through the community irrigation system to the paddy soils. The aim of this research is to (i) investigate the geochemical transformation of Cd as it is transported from the main irrigation creek through the canals and to the paddy fields, (ii) assess the availability of Cd to rice plants, which may be affected by both chemical and physical factors, and (iii) trial some practical treatments to minimise Cd concentrations in rice grains. Soils, irrigation canal sediments and water samples were collected during the dry season and at the onset of the rainy season. Rice samples were collected at harvesting time and samples of soil fertiliser were also obtained. Water samples were filtered, ultrafiltered and analysed by ICP-MS whilst sub-samples of dried, ground soils and sediments were first subjected to micro-wave assisted acid digestion (modified US EPA method 3052). XRD and SEM-EDX methods were used for mineralogical characterisation and selective chemical extractions have assisted in the characterisation of solid phase Cd associations. Soil Cd concentrations were in the range 2.5-87.6 µg g-1, with higher values being obtained for fields furthest from the main creek. Although current irrigation water Cd inputs are low (mean 1.9 μg L-1; flood period), high loads of suspended particles still contribute additional Cd (4.2-9.8 µg L-1) to the paddy fields. For bioavailability assessment by a 3-step BCR sequential extraction, 70-90% Cd was in the exchangeable; HOAc-extractable fraction. That indicated that most of the Cd was in water soluble, exchangeable and carbonate-bound forms. For the fields with highest Cd concentration, SEM-EDX analysis identified two forms of Cd, i.e. Cd-Clay and Cd-CaCO3, in good agreement with the sequential extraction data. The predominance of easily extractable forms in the paddy field soils suggests that Cd may be readily absorbed by the rice plants. After harvesting, the Cd concentration in rice grains ranged from 0.05-4.0 µg g-1 and the concentration trends across the group of 18 fields matched well with the soil Cd data. Rice from nine out of the 18 fields contained Cd at greater than the safe level of 0.4 µg g-1.

  10. Depth distribution of radiocesium in Fukushima paddy fields and implications for ongoing decontamination works

    NASA Astrophysics Data System (ADS)

    Lepage, H.; Evrard, O.; Onda, Y.; Lefvre, I.; Laceby, J. P.; Ayrault, S.

    2014-09-01

    Large quantities of radiocesium were deposited across a 3000 km2 area northwest of the Fukushima Dai-ichi nuclear power plant after the March 2011 accident. Although many studies have investigated the fate of radiocesium in soil in the months following the accident, the potential migration of this radioactive contaminant in rice paddy fields requires further examination after the typhoons that occurred in this region. Such investigations will help minimize potential human exposure in rice paddy fields or transfer of radioactive contaminants from soils to rice. Radionuclide activity concentrations and organic content were analysed in 10 soil cores sampled from paddy fields in November 2013, 20 km north of the Fukushima power plant. Our results demonstrate limited depth migration of radiocesium with the majority concentrated in the uppermost layers of soils (< 5 cm). More than 30 months after the accident, 81.5 to 99.7% of the total 137Cs inventories was still found within the < 5 cm of the soil surface, despite cumulative rainfall totalling 3300 mm. Furthermore, there were no significant correlations between radiocesium migration depth and total organic carbon content. We attributed the maximum depth penetration of 137Cs to maintenance (grass cutting - 97% of 137Cs in the upper 5 cm) and farming operations (tilling - 83% of 137Cs in the upper 5 cm). As this area is exposed to erosive events, ongoing decontamination works may increase soil erodibility. We therefore recommend the rapid removal of the uppermost - contaminated - layer of the soil after removing the vegetation to avoid erosion of contaminated material during the subsequent rainfall events. Remediation efforts should be concentrated on soils characterised by radiocesium activities > 10 000 Bq kg-1 to prevent the contamination of rice. Further analysis is required to clarify the redistribution of radiocesium eroded on river channels.

  11. Depth distribution of cesium-137 in paddy fields across the Fukushima pollution plume in 2013.

    PubMed

    Lepage, Hugo; Evrard, Olivier; Onda, Yuichi; Lefèvre, Irène; Laceby, J Patrick; Ayrault, Sophie

    2015-09-01

    Large quantities of radiocesium were deposited across a 3000 km(2) area northwest of the Fukushima Dai-ichi nuclear power plant after the March 2011 accident. Although many studies have investigated the fate of (137)Cs in soil in the months following the accident, the depth distribution of this radioactive contaminant in rice paddy fields requires further examination after the typhoons that occurred in this region. Such investigations will help minimize potential human exposure in rice paddy fields. Radionuclide activity concentrations, organic content and particle size were analysed in 10 soil cores sampled from paddy fields in November 2013, 20 km north of the Fukushima power plant. Our results demonstrate limited depth migration of (137)Cs with the majority concentrated in the uppermost layers of soils (<5 cm). More than 30 months after the accident, between 46.8 and 98.7% of the total (137)Cs inventories was found within the top 5 cm of the soil surface, despite cumulative rainfall totalling 3300 mm. Furthermore, there were no significant correlations between (137)Cs depth distribution and the other parameters. We attributed the maximum depth penetration of (137)Cs to grass cutting (73.6-98.5% of (137)Cs in the upper 5 cm) and farming operations (tillage - 46.8-51.6% of (137)Cs in the upper 5 cm). As this area is exposed to erosive events, ongoing decontamination works may increase soil erodibility. We therefore recommend the rapid removal of the uppermost - contaminated - layer of the soil after removing the vegetation to avoid erosion of contaminated material during the subsequent rainfall events. Further analysis is required to thoroughly understand the impacts of erosion on the redistribution of radiocesium throughout the Fukushima Prefecture. PMID:26026933

  12. Behavior of iodine-129 in rice paddy fields

    SciTech Connect

    Uchida, Shigeo; Muramatsu, Yasuyuki

    1995-12-31

    Transfer factors of iodine from soil to rice were obtained by laboratory experiments using {sup 125}I tracer. Two typical soil types in Japan, Andosol and Gray lowland soil, were used. The transfer factor (TF) is defined as concentration of the nuclide in a plant organ at harvest divided by concentration of the nuclide in dry soil. The TFs for brown (hulled) rice were 0.006 for Andosol and 0.002 for Gray lowland soil. The TFs for different organs of rice plants decreased in the order of blade > stem > rachis > unhulled rice {much_gt} brown rice. The concentration of iodine in soil solution under flooded conditions varied with time during cultivation. The iodine concentration in rice plants seemed to be influenced by the soil solution. The effect of removal of I-129 from paddy fields by harvesting rice plants was also modeled. Even assuming continuous deposition of I-129 on the field, annual harvesting of the blades and stems of rice plants could effectively reduce the amount of the nuclide in the root zone.

  13. Bacillus huizhouensis sp. nov., isolated from a paddy field soil.

    PubMed

    Li, Jibing; Yang, Guiqin; Wu, Min; Zhao, Yong; Zhou, Shungui

    2014-08-01

    A Gram-stain positive, facultative aerobic bacterium, designated as strain GSS03(T), was isolated from a paddy field soil. The cells were observed to be endospore forming, rod-shaped and motile with flagella. The organism was found to grow optimally at 35C at pH 7.0 and in the presence of 1% NaCl. The strain was classified as a novel taxon within the genus Bacillus on the basis of phenotypic and phylogenetic analyses. The closest phylogenetic relatives were identified as Bacillus psychrosaccharolyticus DSM 6(T) (97.61%), Bacillus muralis DSM 16288(T) (97.55%), Bacillus asahii JCM 12112(T) (97.48%), Bacillus simplex DSM 1321(T) (97.48%) and "Bacillus frigoritolerans" DSM 8801(T) (97.38%). The menaquinone was identified as MK-7, the major cellular fatty acid was identified as anteiso-C15:0 and the major cellular polar lipids as phosphatidylethanolamine, phosphatidylmonomethylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and three unknown polar lipids. The DNA G+C content was determined to be 40.2mol%. The DNA-DNA relatedness with the closest relatives was below 48%. Therefore, on the basis of all the results, strain GSS03(T) is considered to represent a novel species within the genus Bacillus, for which the name Bacillus huizhouensis sp. nov. is proposed. The type strain is GSS03(T) (=KCTC 33172(T) =CCTCC AB 2013237(T)). PMID:24903955

  14. Measurement and estimation of radiocesium discharge rate from paddy field during land preparation and mid-summer drainage.

    PubMed

    Miyazu, Susumu; Yasutaka, Tetsuo; Yoshikawa, Natsuki; Tamaki, Shouhei; Nakajima, Kousei; Sato, Iku; Nonaka, Masanori; Harada, Naoki

    2016-05-01

    In this research, we evaluated the range of (137)Cs discharge rates from paddy fields during land preparation and mid-summer drainage. First, we investigated (137)Cs discharge loads during land preparation and mid-summer drainage and their ratio to the (137)Cs inventory of paddy field soil. We found that total discharge rates were 0.003-0.028% during land preparation and 0.001-0.011% during mid-summer drainage. Next, we validated the range of obtained total discharge of (137)Cs from the paddy fields using a simplified equation and literature review. As a result, we conclude that the range of total outflow loads of suspended solids for the investigated paddy field was generally representative of paddy fields in Japan. Moreover, the (137)Cs discharge ratio had a wide range, but was extremely small relative to (137)Cs present in paddy field soil before irrigation. PMID:26895347

  15. [Selenium cycling and transformation in paddy field and selenium nutrition of rice: a review].

    PubMed

    Zhang, Jun-Hua; Zhu, Lian-Feng; Yu, Sheng-Miao; Jin, Qian-Yu

    2012-10-01

    Due to the alternate variation of soil redox potential and the particularity of soil components in paddy field, the selenium (Se) cycling and transformation in paddy soil are obviously different from those in upland soil, and can affect the Se availability in soil and the Se absorption and accumulation by rice. To deeply understand the Se cycling and transformation in paddy soil and the Se absorption and accumulation by rice is of great importance in studying the transformation of soil inorganic Se to organic Se. This paper summarized the researches on the cycling mechanisms and form transformation of Se in paddy soil and the metabolic mechanisms and absorption characteristics of Se by rice, and discussed the present status and development trend of the studies on the Se transformation in soil-rice system and the Se translocation in rice plant, which could provide references for the study of soil Se availability and the cultivation of Se-enriched rice. PMID:23359956

  16. Plant/microbe cooperation for electricity generation in a rice paddy field.

    PubMed

    Kaku, Nobuo; Yonezawa, Natsuki; Kodama, Yumiko; Watanabe, Kazuya

    2008-05-01

    Soils are rich in organics, particularly those that support growth of plants. These organics are possible sources of sustainable energy, and a microbial fuel cell (MFC) system can potentially be used for this purpose. Here, we report the application of an MFC system to electricity generation in a rice paddy field. In our system, graphite felt electrodes were used; an anode was set in the rice rhizosphere, and a cathode was in the flooded water above the rhizosphere. It was observed that electricity generation (as high as 6 mW/m(2), normalized to the anode projection area) was sunlight dependent and exhibited circadian oscillation. Artificial shading of rice plants in the daytime inhibited the electricity generation. In the rhizosphere, rice roots penetrated the anode graphite felt where specific bacterial populations occurred. Supplementation to the anode region with acetate (one of the major root-exhausted organic compounds) enhanced the electricity generation in the dark. These results suggest that the paddy-field electricity-generation system was an ecological solar cell in which the plant photosynthesis was coupled to the microbial conversion of organics to electricity. PMID:18320186

  17. Effects of cracks and some key factors on emissions of nitrous oxide in paddy fields.

    PubMed

    Huang, Shu-hui; Lu, Jun; Tian, Guang-ming

    2005-01-01

    Paddy field is a primary agricultural landscape in the south of China and is often regarded as one of main sources emitting nitrous oxide to atmosphere. The nitrous oxide emissions under a variety of paddy field practices, such as fertilization, flooding/draining management were investigated to study on agricultural activities on paddy field affect the dynamic process of the emission. Under no addition of fertilizers the average emission flux of nitrous oxide was 8.55 microg/(m2 x h) during the rice( Oryza Sativa L. ) growth season. The results indicated that most of nitrous oxide emissions occurred during the crack forming-and-expansion period when paddy field was being drained. The diurnal emissions peak of nitrous oxide appeared at 20:30 at night in cracked rice fields. The statistical analysis suggested that the correlation of nitrous oxide emissions flux ( Y) with soil water content ( X1 ), soil temperature ( X2 ), and Eh ( X3 ), could be described in a regression equation: Y= - 1498.95 + 2895.48X, + 50.63 X2 - 96.99X1 x X2 + 0.006X2 x X3. There were the different power equations to simulate the correlations between the everyday dynamic N2O emissions and the mean surface area of cracks, mean volume and depth of cracks respectively during paddy soil drying by soil columns incubation experiments. Taken all together, the current study presented a dynamic analysis of nitrous oxide emission of paddy field under various conditions, therefore provided a basis for the management to balance between environmental effect and paddy field activities. PMID:15900754

  18. Fipronil application on rice paddy fields reduces densities of common skimmer and scarlet skimmer.

    PubMed

    Kasai, Atsushi; Hayashi, Takehiko I; Ohnishi, Hitoshi; Suzuki, Kazutaka; Hayasaka, Daisuke; Goka, Koichi

    2016-01-01

    Several reports suggested that rice seedling nursery-box application of some systemic insecticides (neonicotinoids and fipronil) is the cause of the decline in dragonfly species noted since the 1990s in Japan. We conducted paddy mesocosm experiments to investigate the effect of the systemic insecticides clothianidin, fipronil and chlorantraniliprole on rice paddy field biological communities. Concentrations of all insecticides in the paddy water were reduced to the limit of detection within 3 months after application. However, residuals of these insecticides in the paddy soil were detected throughout the experimental period. Plankton species were affected by clothianidin and chlorantraniliprole right after the applications, but they recovered after the concentrations decreased. On the other hand, the effects of fipronil treatment, especially on Odonata, were larger than those of any other treatment. The number of adult dragonflies completing eclosion was severely decreased in the fipronil treatment. These results suggest that the accumulation of these insecticides in paddy soil reduces biodiversity by eliminating dragonfly nymphs, which occupy a high trophic level in paddy fields. PMID:26979488

  19. Fipronil application on rice paddy fields reduces densities of common skimmer and scarlet skimmer

    PubMed Central

    Kasai, Atsushi; Hayashi, Takehiko I.; Ohnishi, Hitoshi; Suzuki, Kazutaka; Hayasaka, Daisuke; Goka, Koichi

    2016-01-01

    Several reports suggested that rice seedling nursery-box application of some systemic insecticides (neonicotinoids and fipronil) is the cause of the decline in dragonfly species noted since the 1990s in Japan. We conducted paddy mesocosm experiments to investigate the effect of the systemic insecticides clothianidin, fipronil and chlorantraniliprole on rice paddy field biological communities. Concentrations of all insecticides in the paddy water were reduced to the limit of detection within 3 months after application. However, residuals of these insecticides in the paddy soil were detected throughout the experimental period. Plankton species were affected by clothianidin and chlorantraniliprole right after the applications, but they recovered after the concentrations decreased. On the other hand, the effects of fipronil treatment, especially on Odonata, were larger than those of any other treatment. The number of adult dragonflies completing eclosion was severely decreased in the fipronil treatment. These results suggest that the accumulation of these insecticides in paddy soil reduces biodiversity by eliminating dragonfly nymphs, which occupy a high trophic level in paddy fields. PMID:26979488

  20. Influence of bird feces to water quality in paddy fields during winter season

    NASA Astrophysics Data System (ADS)

    Somura, H.; Takeda, I.; Masunaga, T.; Mori, Y.; Ide, J.

    2009-12-01

    Thousands of migratory birds such as tundra swan came to the paddy fields for overwintering in recent years in the study area. They stayed in paddy fields during night time for sleeping and used around the fields as a feeding ground during day time. During the birds stay, it was observed that water pooled in the paddy fields gradually turned green and gave off a bad smell. In this study, we tried to estimate the influence of the birds feces to water quality in the paddy fields. The study area is in the southeastern portion of Matsue City in Shimane Prefecture, Japan. In several paddy fields, puddling procedure was executed after harvesting rice and then water was stored in the paddy fields during winter season. This is because of being easier of farming activities such as weeding next season and of avoiding using pesticide for weeding with rising of environmental awareness. Water in the paddy fields was collected once or twice a month from the target fields and analyzed nitrogen, phosphorus, and organic carbon in 2007. In the study in 2006, as water was sampled once a week and the changes in the water quality had been grasped, we paid attention to behavior of the birds in a day in the field investigation in 2007. The number of the birds was counted once an hour from visible 7 am to 6 pm once a month. In addition to this, fresh feces were sampled from the fields and analyzed the contents of nitrogen, phosphorus, and organic carbon in the feces. As results, average water qualities of TN, TP, and TOC from November 2007 to March 2008 showed very high concentrations compared with a river water concentration used as irrigation water. More than 70% of TN in the water was ammonia nitrogen. Moreover, comparing with a standard fertilizer amount of nitrogen and phosphorus for paddy fields during irrigation period, it was estimated that the amount of nitrogen excreted by the birds feces during the winter season was equivalent to the standard fertilizer amount and the amount of phosphorus was about 30% of the standard amount. From these results, it was concluded that feces and urine from the birds influenced a lot to the water quality in the paddy fields.

  1. Unionid Freshwater Mussels in Irrigation Ditches are Affected by Physical Environmental Factors and Proximity to Paddy Fields.

    PubMed

    Nakano, Mitsunori; Yamamoto, Tatsuya; Takakura, Koh-Ichi; Urabe, Misako

    2015-08-01

    Irrigation ditches are the major habitat of lotic unionid mussels in Japan. To conserve and rebuild irrigation ditches facilitating mussel conservation, suitable physical environments must be clarified. The effect on mussels of paddy fields connected to ditches also needs to be determined. In this study, physical environmental factors that affect the density of unionid mussels were studied in irrigation ditches in Hikone City, Shiga Prefecture, Japan, to examine whether mussel densities were higher around paddy fields. Generalized linear models were used to analyze physical and paddy field environmental variables affecting mussel density. Our results show that sediment type, sediment softness, water depth, and flow velocity of irrigation ditches affect the density of unionid mussels; the effects of each environment factor and their relative importance differed by species. Specifically, the density of Nodularia douglasiae biwae was higher in ditches with sand-gravel sediment, soft sediment, and not adjoining paddy fields. The density of Pronodularia japanensis was higher in ditches with sand-gravel sediment and not adjoining paddy fields. The density of Lanceolaria grayana was higher in ditches with high flow velocity, not adjoining paddy fields, close to Lake Biwa. The density of Sinanodonta japonica was higher in ditches with mud sediment, shallow depth, high flow velocity, and not adjoining paddy fields. The densities of all four species were lower in irrigation ditches that were closely connected to paddy fields, suggesting that paddy drainage water negatively affects the survival of the mussels. PMID:26245225

  2. Heavy metal contents of paddy fields of Alccer do Sal, Portugal.

    PubMed

    Fernandes, J C; Henriques, F S

    1990-01-01

    Recent claims of metal contamination in the lower reaches of the Sado River, in the Alccer do Sal region, Portugal, a major rice-producing area were investigated by carrying out metal surveys in the area. The elements Fe, Mn, Zn, Cu and Pb were measured in the soil and in rice plant parts--roots, shoots and grain--as well as in some weeds growing in the Sado banks, near the paddy fields. Results showed that the metal contents of paddy soils were similar to background concentrations, with the exception of Zn and Cu, which were above those concentrations and reached their highest levels at Vale de Guizo, the monitored station located furthest upstream in the Sado River. At some sites, plant roots accumulated relatively large amounts of Fe, Mn, Zn and Cu, but the shoot levels of these metals were within the normal range for rice plants. It is possible that varying, but significant, amounts of Fe associated with the roots were in the form of ferric hydroxide plaque covering their surfaces. Copper levels in the shoots of rice were below the normal contents cited for this plant in the literature. Metal levels of river sediments collected near Vale de Guizo seem to corroborate the possibility of some metal contamination in the Sado River, most probably derived from pyrites mining activity in the upper zone of the Sado basin. PMID:2305246

  3. Measuring and modeling the temporal dynamics of nitrogen balance in an experimental-scale paddy field

    NASA Astrophysics Data System (ADS)

    Tseng, C.; Lin, Y.

    2013-12-01

    Nitrogen balance involves many mechanisms and plays an important role to maintain the function of nature. Fertilizer application in agriculture activity is usually seen as a common and significant nitrogen input to environment. Improper fertilizer application on paddy field can result in great amount of various types of nitrogen losses. Hence, it is essential to understand and quantify the nitrogen dynamics in paddy field for fertilizer management and pollution control. In this study, we develop a model which considers major transformation processes of nitrogen (e.g. volatilization, nitrification, denitrification and plant uptake). In addition, we measured different types of nitrogen in plants, soil and water at plant growth stages in an experimental-scale paddy field in Taiwan. The measurement includes total nitrogen in plants and soil, and ammonium-N (NH4+-N), nitrate-N (NO3--N) and organic nitrogen in water. The measured data were used to calibrate the model parameters and validate the model for nitrogen balance simulation. The results showed that the model can accurately estimate the temporal dynamics of nitrogen balance in paddy field during the whole growth stage. This model might be helpful and useful for future fertilizer management and pollution control in paddy field.

  4. Ammonia Volatilization Losses from Paddy Fields under Controlled Irrigation with Different Drainage Treatments

    PubMed Central

    He, Yupu; Yang, Shihong; Wang, Yijiang

    2014-01-01

    The effect of controlled drainage (CD) on ammonia volatilization (AV) losses from paddy fields under controlled irrigation (CI) was investigated by managing water table control levels using a lysimeter. Three drainage treatments were implemented, namely, controlled water table depth 1 (CWT1), controlled water table depth 2 (CWT2), and controlled water table depth 3 (CWT3). As the water table control levels increased, irrigation water volumes in the CI paddy fields decreased. AV losses from paddy fields reduced due to the increases in water table control levels. Seasonal AV losses from CWT1, CWT2, and CWT3 were 59.8, 56.7, and 53.0 kg N ha−1, respectively. AV losses from CWT3 were 13.1% and 8.4% lower than those from CWT1 and CWT2, respectively. A significant difference in the seasonal AV losses was confirmed between CWT1 and CWT3. Less weekly AV losses followed by TF and PF were also observed as the water table control levels increased. The application of CD by increasing water table control levels to a suitable level could effectively reduce irrigation water volumes and AV losses from CI paddy fields. The combination of CI and CD may be a feasible water management method of reducing AV losses from paddy fields. PMID:24741349

  5. Water-saving irrigation of paddy field to reduce nutrient runoff.

    PubMed

    Hitomi, Tadayoshi; Iwamoto, Yusaku; Miura, Asa; Hamada, Koji; Takaki, Kyoji; Shiratani, Eisaku

    2010-01-01

    The purpose of this work is to study the effect of a type of water-saving irrigation (WSI) on nutrient runoff of paddy field. The volume of surface drainage was maintained low by WSI. In particular, WSI effectively reduced surface drainage in rain events. Model simulation indicated that net runoff load of total nitrogen (TN) from the paddy field was increased by WSI. Meanwhile, net runoff loads of total phosphorus (TP) and total organic carbon (TOC) from the paddy field was decreased by WSI. Because ponding waters of the study fields were enriched with TP and TOC, WSI reduced runoff of these nutrients by controlling the volume of surface drainage. WSI could be considered an efficient method for reducing runoff loads and could conserve water quality in an agricultural watershed. PMID:20923101

  6. Estimating soil moisture in rainfed paddy fields using ERS-2 C-band SAR data

    NASA Astrophysics Data System (ADS)

    Ugsang, Donald M.; Honda, Kiyoshi; Eiumnoh, Apisit; Tokunaga, Mitsuharu

    2002-01-01

    This study evaluates the potential and limitations of using ERS-2 C-band SAR data for estimating soil moisture in rainfeld paddy fields. Results of the study show that ERS-2 band SAR data can be used to measure soil moisture at the top 5-cm layer of the soil profile in rainfed paddy fields. An empirical function was established to estimate the soil moisture content from the backscattering coefficient of the ERS-2 C-band SAR data, with an accuracy of R2 ~ 0,91. The function was established under two conditions. First, when the rainfed paddy fields were bare until they are covered with rice crop at the early vegetative growth stage - 38 cm in height or 425 and 102 g/sq.m. in wet and dry biomass, rspectively. Second, when the change in surface roughness throughout the growing period is small.

  7. ?Cs in irrigation water and its effect on paddy fields in Japan after the Fukushima nuclear accident.

    PubMed

    Yoshikawa, Natsuki; Obara, Hitomi; Ogasa, Marie; Miyazu, Susumu; Harada, Naoki; Nonaka, Masanori

    2014-05-15

    There is concern that radiocesium deposited in the environment after the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011 will migrate to paddy fields through hydrological pathways and cause serious and long-lasting damage to the agricultural activities. This study was conducted in the Towa region of Nihonmatsu in the northern part of Fukushima Prefecture, Japan, (1) to quantify (137)Cs in stream water used to irrigate paddy fields by separating the dissolved and particulate components in water samples and then fractionating the particulate components bonded in different ways using a sequential extraction procedure, and (2) to determine the amounts of radiocesium newly added to paddy fields in irrigation water relative to the amounts of radiocesium already present in the fields from the deposition of atmospheric fallout immediately after the FDNPP accident. Three catchments were studied, and the (137)Cs activity concentrations in stream water samples were 79-198 mBq L(-1) under stable runoff conditions and 702-13,400 Bq L(-1) under storm runoff conditions. The residual fraction (F4, considered to be non-bioavailable) was dominant, accounting for 59.5-82.6% of the total (137)Cs activity under stable runoff conditions and 69.4-95.1% under storm runoff conditions. The (137)Cs newly added to paddy fields in irrigation water only contributed 0.03-0.05% of the amount already present in the soil (201-348 kBq m(-2)). This indicates that the (137)Cs inflow load in irrigation water is negligible compared with that already in the soil. However, the contribution from the potentially bioavailable fractions (F1+F2+F3) was one order of magnitude larger, accounting for 0.20-0.59%. The increase in the dissolved and soluble radiocesium fraction (F1) was especially large (3.0% to infinity), suggesting that radiocesium migration in irrigation water is increasing the accumulation of radiocesium in rice. PMID:24602909

  8. Modelling field-data of preferential flow in paddy soil induced by earthworm burrows.

    PubMed

    Sander, Till; Gerke, Horst H

    2009-02-16

    Dye tracer studies revealed that earthworm burrows in the compacted plough pan of a Chinese paddy rice field can serve as preferential flow paths. It is, however, unclear whether the observed bypass of the compacted soil horizon might be explained by differences in hydraulic properties between the plough pan, the worm burrows with a surrounding denser drilosphere and the un-compacted subsoil, or by lower-permeable macropore walls. The objective is to separately analyse effects of the individual flow domains and to identify possible limiting factors (bottlenecks) in the flow system for better soil drainage management. Hydraulic properties are inversely estimated from in situ measurements of pressure heads and evaporation by using HYDRUS_1D code. Field data of 2D pressure head progression after dye tracer infiltration in the vicinity of worm burrows are simulated using HYDRUS_2D. The axisymmetric 2D flow model considers a highly permeable cylindrical macropore region in the centre of the flow domain, assuming Darcy's law is valid. The match between simulated and measured pressure head fields improved after including a lower-permeable drilosphere pore domain. Scenario simulations show that the inflow into the 'bypass-flow' domain are reduced by the homogenized topsoil (i.e., after puddling) and limited if the macropore domain is relatively shallow. The results suggest that basic structural features may in this concept be considered as one possibility to describe observed preferential flow patterns. The separate consideration of soil structural effects may help developing and improving management strategies for manipulation of preferential flow in soils of paddy fields. PMID:19064301

  9. Uncertainties in estimating regional methane emissions from rice paddies due to data scarcity in the modeling approach

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Zhang, Q.; Huang, Y.; Li, T. T.; Bian, J. Y.; Han, P. F.

    2014-06-01

    Rice paddies are a major anthropogenic source of the atmospheric methane. However, because of the high spatial heterogeneity, making accurate estimations of the methane emission from rice paddies is still a big challenge, even with complicated models. Data scarcity is one of the substantial causes of the uncertainties in estimating the methane emissions on regional scales. In the present study, we discussed how data scarcity affected the uncertainties in model estimations of rice paddy methane emissions, from county/provincial scale up to national scale. The uncertainties in methane emissions from the rice paddies of China was calculated with a local-scale model and the Monte Carlo simulation. The data scarcities in five of the most sensitive model variables, field irrigation, organic matter application, soil properties, rice variety and production were included in the analysis. The result showed that in each individual county, the within-cell standard deviation of methane flux, as calculated via Monte Carlo methods, was 13.5-89.3% of the statistical mean. After spatial aggregation, the national total methane emissions were estimated at 6.44-7.32 Tg, depending on the base scale of the modeling and the reliability of the input data. And with the given data availability, the overall aggregated standard deviation was 16.3% of the total emissions, ranging from 18.3-28.0% for early, late and middle rice ecosystems. The 95% confidence interval of the estimation was 4.5-8.7 Tg by assuming a gamma distribution. Improving the data availability of the model input variables is expected to reduce the uncertainties significantly, especially of those factors with high model sensitivities.

  10. Effect of phosphate fertilizer application on phosphorus (P) losses from paddy soils in Taihu Lake Region. I. Effect of phosphate fertilizer rate on P losses from paddy soil.

    PubMed

    Zhang, H C; Cao, Z H; Shen, Q R; Wong, M H

    2003-02-01

    A field plot study was conducted on two types of paddy soils in the Taihu Lake Region, during the rice season of year 2000 in order to assess phosphorus (P) losses by runoff and vertical leaching, which are considered the two main pathways of P movement from paddy soil into its surrounding water course. Commercial NPK compound fertilizer and single superphosphate fertilizer were applied to furnish 0, 30, 150, and 300 kg applied P ha m(-2). The experiments consisted of three replicates of each treatment in Changshu site and four replicates in Anzhen site, with a plot size of 5 x 6 m2 in a randomized block. Results revealed that the average concentration range for total P (TP) in runoff was 1.857-7.883, 1.038-5.209, 0.783-1.255 and 0.572-0.691 mg P l(-1) respectively for P300, P150, P30 and P0 in Anzhen, while it was 2.431-2.449, 1.578-1.890, 1.050-1.315 and 0.749-0.941 mg P l(-1) respectively in Changshu. In all treatments, particulate P (PP) represented a major portion of the TP lost in runoff, it was 80% in Anzhen, and it was even more (>90%) in Changshu. Phosphate fertilizer treatments significantly affected P concentrations and P loads in the runoff. The mean concentration and average seasonal TP load from the P150 plots were 1.809 mg P l(-1) and 395 g P ha m(-2) season(-1) respectively, and lower than that from the P300 plots (2.957 mg P l(-1) and 652 g P ha m(-2) season(-1)). These were obviously higher than from the P30 (0.761 mg P l(-1) and 221 g P ha m(-2) season(-1)) and P0 (0.484 mg P l(-1) and 146 g P ha m(-2) season(-1)) respectively. There was no significant difference found between the P30 and the P0 in both sites. Under usual P application rate, there were total 31.7 and 20.6 tones P removed by runoff from permeable (Anzhen site) and waterlogged (Changshu site) paddy soils in the southern Jiangsu region (major part of the TLR) in the rice season of the year 2000. But if the P application rate is unusual high, or the Olsen P in soil accumulates to above a certain level, then this could sharply increase in the future. The average concentration of molybdate reactive phosphorus (MRP) in the vertical leachate from the four different P treatments ranged from 0.058 to 0.304 mg P l(-1) in Anzhen and from 0.048 to 0.394 mg P l(-1) in Changshu. P application rate significantly affected the MRP concentration at each depth in both sites, except for the 90 cm in Anzhen. The average MRP loads during the rice season moved by vertical leaching from the four treatments ranged from 163 to 855 g P ha m(-2) season(-1) in Anzhen and 208-1,825 g P ha m(-2) season(-1) in Changshu. Vertical leachate movement does not necessarily mean that it moves towards surface water and contaminate the watercourses in this flat plain paddy soil region, it does, however, imply that P can move down from surface layers of soil to deeper levels. PMID:12688478

  11. Generation of methane from paddy fields and cattle in India, and its reduction at source

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, T. K.; Goyal, P.; Singh, M. P.

    Methane (CH4) is a saturated organic gas. About 500 Tg yr -1 methane is generated globally. It is evident that 70% of the total emission have anthropogenic sources. The paddy fields contribute a significant portion of the total methane generated. About 20% of the total methane is generated from the paddy fields. In India, methane efflux rate is negative to 49 mg m -2 hr -1. The mean CH4 flux from Indian paddy fields is calculated to be 4.0 Tgyr -1. Livestock, and in particular ruminants are one of the important sources of methane emission on a global scale. There are two sources of methane emission from live stock: (1) from digestive process of ruminants, (2) from animal wastes. The estimated value of methane emission from digestive process of ruminants in India accounts for 6.47 Tgyr -1, and animal wastes accounts for 1.60 Tgyr -1. Total generation of methane from animals in India is about 8.0 Tg yr -1 . In paddy fields the key of controlling methane emission lies in the control of irrigation water. The methane emission can be decreased drastically if the field is under dry conditions for a few days at the end of tillering. In the case of livestock, reduction of methane emission can be done by (1) increasing the intake of the animal, (2) modifying the composition of the diet, (3) eliminating protozoa in rumen, (4) improving fibre digestion efficiency and (5) inhibiting activity of methanogenic bacteria.

  12. Can't See the Forest for the Rice: Factors Influencing Spatial Variations in the Density of Trees in Paddy Fields in Northeast Thailand

    NASA Astrophysics Data System (ADS)

    Watanabe, Moriaki; Vityakon, Patma; Rambo, A. Terry

    2014-02-01

    The widespread presence of trees in paddy fields is a unique feature of Northeast Thailand's agricultural landscape. A survey of spatial variability in the density of trees in paddy fields in the Northeast Region was conducted utilizing high resolution satellite images and found that the mean density in the whole region was 12.1 trees/ha (varying from a high of 44.6 trees/ha to a low of 0.8 trees/ha). In general, tree densities are higher in the southeastern part of the region and much lower in the northern central part. Tree density was influenced by multiple factors including: (1) the history of land development, with more recently developed paddy fields having higher densities, (2) topography, with fields located at higher topographical positions having a higher mean density of trees, (3) access to natural forest resources, with fields in areas located close to natural forests having higher densities, (4) amount of annual rainfall, with fields in areas with higher average annual rainfall having higher tree densities, and (5) landholding size, with fields in areas with larger-sized landholdings having more trees. However, there is a considerable extent of co-variation among these factors. Although trees remain an important element of the paddy field landscape in the Northeast, it appears that their density has been declining in recent years. If this trend continues, then the vast "invisible forest" represented by trees in paddy fields may truly disappear, with negative consequences for the villagers' livelihoods, biodiversity conservation, and carbon sequestration in the rural ecosystem.

  13. Can't see the forest for the rice: factors influencing spatial variations in the density of trees in paddy fields in northeast Thailand.

    PubMed

    Watanabe, Moriaki; Vityakon, Patma; Rambo, A Terry

    2014-02-01

    The widespread presence of trees in paddy fields is a unique feature of Northeast Thailand's agricultural landscape. A survey of spatial variability in the density of trees in paddy fields in the Northeast Region was conducted utilizing high resolution satellite images and found that the mean density in the whole region was 12.1 trees/ha (varying from a high of 44.6 trees/ha to a low of 0.8 trees/ha). In general, tree densities are higher in the southeastern part of the region and much lower in the northern central part. Tree density was influenced by multiple factors including: (1) the history of land development, with more recently developed paddy fields having higher densities, (2) topography, with fields located at higher topographical positions having a higher mean density of trees, (3) access to natural forest resources, with fields in areas located close to natural forests having higher densities, (4) amount of annual rainfall, with fields in areas with higher average annual rainfall having higher tree densities, and (5) landholding size, with fields in areas with larger-sized landholdings having more trees. However, there is a considerable extent of co-variation among these factors. Although trees remain an important element of the paddy field landscape in the Northeast, it appears that their density has been declining in recent years. If this trend continues, then the vast "invisible forest" represented by trees in paddy fields may truly disappear, with negative consequences for the villagers' livelihoods, biodiversity conservation, and carbon sequestration in the rural ecosystem. PMID:24281918

  14. Microbial electricity generation in rice paddy fields: recent advances and perspectives in rhizosphere microbial fuel cells.

    PubMed

    Kouzuma, Atsushi; Kaku, Nobuo; Watanabe, Kazuya

    2014-12-01

    Microbial fuel cells (MFCs) are devices that use living microbes for the conversion of organic matter into electricity. MFC systems can be applied to the generation of electricity at water/sediment interfaces in the environment, such as bay areas, wetlands, and rice paddy fields. Using these systems, electricity generation in paddy fields as high as ?80 mW m(-2) (based on the projected anode area) has been demonstrated, and evidence suggests that rhizosphere microbes preferentially utilize organic exudates from rice roots for generating electricity. Phylogenetic and metagenomic analyses have been conducted to identify the microbial species and catabolic pathways that are involved in the conversion of root exudates into electricity, suggesting the importance of syntrophic interactions. In parallel, pot cultures of rice and other aquatic plants have been used for rhizosphere MFC experiments under controlled laboratory conditions. The findings from these studies have demonstrated the potential of electricity generation for mitigating methane emission from the rhizosphere. Notably, however, the presence of large amounts of organics in the rhizosphere drastically reduces the effect of electricity generation on methane production. Further studies are necessary to evaluate the potential of these systems for mitigating methane emission from rice paddy fields. We suggest that paddy-field MFCs represent a promising approach for harvesting latent energy of the natural world. PMID:25394406

  15. Responses of seasonal and diurnal soil CO2 effluxes to land-use change from paddy fields to Lei bamboo (Phyllostachys praecox) stands

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Li, Yongfu; Chang, Scott X.; Jiang, Peikun; Zhou, Guomo; Zhang, Jiaojiao; Liu, Juan

    2013-10-01

    Land-use change often markedly alters soil carbon (C) dynamics such as soil surface CO2 efflux. This study aims to test the hypotheses that converting paddy fields to bamboo stands would markedly reduce soil CO2 efflux and their temperature sensitivity (change of soil CO2 efflux rate by increasing 10 °C of temperature), and change the relationship between soil CO2 efflux and other environmental factors. A 12-month field study was conducted to measure the seasonal and diurnal soil CO2 effluxes in three adjacent paddy field-bamboo forest pairs with the automated soil CO2 flux system (LI-8100). Results showed that soil CO2 effluxes from both of the two land-uses had distinct seasonal patterns, and were reduced from 45.4 to 34.7 t CO2 ha-1 yr-1 in cumulative CO2 emissions when paddy fields were converted to bamboo stands. About 80% of the variation in soil respiration in the bamboo stands was explained by soil temperature; however, a positive relationship between soil CO2 efflux and soil temperature in the paddy field was observed only when the soil was not submerged under water, indicating that soil water saturation in the paddy fields altered the soil CO2 efflux-temperature relationship. A negative relationship (P < 0.01) between soil CO2 efflux and soil moisture was observed in the paddy fields, while no such relationship was observed in the bamboo stands. The apparent temperature sensitivity of soil respiration (Q10) was dependent on the depth of the soil temperature measurement and was increased by converting paddy fields to bamboo stands, rejecting the hypothesis. In Lei bamboo stands, the R2 for the soil respiration-temperature regression was higher using seasonal and diurnal CO2 efflux data together than using the seasonal data alone. We conclude that the conversion of paddy fields to Lei bamboo stands decreased the annual soil CO2 efflux but increased its temperature sensitivity, and altered the relationship between soil respiration and soil moisture. When calculating the Q10, the soil temperature measurement depth and data with diurnal timescale should be taken into account. If such land-use conversion effects are confirmed over the subtropical region in China in future research, this land-use conversion could increase C sequestration in the ecosystem and help mitigate climate change.

  16. Behavior of Suspended Sediments with Radionuclide in the Paddy Field, Fukushima Japan

    NASA Astrophysics Data System (ADS)

    Wakahara, T.; Onda, Y.; Kato, H.

    2011-12-01

    After the nuclear reactor accident in Fukushima on March 11, 2011, huge amounts of radionuclide such as Caesium-137, which is an artificial radionuclide with a half-life of 30.17 years, has been produced. Most of the fallen Cs-137 infiltrated into soil together with rainfall and was absorbed by soil sediments. The potential concentration of radionuclides into paddy field, as investigated in this study, has consequency on health, agriculture and remediation of contaminated areas. Paddy field typically are flat, surrounded by dams (10-50 cm)delimiting small pools with a water level of approximately20cm. Therefore, they can potentially catch huge amounts of suspended sediments from incoming rivers. However, recent studies suggested the paddy field can be a source of suspended sediments in some conditions. In this study, we intended to investigate the characteristics of Cs137 associated to sediment into paddy field as well as its incoming and outgoing and flux of that in paddy field. The study site was set on the Yoshiguchi, Kawamata-cho, Fukushima prefecture(N 37 35' 26.15", E140 38' 14.97"). This place is located 30km from the damaged Fukushima nuclear reactor. Two plots were set: One was tillaged as usual (plot UE, 30x17m), while the upper 5 to 10 cm of the other plot's surface was scraped before tillage.(plot ST, 43x17m). The lower part of each plot has a Parshall flume with water gauge, turbidimeter and rain gauge. After tillage, water was put into the plot field and rice seedlings were transplanted. Every week we corrected a suspended sediment samples and measured Cs137 concentration. At the plot ST, out flow of the Cs137 density was less than 35% of that of UE plot.

  17. Effects of Fipronil Insecticide Application on Sympetrum sp. Larvae and Adults in Experimental Rice Paddy Field

    NASA Astrophysics Data System (ADS)

    Jinguji, Hiroshi; Ueda, Tetsuyuki; Tsunoda, Manami; Aihara, Shoko; Saito, Mitsuo

    The effect of on sowing and before transplanting application of the phenyl pyrazole insecticide, fipronil, on the survivorship Sympetrum spp. was investigated in plots of an experimental rice paddy field. In addition, the effect of two pesticide applications on rice weevils was investigated. A total of nine paddy plots were used in this study: three were treated with fipronil at the before transplanting application , three at the on sowing application, and the three remaining plots were left untreated for use as controls. Fipronil concentrations in paddy water at the time of application in before transplanting and on sowing treatments reached 1.45 and 1.20 ?g/L, respectively. A comparison of experimental and control plots revealed a marked absence of Sympetrum frequens larvae, exuviae and adults from fipronil-treated fields. Adult density of Sympetrum sp. and members of Lestidae in paddy fields before transplanting application were considerably lower than in control plots. Our results show that before transplanting application is more effective than on sowing application for treating rice weevils, but that on sowing application may still be harm against dragonflies.

  18. Crop Uptake of Arsenic from Flooded Paddy Fields in the Mekong Delta

    NASA Astrophysics Data System (ADS)

    Mohr, K.; Boye, K.

    2014-12-01

    Arsenic is found naturally in the soils in the Mekong delta in Vietnam and Cambodia. It originates from erosion in the Himalayas. When similar levels of arsenic are present in well aerated soil, it is not dangerous, because it is strongly bound to soil particles and not readily plant available. Arsenic is released when the soil is saturated with water, and therefore contaminates crops grown in flooded fields. This results in people being exposed to unsafe levels of arsenic from their food, such as rice and lotus, which are normally grown under flooded conditions. Rice is a staple food in these regions, so the transfer of arsenic from soil, to water, and ultimately into the grain, poses a threat to human health. We have conducted a limited, preliminary field survey of arsenic levels in soil, flood water, and crops from distinctly different paddy fields in the lower Mekong delta in Vietnam and Cambodia. The purpose of the study was to identify soils and crops (or specific plant parts) that are especially prone to arsenic transfer from soil to crop, and vice versa (i.e. arsenic uptake is prevented in spite of being present in the soil). In addition to arsenic concentration in soil, plant and water, we are examining other elements, such as carbon, nitrogen, sulfur and iron, which give us clues about what chemical and microbial processes that control the overall arsenic uptake.

  19. The variations of Oxidation-Reduction Potential in paddy soil and effects on the methane emission from a periodically irrigated paddy field.

    NASA Astrophysics Data System (ADS)

    Yagi, K.; Iwata, T.; Wakikuromaru, N.

    2014-12-01

    Paddy fields are one of the most important eco-system in monsoon Asia and one of the largest source of CH4 emission. CH4 has significant contribution to the global warming next to CO2 and its greenhouse effect is about 21 times as large as same amount of CO2. CH4 is generated by decomposition of organic matter in soil under anaerobic condition. Oxidation-Reduction Potential (ORP) is the most suitable index representing soil aerobic condition. Or, CH4 is more generated under lower ORP conditions. In this study, ORP in paddy soil was measured during rice cultivated season at a periodically irrigated paddy field, and some effects on the methane flux from the paddy soil was investigated. 3-days flood and 4-days drained condition were regularly repeated at the site from late-June to early October. ORP under flooded condition was measured during irrigated term in 2013 at two mode; regular interval measurement every 2 weeks and intensive measurements during two flooded periods. Methane flux was also measured by the aerodynamic gradient technique. ORP showed rapid decrease when irrigation water was introduced in the paddy field, and lower ORP was shown under the longer flooded condition. From the seasonal-term point of view, lower ORP was shown in later rice season. ORP was suitably modeled as a function of irrigation time. During an irrigation period for four days, higher methane emissions were shown under lower OPR conditions as shown in Fig.1. From the seasonal-term point of view, however, no significant relationship between ORP and methane fluxes. Rapid rise of CH4 flux in early August and gradual decrease between late August and September were shown. It is suggested that seasonal change of methane flux is affected by seasonal changes of soil temperature or the growth level of rice plants.

  20. Effect of residual biomass burning on CO2 flux at a paddy field in Japan

    NASA Astrophysics Data System (ADS)

    Taniguchi, Y.; Iwata, T.; Nakaya, K.

    2014-12-01

    Paddy field is one of the most important ecosystem in monsoon Asia, and takes a great important role in CO2 uptake. Carbon budget in agricultural fields is largely influenced by some artificial managements. After the harvest of crops, residual biomass is burned on fields, brought out from fields, or left and plowed into paddy soils. If the open burning is conducted on fields, one part of biomass carbon would be emitted to atmosphere as CO2, and the other part would be plowed into soils. In this study, an experimental paddy field was divided into two areas to investigate what impact is brought on the annual CO2 flux by the difference of disposal management of residual biomass after the harvest. At the one area, residual biomass was burned and plowed into soils after the harvest in late November 2011, 2012, and 2013. At the other area, residue was not burned and plowed into soils as usual. From three-years average of sampling surveys, carbon content of residue plowed into soils after the harvest was estimated 2931 and 22036 g C m-2 at no-burned and burned area, respectively. Continuous eddy-covariance measurements of CO2 fluxes at each area were conducted for three years. A little bit of difference in CO2 flux between two areas was shown during rice season.

  1. Localization and Classification of Paddy Field Pests using a Saliency Map and Deep Convolutional Neural Network

    PubMed Central

    Liu, Ziyi; Gao, Junfeng; Yang, Guoguo; Zhang, Huan; He, Yong

    2016-01-01

    We present a pipeline for the visual localization and classification of agricultural pest insects by computing a saliency map and applying deep convolutional neural network (DCNN) learning. First, we used a global contrast region-based approach to compute a saliency map for localizing pest insect objects. Bounding squares containing targets were then extracted, resized to a fixed size, and used to construct a large standard database called Pest ID. This database was then utilized for self-learning of local image features which were, in turn, used for classification by DCNN. DCNN learning optimized the critical parameters, including size, number and convolutional stride of local receptive fields, dropout ratio and the final loss function. To demonstrate the practical utility of using DCNN, we explored different architectures by shrinking depth and width, and found effective sizes that can act as alternatives for practical applications. On the test set of paddy field images, our architectures achieved a mean Accuracy Precision (mAP) of 0.951, a significant improvement over previous methods. PMID:26864172

  2. Localization and Classification of Paddy Field Pests using a Saliency Map and Deep Convolutional Neural Network.

    PubMed

    Liu, Ziyi; Gao, Junfeng; Yang, Guoguo; Zhang, Huan; He, Yong

    2016-01-01

    We present a pipeline for the visual localization and classification of agricultural pest insects by computing a saliency map and applying deep convolutional neural network (DCNN) learning. First, we used a global contrast region-based approach to compute a saliency map for localizing pest insect objects. Bounding squares containing targets were then extracted, resized to a fixed size, and used to construct a large standard database called Pest ID. This database was then utilized for self-learning of local image features which were, in turn, used for classification by DCNN. DCNN learning optimized the critical parameters, including size, number and convolutional stride of local receptive fields, dropout ratio and the final loss function. To demonstrate the practical utility of using DCNN, we explored different architectures by shrinking depth and width, and found effective sizes that can act as alternatives for practical applications. On the test set of paddy field images, our architectures achieved a mean Accuracy Precision (mAP) of 0.951, a significant improvement over previous methods. PMID:26864172

  3. [Research on characteristics of soil clay mineral evolution in paddy field and dry land by XRD spectrum].

    PubMed

    Zhang, Zhi-dan; Li, Qiao; Luo, Xiang-li; Jiang, Hai-chao; Zheng, Qing-fu; Zhao, Lan-po; Wang, Ji-hong

    2014-08-01

    The present paper took the typical saline-alkali soil in Jilin province as study object, and determinated the soil clay mineral composition characteristics of soil in paddy field and dry land. Then XRD spectrum was used to analyze the evolutionary mechanism of clay mineral in the two kinds of soil. The results showed that the physical and chemical properties of soil in paddy field were better than those in dry land, and paddy field would promote the weathering of mineral particles in saline-alkali soil and enhance the silt content. Paddy field soil showed a strong potassium-removal process, with a higher degree of clay mineral hydration and lower degree of illite crystallinity. Analysis of XRD spectrum showed that the clay mineral composition was similar in two kinds of soil, while the intensity and position of diffraction peak showed difference. The evolution process of clay mineral in dry land was S/I mixture-->vermiculite, while in paddy field it was S/I mixture-->vermiculite-->kaolinite. One kind of hydroxylated 'chlorite' mineral would appear in saline-alkali soil in long-term cultivated paddy field. Taking into account that the physical and chemical properties of soil in paddy field were better then those in dry land, we could know that paddy field could help much improve soil structure, cultivate high-fertility soil and improve saline-alkali soil. This paper used XRD spectrum to determine the characteristics of clay minerals comprehensively, and analyzed two'kinds of land use comparatively, and was a new perspective of soil minerals study. PMID:25508755

  4. [Research on characteristics of soil clay mineral evolution in paddy field and dry land by XRD spectrum].

    PubMed

    Zhang, Zhi-dan; Li, Qiao; Luo, Xiang-li; Jiang, Hai-chao; Zheng, Qing-fu; Zhao, Lan-po; Wang, Ji-hong

    2014-08-01

    The present paper took the typical saline-alkali soil in Jilin province as study object, and determinated the soil clay mineral composition characteristics of soil in paddy field and dry land. Then XRD spectrum was used to analyze the evolutionary mechanism of clay mineral in the two kinds of soil. The results showed that the physical and chemical properties of soil in paddy field were better than those in dry land, and paddy field would promote the weathering of mineral particles in saline-alkali soil and enhance the silt content. Paddy field soil showed a strong potassium-removal process, with a higher degree of clay mineral hydration and lower degree of illite crystallinity. Analysis of XRD spectrum showed that the clay mineral composition was similar in two kinds of soil, while the intensity and position of diffraction peak showed difference. The evolution process of clay mineral in dry land was S/I mixture-->vermiculite, while in paddy field it was S/I mixture-->vermiculite-->kaolinite. One kind of hydroxylated 'chlorite' mineral would appear in saline-alkali soil in long-term cultivated paddy field. Taking into account that the physical and chemical properties of soil in paddy field were better then those in dry land, we could know that paddy field could help much improve soil structure, cultivate high-fertility soil and improve saline-alkali soil. This paper used XRD spectrum to determine the characteristics of clay minerals comprehensively, and analyzed two'kinds of land use comparatively, and was a new perspective of soil minerals study. PMID:25474976

  5. Influence of biochar amendment on greenhouse gases emission and rice production in paddy field, China

    NASA Astrophysics Data System (ADS)

    Liu, X.; Pan, G. X.; Li, L. Q.; Zhou, T.

    2012-04-01

    Biochar incorporating into agricultural soils as a strategy to increase soil carbon content and mitigate climate change received great attention. We present a field study about biochar amendment into paddy field in Sichuan province 2010, China. The objective was to evaluate the impacts of biochar incorporation on rice production and greenhouse gas emissions. Biochar used in this study was produced from wheat straw at temperature 350-550C. Biochar incorporated into paddy field before rice transplanting. Methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) fluxes were measured in situ using closed chamber method during whole rice growing season. Flux of greenhouse gases was monitored at about 7 day's interval. Two rates of N fertilizer (0 and 240 kg N/ha) were applied as urea in combination with 3 biochar rates (0, 20 and 40 t/ha). Amendment of biochar had no influence on rice yield even at the hightest rate of 40 t/ha. However, rice production was greatly relying on chemical N fertilization input. No interact effect was detected between biochar and N fertilizer. Amendment of biochar suppressed N2O emission. During the whole rice growing season, the total N2O emission from chemical fertilizer was reduce by 29% and 53% under biochar amendment rates of 20t/ha and 40t/ha respectively. Total amounts of CO2 and CH4 emitted from paddy fields during whole rice growing season were not greatly increased despite of much carbon brought into soil with biochar. However, biochar amendment slightly increased CO2 emission in the absence of N fertilizer. Our results showed that biochar amendment into paddy field did not increase the global warming potential (GPW) and greenhouse gases emission intensity (GHGI).

  6. Flood control and loss estimation for paddy field at midstream of Chao Phraya River Basin, Thailand

    NASA Astrophysics Data System (ADS)

    Cham, T. C.; Mitani, Y.

    2015-09-01

    2011 Thailand flood has brought serious impact to downstream of Chao Phraya River Basin. The flood peak period started from August, 2011 to the end of October, 2011. This research focuses on midstream of Chao Phraya River Basin, which is Nakhon Sawan area includes confluence of Nan River and Yom River, also confluence of Ping River and Nan River. The main purpose of this research is to understand the flood generation, estimate the flood volume and loss of paddy field, also recommends applicable flood counter measurement to ease the flood condition at downstream of Chao Phraya River Basin. In order to understand the flood condition, post-analysis is conducted at Nakhon Sawan. The post-analysis consists of field survey to measure the flood marks remained and interview with residents to understand living condition during flood. The 2011 Thailand flood generation at midstream is simulated using coupling of 1D and 2D hydrodynamic model to understand the flood generation during flood peak period. It is calibrated and validated using flood marks measured and streamflow data received from Royal Irrigation Department (RID). Validation of results shows good agreement between simulated result and actual condition. Subsequently, 3 scenarios of flood control are simulated and Geographic Information System (GIS) is used to assess the spatial distribution of flood extent and reduction of loss estimation at paddy field. In addition, loss estimation for paddy field at midstream is evaluated using GIS with the calculated inundation depth. Results show the proposed flood control at midstream able to minimize 5% of the loss of paddy field in 26 provinces.

  7. Purification of contaminated paddy fields by clean water irrigation over two decades.

    PubMed

    Tai, Yiping; Lu, Huanping; Li, Zhian; Zhuang, Ping; Zou, Bi; Xia, Hanping; Wang, Faming; Wang, Gang; Duan, Jun; Zhang, Jianxia

    2013-10-01

    Paddy fields near a mining site in north part of Guangdong Province, PR China, were severely contaminated by heavy metals as a result of wastewater irrigation from the tailing pond. The following clean water irrigation for 2 decades produced marked rinsing effect, especially on Pb and Zn. Paddy fields continuously irrigated with wastewater ever since mining started (50 years) had 1,050.0 mg kg?1 of Pb and 810.3 mg kg?1 of Zn for upper 20 cm soil, in comparison with 215.9 mg kg?1 of Pb and 525.4 mg kg?1 of Zn, respectively, with clean water irrigation for 20 years. Rinsing effect mainly occurred to a depth of upper 40 cm, of which the soil contained highest metals. Copper and Cd in the farmlands were also reduced due to clean water irrigation. Higher availability of Pb might partly account for more Pb transferred from the tailing pond to the farmland and also more Pb removal from the farmland as a result of clean water irrigation. Neither rice in the paddy field nor dense weeds in the uncultivated field largely took up the metals. However, they might contribute to activate metals differently, leading to a different purification extent. Rotation of rice and weed reduced metal retention in the farmland soil, in comparison with sole rice growth. Harvesting of rice grain (and partially rice stalk) only contributed small fraction of total amount of removed metal. In summary, heavy metal in paddy field resulting from irrigation of mining wastewater could be largely removed by clean water irrigation for sufficient time. PMID:23797601

  8. Effects of supplementary composts on microbial communities and rice productivity in cold water paddy fields.

    PubMed

    Xie, Kaizhi; Xu, Peizhi; Yang, Shaohai; Lu, Yusheng; Jiang, Ruiping; Gu, Wenjie; Li, Wenying; Sun, Lili

    2015-05-01

    Cold water paddy field soils are relatively unproductive, but can be ameliorated by supplementing with inorganic fertilizer from animal waste-based composts. The yield of two rice cultivars was significantly raised by providing either chicken manure or cow dung-based compost. The application of these composts raised the soil pH as well as both the total nitrogen and ammonium nitrogen content, which improved the soil's fertility and raised its nitrification potential. The composts had a measurable effect on the abundance of nitrogencycling- related soil microbes, as measured by estimating the copy number of various bacterial and archaeal genes using quantitative real-time PCR. The abundance of ammonia oxidizing archaea and bacteria was markedly encouraged by the application of chicken manure-based compost. Supplementation with the composts helped promote the availability of soil nitrogen in the cold water paddy field, thereby improving the soil's productivity and increasing the yield of the rice crop. PMID:25406532

  9. Effects of residual biomass burning on the methane emission from a paddy field

    NASA Astrophysics Data System (ADS)

    Kunishio, A.; Akaike, Y.; Kawamoto, Y.; Murakami, H.; Ono, K.; Iwata, T.

    2012-12-01

    Methane (CH4) is generated by organic matter decomposition in anaerobic soil. It is said that about 20% of CH4 sources is paddy fields. At some paddy fields, residual biomass left after the harvest is burned and plowed into soil. And at the other fields, unburned residue is directly plowed. It is an unsolved problem what impact is brought on CH4 budget during following cultivated period by the difference in the plowed biomass amount in soil after the harvest. In this study, an experimental paddy field was divided into two areas. At one area biomass residue is burned and at the other area residue is directly plowed. On that basis, long-term continuous measurements of micrometeorological CH4 flux were conducted in both areas. Experimental site is located reclaimed land in the southern part of Okayama Prefecture, Japan. Single rice cropping cultivation has continued in a similar way every year. Intermittent irrigation water managements, or 3-days flooded and 4-days drained conditions, were carried out during almost all the period of rice cultivated term. CH4 flux was calculated by aerodynamic gradient technique. The open biomass burning experiment was conducted at one area in November 29, 2011. We illustrate some results for the control term before the burning experiment, and for the comparison term after the experiment.

  10. Comparison of greenhouse gas emissions from rice paddy fields under different nitrogen fertilization loads in Chongming Island, Eastern China.

    PubMed

    Zhang, Xianxian; Yin, Shan; Li, Yinsheng; Zhuang, Honglei; Li, Changsheng; Liu, Chunjiang

    2014-02-15

    Rice is one of the major crops of southern China and Southeast Asia. Rice paddies are one of the largest agricultural greenhouse gas (GHG) sources in this region because of the application of large quantities of nitrogen (N) fertilizers to the plants. In particular, the production of methane (CH4) is a concern. Investigating a reasonable amount of fertilizers to apply to plants is essential to maintaining high yields while reducing GHG emissions. In this study, three levels of fertilizer application [high (300 kg N/ha), moderate (210 kg N/ha), and low (150 kg N/ha)] were designed to examine the effects of variation in N fertilizer application rate on carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions from the paddy fields in Chongming Island, Shanghai, China. The high level (300 kg N/ha) represented the typical practice adopted by the local farmers in the area. Maximum amounts of CH4 and N2O fluxes were observed upon high-level fertilizer application in the plots. Cumulative N2O emissions of 23.09, 40.10, and 71.08 mg N2O/m(2) were observed over the growing season in 2011 under the low-, moderate-, and high-level applications plots, respectively. The field data also indicated that soil temperatures at 5 and 10 cm soil depths significantly affected soil respiration; the relationship between Rs and soil temperature in this study could be described by an exponential model. Our study showed that reducing the high rate of fertilizer application is a feasible way of attenuating the global-warming potential while maintaining the optimum yield for the studied paddy fields. PMID:24295754

  11. Characterization of contamination, source and degradation of petroleum between upland and paddy fields based on geochemical characteristics and phospholipid fatty acids.

    PubMed

    Zhang, Juan; Wang, Renqing; Du, Xiaoming; Li, Fasheng; Dai, Jiulan

    2012-01-01

    To evaluate contamination caused by petroleum, surface soil samples were collected from both upland and paddy fields along the irrigation canals in the Hunpu wastewater irrigation region in northeast China. N-alkanes, terpanes, steranes, and phospholipid fatty acids (PLFA) in the surface soil samples were analyzed. The aliphatic hydrocarbon concentration was highest in the samples obtained from the upland field near an operational oil well; it was lowest at I-3P where wastewater irrigation promoted the downward movement of hydrocarbons. The Hunpu region was found contaminated by heavy petroleum from oxic lacustrine fresh water or marine deltaic source rocks. Geochemical parameters also indicated significantly heavier contamination and degradation in the upland fields compared with the paddy fields. Principal component analysis based on PLFA showed various microbial communities between petroleum contaminated upland and paddy fields. Gram-negative bacteria indicated by 15:0, 3OH 12:0, and 16:1(9) were significantly higher in the paddy fields, whereas Gram-positive bacteria indicated by i16:0 and 18:1(9)c were significantly higher in the upland fields (p < 0.05). These PLFAs were related to petroleum contamination. Poly-unsaturated PLFA (18:2omega6, 9; indicative of hydrocarbon-degrading bacteria and fungi) was also significantly elevated in the upland fields. This paper recommends more sensitive indicators of contamination and degradation of petroleum in soil. The results also provide guidelines on soil pollution control and remediation in the Hunpu region and other similar regions. PMID:23534234

  12. Draft Genome Sequence of Bacteroidales Strain 6E, Isolated from a Rice Paddy Field in Japan

    PubMed Central

    Tourlousse, Dieter M.; Honda, Takuya; Matsuura, Norihisa; Ohashi, Akiko; Tonouchi, Akio

    2015-01-01

    We generated a high-quality draft genome sequence of Bacteroidales strain 6E, a strict anaerobe newly isolated from Japanese rice paddy field soil. The genome consists of 61 contigs, with a total size of 4,436,542bp and mean G+C content of 45.4%. Annotation predicted 3,620 protein-coding and 54 RNA genes. PMID:26450736

  13. [Effects of controlled release fertilizers on N2O emission from paddy field].

    PubMed

    Li, Fangmin; Fan, Xiaolin; Liu, Fang; Wang, Qiang

    2004-11-01

    With close chamber method, this paper studied the effects of controlled release fertilizer (CRF), non-coated compound fertilizer (Com) and conventional urea (CK) on N2O emission from paddy field. The results showed that within 10 days after transplanting, the ammonium and nitrate concentrations in the surface water of the plot treated with CRF were significantly different from those treated with Com. The partial coefficient between N2O emission rates and corresponding nitrate concentrations in the water was significantly high (r = 0.6834). Compared with Com, CRF was able to reduce N2O emission from the paddy field. Within 100 days after basal application, the N2O emission rate of treatment CRF was only 13.45%-21.26% of Corn and 71.17%-112.47% of CK. The N2O emission of Com was mainly concentrated in 1-25 d after basal fertilization and mid-aeration period, but that of CRF was remarkably lower during same period, while the peak of N2O emission of CK was postponed and reduced. It was concluded that both one-time fertilization of CRF and several-time fertilizations of conventional urea were able to reduce N2O emission from the paddy field. PMID:15707336

  14. [Effect of rice-duck mutualism on nutrition ecology of paddy field and rice quality].

    PubMed

    Wang, Qiangsheng; Huang, Pisheng; Zhen, Ruohong; Jing, Liuming; Tang, Hebao; Zhang, Chunyang

    2004-04-01

    The production of nuisanceless rice was conducted by the technique of rice-duck mutualism without applying any pesticide and chemical fertilizer. The results showed that compared to the control, the effect of eliminating weeds was over 99.4%, and the cardinal numbers of plant diseases and insect pests reduced obviously. Nutrients and dissolved oxygen in paddy water and rapidly available nutrients in soil increased, but after maturing stage, compared to basal fertility, rapidly available P and K decreased. The N, P, and K absorption amounts of rice plant, rice yield, setting panicles rate, filled grains and ripened rate increased. The milling, appearance, nutritional, cooking and eating quality of rice improved, especially in reducing chalkiness. The comprehensive benefits of paddy field enhanced obviously. PMID:15334961

  15. Microbial fuel cell as mitigation strategy for methane emissions from paddy field

    NASA Astrophysics Data System (ADS)

    Rizzo, Anacleto; Boano, Fulvio; Revelli, Roberto; Ridolfi, Luca

    2013-04-01

    Microbial fuel cells (MFCs) are bioelectrochemical systems able to generate electricity from wetland soils, including paddies, exploiting the microbial decomposition of organic matter. A MFC is composed of an anode buried in the anaerobic submerged soil linked to a cathode placed on the top of the soil in the aerobic ponding water. A biofilm develops on the anode, where bacteria release electrons, oxidizing dissolved organic carbon (DOC) and using oxygen available at the cathode as electron acceptor. MFC technology is now in an early development stage and the efficiency in electricity production is still low. However, MFC can also be applied for secondary aims, among which one of great interest is the reduction of methane (CH4) emissions from paddy fields. Indeed, DOC oxidation at the anode can be seen as an additional DOC sink in paddy soil environment, limiting the DOC availability for methanogens. In this work, a process-based mathematical model is proposed for a preliminary investigation of the efficiency of MFCs in limiting CH4 emissions. The model relies on a system of partial differential mass balance equations to describe the vertical dynamics of the chemical compounds leading to CH4 production. Many physico-chemical processes and features characteristic of paddy soil are included: paddy soil stratigraphy; spatio-temporal variations of plant-root compartment; water and heat transport; SOC decomposition; heterotrophic reactions in both aerobic and anaerobic conditions; root radial oxygen loss; root solute uptake; DOC root exudation; plant-mediated, ebullition, and diffusion gas exchange pathways. MFC is modeled as a DOC sink term, following a zero-order kinetic where the current density is assumed constant for the whole growing season. Different values of current density are tested, in accordance with values reported in literature about efficiency reached in paddy soils. Our results show a reduction of CH4 emissions up to -28.1%, -24.1%, and -26.5% of daily minimum, daily maximum and total over the whole growing season, respectively, confirming the potential validity of MFC as a novel CH4 mitigation strategy. Moreover, it is shown that transport processes limit the mitigation of CH4 emissions at high current density. Finally, in order to maximize the reduction of CH4 emissions, simulation results suggest to place the anode in the middle portion of the superficial layer.

  16. Paddy field mapping and yield estimation by satellite imagery and in situ observations

    NASA Astrophysics Data System (ADS)

    Oyoshi, K.; Sobue, S.

    2011-12-01

    Since Asian countries are responsible for approximately 90% of the world rice production and consumptions, rice is the most significant cereal crop in Asia. In order to ensure food security and take mitigation strategies or policies to manage food shortages, timely and accurate statistics of rice production are essential. It is time and cost consuming work to create accurate statistics of rice production by ground-based measurements. Hence, satellite remote sensing is expected to contribute food security through the systematic collection of food security related information such as crop growth or yield estimation. In 2011, Japan Aerospace Exploration Agency (JAXA) is collaborating with GISTDA (Geo-Informatics and Space Technology Development Agency, Thailand) in research projects of rice yield estimation by integrating satellite imagery and in situ data. Thailand is one of the largest rice production countries and the largest rice exporting country, therefore rice related statistics are imperative for food security and economy in the country. However, satellite observation by optical sensor in tropics including Thailand is highly limited, because the area is frequently covered by cloud. In contrast, Japanese microwave sensor, namely Phased-Array L-Band Synthetic Aperture Radar (PALSAR) on board Advanced Land Observing Satellite (ALOS) is suitable for monitoring cloudy area such as Southeast Asia, because PALSAR can penetrate clouds and collect land-surface information even if the area is covered by cloud. In this study, rice crop yield over Khon Kaen, northeast part of Thailand was estimated by combining satellite imagery and in-situ observation. This study consists of mainly two parts, paddy field mapping and yield estimation by numerical crop model. First, paddy field areas were detected by integrating PALSAR and AVNIR-2 data. PALSAR imagery has much speckle noise and the border of each landcover is ambiguous compared to that of optical sensor. To overcome this problem, we used AVNIR-2 data for object-based image analysis and derived each object was linked with backscatter coefficient of PALSAR. Then, paddy field areas were detected by using seasonal changes of backscatter coefficients. Derived paddy field map over Kohn Kean area was validated with ground-based measurements and it showed high accuracy. Finally, in order to estimate rice crop yield, numerical crop model was run with model parameters related to physiological aspect of rice and meteorological data collected by Automatic Weather Station (AWS) placed at study area, field survey and satellite products. This processing was implemented all over the detected paddy filed areas and overall yield was estimated by counting up each result. Consequently, it was found that the yield estimation was reasonable validated with agricultural statistics in Thailand.

  17. Seasonal and diurnal variations in net carbon dioxide flux throughout the year from soil in paddy field

    NASA Astrophysics Data System (ADS)

    Nishimura, Seiichi; Yonemura, Seiichiro; Minamikawa, Kazunori; Yagi, Kazuyuki

    2015-01-01

    contrast to upland croplands, carbon dioxide (CO2) emission from soils has rarely been investigated previously in fields with paddy rice cultivation. In this study, we hypothesized that CO2 emission from paddy soils is suppressed to be a low level due the soil submergence for months for paddy rice cultivation and conducted a continuous measurement of net CO2 flux from the soil/water surface of a paddy field throughout the year, including both the submerged and drained periods. The net CO2 flux was generally near zero during the submerged period with paddy rice cultivation and showed a slight CO2 influx in the daytime and efflux at nighttime, indicating dominance of photosynthetic CO2 uptake and respiratory CO2 release by aquatic weeds and algae in paddy water. The diurnal variations in net CO2 flux and dissolved CO2 concentration had negative correlations with the pH of paddy water. A remarkably high CO2 efflux was observed during the period with intermittent drainage in summer. Unexpectedly, the cumulative CO2 emissions throughout the year were not considerably lower than those reported in upland croplands ranging from 1309 to 2160 g CO2 m-2 yr-1, of which 41-48% was emitted from the first drainage in summer to the rice harvest in autumn. In summary, in this study, we revealed that CO2 emission from soil in paddy fields is strictly suppressed during the submerged period, but considerably enhanced by the succeeding drainage, which may negate the suppressed CO2 emission during the submerged period.

  18. [Establishing a minimum data set of soil quality assessment for cold-waterlogged paddy field in Fujian Province, China].

    PubMed

    Wang, Fei; Li, Qing-hua; Lin, Cheng; He, Chun-mei; Zhong, Shao-jie; Li, Yu; Lin, Xin-jian

    2015-05-01

    The yields of cold-waterlogged (CW) paddy fields widely spreading in Jiangnan mountainous areas are moderate or low but have a high potential to be increased. Based on data including 41 soil characteristics of 17 pairs of typical surface soils of cold-waterlogged paddy field and non cold-waterlogged (NCW) paddy field at a neighboring landscape unit in Fujian Province, various index differences of soil properties and causes between CW paddy field and NCW paddy field were systematically studied, and a minimum data set (MDS) of soil quality assessment for CW paddy field was established by principal component analysis. By pair analysis, soil characteristics of CW paddy field showed that the content of organic matter increased by 31.7%, but the microbial biomass C decreased by 37.8%, which belonged to active soil organic matter component. The content of ferrous iron (Fe2+) increased by 177.0%, but the available phosphorus (P) and potassium (K) decreased by 52.3% and 22.8%, respectively. Catalase and invertase activities increased by 58.3% and 22. 1%, but phosphatase, nitrate reductase activities and microflora decreased by 47. 8%, 66.6% and 29.8%-46.0%, respectively. The sand content increased about 8.0%, but the water immersed bulk density decreased by 25.8%. There were significant differences of indices for 28 of all 41 soil characteristics. Five principal components cumulatively exhibiting about 78.5% contribution were concluded from the 28 soil characteristics to reflect characteristics related to soil biochemistry, active organic nitrogen, reducing barriers, physical and chemical nutrients, respectively. Eventually, correlation analysis combined with expert experience method were applied to optimize MDS containing six factors for soil quality assessments, including C/N, bacteria, microbial biomass N, total reducing agents, physical sand and total P. PMID:26571666

  19. Effects of residual biomass burning on the CO2 flux from a paddy field

    NASA Astrophysics Data System (ADS)

    Murakami, H.; Kunishio, A.; Akaike, Y.; Kawamoto, Y.; Ono, K.; Iwata, T.

    2012-12-01

    Paddy field is one of the most important eco-system in monsoon Asia, and takes a great important role in CO2 uptake. Carbon budget in agricultural field is influenced by some artificial management. After the harvest, residual biomass is burned on fields, brought out from fields, or remained and harrowed into the fields. If open burning was conducted in a field, one part of biomass carbon is emitted into atmosphere as CO2, and the other part is harrowed into soils. In this study, quantity of lost carbon according to burning of residual biomass were investigated at a single rice cropping field in western Japan, in which long-term continuous CO2 flux (NEE) measurement by the eddy-covariance technique was conducted. In addition, an experimental paddy field was divided into two areas to investigate what impact is brought on the annual CO2 flux by the difference of disposal management of residual biomass after the harvest. Residual biomass was burned and plowed into soil at the one area on Nov. 29th, 2011, and residue was not burned and directly plowed into soil at the other area as usual. We illustrate some results for the control term before the burning experiment, and for the comparison term after the experiment.

  20. Simulation of future global warming scenarios in rice paddies with an open-field warming facility

    PubMed Central

    2011-01-01

    To simulate expected future global warming, hexagonal arrays of infrared heaters have previously been used to warm open-field canopies of upland crops such as wheat. Through the use of concrete-anchored posts, improved software, overhead wires, extensive grounding, and monitoring with a thermal camera, the technology was safely and reliably extended to paddy rice fields. The system maintained canopy temperature increases within 0.5°C of daytime and nighttime set-point differences of 1.3 and 2.7°C 67% of the time. PMID:22145582

  1. Modeling of Movement of Field Gudgeon, Gnathopogon elongatus elongatus, in Agricultural Canals in Yatsu Paddy Fields

    NASA Astrophysics Data System (ADS)

    Takemura, Takeshi; Koizumi, Noriyuki; Mizutani, Masakazu; Mori, Atsushi; Watabe, Keiji

    It is important as quantitative information for making a decision of project sites for networking of water area, to predict reproductive process of fish population when consolidating fish-ways on points dividing fish habitat. To that end, it is necessary to predict the number of individuals migrating to new habitats. Hence, modeling of movement of individuals is necessary as a first step in population modeling. We constructed a mathematical model of movement of field gudgeon in agricultural canals, comparing with observed data obtained by our surveys. A unit time span of this model is 50 days. This model is able to consider existence of 2 types of movement, namely, individuals of sedentary type and individuals of ambulant type. Parameters of the model were decided based on observed data which correspond to 1 unit span. Next, moving distances of 6 individuals for 4 unit span were calculated using those parameters. A histogram of calculated values was similar to that of observed data which correspond to 4 unit span. The model is expected to provide an important immigration component to a population dynamics model which is currently under development. The population model is needed to predict population recovery processes where areas of paddy fields are joined in larger networks through construction of fish-ways.

  2. Analysis of the spatial variation in the net ecosystem production of rice paddy fields using the diagnostic biosphere model BEAMS

    NASA Astrophysics Data System (ADS)

    Sasai, T.; Nakai, S.; Setoyama, Y.; Ono, K.; Kato, S.; Mano, M.; Miyata, A.; Saigusa, N.; Nemani, R. R.; Nasahara, K. N.

    2012-12-01

    To realistically understand spatial and temporal variations in the net ecosystem production (NEP) of rice paddies in Japan, we enhanced the existing diagnostic-type biosphere model with the addition of agricultural processes. Validated with a comparison of seasonal and annual variations over 5 years, the NEP estimations bore good agreement with the measurements. In regional-scale analyses, we targeted all rice paddy fields in Japan from January 2001 to December 2009. Before and after the model enhancement, the NEP showed very different spatial variations and absolute values, suggesting that the most effective improvements were the introduction of harvest and soil oxidation-reduction processes. In annual anomaly analyses covering a 9-year period, the NEP was found to be negative in 2003 and 2006 (-0.11 and -0.25 TgC/year) and positive in 2004 and 2007 (+0.02 and +0.21 TgC/year). We found that the negative values were caused by decreases in solar radiation and air temperature and the positive values were caused by increases in these two parameters and precipitation. In response to the NEP, our obtained harvested grain biomass values in 2003 and 2006 were lower than usual. The results were in good agreement with the results from reports of the Japan Meteorological Agency and the Ministry of Agriculture, Forestry, and Fisheries.

  3. Seasonal trends and environmental controls of methane emissions in a rice paddy field in Northern Italy

    NASA Astrophysics Data System (ADS)

    Meijide, A.; Manca, G.; Goded, I.; Magliulo, V.; di Tommasi, P.; Seufert, G.; Cescatti, A.

    2011-12-01

    Rice paddy fields are one of the greatest anthropogenic sources of methane (CH4), the third most important greenhouse gas after water vapour and carbon dioxide. In agricultural fields, CH4 is usually measured with the closed chamber technique, resulting in discontinuous series of measurements performed over a limited area, that generally do not provide sufficient information on the short-term variation of the fluxes. On the contrary, aerodynamic techniques have been rarely applied for the measurement of CH4 fluxes in rice paddy fields. The eddy covariance (EC) technique provides integrated continuous measurements over a large area and may increase our understanding of the underlying processes and diurnal and seasonal pattern of CH4 emissions in this ecosystem. For this purpose a Fast Methane Analyzer (Los Gatos Research Ltd.) was installed in a rice paddy field in the Po Valley (Northern Italy). Methane fluxes were measured during the rice growing season with both EC and manually operated closed chambers. Methane fluxes were strongly influenced by the height of the water table, with emissions peaking when it was above 10-12 cm. Soil temperature and the developmental stage of rice plants were also responsible of the seasonal variation on the fluxes. The measured EC fluxes showed a diurnal cycle in the emissions, which was more relevant during the vegetative period, and with CH4 emissions being higher in the late evening, possibly associated with higher water temperature. The comparison between the two measurement techniques shows that greater fluxes are measured with the chambers, especially when higher fluxes are being produced, resulting in 30 % higher seasonal estimations with the chambers than with the EC (41.1 and 31.7 g CH4 m-2 measured with chambers and EC respectively) and even greater differences are found if shorter periods with high chamber sampling frequency are compared. The differences may be a result of the combined effect of overestimation with the chambers and of the possible underestimation by the EC technique.

  4. Comparative metagenomics of anode-associated microbiomes developed in rice paddy-field microbial fuel cells.

    PubMed

    Kouzuma, Atsushi; Kasai, Takuya; Nakagawa, Gen; Yamamuro, Ayaka; Abe, Takashi; Watanabe, Kazuya

    2013-01-01

    In sediment-type microbial fuel cells (sMFCs) operating in rice paddy fields, rice-root exudates are converted to electricity by anode-associated rhizosphere microbes. Previous studies have shown that members of the family Geobacteraceae are enriched on the anodes of rhizosphere sMFCs. To deepen our understanding of rhizosphere microbes involved in electricity generation in sMFCs, here, we conducted comparative analyses of anode-associated microbiomes in three MFC systems: a rice paddy-field sMFC, and acetate- and glucose-fed MFCs in which pieces of graphite felt that had functioned as anodes in rice paddy-field sMFC were used as rhizosphere microbe-bearing anodes. After electric outputs became stable, microbiomes associated with the anodes of these MFC systems were analyzed by pyrotag sequencing of 16S rRNA gene amplicons and Illumina shotgun metagenomics. Pyrotag sequencing showed that Geobacteraceae bacteria were associated with the anodes of all three systems, but the dominant Geobacter species in each MFC were different. Specifically, species closely related to G. metallireducens comprised 90% of the anode Geobacteraceae in the acetate-fed MFC, but were only relatively minor components of the rhizosphere sMFC and glucose-fed MFC, whereas species closely related to G. psychrophilus were abundantly detected. This trend was confirmed by the phylogenetic assignments of predicted genes in shotgun metagenome sequences of the anode microbiomes. Our findings suggest that G. psychrophilus and its related species preferentially grow on the anodes of rhizosphere sMFCs and generate electricity through syntrophic interactions with organisms that excrete electron donors. PMID:24223712

  5. Comparative Metagenomics of Anode-Associated Microbiomes Developed in Rice Paddy-Field Microbial Fuel Cells

    PubMed Central

    Kouzuma, Atsushi; Kasai, Takuya; Nakagawa, Gen; Yamamuro, Ayaka; Abe, Takashi; Watanabe, Kazuya

    2013-01-01

    In sediment-type microbial fuel cells (sMFCs) operating in rice paddy fields, rice-root exudates are converted to electricity by anode-associated rhizosphere microbes. Previous studies have shown that members of the family Geobacteraceae are enriched on the anodes of rhizosphere sMFCs. To deepen our understanding of rhizosphere microbes involved in electricity generation in sMFCs, here, we conducted comparative analyses of anode-associated microbiomes in three MFC systems: a rice paddy-field sMFC, and acetate- and glucose-fed MFCs in which pieces of graphite felt that had functioned as anodes in rice paddy-field sMFC were used as rhizosphere microbe-bearing anodes. After electric outputs became stable, microbiomes associated with the anodes of these MFC systems were analyzed by pyrotag sequencing of 16S rRNA gene amplicons and Illumina shotgun metagenomics. Pyrotag sequencing showed that Geobacteraceae bacteria were associated with the anodes of all three systems, but the dominant Geobacter species in each MFC were different. Specifically, species closely related to G. metallireducens comprised 90% of the anode Geobacteraceae in the acetate-fed MFC, but were only relatively minor components of the rhizosphere sMFC and glucose-fed MFC, whereas species closely related to G. psychrophilus were abundantly detected. This trend was confirmed by the phylogenetic assignments of predicted genes in shotgun metagenome sequences of the anode microbiomes. Our findings suggest that G. psychrophilus and its related species preferentially grow on the anodes of rhizosphere sMFCs and generate electricity through syntrophic interactions with organisms that excrete electron donors. PMID:24223712

  6. Effects of "open burning" on the greenhouse gas exchange from a single-rice paddy field in Japan

    NASA Astrophysics Data System (ADS)

    Kawamoto, Y.; Akaike, Y.; Kunishio, A.; Murakami, H.; Ono, K.; Hayashi, K.; Iwata, T.

    2012-12-01

    Paddy fields are artificially maintained wetland and are one of the large source of CH4. Besides, a large quantity of N2O is emitted from the soil surface due to the decomposition of inorganic fertilizer. A long term continuous measurement of GHG fluxes between atmosphere and paddy ecosystem is effective method to clarify the contribution of paddy fields to recent rapid increase of GHG concentration. In this study, three techniques for flux measurement (eddy covariance, aerodynamic gradient, and chamber techniques) were applied to investigate the annual variation of three GHG (CO2, CH4 and N2O) exchanges at a single-rice paddy field for two years. An observational site is located on reclaimed land in the southern part of Okayama Prefecture, Japan. In addition, an experimental paddy field was divided into two areas to investigate what impact is brought on the annual GHG fluxes by the difference of disposal management of residual biomass after the harvest. Residual biomass was burned and plowed into soil at the one area on Nov. 29th, 2011, and residue was not burned and directly plowed into soil at the other area as usual. We illustrate some results for the control term before the burning experiment, and for the comparison term after the experiment.

  7. A study on characteristics of Methane emission from a periodically irrigated paddy field in Japan

    NASA Astrophysics Data System (ADS)

    Wakikuromaru, N.; Iwata, T.; Yagi, K.

    2014-12-01

    Methane (CH4) is generated by organic matter decomposition in the anaerobic soil. Paddy field is one of the most important eco-system in monsoon Asia. It is said that about 10% of CH4sources is paddy fields (IPCC AR4, 2007). In this study, methane emission from a single-rice crop field was estimated by long-term micrometeorological measurements. Methane emission was calculated by the aerodynamic gradient technique from January 2011 to August 2014. Intermittent water management was carried out during cultivation period at the observational site, HCH, located in Okayama, Japan. 3-days flood and 4-days drained condition were regularly repeated from late-June to early October. Seasonal variations of CH4flux for irrigation term from 2011 to 2013 were shown in Fig.1. Remarkably large fluxes were shown at early stage of irrigation term in 2011.It seemed to be caused by the relatively longer flooded condition that the first flooded period was 20 days. Flux in 2012 was smaller than in other year through the entire irrigation period. Rapid rise in flux for early August and gradual decrease between late August and September were shown in 2013. Fluxes under drained condition showed larger emission than under flooded condition. Cumulative CH4 emissions during cultivated period from 2011 to 2013 were estimated 15.7, 8.6, and 12.9 gC/m2, respectively.

  8. Composition of archaeal community in a paddy field as affected by rice cultivar and N fertilizer.

    PubMed

    Wu, Liqin; Ma, Ke; Li, Qi; Ke, Xiubin; Lu, Yahai

    2009-11-01

    Methanogenesis in paddy fields is significantly influenced by environmental and field management factors such as rice cultivar and nitrogenous fertilizer. However, it has been unclear whether such effects are reflected in the structure of methanogenic archaeal populations. In the present study, molecular analyses including cloning and sequencing and terminal restriction fragment length polymorphism (T-RFLP) fingerprinting of archaeal 16S rRNA genes were used to characterize the methanogenic archaeal assemblages and to identify the effect of environmental variables including rice cultivar and N fertilizer on archaeal community compositions in a Chinese paddy field soil. The correlation between methanogenic archaeal composition and environmental variables was explored by correspondence analysis. The results showed that the spatial or niche factor (rice roots versus rhizosphere, surface, and the deeper layer soils) had the greatest influence on the archaeal community composition. There was an obvious enrichment or selection of hydrogenotrophic as opposed to acetoclastic methanogens by rice roots. The archaeal community also changed, though slightly, between the rhizosphere and bulk soils and between the surface soil and the deeper layer soil. However, rice cultivar and N fertilizer appear to have an effect only on methanogens tightly associated with rice roots. PMID:19562245

  9. Can arbuscular mycorrhiza and fertilizer management reduce phosphorus runoff from paddy fields?

    PubMed

    Zhang, Shujuan; Wang, Li; Ma, Fang; Zhang, Xue; Li, Zhe; Li, Shiyang; Jiang, Xiaofeng

    2015-07-01

    Our study sought to assess how much phosphorus (P) runoff from paddy fields could be cut down by fertilizer management and inoculation with arbuscular mycorrhizal fungi. A field experiment was conducted in Lalin River basin, in the northeast China: six nitrogen-phosphorus-potassium fertilizer levels were provided (0, 20%, 40%, 60%, 80%, and 100% of the recommended fertilizer supply), with or without inoculation with Glomus mosseae. The volume and concentrations of particle P (PP) and dissolved P (DP) were measured for each runoff during the rice growing season. It was found that the seasonal P runoff, including DP and PP, under the local fertilization was 3.7 kg/ha, with PP, rather than DP, being the main form of P in runoff water. Additionally, the seasonal P runoff dropped only by 8.9% when fertilization decreased by 20%; rice yields decreased with declining fertilization. We also found that inoculation increased rice yields and decreased P runoff at each fertilizer level and these effects were lower under higher fertilization. Conclusively, while rice yields were guaranteed arbuscular mycorrhizal inoculation and fertilizer management would play a key role in reducing P runoff from paddy fields. PMID:26141895

  10. High abundance and diversity of nitrite-dependent anaerobic methane-oxidizing bacteria in a paddy field profile.

    PubMed

    Zhou, Leiliu; Wang, Yu; Long, Xi-En; Guo, Jianhua; Zhu, Guibing

    2014-11-01

    The discovery of nitrite-dependent anaerobic methane oxidation (n-damo) mediated by 'Candidatus Methylomirabilis oxyfera' with nitrite and methane as substrates has connected biogeochemical carbon and nitrogen cycles in a new way. The paddy fields often carry substantial methane and nitrate, thus may be a favorable habitat for n-damo bacteria. In this paper, the vertical-temporal molecular fingerprints of M. oxyfera-like bacteria, including abundance and community composition, were investigated in a paddy soil core in Jiangyin, near the Yangtze River. Through qPCR investigation, high abundance of M. oxyfera-like bacteria up to 1.0 10(8) copies (g d.w.s.)(-1) in summer and 8.5 10(7) copies (g d.w.s.)(-1) in winter was observed in the ecotone of soil and groundwater in the paddy soil core, which was the highest in natural environments to our knowledge. In the ecotone, the ratio of M. oxyfera-like bacteria to total bacteria reached peak values of 2.80% in summer and 4.41% in winter. Phylogenetic analysis showed n-damo bacteria in the paddy soil were closely related to M. oxyfera and had high diversity in the soil/groundwater ecotone. All of the results indicated the soil/groundwater ecotone of the Jiangyin paddy field was a favorable environment for the growth of n-damo bacteria. PMID:25109910

  11. Winter runoff losses of phosphorus from paddy soils in the Taihu Lake Region of South China.

    PubMed

    Zhang, Huanchao; Cao, Zhihong; Wang, Gaiping; Zhang, Hongai; Wong, M H

    2003-09-01

    A winter wheat field plot experiment was conducted on two types of paddy soils, from November, 2000 to June, 2001 to assess P losses to its surrounding watercourses by runoff in the Taihu Lake Region. Commercial NPK compound fertilizer and single superphosphate fertilizer were applied to furnish 0, 20, 80, and 160 kg P ha(-1). The experiments consisted of six replicates of each treatment in Changshu site and four replicates in Anzhen site, with a plot size of 5x6 m2 in a randomized block design. Results revealed that the average concentration of dissolved P (DP), particulate P (PP), and total P (TP) in runoff water during the winter season was 0.13, 0.90 and 1.04 mg P l(-1) respectively, from P20 plots in Anzhen site. While it was 0.67, 1.08 and 1.75 mg P l(-1) respectively, from P20 plots in Changshu site. The seasonal TP load (mass loss) from P20 plot ranged from a low of 290.88 g P ha(-1)season(-1) to a high of 483.54 g P ha(-1)season(-1), with a mean of 382.29 g P ha(-1)season(-1) in Anzhen, but from 444.92 to 752.21 g P ha(-1)season(-1), with a mean of 539.13 g P ha(-1)season(-1) in Changshu. Both in Anzhen and Changshu PP represented a major portion of the TP lost in runoff, the average PP/TP was about more than 80% in P0 and P20 plot, but it was decreased with the increase of P rate. The average seasonal P loads (DP, PP, and TP) in Changshu were greater than in Anzhen although runoff volume in Anzhen (45 mm season(-1)) was more than in Changshu (36 mm season(-1)). This was probably associated with the differences of soil physical and chemical properties between the two sites. Phosphate fertilizer rate significantly affected P concentrations and P loads by runoff. Both the mean concentrations and the average seasonal P loads from the P80 plots were lower than from the P160 plots, but obviously higher than from the P20 and P0 plots. There was no significant difference found between the P20 plots and the P0 plots both in Anzhen and Changshu sites. It indicated that P loads by runoff would be greatly increased in 5-10 years due to the accumulation of soil P if 20 kg P ha(-1) applied each wheat season in this area. PMID:12867176

  12. Mapping paddy rice planting area in cold temperate climate region through analysis of time series Landsat 8 (OLI), Landsat 7 (ETM+) and MODIS imagery

    NASA Astrophysics Data System (ADS)

    Qin, Yuanwei; Xiao, Xiangming; Dong, Jinwei; Zhou, Yuting; Zhu, Zhe; Zhang, Geli; Du, Guoming; Jin, Cui; Kou, Weili; Wang, Jie; Li, Xiangping

    2015-07-01

    Accurate and timely rice paddy field maps with a fine spatial resolution would greatly improve our understanding of the effects of paddy rice agriculture on greenhouse gases emissions, food and water security, and human health. Rice paddy field maps were developed using optical images with high temporal resolution and coarse spatial resolution (e.g., Moderate Resolution Imaging Spectroradiometer (MODIS)) or low temporal resolution and high spatial resolution (e.g., Landsat TM/ETM+). In the past, the accuracy and efficiency for rice paddy field mapping at fine spatial resolutions were limited by the poor data availability and image-based algorithms. In this paper, time series MODIS and Landsat ETM+/OLI images, and the pixel- and phenology-based algorithm are used to map paddy rice planting area. The unique physical features of rice paddy fields during the flooding/open-canopy period are captured with the dynamics of vegetation indices, which are then used to identify rice paddy fields. The algorithm is tested in the Sanjiang Plain (path/row 114/27) in China in 2013. The overall accuracy of the resulted map of paddy rice planting area generated by both Landsat ETM+ and OLI is 97.3%, when evaluated with areas of interest (AOIs) derived from geo-referenced field photos. The paddy rice planting area map also agrees reasonably well with the official statistics at the level of state farms (R2 = 0.94). These results demonstrate that the combination of fine spatial resolution images and the phenology-based algorithm can provide a simple, robust, and automated approach to map the distribution of paddy rice agriculture in a year.

  13. Estimation of CO2 flux at paddy fields in Asia by MODIS data

    NASA Astrophysics Data System (ADS)

    Iwata, T.; Nakaya, K.; Taniguchi, Y.; Ono, K.; Miyata, A.; Maruyama, A.

    2014-12-01

    Paddy fields in monsoon Asia have a great important role in the global budget of GHGs. Recently long-term fluxes are continuously observed at cropland ecosystems in Asia. In this study, the exchanges of CO2 at a number of paddy fields were estimated by a satellite-based empirical model with the Terra/MODIS data, and the results were compared with the ground-based observation data. Gross primary productivity (GPP) is estimated from normalized difference vegetation index (NDVI) and photosynthetically active radiation (PAR). Ecosystem respiration (RE) is also estimated from NDVI and land surface temperature. And, net ecosystem exchange of CO2 (NEE) was calculated the difference between GPP and RE. Some parameters used in the model were determined by the ground data measured at HCH, the single-rice site in western Japan (34N32,133E56). CO2 exchanges at four sites -- HCH, MSE, SGA, and IRRI -- were estimated. PAR and air temperature as input data were also tested by ground data at each sites. Seasonal variations of Gpp, Re, and NEE during cultivated period at four sites were compared. The model reasonably reproduced the seasonal variation of CO2 exchange at three sites in Japan. However, Gpp by the model was overestimated in early stage of the first cropping and through the second cropping at the Phillipine site, IRRI. Cumulative NEE by the model showed the difference by from -6.8 to 10.1 % compared with the observed NEE.

  14. Factors Affecting Groundwater Chemistry in Abandoned Terraced Paddy Fields on Sado Island, Japan

    NASA Astrophysics Data System (ADS)

    Oyanagi, Nobuhiro; Nakata, Makoto; Matsuyama, Keiko; Tsujii, Norie; Tsuchida, Takeyoshi

    The factors affecting the groundwater level and chemistry in abandoned terraced paddy fields on Sado Island, Japan, were investigated. Seasonal changes of the groundwater level in site A, which is on the bottom of the slope, was slight throughout the year compared with that in site B, which is on the middle part of the gentle slope. EC, pH, and some components involved in mineral weathering (Na+, Ca2+ and alkalinity) in the groundwater from site A were higher than those from site B. These results showed that the infiltrating water from the upper part of the slope was the main source of the groundwater in site A. On the other hand, the impact of sea salt components (Na+ and Cl-) was evident in site B, because the concentration of these components increased during winter. Groundwater chemistry was also affected by other factors such as the dilution of groundwater caused by rainfall, sulfur redox, and nutrient uptake by vegetation. The effects of each factor on groundwater chemistry differed between sites because the topography of the two adjacent sites was different. The characteristics of water environment, such as the groundwater level and chemistry, should be considered in the management of abandoned terraced paddy fields on Sado Island.

  15. Co-contamination of Cu and Cd in paddy fields: Using periphyton to entrap heavy metals.

    PubMed

    Yang, Jiali; Tang, Cilai; Wang, Fengwu; Wu, Yonghong

    2016-03-01

    The ubiquitous native periphyton was used to entrap Cu and Cd from paddy fields. Results showed that Cu- and Cd-hydrate species such as CuOH(+), Cu2(OH)2(2+), CdOH(+), and Cu3(OH)4(2+) decreased with time in the presence of periphyton. When the initial concentrations of Cu and Cd were 10mg/L, the heavy metal content in the periphyton fluctuated from 145.20mg/kg to 342.42mg/kg for Cu and from 101.75mg/kg to 236.29mg/kg for Cd after 2h exposure. The concentration of Cd in periphytic cells varied from 42.93mg/kg to 174mg/kg after 2h. The dominant periphyton microorganism species shifted from photoautotrophs to heterotrophs during the exposure of periphyton to Cu and Cd co-contamination. Although Cu and Cd could inhibit periphyton photosynthesis and carbon utilization, the periphyton was able to adapt to the test conditions. Cu and Cd accumulation in rice markedly decreased in the presence of periphyton while the number of rice seeds germinating was higher in the periphyton treatments. These results suggest that the inclusion of native periphyton in paddy fields provides a promising buffer to minimize the effects of Cu and Cd pollution on rice growth and food safety. PMID:26551219

  16. [Influence of paddy rice-upland crop rotation of cold-waterlogged paddy field on crops produc- tion and soil characteristics].

    PubMed

    Wang, Fei; Li, Qing-hua; Lin, Cheng; He, Chun-mei; Zhong, Shao-jie; Li, Yu; Lin, Xin-jian; Huang, Jian-cheng

    2015-05-01

    Two consecutive years (4-crop) experiments were conducted to study the influence of different paddy rice-upland crop rotation in cold-waterlogged paddy field on the growth of crops and soil characteristics. The result showed that compared with the rice-winter fallow (CK) pattern, the two-year average yield of paddy rice under four rotation modes, including rape-rice (R-R), spring corn-rice (C-R), Chinese milk vetch-rice (M-R) and bean-rice (B-R), were increased by 5.3%-26.7%, with significant difference observed in C-R and R-R patterns. Except for M-R pattern, the annual average total economic benefits were improved by 79.0%-392.4% in all rotation pattern compared with the CK, and the ration of output/input was enhanced by 0.06-0.72 unit, with the most significant effect found in the C-R pattern. Likewise, compared with the CK, the contents of chlorophyll and carotenoid, and net photosynthetic rate (Pn) of rice plant were all increased during the full-tillering stage of rice in all rotation patterns. The rusty lines and rusty spots of soils were more obvious compared with the CK during the rice harvest, particularly in R-R, C-R and B-R patterns. The ratio of water-stable soil macro aggregates of plough layer of soil (> 2 mm) decreased at different levels in all rotation patterns while the ratios of middle aggregate (0.25-2 mm, expect for M-R) and micro aggregate of soil (< 0.25 mm) were opposite. There was a decreasing trend for soil active reducing agents in all rotation patterns, whereas the available nutrient increased. The amounts of soil bacteria in C-R and B-R patterns, fungi in B-R rotation pattern, cellulose bacteria in R-R, C-R and B-R patterns and N-fixing bacteria in B-R pattern were improved by 285.7%-403.0%, 221.7%, 64.6-92.2% and 162.2%, respectively. Moreover, the differences in all microorganisms were significant. Thus, based on the experimental results of cold-waterlogged paddy field, it was concluded that changing from single cropping rice system to C-R, R-R and B-R rotation patterns had good effect in terms of improving total yield and economic benefits, and soil physical and chemical properties were improved. PMID:26571667

  17. Arsenic dynamics in porewater of an intermittently irrigated paddy field in Bangladesh.

    PubMed

    Roberts, Linda C; Hug, Stephan J; Voegelin, Andreas; Dittmar, Jessica; Kretzschmar, Ruben; Wehrli, Bernhard; Saha, Ganesh C; Badruzzaman, A Borhan M; Ali, M Ashraf

    2011-02-01

    In Bangladesh, irrigation of dry season rice (boro) with arsenic-contaminated groundwater is leading to increased As levels in soils and rice, and to concerns about As-induced yield reduction. Arsenic concentrations and speciation in soil porewater are strongly influenced by redox conditions, and thus by water management during rice growth. We studied the dynamics of As, Fe, P, Si, and other elements in porewater of a paddy field near Sreenagar (Munshiganj), irrigated according to local practice, in which flooding was intermittent. During early rice growth, As porewater concentrations reached up to 500 μg L(-1) and were dominated by As(III), but As release was constrained to the lower portion of the soil above the plow pan. In the later part of the season, soil conditions were oxic throughout the depth range relevant to rice roots and porewater concentrations only intermittently increased to ∼150 μg L(-1) As(V) following irrigation events. Our findings suggest that intermittent irrigation, currently advocated in Bangladesh for water-saving purposes, may be a promising means of reducing As input to paddy soils and rice plant exposure to As. PMID:21166387

  18. Seasonal trends and environmental controls of methane emissions in a rice paddy field in Northern Italy

    NASA Astrophysics Data System (ADS)

    Meijide, A.; Manca, G.; Goded, I.; Magliulo, V.; di Tommasi, P.; Seufert, G.; Cescatti, A.

    2011-09-01

    Rice paddy fields are one of the greatest anthropogenic sources of methane (CH4), the third most important greenhouse gas after water vapour and carbon dioxide. In agricultural fields, CH4 is usually measured with the closed chamber technique, resulting in discontinuous series of measurements performed over a limited area, that generally do not provide sufficient information on the short-term variation of the fluxes. On the contrary, aerodynamic techniques have been rarely applied for the measurement of CH4 fluxes in rice paddy fields. The eddy covariance (EC) technique provides integrated continuous measurements over a large area and may increase our understanding of the underlying processes and diurnal and seasonal pattern of CH4 emissions in this ecosystem. For this purpose a Fast Methane Analyzer (Los Gatos Research Ltd.) was installed in an eddy-covariance field set-up in a rice paddy field in the Po Valley (Northern Italy). Methane fluxes were measured during the rice growing season, both with EC and with manually operated closed chambers. Methane fluxes were strongly influenced by the presence of the water table, with emissions peaking when it was above 10-12 cm. Further studies are required to evaluate if water table management could decrease CH4 emissions. The development of rice plants and soil temperature were also responsible of the seasonal variation on the fluxes. The EC measured showed a diurnal cycle in the emissions, which was more relevant during the vegetative period, and with CH4 emissions being higher in the late evening, possibly associated with higher water temperature. The comparison between both measurement techniques shows that greater fluxes are measured with the chambers, especially when higher fluxes are being produced, resulting in 30 % higher seasonal estimations with the chambers than with the EC (41.1 and 31.8 g CH4 m-2 measured with chambers and EC respectively). The differences may be a result of the combined effect of overestimation with the chambers, the possible underestimation by the EC technique and of not having considered the daily course of the fluxes for the calculation of seasonal emissions from chambers.

  19. [Rules and impact factors of greenhouse gases emission in the saline-alkali paddy fields in different years].

    PubMed

    Tang, Jie; Fang, Tian-Ru; Hou, Ke-Yi; Zhao, Ren-Zhu; Liang, Shuang

    2014-12-01

    With the method of combining field sampling and plot test, we took saline-alkali paddy field of Qianguo county, Jilin province as an investigation object. According to the nature of soil in the area, we monitored CH4 and N2O which released from soil during rice growth period and tested the soil pH and soil organic carbon to analyze the law and reasons of greenhouse gas emission in the paddy fields. The results showed that N2O emission from paddy fields presented three peaks with distinct seasonal patterns. Application of fertilizer provided additional reactive substrate, which affected N2O emission significantly. Under flooding conditions, the main source of N2O is a denitrification process, while after drainage, nitrification was the predominance. CH4 emission showed a single peak at rice tillering stage when rice grew vigorously. That deoxidation condition dominated in the deep water layer in the paddy fields provided suitable conditions for CH4 producing microorganisms, which result in the emergence of CH4 emission peak. The pH doesn't have an obvious influence on CH4 and N2O, while SOC content in soil and pattern of CH4 emission showed a significantly positive correlation. PMID:25826947

  20. Heavy Metals Uptake by Asian Swamp Eel, Monopterus albus from Paddy Fields of Kelantan, Peninsular Malaysia: Preliminary Study

    PubMed Central

    Yin, Sow Ai; Ismail, Ahmad; Zulkifli, Syaizwan Zahmir

    2012-01-01

    Swamp eel, Monopterus albus is one of the common fish in paddy fields, thus it is suitable to be a bio-monitor for heavy metals pollution studies in paddy fields. This study was conducted to assess heavy metals levels in swamp eels collected from paddy fields in Kelantan, Malaysia. The results showed zinc [Zn (86.40 μg/g dry weight)] was the highest accumulated metal in the kidney, liver, bone, gill, muscle and skin. Among the selected organs, gill had the highest concentrations of lead (Pb), cadmium (Cd) and nickel (Ni) whereas muscle showed the lowest total metal accumulation of Zn, Pb, copper (Cu), Cd and Ni. Based on the Malaysian Food Regulation, the levels of Zn and Cu in edible parts (muscle and skin) were within the safety limits. However, Cd, Pb and Ni exceeded the permissible limits. By comparing with the maximum level intake (MLI), Pb, Ni and Cd in edible parts can still be consumed. This investigation indicated that M. albus from paddy fields of Kelantan are safe for human consumption with little precaution. PMID:24575231

  1. Impacts of the herbicide butachlor on the larvae of a paddy field breeding frog (Fejervarya limnocharis) in subtropical Taiwan

    USGS Publications Warehouse

    Liu, Wan-Yi; Wang, Ching-Yuh; Wang, Tsu-Shing; Fellers, Gary M.; Lai, Bo-Chi; Kam, Yeong-Choy

    2011-01-01

    Butachlor is the most commonly used herbicide on paddy fields in Taiwan and throughout Southeast Asia. Since paddy fields provide habitat for pond breeding amphibians, we examined growth, development, time to metamorphosis, and survival of alpine cricket frog tadpoles (Fejervarya limnocharis) exposed to environmentally realistic concentrations of butachlor. We documented negative impacts of butachlor on survival, development, and time to metamorphosis, but not on tadpole growth. The 96 h LC50 for tadpoles was 0.87 mg/l, much lower than the 4.8 mg/l recommended dosage for application to paddy fields. Even given the rapid breakdown of butachlor, tadpoles would be exposed to concentrations in excess of their 96 h LC50 for an estimated 126 h. We also documented DNA damage (genotoxicity) in tadpoles exposed to butachlor at concentrations an order of magnitude less than the 4.8 mg/l recommended application rate. We did not find that butachlor depressed cholinesterase activity of tadpoles, unlike most organophosphorus insecticides. We conclude that butachlor is likely to have widespread negative impacts on amphibians occupying paddy fields with traditional herbicide application.

  2. Improvements in the Weeding of Levee Slope of Terraced Paddy Fields with Statutory Regulation of Places of Scenic Beauty

    NASA Astrophysics Data System (ADS)

    Uchikawa, Yoshiyuki; Kimura, Kazuhiro; Hirata, Ayumi

    A growing number of terraced paddy fields in Japan are being conserved as cultural assets like places of scenic beauty. This has meant that the task of weeding levee slope of these terraced paddy fields has become increasingly important, not only for general maintenance of the terraced paddy fields, but also because of the impact landscape, vegetation and the surrounding environment. However, the steep gradient of the levee slope and lack of footholds mean that the workability and safety associated with this weeding work is problematic. In addition, in the event that an area has been designated as a cultural asset, there are restrictions regarding how it can be modified and local farmers are reluctant to change their traditional farming methods in such cases. This study therefore sought to clarify the actual condition of the levee slope weeding work undertaken in the places of scenic beauty Obasute Tanada district. Empirical validations of potential measures for reforming the work environment were evaluated based on the findings of this investigation. We demonstrated that it is possible to modify current work practices while still maintaining and preserving the terraced paddy fields, even in designated scenic locations. To improve the working environment for levee slope weeding, we propose creating berms to serve as footholds at the toes of slopes.

  3. Mapping paddy rice distribution using multi-temporal Landsat imagery in the Sanjiang Plain, northeast China

    NASA Astrophysics Data System (ADS)

    Jin, Cui; Xiao, Xiangming; Dong, Jinwei; Qin, Yuanwei; Wang, Zongming

    2015-07-01

    Information of paddy rice distribution is essential for food production and methane emission calculation. Phenology-based algorithms have been utilized in the mapping of paddy rice fields by identifying the unique flooding and seedling transplanting phases using multi-temporal moderate resolution (500 m to 1 km) images. In this study, we developed simple algorithms to identify paddy rice at a fine resolution at the regional scale using multi-temporal Landsat imagery. Sixteen Landsat images from 2010-2012 were used to generate the 30 m paddy rice map in the Sanjiang Plain, northeast Chinaone of the major paddy rice cultivation regions in China. Three vegetation indices, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), and Land Surface Water Index (LSWI), were used to identify rice fields during the flooding/transplanting and ripening phases. The user and producer accuracies of paddy rice on the resultant Landsat-based paddy rice map were 90% and 94%, respectively. The Landsat-based paddy rice map was an improvement over the paddy rice layer on the National Land Cover Dataset, which was generated through visual interpretation and digitalization on the fine-resolution images. The agricultural census data substantially underreported paddy rice area, raising serious concern about its use for studies on food security.

  4. Mapping paddy rice distribution using multi-temporal Landsat imagery in the Sanjiang Plain, northeast China

    NASA Astrophysics Data System (ADS)

    Jin, Cui; Xiao, Xiangming; Dong, Jinwei; Qin, Yuanwei; Wang, Zongming

    2016-03-01

    Information of paddy rice distribution is essential for food production and methane emission calculation. Phenology-based algorithms have been utilized in the mapping of paddy rice fields by identifying the unique flooding and seedling transplanting phases using multi-temporal moderate resolution (500 m to 1 km) images. In this study, we developed simple algorithms to identify paddy rice at a fine resolution at the regional scale using multi-temporal Landsat imagery. Sixteen Landsat images from 2010-2012 were used to generate the 30 m paddy rice map in the Sanjiang Plain, northeast China—one of the major paddy rice cultivation regions in China. Three vegetation indices, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), and Land Surface Water Index (LSWI), were used to identify rice fields during the flooding/transplanting and ripening phases. The user and producer accuracies of paddy rice on the resultant Landsat-based paddy rice map were 90% and 94%, respectively. The Landsat-based paddy rice map was an improvement over the paddy rice layer on the National Land Cover Dataset, which was generated through visual interpretation and digitalization on the fine-resolution images. The agricultural census data substantially underreported paddy rice area, raising serious concern about its use for studies on food security.

  5. Conversion of upland to paddy field specifically alters the community structure of archaeal ammonia oxidizers in an acid soil

    NASA Astrophysics Data System (ADS)

    Alam, M. S.; Ren, G. D.; Lu, L.; Zheng, Y.; Peng, X. H.; Jia, Z. J.

    2013-08-01

    The function of ammonia-oxidizing archaea (AOA) and bacteria (AOB) depends on the major energy-generating compounds (i.e., ammonia and oxygen). The diversification of AOA and AOB communities along ecological gradients of substrate availability in a complex environment have been much debated but rarely tested. In this study, two ecosystems of maize and rice crops under different fertilization regimes were selected to investigate the community diversification of soil AOA and AOB upon conversion of an upland field to a paddy field and long-term field fertilization in an acid soil. Real-time quantitative polymerase chain reaction of ammonia monooxygenase (amoA) genes demonstrated that the abundance of AOA was significantly stimulated after conversion of upland to paddy soils for more than 100 yr, whereas a slight decline in AOB numbers was observed. Denaturing gradient gel electrophoresis fingerprints of amoA genes further revealed remarkable changes in the community compositions of AOA after conversion of aerobic upland to flooded paddy field. Sequencing analysis revealed that upland soil was dominated by AOA within the soil group 1.1b lineage, whereas the marine group 1.1a-associated lineage predominated in AOA communities in paddy soils. Irrespective of whether the soil was upland or paddy soil, long-term field fertilization led to increased abundance of amoA genes in AOA and AOB compared with control treatments (no fertilization), whereas archaeal amoA gene abundances outnumbered their bacterial counterparts in all samples. Phylogenetic analyses of amoA genes showed that Nitrosospira cluster-3-like AOB dominated bacterial ammonia oxidizers in both paddy and upland soils, regardless of fertilization treatment. The results of this study suggest that the marine group 1.1a-associated AOA will be better adapted to the flooded paddy field than AOA ecotypes of the soil group 1.1b lineage, and indicate that long-term flooding is the dominant selective force driving the community diversification of AOA populations in the acid soil tested.

  6. Sediment trap efficiency of paddy fields at the watershed scale in a mountainous catchment in Northwest Vietnam

    NASA Astrophysics Data System (ADS)

    Slaets, J. I. F.; Schmitter, P.; Hilger, T.; Vien, T. D.; Cadisch, G.

    2015-12-01

    Composite agricultural systems with permanent maize cultivation in the uplands and irrigated rice in the valleys are very common in mountainous Southeast Asia. The soil loss and fertility decline of the upland fields is well documented, but little is known about reallocation of these sediments within the landscape. In this study, a turbidity-based linear mixed model was used to quantify sediment inputs, from surface reservoir irrigation water and from direct overland flow, into a paddy area of 13 hectares. Simultaneously, the sediment load exported from the rice fields was determined. Mid-infrared spectroscopy was applied to analyze sediment particle size. Our results showed that per year, 64 Mg ha-1 of sediments were imported into paddy fields, of which around 75 % were delivered by irrigation water and the remainder by direct overland flow during rainfall events. Overland flow contributed one third of the received sandy fraction, while irrigated sediments were predominantly silty. Overall, rice fields were a net sink for sediments, trapping 28 Mg ha-1 a-1 or almost half of total sediment inputs. As paddy outflow consisted almost exclusively of silt- and clay-sized material, 24 Mg ha-1 a-1 of the trapped amount of sediment was estimated to be sandy. Under continued intensive upland maize cultivation, such a sustained input of coarse material could jeopardize paddy soil fertility, puddling capacity and ultimately also food security of the inhabitants of these mountainous areas. Preventing direct overland flow from entering the paddy fields, however, could reduce sand inputs by up to 34 %.

  7. Cadmium availability in rice paddy fields from a mining area: The effects of soil properties highlighting iron fractions and pH value.

    PubMed

    Yu, Huan-Yun; Liu, Chuanping; Zhu, Jishu; Li, Fangbai; Deng, Dong-Mei; Wang, Qi; Liu, Chengshuai

    2016-02-01

    Cadmium (Cd) availability can be significantly affected by soil properties. The effect of pH value on Cd availability has been confirmed. Paddy soils in South China generally contain high contents of iron (Fe). Thus, it is hypothesized that Fe fractions, in addition to pH value, may play an important role in the Cd bioavailability in paddy soil and this requires further investigation. In this study, 73 paired soil and rice plant samples were collected from paddy fields those were contaminated by acid mine drainage containing Cd. The contents of Fe in the amorphous and DCB-extractable Fe oxides were significantly and negatively correlated with the Cd content in rice grain or straw (excluding DCB-extractable Fe vs Cd in straw). In addition, the concentration of HCl-extractable Fe(II) derived from Fe(III) reduction was positively correlated with the Cd content in rice grain or straw. These results suggest that soil Fe redox could affect the availability of Cd in rice plant. Contribution assessment of soil properties to Cd accumulation in rice grain based on random forest (RF) and stochastic gradient boosting (SGB) showed that pH value should be the most important factor and the content of Fe in the amorphous Fe oxides should be the second most important factor in affecting Cd content in rice grain. Overall, compared with the studies from temperate regions, such as Europe and northern China, Fe oxide exhibited its unique role in the bioavailability of Cd in the reddish paddy soil from our study area. The exploration of practical remediation strategies for Cd from the perspective of Fe oxide may be promising. PMID:26629644

  8. [Controlling effects of multiple species coexistence on rice diseases, pests and weeds in paddy field ecosystem].

    PubMed

    Wang, Han; Tang, Jian-jun; Xie, Jian; Chen, Xin

    2007-05-01

    Establishing a species-diversified cropping system to control crop diseases, insect pests and weeds is an important approach to sustainable agricultural development. This paper reviewed the researches on paddy field species-diversified cropping systems at home and abroad, and discussed the controlling effects and mechanisms of multiple species coexistence on rice diseases, pests and weeds control. The multiple species coexistence models such as rice-fish, rice-duck, rice-azolla-fish and rice-azolla-duck had effective controlling effects on Thanatephorus cucumeris (Frank) Donk, Nilaparata lugens Stal, Chaphalocrocis medinalis Gueneeand, and weeds. Other models like intercropping rice with Zizania caduciflora L. and with other wetland crops also had effective effects in controlling the occurrence and spread of Pyricularia grisea. It was suggested that further studies should be strengthened from the viewpoints of crop culture, molecular biology, and chemical ecolo- PMID:17650871

  9. Influence of rice growth on the fate of polycyclic aromatic hydrocarbons in a subtropical paddy field: a life cycle study.

    PubMed

    Wang, Yan; Wang, Shaorui; Luo, Chunling; Xu, Yue; Pan, Suhong; Li, Jun; Ming, Lili; Zhang, Gan; Li, Xiangdong

    2015-01-01

    We measured the concentrations and profiles of polycyclic aromatic hydrocarbons (PAHs) in the soil, water, and rice tissues from a typical subtropical paddy system at various stages of rice growth over two growing seasons. Rice growth had a significant impact on the distribution and dissipation of PAHs in the paddy field. While rice was growing, the concentrations of PAHs in the soils decreased at an average decline rate of 5.32.9 ng PAHs g(-1) soild(-1), whereas, the concentrations of PAHs in rice tissues increased with growth time. However, the concentrations of PAHs in the rice leaves decreased during the heading stage of both two growing seasons. PAH profiles in soil, water, and different rice tissues also showed different patterns with the growing time of rice. Irrigation water was a significant source of PAHs to the paddy field. Rice growth enhanced the dissipation and transport of PAHs in the paddy system, while the sewage irrigation and straw burning after harvest added or returned PAHs to the system. For food safety precaution, sewage irrigation and straw burning should be well monitored and controlled. PMID:25460766

  10. From Laboratory to Field: OsNRAMP5-Knockdown Rice Is a Promising Candidate for Cd Phytoremediation in Paddy Fields

    PubMed Central

    Bashir, Khurram; Senoura, Takeshi; Sugimoto, Kazuhiko; Ono, Kazuko; Suzui, Nobuo; Kawachi, Naoki; Ishii, Satomi; Yin, Yong-Gen; Fujimaki, Shu; Yano, Masahiro; Nishizawa, Naoko K.; Nakanishi, Hiromi

    2014-01-01

    Previously, we reported that OsNRAMP5 functions as a manganese, iron, and cadmium (Cd) transporter. The shoot Cd content in OsNRAMP5 RNAi plants was higher than that in wild-type (WT) plants, whereas the total Cd content (roots plus shoots) was lower. For efficient Cd phytoremediation, we produced OsNRAMP5 RNAi plants using the natural high Cd-accumulating cultivar Anjana Dhan (A5i). Using a positron-emitting tracer imaging system, we assessed the time-course of Cd absorption and accumulation in A5i plants. Enhanced 107Cd translocation from the roots to the shoots was observed in A5i plants. To evaluate the phytoremediation capability of A5i plants, we performed a field experiment in a Cd-contaminated paddy field. The biomass of the A5i plants was unchanged by the suppression of OsNRAMP5 expression; the A5i plants accumulated twice as much Cd in their shoots as WT plants. Thus, A5i plants could be used for rapid Cd extraction and the efficient phytoremediation of Cd from paddy fields, leading to safer food production. PMID:24901230

  11. Soil type-depending effect of paddy management: Organic carbon distribution and stocks

    NASA Astrophysics Data System (ADS)

    Klbl, Angelika; Drechsler, Susanne; Wissing, Livia; Schad, Peter; Rahayu Utami, Sri; Cao, Zhihong; Kgel-Knabner, Ingrid

    2013-04-01

    Paddy soils may originate from many different types of soil but are highly modified by human activities. These soils are mostly managed under submerged conditions, a management which is assumed to favour carbon sequestration. Therefore, the present study aims to investigate the impact of paddy management on soil organic carbon distributions and stocks in major soil types that are typically used for rice cultivation in Asia. Fluvisol and Acrisol sites (sub-tropical monsoon climate, PR China) as well as Andosol, Vertisol and Ferralsol sites (tropical climate of Java, Indonesia) were compared, as they represent a large range of soil properties to be expected in Asian paddy fields. Paddy rice at all of these sites is cultivated under flooded conditions followed by an upland crop. To evaluate the impact of paddy management, paddy soils as well as adjacent agricultural soils which are not used for paddy rice production (non-paddy soils) were chosen. At each site, three soil profiles of paddy and non-paddy soils were sampled horizontally. All samples were analysed for bulk density and organic carbon (OC) concentrations, and the corresponding OC stocks were calculated. Paddy soils derived from Fluvisols and Acrisols(PR China) showed clearly higher OC concentrations in the topsoils, leading to higher cumulative OC stocks in paddy soils compared to the respective non-paddy soils. However, other soil types did not show the expected higher OC sequestration under paddy management. For example, paddy soils derived from Ferralsols and Vertisols of Java are characterised by very similar OC concentrations and OC stocks as compared to their respective non-paddy soils. Also paddy and non-paddy soils derived from Andosols (Java) showed similar OC concentrations and depth distributions; only the slightly higher bulk density values under paddy management lead to slightly higher OC stocks in these soils. As clearly shown by our results, we cannot necessarily assume that rice production under submerged conditions always leads to enhanced carbon sequestration. We conclude that not only the soil type, but also the climate region may control the mechanisms of OC accumulation and the impact of management on OC stocks and distributions.

  12. Characterization of the exchange of PBDEs in a subtropical paddy field of China: A significant inputs of PBDEs via air-foliage exchange.

    PubMed

    Wang, Yan; Wang, Shaorui; Xu, Yue; Luo, Chunling; Li, Jun; Zhang, Gan

    2015-10-01

    Rice and the distinctive cultivation practices employed in rice growth can significantly influence the environmental fate of polybrominated diphenyl ethers (PBDEs) in a paddy field. We studied variations in PBDE concentrations in multiple compartments of a paddy field in the suburban area of Guangzhou, South China, including air, soil, water, and rice tissues. The input/output fluxes of air-surface and air-foliage exchange, atmospheric deposition and water input during different rice growth stages were measured simultaneously. Air-foliage and air-water diffusion exchanges were the key processes controlling inputs and outputs of PBDEs in paddy fields, respectively, whereas atmospheric deposition dominated inputs of higher brominated PBDEs. The high input of PBDEs via air-foliage exchange suggested that vegetation can significantly increase the air-to-field transport of PBDEs in ecosystems. The annual input of PBDEs in all paddy fields in Guangdong Province was estimated to be 22.1 kg. PMID:25993429

  13. Assessing the pollution risk of soil Chromium based on loading capacity of paddy soil at a regional scale

    NASA Astrophysics Data System (ADS)

    Qu, Mingkai; Li, Weidong; Zhang, Chuanrong; Huang, Biao; Zhao, Yongcun

    2015-12-01

    The accumulation of a trace metal in rice grain is not only affected by the total concentration of the soil trace metal, but also by crop variety and related soil properties, such as soil pH, soil organic matter (SOM) and so on. However, these factors were seldom considered in previous studies on mapping the pollution risk of trace metals in paddy soil at a regional scale. In this study, the spatial nonstationary relationships between rice-Cr and a set of perceived soil properties (soil-Cr, soil pH and SOM) were explored using geographically weighted regression; and the relationships were then used for calculating the critical threshold (CT) of soil-Cr concentration that may ensure the concentration of rice-Cr being below the permissible limit. The concept of “loading capacity” (LC) for Cr in paddy soil was then defined as the difference between the CT and the real concentration of Cr in paddy soil, so as to map the pollution risk of soil-Cr to rice grain and assess the risk areas in Jiaxing city, China. Compared with the information of the concentration of the total soil-Cr, such results are more valuable for spatial decision making in reducing the accumulation of rice-Cr at a regional scale.

  14. Assessing the pollution risk of soil Chromium based on loading capacity of paddy soil at a regional scale.

    PubMed

    Qu, Mingkai; Li, Weidong; Zhang, Chuanrong; Huang, Biao; Zhao, Yongcun

    2015-01-01

    The accumulation of a trace metal in rice grain is not only affected by the total concentration of the soil trace metal, but also by crop variety and related soil properties, such as soil pH, soil organic matter (SOM) and so on. However, these factors were seldom considered in previous studies on mapping the pollution risk of trace metals in paddy soil at a regional scale. In this study, the spatial nonstationary relationships between rice-Cr and a set of perceived soil properties (soil-Cr, soil pH and SOM) were explored using geographically weighted regression; and the relationships were then used for calculating the critical threshold (CT) of soil-Cr concentration that may ensure the concentration of rice-Cr being below the permissible limit. The concept of "loading capacity" (LC) for Cr in paddy soil was then defined as the difference between the CT and the real concentration of Cr in paddy soil, so as to map the pollution risk of soil-Cr to rice grain and assess the risk areas in Jiaxing city, China. Compared with the information of the concentration of the total soil-Cr, such results are more valuable for spatial decision making in reducing the accumulation of rice-Cr at a regional scale. PMID:26675587

  15. Assessing the pollution risk of soil Chromium based on loading capacity of paddy soil at a regional scale

    PubMed Central

    Qu, Mingkai; Li, Weidong; Zhang, Chuanrong; Huang, Biao; Zhao, Yongcun

    2015-01-01

    The accumulation of a trace metal in rice grain is not only affected by the total concentration of the soil trace metal, but also by crop variety and related soil properties, such as soil pH, soil organic matter (SOM) and so on. However, these factors were seldom considered in previous studies on mapping the pollution risk of trace metals in paddy soil at a regional scale. In this study, the spatial nonstationary relationships between rice-Cr and a set of perceived soil properties (soil-Cr, soil pH and SOM) were explored using geographically weighted regression; and the relationships were then used for calculating the critical threshold (CT) of soil-Cr concentration that may ensure the concentration of rice-Cr being below the permissible limit. The concept of “loading capacity” (LC) for Cr in paddy soil was then defined as the difference between the CT and the real concentration of Cr in paddy soil, so as to map the pollution risk of soil-Cr to rice grain and assess the risk areas in Jiaxing city, China. Compared with the information of the concentration of the total soil-Cr, such results are more valuable for spatial decision making in reducing the accumulation of rice-Cr at a regional scale. PMID:26675587

  16. Radiocesium discharge from paddy fields with different initial scrapings for decontamination after the Fukushima Dai-ichi Nuclear Power Plant accident.

    PubMed

    Wakahara, Taeko; Onda, Yuich; Kato, Hiroaki; Sakaguchi, Aya; Yoshimura, Kazuya

    2014-11-01

    To explore the behavior of radionuclides released after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011, and the distribution of radiocesium in paddy fields, we monitored radiocesium (Cs) and suspended sediment (SS) discharge from paddy fields. We proposed a rating scale for measuring the effectiveness of surface soil removal. Our experimental plots in paddy fields were located ?40 km from the FDNPP. Two plots were established: one in a paddy field where surface soil was not removed (the "normally cultivated paddy field") and the second in a paddy field where the top 5-10 cm of soil was removed before cultivation (the "surface-removed paddy field"). The amounts of Cs and SS discharge from the paddy fields were continuously measured from June to August 2011. The Cs soil inventory measured 3 months after the FDNPP accident was approximately 200 kBq m(-2). However, after removing the surface soil, the concentration of Cs-137 decreased to 5 kBq m(-2). SS discharged from the normally cultivated and surface-removed paddy fields after puddling (mixing of soil and water before planting rice) was 11.0 kg and 3.1 kg, respectively, and Cs-137 discharge was 630,000 Bq (1240 Bq m(-2)) and 24,800 Bq (47.8 Bq m(-2)), respectively. The total amount of SS discharge after irrigation (natural rainfall-runoff) was 5.5 kg for the normally cultivated field and 70 kg for the surface-removed field, and the total amounts of Cs-137 discharge were 51,900 Bq (102 Bq m(-2)) and 165,000 Bq (317 Bq m(-2)), respectively. During the irrigation period, discharge from the surface-removed plot showed a twofold greater inflow than that from the normally cultivated plot. Thus, Cs inflow may originate from the upper canal. The topsoil removal process eliminated at least approximately 95% of the Cs-137, but upstream water contaminated with Cs-137 flowed into the paddy field. Therefore, to accurately determine the Cs discharge, it is important to examine Cs inflow from the upper channel. Furthermore, puddling and irrigation processes inhibit the discharge of radiocesium downstream. This indicates that water control in paddy fields is an important process in the prevention of river pollution and radionuclide transfer. PMID:25247992

  17. Nannophya pygmaea (Odonata: Libellulidae), an endangered dragonfly in Korea, prefers abandoned paddy fields in the early seral stage.

    PubMed

    Yoon, Jihyun; Nam, Jong Min; Kim, Heungtae; Bae, Yeon Jae; Kim, Jae Geun

    2010-04-01

    To characterize habitats of Nannophya pygmaea Rambur (the northern pygmyfly; Odonata: Lilbellulidae), which is endangered in Korea, we analyzed characteristics of surface water and soil, landscape properties, and vegetation types in 22 habitats in eight areas of Korea where nymphs of N. pygmaea have been found since 2005. We divided the habitats into two groups: DS (dwelling site) habitats, where N. pygmaea was observed at the time of the study, and PDS (past dwelling site) habitats, where N. pygmaea recently lived but is no longer found. The habitats were mostly located in former paddy fields on mountain slopes that have been abandoned for 3-7 yr. The main water sources for these habitats were ground water and surface runoff, and the water level was stable at 3-7 cm in depth. The habitats ranged from 300 to 1000 m(2) and were dominated by Juncus effusus, which formed tussock mounds. According to the hydrosere model of succession, N. pygmaea appeared mostly in the early stages of plant succession (the period approximately 3-7 yr after the initiation of succession in former paddy fields) and N. pygmaea preferred habitats displaying the water and soil characteristics that are typical of the early stages of succession in abandoned paddy fields. These results indicate that the primary habitats of N. pygmaea in Korea are recently abandoned paddy fields that are in an oligotrophic state. As succession proceeds in these habitats, N. pygmaea disappears. A habitat management program should be launched to conserve the habitats and populations of N. pygmaea. PMID:20388254

  18. Alterations of biochemical indicators in hepatopancreas of the golden apple snail, Pomacea canaliculata, from paddy fields in Taiwan.

    PubMed

    Chiu, Yuh-Wen; Wu, Jui-Pin; Hsieh, Tsung-Chih; Liang, Shih-Hsiung; Chen, Chien-Min; Huang, Da-Ji

    2014-07-01

    The freshwater golden apple snail, Pomacea canaliculata, is one of the world's 100 worst invasive alien species. The snails' wide distribution, high abundance, and sensitivity to environmental pollution make them a potential bioindicator for environmental contamination. In this study, the biochemical status of golden apple snails collected from paddy fields throughout the island of Taiwan was examined. This study found that the biochemical status of apple snails collected from paddy fields differed from that of animals bred and maintained in the laboratory. Furthermore, certain biochemical endpoints of the snails collected from the paddy fields before and after agricultural activities were also different-hemolymphatic vitellogenin protein was induced in male snail after exposure to estrogen-like chemicals, the hepatic monooxygenase (1.97 +/- 0.50 deltaA(650mm) 30 min(-1) mg(-1) protein in control group) and glutathione S transferase (0.02 +/- 0.01 delta A(340mm) 30 min(-1) mg(-1) protein in control group) snails exposed to pesticides, as well as the hepatopancreatic levels of aspartate aminotransferase (450.00 +/- 59.40 U mg(-1) mg(-1) protein in control group) and alanine aminotransferase (233.27 +/- 42.09 U mg(-1) mg(-1) protein in control group) decreased the indicating that xenobiotics destroyed hepatopancreatic. The above findings reveal that apple snail could be used as a practical bioindicator to monitor anthropogenic environmental pollution. PMID:25004751

  19. Methanogenic degradation of lignin-derived monoaromatic compounds by microbial enrichments from rice paddy field soil.

    PubMed

    Kato, Souichiro; Chino, Kanako; Kamimura, Naofumi; Masai, Eiji; Yumoto, Isao; Kamagata, Yoichi

    2015-01-01

    Anaerobic degradation of lignin-derived aromatics is an important metabolism for carbon and nutrient cycles in soil environments. Although there are some studies on degradation of lignin-derived aromatics by nitrate- and sulfate-reducing bacteria, knowledge on their degradation under methanogenic conditions are quite limited. In this study, methanogenic microbial communities were enriched from rice paddy field soil with lignin-derived methoxylated monoaromatics (vanillate and syringate) and their degradation intermediates (protocatechuate, catechol, and gallate) as the sole carbon and energy sources. Archaeal community analysis disclosed that both aceticlastic (Methanosarcina sp.) and hydrogenotrophic (Methanoculleus sp. and Methanocella sp.) methanogens dominated in all of the enrichments. Bacterial community analysis revealed the dominance of acetogenic bacteria (Sporomusa spp.) only in the enrichments on the methoxylated aromatics, suggesting that Sporomusa spp. initially convert vanillate and syringate into protocatechuate and gallate, respectively, with acetogenesis via O-demethylation. As the putative ring-cleavage microbes, bacteria within the phylum Firmicutes were dominantly detected from all of the enrichments, while the dominant phylotypes were not identical between enrichments on vanillate/protocatechuate/catechol (family Peptococcaceae bacteria) and on syringate/gallate (family Ruminococcaceae bacteria). This study demonstrates the importance of cooperation among acetogens, ring-cleaving fermenters/syntrophs and aceticlastic/hydrogenotrophic methanogens for degradation of lignin-derived aromatics under methanogenic conditions. PMID:26399549

  20. Comparative proteomics of oxidative stress response in three cyanobacterial strains native to Indian paddy fields.

    PubMed

    Panda, Bandita; Basu, Bhakti; Rajaram, Hema; Apte, Shree Kumar

    2015-09-01

    Three strains of photoautotrophic, heterocystous, nitrogen-fixing cyanobacterium Anabaena, native to Indian paddy fields, were examined for their tolerance and proteomic response to the frequently used weedicide paraquat (methyl viologen). Anabaena 7120 (LD50 dose: 2?M for 6h) and Anabaena L-31 (LD50 dose: 2?M for 5h) showed distinctly better tolerance than Anabaena doliolum (LD50 dose: 2?M for 3h), to methyl viologen induced oxidative stress. The proteomic response, at respective LD50 dose, was mapped by 2D gel protein electrophoresis followed by protein identification by MALDI-ToF mass spectrometry. About 92 and 41 oxidative stress-responsive proteins were identified from Anabaena L-31 and A. doliolum, respectively, and compared with methyl viologen responsive proteins reported from Anabaena 7120 earlier. Upregulation of proteins involved in oxidative stress alleviation and protein homeostasis and downregulation of photosynthesis and carbon metabolism related enzymes appeared to underlie the oxidative stress response in all three Anabaena strains. Reduced photosynthesis and cellular reserves of molecular energy [ATP+NAD(P)H] seemed to overwhelm the cellular machinery to combat oxidative stress and protein denaturation, in preference to other adaptations, while the strain specific differences observed in proteome response appeared to determine the methyl viologen tolerance of individual cyanobacterial strains. This article is part of a Special Issue entitled: Proteomics in India. PMID:26013413

  1. Geochemical associations and availability of cadmium (Cd) in a paddy field system, northwestern Thailand.

    PubMed

    Kosolsaksakul, Peerapat; Farmer, John G; Oliver, Ian W; Graham, Margaret C

    2014-04-01

    The Mae Tao watershed, northwest Thailand, has become contaminated with cadmium (Cd) as a result of zinc ore extraction (Padaeng deposit) in the nearby Thanon-Thongchai mountains. Consumption of contaminated rice has led to documented human health impacts. The aim of this study was to elucidate transfer pathways from creek and canal waters to the paddy field soils near Baan Mae Tao Mai village and to determine the relationship between Cd speciation in the soil and uptake by rice plants. Transfer mainly occurred in association with particulate matter during flooding and channel dredging and, in contrast with many other studies, most of the soil Cd was associated with exchangeable and carbonate-bound fractions. Moreover, there was a linear relationship between soil total Cd and rice grain Cd (R(2)=0.715), but a stronger relationship between both the Tessier-exchangeable soil Cd and the BCR-exchangeable soil Cd and rice grain Cd (R(2)=0.898 and 0.862, respectively). PMID:24502996

  2. [Further reduction of nitrogen fertilizer application in paddy field under green manuring of Taihu Area, China].

    PubMed

    Zhao, Dong; Yan, Ting-mei; Qiao, Jun; Yang, Lin-zhang; Tang, Fang; Song, Yun-fei

    2015-06-01

    This study focused on the nitrogen loss via runoff, change of nitrogen in different forms in surface water in paddy field, and grain yield, through further reduction of nitrogen fertilizer application rate under green manuring without basal dressing. Results showed that with 150 kg hm(-2) inorganic N fertilizer input after return of green manure to soil, no basal dressing could not only sharply reduce N concentration in surface water and decrease 17.2% of N loss, but also increase 2.8% of grain yield in comparison with basal dressing. It was a worthwhile farming method that inorganic nitrogen fertilizer was not used for basal dressing but for topdressing after return of green ma- nure to soil in Taihu Area. However, the grain yield would decrease if the rate of topdressing nitro- gen was excessively reduced or increased. After all, it was feasible to realize harmonization of grain yield and environmental benefits in Taihu Area, with 133 kg hm(-2) inorganic N fertilizer input after return of green manure to soil as well as no application of basal dressing, which could greatly reduce N fertilizer input and N loss as well as ensure rice yield. PMID:26572018

  3. Methanogenic degradation of lignin-derived monoaromatic compounds by microbial enrichments from rice paddy field soil

    PubMed Central

    Kato, Souichiro; Chino, Kanako; Kamimura, Naofumi; Masai, Eiji; Yumoto, Isao; Kamagata, Yoichi

    2015-01-01

    Anaerobic degradation of lignin-derived aromatics is an important metabolism for carbon and nutrient cycles in soil environments. Although there are some studies on degradation of lignin-derived aromatics by nitrate- and sulfate-reducing bacteria, knowledge on their degradation under methanogenic conditions are quite limited. In this study, methanogenic microbial communities were enriched from rice paddy field soil with lignin-derived methoxylated monoaromatics (vanillate and syringate) and their degradation intermediates (protocatechuate, catechol, and gallate) as the sole carbon and energy sources. Archaeal community analysis disclosed that both aceticlastic (Methanosarcina sp.) and hydrogenotrophic (Methanoculleus sp. and Methanocella sp.) methanogens dominated in all of the enrichments. Bacterial community analysis revealed the dominance of acetogenic bacteria (Sporomusa spp.) only in the enrichments on the methoxylated aromatics, suggesting that Sporomusa spp. initially convert vanillate and syringate into protocatechuate and gallate, respectively, with acetogenesis via O-demethylation. As the putative ring-cleavage microbes, bacteria within the phylum Firmicutes were dominantly detected from all of the enrichments, while the dominant phylotypes were not identical between enrichments on vanillate/protocatechuate/catechol (family Peptococcaceae bacteria) and on syringate/gallate (family Ruminococcaceae bacteria). This study demonstrates the importance of cooperation among acetogens, ring-cleaving fermenters/syntrophs and aceticlastic/hydrogenotrophic methanogens for degradation of lignin-derived aromatics under methanogenic conditions. PMID:26399549

  4. Seasonality of ecosystem respiration in a double-cropping paddy field in Bangladesh

    NASA Astrophysics Data System (ADS)

    Hossen, M. S.; Mano, M.; Miyata, A.; Baten, M. A.; Hiyama, T.

    2011-08-01

    Ecosystem respiration (RE) from cultivated ecosystems is important for understanding the role of these ecosystems in the global carbon balance. To evaluate carbon dynamics in a double-rice cropping paddy field, we conducted long-term measurements at Mymensingh, Bangladesh in 2007 using a tower-based eddy covariance technique. The study objectives were to investigate the diurnal and seasonal variations in RE and to develop and evaluate empirical models for predicting variations in RE using environmental parameters. We found that the diurnal pattern of RE was driven by soil temperature (Ts) whereas the seasonal variation in RE was controlled primarily by Ts and soil water content (SWC). Under high biomass conditions, Ts plays a dominant role in the magnitude of CO2 release. Both the amount and magnitude of RE variation were larger in the "Boro" dry-season rice growing period from late winter to mid-summer than in the "Aman" wet-season rice growing period from late summer to early winter. Annually, the ratio of RE to gross primary production (GPP) was 0.67, indicating a net sink of carbon; the two growing seasons had RE/GPP ratios of 0.58 and 0.52. A model using Ts, SWC, and aboveground biomass predicted daily RE with R2 values of 0.87 and 0.62 for the Boro and Aman seasons, respectively.

  5. Mapping Spatial Variability of Soil Salinity in a Coastal Paddy Field Based on Electromagnetic Sensors

    PubMed Central

    Guo, Yan; Huang, Jingyi; Shi, Zhou; Li, Hongyi

    2015-01-01

    In coastal China, there is an urgent need to increase land area for agricultural production and urban development, where there is a rapid growing population. One solution is land reclamation from coastal tidelands, but soil salinization is problematic. As such, it is very important to characterize and map the within-field variability of soil salinity in space and time. Conventional methods are often time-consuming, expensive, labor-intensive, and unpractical. Fortunately, proximal sensing has become an important technology in characterizing within-field spatial variability. In this study, we employed the EM38 to study spatial variability of soil salinity in a coastal paddy field. Significant correlation relationship between ECa and EC1:5 (i.e. r >0.9) allowed us to use EM38 data to characterize the spatial variability of soil salinity. Geostatistical methods were used to determine the horizontal spatio-temporal variability of soil salinity over three consecutive years. The study found that the distribution of salinity was heterogeneous and the leaching of salts was more significant in the edges of the study field. By inverting the EM38 data using a Quasi-3D inversion algorithm, the vertical spatio-temporal variability of soil salinity was determined and the leaching of salts over time was easily identified. The methodology of this study can be used as guidance for researchers interested in understanding soil salinity development as well as land managers aiming for effective soil salinity monitoring and management practices. In order to better characterize the variations in soil salinity to a deeper soil profile, the deeper mode of EM38 (i.e., EM38v) as well as other EMI instruments (e.g. DUALEM-421) can be incorporated to conduct Quasi-3D inversions for deeper soil profiles. PMID:26020969

  6. Mapping spatial variability of soil salinity in a coastal paddy field based on electromagnetic sensors.

    PubMed

    Guo, Yan; Huang, Jingyi; Shi, Zhou; Li, Hongyi

    2015-01-01

    In coastal China, there is an urgent need to increase land area for agricultural production and urban development, where there is a rapid growing population. One solution is land reclamation from coastal tidelands, but soil salinization is problematic. As such, it is very important to characterize and map the within-field variability of soil salinity in space and time. Conventional methods are often time-consuming, expensive, labor-intensive, and unpractical. Fortunately, proximal sensing has become an important technology in characterizing within-field spatial variability. In this study, we employed the EM38 to study spatial variability of soil salinity in a coastal paddy field. Significant correlation relationship between ECa and EC1:5 (i.e. r >0.9) allowed us to use EM38 data to characterize the spatial variability of soil salinity. Geostatistical methods were used to determine the horizontal spatio-temporal variability of soil salinity over three consecutive years. The study found that the distribution of salinity was heterogeneous and the leaching of salts was more significant in the edges of the study field. By inverting the EM38 data using a Quasi-3D inversion algorithm, the vertical spatio-temporal variability of soil salinity was determined and the leaching of salts over time was easily identified. The methodology of this study can be used as guidance for researchers interested in understanding soil salinity development as well as land managers aiming for effective soil salinity monitoring and management practices. In order to better characterize the variations in soil salinity to a deeper soil profile, the deeper mode of EM38 (i.e., EM38v) as well as other EMI instruments (e.g. DUALEM-421) can be incorporated to conduct Quasi-3D inversions for deeper soil profiles. PMID:26020969

  7. Seasonal variations of CH4 and N2O emissions in response to water management of paddy fields located in Southeast China.

    PubMed

    Hou, Huijing; Peng, Shizhang; Xu, Junzeng; Yang, Shihong; Mao, Zhi

    2012-10-01

    Water management is one of the most important practices that affect methane (CH(4)) and nitrous oxide (N(2)O) emissions from paddy fields. A field experiment was designed to study the effects of controlled irrigation (CI) on CH(4) and N(2)O emissions from paddy fields, with traditional irrigation (TI) as the control. The effects of CI on CH(4) and N(2)O emissions from paddy fields were very clear. The peaks of CH(4) emissions from the CI paddies were observed 1-2d after the water layer disappeared. Afterward, the emissions reduced rapidly and remained low until the soil was re-flooded. A slight increase of CH(4) emission was observed in a short period after re-flooding. N(2)O emissions peaks from CI paddies were all observed 8-10d after the fertilization at the WFPS ranging from 78.1% to 85.3%. Soil drying caused substantial N(2)O emissions, whereas no substantial N(2)O emissions were observed when the soil was re-wetted after the dry phase. Compared with TI, the cumulative CH(4) emissions from the CI fields were reduced by 81.8% on the average, whereas the cumulative N(2)O emissions were increased by 135.4% on the average. The integrative global warming potential of CH(4) and N(2)O on a 100-year horizon decreased by 27.3% in the CI paddy fields, whereas no significant difference in the rice yield was observed between the CI and TI fields. These results suggest that CI can effectively mitigate the integrative greenhouse effect caused by CH(4) and N(2)O emissions from paddy fields while ensuring the rice yield. PMID:22673400

  8. Spatial and Temporal Variability of Macronutrients in a Lime-amended Acid Paddy Field

    NASA Astrophysics Data System (ADS)

    Vidal Vzquez, E.; Morales, L. A.; Paz Gonzlez, A.

    2012-04-01

    Soil spatial variability is a natural occurring and or management induced feature that is important for site-specific management practices such as variable rate fertilization. Since rice paddy fields are flat and flooded, apparently they should be homogeneous and subsequently it could be thought that spatial variability in yields and soil attributes might be negligible. However, significant levels of variability in soil general properties, soil nutrients and rice yields have been observed even in small paddy fields. Describing spatial variability of within-field properties is a fundamental first step toward determining management strategies. The aim of this study was to analyze patterns of spatial variability in available macronutrients (NH4+-N, P and K) from an acid rice soil submitted to lime amendment. The experimental site was located at Corrientes province, Argentina. The climate is warm, subtropical with abundant rainfall the whole year round. The study soil was typic Plintacualf. Field trials were set up involving three treatments: control, without lime addition, plus two different dolomite doses of 625 and 1250 kg.ha-1. Before lime addition, soil pH was 3.7; organic matter content was 2.14 % and cation exchange capacity (CEC) was 21.7 Cmolc kg -1. Soil was sampled at three different stages, first before sowing in aerobic conditions and them two more times in anaerobiosis, i.e. by bunch formation and flowering. Ninety-six soil samples per treatment were taken during each of the three sampling periods. NH4+-N, P and K were routinely determined. Spatial variability was assessed through the analysis of semivariograms. Next, kriging maps were constructed and compared for successive sampling dates. The statistical variability of NH4+-N, P and K over the study period was low to medium, depending on treatment and sampling dates. Lime application produced a positive effect on the NH4+ availability at sowing time. Increased Olsen-P availability during sowing and tillering could be also attributed to lime addition, but a negative effect of liming on P availability was observed during flowering. Mehlich I extractable K was in general low to very low and decreased from sowing to flowering, irrespective of lime treatment. Semivariogram analysis showed a rather strong spatial dependence of NH4+, P and K concentrations and this all over the three study periods and for the three lime treatments. Empirical semivariograms could be adjusted quite well by a nugget component (C0) plus a spatial structure (C1), which was described by spherical or exponential models with a correlation range between 40 and 85 m. Geostatistical analysis provided insight into possible processes responsible of the observed spatial variability patterns within the rice soil. Kriging was useful in mapping macronutrient variability allowing identifying microrregions with high or low values of the target soil properties clearly showing the presence of small scale variability for the study soil attributes within each liming treatment and during each of the three sampling dates. Also the position of patches with maxima and minima values changed between successive sampling dates illustrating the lack of temporal stability of the pattern of spatial distribution for the study soil attributes. Results illustrate the potential for applying the principles of precision agriculture to control spatiotemporal variability in rice fields.

  9. DIRECT AND INDIRECT EFFECTS OF MICROBES ON TECHNETIUM INSOLUBILIZATION IN PADDY FIELDS

    SciTech Connect

    Ishii, N.; Tagami, K.; Uchida, S.

    2003-02-27

    Direct and indirect effects of microorganisms on technetium insolubilization in water covering waterlogged soils were studied. Seven soils were waterlogged and then the water covering the soils were collected for further tracer experiments. The samples in contact with air were incubated with 95mTcO4--at 25 C for 4 to 5 days. After incubation, the samples were sequentially separated into four fractions: one insoluble fraction (> 0.2 {micro}m) and three soluble fractions (TcO4 -, cationic, and other forms). The radioactivity of 95mTc in each fraction was measured with a NaI (Tl) scintillation counter. The insolubility of Tc was observed in the untreated samples. The maximum insolubilization radioactivity was 37% of the total radioactivity in P38, which was collected from a paddy field, gray lowland soil. Microscopic observations revealed that bacteria were the dominant species in the insoluble fraction of P38. For the other samples, less than 9% of the Tc was found in insoluble form. In order to clarify biological and nonbiological factor affecting the insolubility, a reducing agent or nutrients were added to the P38 sample. The amount of insoluble Tc was enhanced by the addition of nutrients, while the addition of the reducing agent resulted in a dramatic decrease in the amount of the insoluble Tc. Most of the 95mTcO4 - added to the filtered or autoclaved samples was present in the form of the pertechnetate anion, even in P38. The filtered and autoclaved samples contained metabolites and dead cell particles, respectively. These materials, therefore, did not affect the physicochemical changes in Tc. These results suggest that specific bacteria having the ability to render Tc insoluble even under not strictly anaerobic conditions directly contribute to the insolubility of Tc.

  10. Partitioning of evapotranspiration using high-frequency water vapor isotopic measurement over a rice paddy field

    NASA Astrophysics Data System (ADS)

    Wei, Zhongwang; Yoshimura, Kei; Okazaki, Atsushi; Kim, Wonsik; Liu, Zhongfang; Yokoi, Masaharu

    2015-05-01

    Partitioning ecosystem evapotranspiration (ET) into soil evaporation (E) and transpiration (T) is crucial for understanding hydrological processes. In this study, by using high-frequency isotope measurements and continuous surface water measurements, we investigated the isotope ratios in soil-vegetation-atmosphere transfer and the physical mechanisms involved over a paddy field for a full growing season. The isotopic signals of ?ET, ?T, and ?E were determined by the Keeling plot method, surface water isotopic measurements, and the Craig-Gordon model, respectively. The fraction of transpiration in evapotranspiration (FT) ranged from 0.2 to 1, with an almost continuous increase in the early growing season and a relatively constant value close to 1 later in the year. The result was supported by FT derived from simulated T and eddy correlation measured ET. The seasonal change in the transpiration fraction could be described quite well as a function of the LAI (FT = 0.67LAI0.25, R2 = 0.80), implying that transpiration plays a dominant role in the soil-vegetation-atmosphere continuum during the growing season. The two end-member uncertainty analysis suggested that further improvement in the estimation of ?T and ?ET is necessary for partitioning evapotranspiration using the isotopic method. In the estimation of ?ET, the assumptions underlying Keeling plot method were rarely met and the uncertainty was quite large. A high frequency of precise isotopic measurements in surface water was also necessary for ?T estimation. Furthermore, special care must be taken concerning the kinetic fractionation parameter in the Craig and Gordon Equation for ?E estimation under low-LAI conditions. The results demonstrated the robustness of using isotope measurements for partitioning evapotranspiration.

  11. Assessment of reclaimed wastewater irrigation impacts on water quality, soil, and rice cultivation in paddy fields.

    PubMed

    Kang, Moon Seong; Kim, Sang Min; Park, Seung Woo; Lee, Jeong Jae; Yoo, Kyung H

    2007-03-01

    The objective of this research was to monitor and assess the impact of reclaimed wastewater irrigation on water quality, soil, and rice cultivation by comparing the effects of various wastewater treatment levels on the growth and yield of rice. A randomized complete block design was used for the application methods of the wastewater effluents to paddy rice, with five treatments and six replications. The treatments were: control with groundwater irrigation (GW); irrigation with polluted water form a nearby stream (SW); and three treatments of reclaimed wastewater irrigation at different treatment levels. The three levels of wastewater treatments included wastewater effluents: (i) directly from the wastewater plant (WW); (ii) after passing through a sand filter (WSF); and (iii) after passing a sand filter followed by an ultraviolet treatment (WSFUV). Each plot was 4 x 4 m and was planted with rice (Oryza sativa L.) in 2002 and 2003. The results indicated that irrigation of rice with reclaimed municipal wastewater caused no adverse effects on the growth and yield of rice. The chemical compositions of the rice from all plots were within the normal ranges of brown rice quality in Korea. No adverse effects were observed on chemical concentrations including the heavy metals Cu, As, Cd, Zn, Hg, and Pb, in either the brown rice or the field. The results showed that treated municipal wastewater can be safely used as an alternative water source for the irrigation of rice, although continued monitoring will be needed to determine the long-term effects with regard to soil contamination and other potential health concerns. PMID:17365313

  12. Partitioning of evapotranspiration through high frequency water vapor isotopic measurement over a paddy field

    NASA Astrophysics Data System (ADS)

    Wei, Z.; Okazaki, A.; Yokoi, M.; Kim, W.; Liu, Z.; Yoshimura, K.

    2014-12-01

    Partitioning the ecosystem evapotranspiration (ET) into soil evaporation (E) and transpiration (T) is challenging and crucial to understand hydrological processes in land. In this study, we deployed a recently developed partitioning technique using high frequency in-situ water vapor isotopic measurement and surface/soil water sampling over a paddy field near Tokyo, Japan for a full growing season. We partitioned ET via estimating the isotopic signal of ET (?ET) and its two components, i.e. T (?T) and E (?E). ?ET was determined through the use of Keeling plot. Estimates of ?T was obtained by direct measurement of surface/soil isotopic measurement assuming a steady state of transpiration. ?E was estimated using the Craig-Gordon model in combination with surface and vapor water isotopic measurement. The T/ET ranged approximately from 0.3 to 1, almost kept increasing during early growing season, then kept a relative constant value close to 1 after that. T/ET was strongly controlled by green leaf area index (LAI) in day to day time scale (y=0.14ln(x)+0.66; R-squared=0.62). We also investigated the uncertainties in estimating these three terms (?ET, ?T, and ?E) and their effect on ET partitioning. The uncertainty analysis showed the uncertainty from ?E had a minor impact on the ET partitioning but mainly controlled by uncertainty from ?T and ?ET estimations. During early growing season, ET partitioning uncertainty was mainly due to uneven spatial distribution of surface water isotope (?T). As LAI increases, the impact of ?ET uncertainty became much larger than the other two terms. The results demonstrated the robustness of using isotope measurements for partitioning evapotranspiration.

  13. Understanding the ecological background of rice agriculture on the Ningshao Plain during the Neolithic Age: pollen evidence from a buried paddy field at the Tianluoshan cultural site

    NASA Astrophysics Data System (ADS)

    Li, Chunhai; Zheng, Yunfei; Yu, Shiyong; Li, Yongxiang; Shen, Huadong

    2012-03-01

    The progressive rise of atmospheric CH4 level since 5 ka has been hypothesized to result from human agricultural activities that turned forested lands, which would otherwise be a carbon sink, into paddy fields. Increasing numbers of Neolithic cultural sites unearthed in coastal eastern China, providing unique opportunities to test this hypothesis. Here, we present detailed pollen data from a buried paddy field at Tianluoshan cultural site on the Ningshao Plain, eastern China, to reconstruct the ecological conditions associated with the establishment of paddy fields. Stratigraphic data, radiocarbon ages, and pollen analyses show that vegetation underwent six phases of evolution and paddy fields were developed from 7000 to 4200 cal. yr BP. We found no evidence of slash-and-burn agriculture at the study site. Together with no presence of the irrigation system, our pollen data suggest the paddy fields at this site originated from wetlands. Hence, our findings do not support the hypothesis that anthropogenic-induced deforestation play ed a significant role in the rise of the atmospheric CH4 rise since the middle Holocene.

  14. Effect of ammonium-based, non-sulfate fertilizers on CH 4 emissions from a paddy field with a typical Chinese water management regime

    NASA Astrophysics Data System (ADS)

    Dong, Haibo; Yao, Zhisheng; Zheng, Xunhua; Mei, Baoling; Xie, Baohua; Wang, Rui; Deng, Jia; Cui, Feng; Zhu, Jianguo

    2011-02-01

    The effects of ammonium-based, non-sulfate fertilizers, such as urea and/or ammonium phosphate (NH 4H 2PO 4), on methane (CH 4) emissions from paddy rice fields deserve attention, as they are being used increasingly for rice cultivation. A four-year field campaign was conducted in the Yangtze River Delta from 2004 to 2007 to assess the effects of different application rates of urea plus NH 4H 2PO 4 on the CH 4 emissions from a paddy rice field. The experimental field was under a typical Chinese water regime that follows a flooding-midseason drainage-reflooding-moist irrigation mode. Over the course of four years, the mean cumulative CH 4 emissions during the rice seasons were 221, 136 and 112 kg C ha -1 for nitrogen addition rates of 0, 150 and 250 kg N ha -1, respectively. Compared to the treatment without nitrogen amendments, the 150 kg N ha -1 decreased the CH 4 emissions by 6-59% ( P < 0.01 in one year, but not statistically significant in the others). When the addition rate was further increased to 250 kg N ha -1, the CH 4 emissions were significantly reduced by 35-53% ( P < 0.01) compared to the no-nitrogen treatment. Thus, an addition rate of 250 kg N ha -1, which has been commonly adopted in the delta region in the past two decades, can be regarded as an effective management measure as regards increasing rice yields while reducing CH 4 emissions. Considering that doses of ammonium-based, non-sulfate fertilizers higher than 250 kg N ha -1 currently are, and most likely will continue to be, commonly applied for paddy rice cultivation in the Yangtze River Delta and other parts of China, the inhibitory effects on CH 4 emissions from rice production are expected to be pronounced at the regional scale. However, further studies are required to provide more concrete evidence about this issue. Moreover, further research is needed to determine whether N management measures are also effective in view of net greenhouse gas fluxes (including CH 4, nitrous oxide, ammonia emissions, nitrate leaching and N loss from denitrification).

  15. Differences in ecological impacts of systemic insecticides with different physicochemical properties on biocenosis of experimental paddy fields.

    PubMed

    Hayasaka, Daisuke; Korenaga, Tomoko; Snchez-Bayo, Francisco; Goka, Koichi

    2012-01-01

    The environmental risks of pesticides are typically determined by laboratory single-species tests based on OECD test guidelines, even if biodiversity should also be taken into consideration. To evaluate how realistic these assessments are, ecological changes caused by the systemic insecticides imidacloprid and fipronil, which have different physicochemical properties, when applied at recommended commercial rates on rice fields were monitored using experimental paddy mesocosms. A total of 178 species were observed. There were no significant differences in abundance of crop arthropods among the experimental paddies. However, zooplankton, benthic and neuston communities in imidacloprid-treated field had significantly less abundance of species than control and fipronil fields. Significant differences in abundance of nekton community were also found between both insecticide-treated paddies and control. Influences on the growth of medaka fish were also found in both adults and their fries. Both Principal Response Curve analysis (PRC) and Detrended Correspondence Analysis (DCA) showed the time series variations in community structure among treatments, in particular for imidacloprid during the middle stage of the experimental period. These results show the ecological effect-concentrations (LOEC~1?g/l) of these insecticides in mesocosms, especially imidacloprid, are clearly different from their laboratory tests. We suggest that differences in the duration of the recovery process among groups of species are due to different physicochemical properties of the insecticides. Therefore, realistic prediction and assessment of pesticide effects at the community level should consider not only the sensitivity traits and interaction among species but also the differences in physicochemical characteristics of each pesticide. PMID:21877228

  16. Arsenic concentrations in paddy soil and rice and health implications for major rice-growing regions of Cambodia.

    PubMed

    Seyfferth, Angelia L; McCurdy, Sarah; Schaefer, Michael V; Fendorf, Scott

    2014-05-01

    Despite the global importance of As in rice, research has primarily focused on Bangladesh, India, China, and the United States with limited attention given to other countries. Owing to both indigenous As within the soil and the possible increases arising from the onset of irrigation with groundwater, an assessment of As in rice within Cambodia is needed, which offers a "base-case" comparison against sediments of similar origin that comprise rice paddy soils where As-contaminated water is used for irrigation (e.g., Bangladesh). Here, we evaluated the As content of rice from five provinces (Kandal, Prey Veng, Battambang, Banteay Meanchey, and Kampong Thom) in the rice-growing regions of Cambodia and coupled that data to soil-chemical factors based on extractions of paddy soil collected and processed under anoxic conditions. At total soil As concentrations ranging 0.8 to 18 ?g g(-1), total grain As concentrations averaged 0.2 ?g g(-1) and ranged from 0.1 to 0.37 with Banteay Meanchey rice having significantly higher values than Prey Veng rice. Overall, soil-extractable concentrations of As, Fe, P, and Si and total As were poor predictors of grain As concentrations. While biogeochemical factors leading to reduction of As(V)-bearing Fe(III) oxides are likely most important for predicting plant-available As, husk and straw As concentrations were the most significant predictors of grain-As levels among our measured parameters. PMID:24712677

  17. Interannual Variability in Growing Season Carbon Budget at a Customarily Cultivated Rice Paddy Field in Central Japan

    NASA Astrophysics Data System (ADS)

    Mano, M.; Miyata, A.; Nagai, H.; Yamada, T.; Ono, K.; Han, G.; Yoshikoshi, H.; Saito, M.

    2004-12-01

    Rice paddy fields in eastern Asian countries are irrigated during most of the growing season. Since flooded paddy fields are favorable for methanogenesis, it is necessary to measure both carbon dioxide flux and methane flux in order to estimate carbon budget of the paddy fields. As one of AsiaFlux network sites we continue long-term measurements of carbon dioxide and methane fluxes at a customarily cultivated paddy field in central Japan. At the study site rice is transplanted in early May and harvested in early or middle September. We are measuring carbon dioxide flux by the eddy covariance method and methane flux by the gradient method. In 2003 we had the coolest summer in these 10 years, while the 2004 summer was the third warmest since 1946: Air temperatures averaged from June to August in 2003 and 2004 were 0.6 C below and 1.3 C above the 30-year average, respectively. Carbon dioxide flux showed distinct seasonal variation with rice growth. In 2004, net daily carbon dioxide uptake by the ecosystem became obvious in late May, increased to the maximum daily uptake of 11 gC m-2 d-1 in July, and then decreased to nearly zero at the end of August. In 2003, carbon dioxide uptake showed temporary decrease in mid-growing season because of small amount of solar radiation and low temperature. The sum of carbon dioxide uptake by the ecosystem from the transplanting to the end of August was 443 gC m-2 in 2003, and 553 gC m-2 in 2004. Methane emission in 2004 started a month after transplanting, increased gradually and reached midsummer peak of 331 mgC m-2 d-1 in late July with a flush of methane at the final drainage. The seasonal variation of methane flux in 2003 was generally similar to that in 2004, but flushes of methane at midsummer drainages as well as final drainage were observed more distinctly than in 2004. Despite small amount of methane flushes, seasonal methane emission in 2004 was greater than that in 2003 by 2 gC m-2. Higher soil temperature and larger supply of photosynthate in 2004 presumably enhanced methane production in soil and resulted in larger methane emission. The ratio of methane emission to carbon dioxide uptake was about 4% and showed little difference between 2003 and 2004.

  18. Monitoring and Analysis of Nonpoint Source Pollution - Case study on terraced paddy fields in an agricultural watershed

    NASA Astrophysics Data System (ADS)

    Chen, Shih-Kai; Jang, Cheng-Shin; Yeh, Chun-Lin

    2013-04-01

    The intensive use of chemical fertilizer has negatively impacted environments in recent decades, mainly through water pollution by nitrogen (N) and phosphate (P) originating from agricultural activities. As a main crop with the largest cultivation area about 0.25 million ha per year in Taiwan, rice paddies account for a significant share of fertilizer consumption among agriculture crops. This study evaluated the fertilization of paddy fields impacting return flow water quality in an agricultural watershed located at Hsinchu County, northern Taiwan. Water quality monitoring continued for two crop-periods in 2012, around subject to different water bodies, including the irrigation water, drainage water, and shallow groundwater. The results indicated that obviously increasing of ammonium-N, nitrate-N and TP concentrations in the surface drainage water were observed immediately following three times of fertilizer applications (including basal, tillering, and panicle fertilizer application), but reduced to relatively low concentrations after 7-10 days after each fertilizer application. Groundwater quality monitoring showed that the observation wells with the more shallow water depth, the more significant variation of concentrations of ammonium-N, nitrate-N and TP could be observed, which means that the contamination potential of nutrient of groundwater is related not only to the impermeable plow sole layer but also to the length of percolation route in this area. The study also showed that the potential pollution load of nutrient could be further reduced by well drainage water control and rational fertilizer management, such as deep-water irrigation, reuse of return flow, the rational application of fertilizers, and the SRI (The System of Rice Intensification) method. The results of this study can provide as an evaluation basis to formulate effective measures for agricultural non-point source pollution control and the reuse of agricultural return flow. Keywords:Chemical fertilizer, Nitrogen, Phosphorus, Paddy field, Non-point source pollution.

  19. Sources of methane in China: A program to estimate emissions from rice paddy fields, bio-gas pits, and urban areas: Annual progress report

    SciTech Connect

    Rasmussen, R.A.; Khalil, M.A.K.

    1987-11-30

    We are measuring methane from rice paddy fields and bio-gas pits. The project has produced new results that we are using to sharply focus the present study. We measured ambient concentrations at Minqin, Beijing, and Chendu. We obtained flux measurements from bio-gas pits, and flux measurements from rice paddy fields. Minqin is a background site with no large local sources of methane such as rice fields or urban areas. It serves as control for the experiment. Beijing is representative of a large industrialized Chinese city not affected by rice agriculture but heavily dependent on burning coal for cooking and heating. Chendu is in the heart of the rice producing areas of China where rice paddies cover millions of acres and methane from bio-gas pits is an important source of energy. Further progress was impeded by a lack of a formal agreement between the US and PRC, which was not signed until August 1987. 9 figs.

  20. Environmental evaluation of coexistence of denitrifying anaerobic methane-oxidizing archaea and bacteria in a paddy field.

    PubMed

    Ding, Jing; Fu, Liang; Ding, Zhao-Wei; Lu, Yong-Ze; Cheng, Shuk H; Zeng, Raymond J

    2016-01-01

    The nitrate-dependent denitrifying anaerobic methane oxidation (DAMO) process, which is metabolized together by anaerobic methanotrophic archaea and NC10 phylum bacteria, is expected to be important for the global carbon and nitrogen cycles. However, there are little studies about the existence of this process and the functional microbes in environments. Therefore, the coexistence of DAMO archaea and bacteria in a paddy field was evaluated in this study. Next-generation sequencing showed that the two orders, Methanosarcinales and Nitrospirales, to which DAMO archaea and DAMO bacteria belong, were detected in the four soil samples. Then the in vitro experiments demonstrated both of nitrite- and nitrate-dependent DAMO activities, which confirmed the coexistence of DAMO archaea and DAMO bacteria. It was the first report about the coexistence of DAMO archaea and bacteria in a paddy field. Furthermore, anammox bacteria were detected in two of the four samples. The in vitro experiments did not show anammox activity in the initial period but showed low anammox activity after 20days' enrichment. These results implicated that anammox bacteria may coexist with DAMO microorganisms in this field, but at a very low percentage. PMID:26394860

  1. Application of micrometeorological approaches to measure methane exchange in a dry paddy field in the western coast of Korea.

    PubMed

    Kim, Ki-Hyun; Kim, Min-Young; Kim, Joon

    2005-06-01

    The exchange processes of CH4 were investigated in a paddy field in the Hari area of Kang Hwa Island over an 8 day period in late April 2002. The quantification of CH4 fluxes was made under dry field condition of early spring by concurrently measuring its concentrations (at the two heights of 1 and 5 m) and the relevant micrometeorological parameters. To help elucidate the factors determining the mobilization characteristics of CH4, the results of our measurement data were examined using a number of approaches. The results of the trajectory analysis indicated that its concentration changed very sensitively with the influence of different source types, as seen from the air mass movement patterns. The concentrations and fluxes of methane, when examined over this short-term scale, showed moderately strong patterns across 24h period in which higher values tend to occur during morning or evening. The overall results of our field measurements suggest that CH4 exchange processes in the paddy area proceeded in a fairly complicated manner. The study area behaved as a net source of CH4 to the atmosphere with a net daily emission rate of 3.6 mgm(-2) despite the fact that downward deposition was observed more frequently than upward emission. PMID:15894047

  2. Combination system of full-scale constructed wetlands and wetland paddy fields to remove nitrogen and phosphorus from rural unregulated non-point sources.

    PubMed

    Sun, Haijun; Zhang, Hailin; Yu, Zhimin; Wu, Jiasen; Jiang, Peikun; Yuan, Xiaoyan; Shi, Weiming

    2013-12-01

    Constructed wetlands (CWs) have been used effectively to remove nitrogen (N) and phosphorus (P) from non-point sources. Effluents of some CWs were, however, still with high N and P concentrations and remained to be pollution sources. Widely distributed paddy fields can be exploited to alleviate this concern. We were the first to investigate a combination system of three-level CWs with wetland paddy fields in a full scale to remove N and P from rural unregulated non-point sources. The removal efficiencies (REs) of CWs reached 57.3 % (37.4-75.1 %) for N and 76.3 % (62.0-98.4 %) for P. The CWs retained about 1,278 kg N ha(-1) year(-1) and 121 kg P ha(-1) year(-1). There was a notable seasonal change in REs of N and P, and the REs were different in different processing components of CWs. The removal rates of wetland paddy fields adopt "zero-drainage" water management according to local rainfall forecast and physiological water demand of crop growth reached 93.2 kg N ha(-1) year(-1) and 5.4 kg P ha(-1) year(-1). The rice season had higher potential in removing N and P than that in the wheat season. The whole combined system (0.56 ha CWs and 5.5 ha wetland paddy fields) removed 1,790 kg N year(-1) and 151 kg P year(-1), which were higher than those from CWs functioned alone. However, another 4.7-ha paddy fields were needed to fully remove the N and P in the effluents of CWs. The combination of CWs and paddy fields proved to be a more efficient nutrient removal system. PMID:23703587

  3. Mosquitoes and other aquatic insects in fallow field biotopes and rice paddy fields.

    PubMed

    Ohba, S Y; Matsuo, T; Takagi, M

    2013-03-01

    Fallow field biotopes that develop from abandoned rice fields are man-made wetlands that provide new habitats for various aquatic animals. Although consideration of such biotopes generally focuses on their positive aspects, this study evaluated the negative aspects of establishing fallow field biotopes with regard to mosquito breeding sites. To determine whether fallow field biotopes become breeding habitats for vector mosquitoes, we evaluated mosquito fauna in fallow field biotopes and adjacent rice fields. We found larvae of Anopheles lesteri, Anopheles sinensis and Culex tritaeniorhynchus (all: Diptera: Culicidae) in the biotopes. Although abundances of mosquito larvae in the biotopes and rice fields were statistically similar, mosquito abundances in rice fields increased dramatically in August when the water level reduced after the rainy season. The abundance and variety of the mosquitoes' natural predators were greater in biotopes than in rice fields because the former are a permanent and stable aquatic environment. A generalized linear mixed model showed a negative effect of predator diversity on mosquito larvae abundance in both habitats. Although fallow field biotopes become breeding habitats for vector mosquitoes, establishing biotopes from fallow fields in order to protect various aquatic animals, including mosquito insect predators, may help to control mosquito breeding. PMID:23167444

  4. Liquid chromatographic-diode-array detection multiresidue determination of rice herbicides in drinking and paddy-field water.

    PubMed

    Roehrs, Rafael; Zanella, Renato; Pizzuti, Ionara; Adaime, Martha B; Pareja, Lucía; Niell, Silvina; Cesio, María V; Heinzen, Horacio

    2009-01-01

    A sensitive, rapid, and simple multiresidue method for the simultaneous determination of six postemergence herbicides currently used in rice cultivation--metsulfuron methyl, bensulfuron methyl, pyrazosulfuron ethyl, bentazone, bispyribac sodium, and cyhalofop butyl--in drinking and paddy-field water is presented. Water samples were extracted with solid-phase extraction cartridges. Final determination was made by LC with diode-array detection. The extraction efficiencies of C18 and HLB cartridges were compared. The average recovery obtained for these compounds for the lowest spiked level (0.1 microg/L) varied from 70 to 122% for C18 and 75-119% for HLB, with RSDs of 11 and 8.3%, respectively. The method had good linearity, and the lower detection limit for the pesticides studied varied from 0.03 to 0.04 microg/L. The proposed method was also tested in paddy-field water, with recovery studies giving good results with low RSDs at 1.0 microg/L. PMID:19714989

  5. Phylogenetic and functional diversity of denitrifying bacteria isolated from various rice paddy and rice-soybean rotation fields.

    PubMed

    Tago, Kanako; Ishii, Satoshi; Nishizawa, Tomoyasu; Otsuka, Shigeto; Senoo, Keishi

    2011-01-01

    Denitrifiers can produce and consume nitrous oxide (N(2)O). While little N(2)O is emitted from rice paddy soil, the same soil produces N(2)O when the land is drained and used for upland crop cultivation. In this study, we collected soils from two types of fields each at three locations in Japan; one type of field had been used for continuous cultivation of rice and the other for rotational cultivation of rice and soybean. Active denitrifiers were isolated from these soils using a functional single-cell isolation method, and their taxonomy and denitrifying properties were examined. A total of 110 denitrifiers were obtained, including those previously detected by a culture-independent analysis. Strains belonging to the genus Pseudogulbenkiania were dominant at all locations, suggesting that Pseudogulbenkiania denitrifiers are ubiquitous in various rice paddy soils. Potential denitrifying activity was similar among the strains, regardless of the differences in taxonomic position and soil of origin. However, relative amounts of N(2) in denitrification end products varied among strains isolated from different locations. Our results also showed that crop rotation had minimal impact on the functional diversity of the denitrifying strains. These results indicate that soil and other environmental factors, excluding cropping systems, could select for N(2)-producing denitrifiers. PMID:21487200

  6. [Effects of labor-saving rice cultivation modes on the diversity of potential weed communities in paddy fields].

    PubMed

    Li, Shu-Shun; Qiang, Sheng; Jiao, Jun-Sen

    2009-10-01

    Aimed to understand the effects of various labor-saving rice cultivation modes on the diversity of potential weed communities in paddy fields, an investigation was made on the quantitative characteristics of the weed seed bank under dry direct seeding, water direct seeding, seedling throwing, mechanized-transplanting, wheat-rice interplanting, and conventional manual transplanting. Under dry direct seeding, the density of the weed seed bank was up to 228,416 seeds x m(-2), being significantly higher than that under the other five cultivation modes. Wheat-rice interplanting ranked the second place. The seed density of sedge weeds under dry direct seeding and that of broad leaf weeds under wheat-rice interplanting were significantly higher than the seed densities of various kinds of weeds under other cultivation modes. Conventional manual transplanting mode had the highest species richness, with Margalef index being 1.86. The diversity indices, including Shannon-Wiener index, Gini index, and Pielou evenness index under water direct seeding and wheat-rice interplanting were higher than those under other cultivation modes. Comparing with conventional manual transplanting mode, the other five cultivation modes had their own dominant species in the potential weed community, and thereby, different labor-saving rice cultivation modes should be applied by turns to control the potential weed community in paddy fields effectively and persistently. PMID:20077702

  7. [Modeling the ammonia volatilization from common urea and controlled releasing urea fertilizers in paddy soil of Taihui region of China by Jayaweera-Mikkelsen model].

    PubMed

    Li, Hui-lin; Han, Yong; Cai, Zu-cong

    2008-04-01

    The ammonia volatilization on the Typic Gleyi-stagnic Anthrosol with application of common urea and controlled release urea (LP-S100) fertilizers in the rice seasons in paddy soil of Taihui region of China was modeled by Jayaweera-Mikkelsen model. Results showed great difference of ammonia volatilization from two type fertilizers was detected with lysimeter experiment in the rice season. Nitrogen loss via ammonia volatilization after common urea application with conventional ways was 29%-35%, while only 5% of controlled release urea-N was volatilized. The Jayaweera-Mikkelsen model was over estimated the total amount of ammonia volatilization in the whole season, and great deviation from the measured data was obvious for the higher volatilization from common urea fertilizer. The estimated data were 2.95-4.19 times of the measures one for common urea treatments, while they were 1.19-1.40 times of those measured for LP-S100 treatments. The order of magnitude quotient was one of the indicators to evaluate the model estimation. The value of it was 0.8, which indicated the estimation of the model need improvement. Though sensitive analysis for the five parameters in the model was tested and amended the parameter of the concentration of NH4+ -N, a limited term was inducted in the model operation. The amended model got better results as the ratio of estimation to measured data was decreased to 1.12-1.28. The alga activity in the paddy field influenced ammonia volatilization and might make the failure of the model estimation of the original model. PMID:18637360

  8. [Cultivated landscape pattern change due to the rice paddy expansion in Northeast China: A case study in Fujin].

    PubMed

    Du, Guo-ming; Pan, Tao; Yin, Zhe-rui; Dong, Jin-wei

    2015-01-01

    On the background of global climate change, agriculture in North China has been experiencing substantial modifications to adapt to the ongoing regional warming. One of the most significant land use change is the conversation from upland cropland to paddy cropland, which is characterized by the dramatic changes of agricultural landscape pattern. In this study, we generated land use maps in Fujin City in 2000 and 2013 by using Landsat TM imagery, and analyzed the landscape pattern changes (cropland composite, special distribution, and patch characteristics, etc.) of croplands by using landscape indices and empirical approach. The results indicated a rapid cropland increase from 512400 hm2(reclamation ratio 60.4%) in 2000 to 699300 hm2(reclamation 82.4%) in 2013, especially, the paddy cropland proportion in the total cropland increased from 6.7% to more than half (54.1%) , that is, the agricultural land use mode had changed from the initial stage of paddy agriculture to the intermediate stage. The reclamation area and common agricultural area showed different paddy agriculture development characteristics: in 2000, the paddy field ratios in the common agricultural area and reclamation area were similar (5.5% and 8.3% respectively); however, in 2013, the paddy field ratio in the common agricultural area (33.6%) was significantly lower than that in reclamation area (83.4%). In 2000, the total number of cropland patches was 2311 in the study, including 1010 patches from the common agricultural area and 1301 patches from the reclamation area. The coefficient of variation (CV) , and shape index (SI) of cropland patches in upland cropland were always higher than in paddy cropland. Upland cropland had larger mean patch size with the plaque area index above 60% and higher connectivity. The patch density of upland cropland was lower than that of paddy cropland. In the conversions to the intermediate and later stages of paddy agriculture, the patch number of cropland increased rapidly with different rates in upland and paddy croplands. The CV of paddy cropland patches increased while fluctuated in upland cropland. The SI of paddy cropland increased first and then decreased, while that of upland cropland decreased continuously. The mean patch sizes of paddy and upland croplands increased and decreased respectively. The patch density increased in upland cropland while decreased in paddy cropland. The connectivity of upland cropland decreased while that of paddy cropland increased. The staggered degree of both cropland types was enhanced from 2000 to 2013. In general, the paddy agriculture was becoming the dominated agricultural land use mode in the study area while the convesions had different rates in two administrative regions (reclamation and common agricultural areas). PMID:25985672

  9. Classification of the field drainage and wetness by using aerial photographs in irrigated paddy rice and upland crop rotation field

    NASA Astrophysics Data System (ADS)

    Ritsuko, Fuchiyama; Takeshi, Ota; Michikazu, Fukuhara

    2013-04-01

    Information about field drainage/wetness is useful for farmers to plan field management in irrigated paddy rice and upland crop rotation field. Wet injury is a loss to farmers in upland crop farming, experience is the most common way of approaching this risk. In this study, we propose to provide efficient and objective classify and mapping method of such field drainage information using aerial photography. Study area (500 ha) is located in Ibaraki Prefecture, Japan. In this area, we acquired multitemporalaerial photographs (ADS40) three times after the rain on winter. Digital Number (DN) of Blue, Green, Red and Near Infrared band were used to analyze. To analyze the relationship between each band DN and soil moisture, mass soil water content of 0-5cm depth was determined using the 100ml core sample at 22 sites on shooting date. And to verify our classification of the drainage and wetness, volumetric soil water content was monitored using TDR sensor (Decagon, ECH2O) at 5cm, 10cm and 20 cm depth at 16 sites. First, optimum band was selected from correlation analysis of mass soil water content and DN. Next, optimum band DN of three aerial photographs at field area was grouped by cluster analysis (ISODATA method). We found a good positive correlation between mass soil water content and red band DN, by selecting optimum bands. 17 groups were found from cluster analysis using three aerial photographs with different soil moisture conditions. After that, we classified them into five levels of field drainage based on red band DN values. We generated maps of drainage/wetness based on these results. We compared volumetric soil water content at the monitoring site for the "Dry" and "Wet" points, water was drained quickly at the "Dry" site but it needed more than 1 week the volume soil water content back to revert before rain at the "Wet" site. By the result, we positively verified our classification. We used three aerial photographs with different soil moisture conditions as proxy of top soil moisture content. It is thought to be an indication of drainage/wetness. Generally, estimating soil water content at field scale from a remote sensing data was difficult. But this method can classify the study area relatively. We think it is enough as a soil information for farmers.

  10. Temporal variations in arsenic uptake by rice plants in Bangladesh: the role of iron plaque in paddy fields irrigated with groundwater

    PubMed Central

    Garnier, J.-M.; Travassac, F.; Lenoble, V.; Rose, J.; Zheng, Y.; Hossain, M.S.; Chowdhury, S. H.; Biswas, A. K.; Ahmed, K.M.; Cheng, Z.; van Geen, A.

    2010-01-01

    The transfer of arsenic to rice grains is a human health issue of growing relevance in regions of southern Asia where shallow groundwater used for irrigation of paddy fields is elevated in As. In the present study, As and Fe concentrations in soil water and in the roots of rice plants, primarily the Fe plaque surrounding the roots, were monitored during the 4-month growing season at two sites irrigated with groundwater containing ~130 μg/L As and two control sites irrigated with water containing <15 μg/L As. At both sites irrigated with contaminated water, As concentrations in soil water increased from <10 μg/L to >1000 μg/L during the first five weeks of the growth season and then gradually declined to <10 μg/L during the last five weeks. At the two control sites, concentrations of As in soil water never exceeded 40 μg/L. At both contaminated sites, the As content of roots and Fe plaque rose to 1000-1500 mg/kg towards the middle of the growth season. It then declined to ~300 mg/kg towards the end, a level still well above As concentration of ~100 mg/kg in roots and plaque measured throughout the growing season at the two control sites. These time series, combined with simple mass balance considerations, demonstrate that the formation of Fe plaque on the roots of rice plants by micro-aeration significant limits uptake of As by rice plants grown in paddy fields. Large variations in the As and Fe content of plant stems at two of the sites irrigated with contaminated water and one of the control sites were also recorded. The origin of these variations, particularly during the last month of the growth season, need to be better understood because they are likely to influence uptake of As in rice grains. PMID:20576285

  11. Homologous expression of cytosolic dehydroascorbate reductase increases grain yield and biomass under paddy field conditions in transgenic rice (Oryza sativa L. japonica).

    PubMed

    Kim, Young-Saeng; Kim, Il-Sup; Bae, Mi-Jung; Choe, Yong-Hoe; Kim, Yul-Ho; Park, Hyang-Mi; Kang, Hong-Gyu; Yoon, Ho-Sung

    2013-06-01

    Dehydroascorbate reductase (DHAR, EC 1.8.5.1) maintains redox pools of ascorbate (AsA) by recycling oxidized AsA to reduced AsA. To investigate whether DHAR affects rice yield under normal environmental conditions, cDNA-encoding DHAR (OsDHAR1) was isolated from rice and used to develop OsDHAR1-overexpressing transgenic rice plants, under the regulation of a maize ubiquitin promoter. Incorporation and expression of the transgene in transgenic rice plants was confirmed by genomic polymerase chain reaction (PCR), semi-quantitative reverse transcription PCR (RT-PCR), western blot, and enzyme activity. The expression levels were at least twofold higher in transgenic (TG) rice plants than in control wild-type (WT) rice plants. In addition, OsDHAR1-overexpression in seven-independent homologous transgenic plants, as compared to WT plants, increased photosynthetic capacity and antioxidant enzyme activities under paddy field conditions, which led to an improved AsA pool and redox homeostasis. Furthermore, OsDHAR1 overexpression significantly improved grain yield and biomass due to the increase of culm and root weights and to enhance panicle and spikelet numbers in the same seven independent TG rice plants during the farming season (2010 and 2011) in South Korea. The OsDHAR protein contained the redox-active site (Cys20), as well as the conserved GSH-binding region, GSH-binding motif, glutathione-S-transferase (GST) N-terminal domain, C-terminal domain interface, and GST C-terminal domain. Therefore, our results indicate that OsDHAR1 overexpression, capable of functioning in AsA recycling, and protein folding increases environmental adaptation to paddy field conditions by the improving AsA pool and redox homeostasis, which enhances rice grain yield and biomass. PMID:23519921

  12. Emissions of CH4 and N2O under Different Tillage Systems from Double-Cropped Paddy Fields in Southern China

    PubMed Central

    Zhang, Hai-Lin; Bai, Xiao-Lin; Xue, Jian-Fu; Chen, Zhong-Du; Tang, Hai-Ming; Chen, Fu

    2013-01-01

    Understanding greenhouse gases (GHG) emissions is becoming increasingly important with the climate change. Most previous studies have focused on the assessment of soil organic carbon (SOC) sequestration potential and GHG emissions from agriculture. However, specific experiments assessing tillage impacts on GHG emission from double-cropped paddy fields in Southern China are relatively scarce. Therefore, the objective of this study was to assess the effects of tillage systems on methane (CH4) and nitrous oxide (N2O) emission in a double rice (Oryza sativa L.) cropping system. The experiment was established in 2005 in Hunan Province, China. Three tillage treatments were laid out in a randomized complete block design: conventional tillage (CT), rotary tillage (RT) and no-till (NT). Fluxes of CH4 from different tillage treatments followed a similar trend during the two years, with a single peak emission for the early rice season and a double peak emission for the late rice season. Compared with other treatments, NT significantly reduced CH4 emission among the rice growing seasons (P<0.05). However, much higher variations in N2O emission were observed across the rice growing seasons due to the vulnerability of N2O to external influences. The amount of CH4 emission in paddy fields was much higher relative to N2O emission. Conversion of CT to NT significantly reduced the cumulative CH4 emission for both rice seasons compared with other treatments (P<0.05). The mean value of global warming potentials (GWPs) of CH4 and N2O emissions over 100 years was in the order of NTregions. PMID:23750250

  13. Emissions of CH4 and N2O under different tillage systems from double-cropped paddy fields in Southern China.

    PubMed

    Zhang, Hai-Lin; Bai, Xiao-Lin; Xue, Jian-Fu; Chen, Zhong-Du; Tang, Hai-Ming; Chen, Fu

    2013-01-01

    Understanding greenhouse gases (GHG) emissions is becoming increasingly important with the climate change. Most previous studies have focused on the assessment of soil organic carbon (SOC) sequestration potential and GHG emissions from agriculture. However, specific experiments assessing tillage impacts on GHG emission from double-cropped paddy fields in Southern China are relatively scarce. Therefore, the objective of this study was to assess the effects of tillage systems on methane (CH4) and nitrous oxide (N2O) emission in a double rice (Oryza sativa L.) cropping system. The experiment was established in 2005 in Hunan Province, China. Three tillage treatments were laid out in a randomized complete block design: conventional tillage (CT), rotary tillage (RT) and no-till (NT). Fluxes of CH4 from different tillage treatments followed a similar trend during the two years, with a single peak emission for the early rice season and a double peak emission for the late rice season. Compared with other treatments, NT significantly reduced CH4 emission among the rice growing seasons (P<0.05). However, much higher variations in N2O emission were observed across the rice growing seasons due to the vulnerability of N2O to external influences. The amount of CH4 emission in paddy fields was much higher relative to N2O emission. Conversion of CT to NT significantly reduced the cumulative CH4 emission for both rice seasons compared with other treatments (P<0.05). The mean value of global warming potentials (GWPs) of CH4 and N2O emissions over 100 years was in the order of NTregions. PMID:23750250

  14. Carbon decomposition process of the residual biomass in the paddy soil of a single-crop rice field

    NASA Astrophysics Data System (ADS)

    Okada, K.; Iwata, T.

    2014-12-01

    In cultivated fields, residual organic matter is plowed into soil after harvest and decaying in fallow season. Greenhouse gases such as CO2 and CH4 is generated by the decomposition of the substantial organic matter and released into the atmosphere. In some fields, open burning is carried out by tradition, when carbon in residual matter is released into atmosphere as CO2. However, burning effect on carbon budget between crop lands and atmosphere is not entirely considered yet. In this study, coarse organic matter (COM) in paddy soil of a single-crop rice field was sampled on regular intervals between January, 2011 and August, 2014 The amount of carbon release from residual matter was estimated by analyzing of the variations in carbon content of COM. Effects of soil temperature (Ts) and soil water content (SWC) at the paddy field on the rate of carbon decomposition was investigated. Though decreasing rate of COM was much smaller in winter season, it is accelerated at the warming season between April and June every year. Decomposition was resisted for next rice cultivated season despite of highest soil temperature. In addition, the observational field was divided into two areas, and three time open burning experiments were conducted in November, 2011, 2012, and 2013. In each year, three sampling surveys, or plants before harvest and residuals before and after the burning experiment, were done. From these surveys, it is suggested that about 482% of carbon contents of above-ground plant was yield out as grain by harvest, and about 272% of carbon emitted as CO2 by burning. Carbon content of residuals plowed into soil after the harvest was estimated 2931 and 22036gC/m2 in no-burned and burned area, respectively, based on three-years average. It is estimated that 70 and 60% of the first input amount of COM was decomposed after a year in no-burned and burned area, respectively.

  15. Simultaneous enantioselective determination of phenylpyrazole insecticide flufiprole and its chiral metabolite in paddy field ecosystem by ultra-high performance liquid chromatography/tandem mass spectrometry.

    PubMed

    Li, Jing; Zhang, Yuting; Cheng, Youpu; Yuan, Shankui; Liu, Lei; Shao, Hui; Li, Hui; Li, Na; Zhao, Pengyue; Guo, Yongze

    2016-03-20

    A novel and sensitive ultra-high performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous enantioselective determination of flufiprole and its hydrolysis metabolite in paddy field ecosystem. The separation and determination were performed using reversed-phase chromatography on a novel cellulose chiral stationary phase, a Lux Cellulose-4 (150mm×2.0mm) column, under isocratic conditions at 0.25mL/min flow rate. The effects of other four different polysaccharide-based chiral stationary phases (CSPs) on the separation and simultaneous enantioseparation of the two target compounds were also evaluated. The elution orders of the eluting enantiomers were identified by an optical rotation detector. Modified QuEChERS (acronym for Quick, Easy, Cheap, Effective, Rugged and Safe) method and solid-phase extraction (SPE) were used for the enrichment and cleanup of paddy water, rice straw, brown rice and paddy soil samples, respectively. Parameters including the matrix effect, linearity, precision, accuracy and stability were evaluated. Under the optimal conditions, the mean recoveries for all enantiomers from the above four sample matrix were ranged from 83.6% to 107%, with relative standard deviations (RSD) in the range of 1.0-5.8%. Coefficients of determination R(2)≥0.998 were achieved for each enantiomer in paddy water, rice straw, brown rice and paddy soil matrix calibration curves within the range of 5-500μg/kg. The limits of quantification (LOQ) for all stereoisomers in the above four matrices were all below 2.0μg/kg. The methodology was successfully applied for simultaneously enantioselective analysis of flufiprole enantiomers and their chiral metabolite in the real samples, indicating its efficacy in investigating the environmental stereochemistry of flufiprole in paddy field ecosystem. PMID:26809615

  16. Arsenic accumulation in a paddy field in Bangladesh: seasonal dynamics and trends over a three-year monitoring period.

    PubMed

    Dittmar, Jessica; Voegelin, Andreas; Roberts, Linda C; Hug, Stephan J; Saha, Ganesh C; Ali, M Ashraf; Badruzzaman, A Borhan M; Kretzschmar, Ruben

    2010-04-15

    Shallow groundwater, often rich in arsenic (As), is widely used for irrigation of dry season boro rice in Bangladesh. In the long term, this may lead to increasing As contents in rice paddy soils, which threatens rice yields, food quality, and human health. The objective of this study was to quantify gains and losses of soil As in a rice paddy field during irrigation and monsoon flooding over a three-year period. Samples were collected twice a year on a 3D-sampling grid to account for the spatially heterogeneous As distribution within the soil. Gains and losses of soil As in different depth segments were calculated using a mass-balance approach. Annual As input with irrigation water was estimated as 4.4 +/- 0.4 kg ha(-1) a(-1). Within the top 40 cm of soil, the mean As accumulation over three years amounted to 2.4 +/- 0.4 kg ha(-1) a(-1), implying that on average 2.0 kg ha(-1) a(-1) were lost from the soil. Seasonal changes of soil As showed that 1.05 to 2.1 kg ha(-1) a(-1) were lost during monsoon flooding. The remaining As-loss (up to 0.95 kg ha(-1) a(-1)) was attributed to downward flow with percolating irrigation water. Despite these losses, we estimate that total As within the top 40 cm of soil at our field site would further increase by a factor of 1.5 to 2 by the year 2050 under current cultivation practices. PMID:20235529

  17. [Distribution characteristics of soil profile nitrous oxide concentration in paddy fields with different rice-upland crop rotation systems].

    PubMed

    Liu, Ping-li; Zhang, Xiao-lin; Xiong, Zheng-qin; Huang, Tai-qing; Ding, Min; Wang, Jin-yang

    2011-09-01

    To investigate the dynamic distribution patterns of nitrous oxide (N2O) in the soil profiles in paddy fields with different rice-upland crop rotation systems, a special soil gas collection device was adopted to monitor the dynamics of N2O at the soil depths 7, 15, 30, and 50 cm in the paddy fields under both flooding and drainage conditions. Two rotation systems were installed, i.e., wheat-single rice and oilseed rape-double rice, each with or without nitrogen (N) application. Comparing with the control, N application promoted the N2O production in the soil profiles significantly (P < 0.01), and there existed significant correlations in the N2O concentration among the four soil depths during the whole observation period (P < 0.01). In the growth seasons of winter wheat and oilseed rape under drainage condition and with or without N application, the N2O concentrations at the soil depths 30 cm and 50 cm were significantly higher than those at the soil depths 7 cm and 15 cm; whereas in the early rice growth season under flooding condition and without N application, the N2O concentrations at the soil depth 7 cm and 15 cm were significantly higher than those at the soil depths 30 cm and 50 cm (P < 0.05). No significant differences were observed in the N2O concentrations at the test soil depths among the other rice cropping treatments. The soil N2O concentrations in the treatments without N application peaked in the transitional period from the upland crops cropping to rice planting, while those in the treatments with N application peaked right after the second topdressing N of upland crops. Relatively high soil N2O concentrations were observed at the transitional period from the upland crops cropping to rice planting. PMID:22126049

  18. Contribution of photosynthesized carbon to the methane emitted from paddy fields

    SciTech Connect

    Minoda, T.; Kimura, M.

    1994-09-01

    Emission rates of CH4 from paddy soil with and without rice straw applications were measured with pot experiments to estimate the contribution of rice straw to total CH4 emissions during the growing season. The CH4 derived from rice straw was calculated to be 50.4% of the total emission. (13)CO2 uptake experiments were carried out three times from Aug. 8 to Sept. 18 to estimate the contribution of photosynthesized carbon to CH4 emission. The contribution percentages of photosynthesized carbon to the total CH4 emitted to the atmosphere were 72-110% around Aug. 8, 29-36% around Aug. 30, and 13-17% around Sept. 18, 1993.

  19. Assessment of factors influencing groundwater-level change using groundwater flow simulation, considering vertical infiltration from rice-planted and crop-rotated paddy fields in Japan

    NASA Astrophysics Data System (ADS)

    Iwasaki, Yumi; Nakamura, Kimihito; Horino, Haruhiko; Kawashima, Shigeto

    2014-12-01

    Assessing factors that influence groundwater levels such as land use and pumping strategy, is essential to adequately manage groundwater resources. A transient numerical model for groundwater flow with infiltration was developed for the Tedori River alluvial fan (140 km2), Japan. The main water input into the groundwater body in this area is irrigation water, which is significantly influenced by land use, namely paddy and upland fields. The proposed model consists of two models, a one-dimensional (1-D) unsaturated-zone water flow model (HYDRUS-1D) for estimating groundwater recharge and a 3-D groundwater flow model (MODFLOW). Numerical simulation of groundwater flow from October 1975 to November 2009 was performed to validate the model. Simulation revealed seasonal groundwater level fluctuations, affected by paddy irrigation management. However, computational accuracy was limited by the spatiotemporal data resolution of the groundwater use. Both annual groundwater levels and recharge during the irrigation periods from 1975 to 2009 showed long-term decreasing trends. With the decline in rice-planted paddy field area, groundwater recharge cumulatively decreased to 61 % of the peak in 1977. A paddy-upland crop-rotation system could decrease groundwater recharge to 73-98 % relative to no crop rotation.

  20. Geographical variation in inorganic arsenic in paddy field samples and commercial rice from the Iberian Peninsula.

    PubMed

    Signes-Pastor, Antonio J; Carey, Manus; Carbonell-Barrachina, Angel A; Moreno-Jiménez, Eduardo; Green, Andy J; Meharg, Andrew A

    2016-07-01

    This study investigated total arsenic and arsenic speciation in rice using ion chromatography with mass spectrometric detection (IC-ICP-MS), covering the main rice-growing regions of the Iberian Peninsula in Europe. The main arsenic species found were inorganic and dimethylarsinic acid. Samples surveyed were soil, shoots and field-collected rice grain. From this information soil to plant arsenic transfer was investigated plus the distribution of arsenic in rice across the geographical regions of Spain and Portugal. Commercial polished rice was also obtained from each region and tested for arsenic speciation, showing a positive correlation with field-obtained rice grain. Commercial polished rice had the lowest i-As content in Andalucia, Murcia and Valencia while Extremadura had the highest concentrations. About 26% of commercial rice samples exceeded the permissible concentration for infant food production as governed by the European Commission. Some cadmium data is also presented, available with ICP-MS analyses, and show low concentration in rice samples. PMID:26920305

  1. Biochar amendment reduces rice Cd uptake in polluted and unpolluted paddy soils: a long term field experiment

    NASA Astrophysics Data System (ADS)

    Bian, R.; Cui, L.; Pan, G.; Li, L.

    2012-04-01

    The bioavailability of Cd in agricultural soils has been a great health concern due to the potential risk through exposure of agro-food produced in Cd-contaminated fields. Yet, rice subject to Cd contamination appears to have expanded at the last decade due to irrigation with waste water and chemical fertilization in south china. This is supposed to raise the Cd accumulation of rice grain. Therefore, techniques to reduce Cd mobility and plant uptake have been a urgent demand for food safety in China.A field experiment was performed in a high-polluted (HP), mid-pollute (MP) and unpolluted (UP) paddy soil with biochar(BC) amendment in 2011. BC was applied in HP, MP and UP in 2008, 2009, 2009 with the rates of 0, 10, 20, 40t ha-1 in HP, MP and 0, 40t ha-1 in UP. The experiment was monitored in 2011. It was observed that BC amendment did not affect rice grain yield but significantly increased soil pH by 0.58-0.77, 1.30 units in MP, UP and there was no difference in HP. The Cacl2 extracted Cd in soil was decreased by 18.1%-28.9% in HP, 49.3%-67.5% in MP and 83.1% in UP, respectively. Meanwhile, H2O extractable Cd in soil was decreased by 20.0%-31.7% in HP, 32.7%-44.2% in MP and 25.0% in UP, respectively. With the BC treatment, rice grain Cd concentration was decreased 4.7%-17.6% in HP, 35.9%-53.4% in MP. Especially in UP field, the rice grain Cd concentration was decreased from 0.22mg kg-1 to 0.07mg kg-1 which was below National standard (0.20mg kg-1) in China. The straw and root Cd contents were also significantly decreased with BC application. Therefore, BC amendment in polluted and unpolluted fields can sustainably reduce rice Cd uptake and it may offer a basic option to reduce Cd levels in rice. Keywords: Biochar, Cd, bioavailability, paddy soil, food safety

  2. Internal aeration of paddy field rice (Oryza sativa) during complete submergence---importance of light and floodwater O2.

    PubMed

    Winkel, Anders; Colmer, Timothy D; Ismail, Abdelbagi M; Pedersen, Ole

    2013-03-01

    Flash floods can submerge paddy field rice (Oryza sativa), with adverse effects on internal aeration, sugar status and survival. Here, we investigated the in situ aeration of roots of rice during complete submergence, and elucidated how underwater photosynthesis and floodwater pO(2) influence root aeration in anoxic soil. In the field, root pO(2) was measured using microelectrodes during 2 d of complete submergence. Leaf gas films that formed on the superhydrophobic leaves were left intact, or experimentally removed, to elucidate their effect on internal aeration. In darkness, root pO(2) declined to very low concentrations (0.24 kPa) and was strongly correlated with floodwater pO(2). In light, root pO(2) was high (14 kPa) and primarily a function of the incident light determining the rates of underwater net photosynthesis. Plants with intact leaf gas films maintained higher underwater net photosynthesis relative to plants without gas films when the submerged shoots were in light. During complete submergence, internal aeration of rice in the field relies on underwater photosynthesis during the day and entry of O(2) from the floodwater during the night. Leaf gas films enhance photosynthesis during submergence leading to improved O(2) production and sugar status, and therefore contribute to the submergence tolerance of rice. PMID:23215967

  3. [Effect of controlled release fertilizer on nitrous oxide emission from paddy field under plastic film mulching cultivation].

    PubMed

    Zhang, Yi; Lü, Shi-Hua; Ma, Jing; Xu, Hua; Yuan, Jiang; Dong, Yu-Jiao

    2014-03-01

    A field experiment was conducted to assess the effect of controlled release fertilizer on N2O emission in paddy field under plastic film mulching cultivation (PM) with water-saving irrigation. Results showed that in the rice growing season, cumulative N2O emissions from the plots applied with urea (PM+U) and with controlled release fertilizer (PM+CRF) were (38.2 +/- 4.4) and (21.5 +/- 5.2) mg N x m(-2), respectively. The N2O emission factors were 0.25% and 0.14% in the treatments PM+U and PM+CRF, respectively. The controlled release fertilizer decreased the total N2O emission by 43.6% compared with urea, of which 49.6% was reduced before the drying period. It also reduced the peak of N2O emission by 52.6%. However, it did not affect soil microbial biomass N and soil NH(4+)-N content at any rice growing stage, and grain yield either. No significant correlation was observed between N2O flux and soil Eh or soil temperature at the depth of 5 cm. PMID:24984495

  4. Avian Diversity and Feeding Guilds in a Secondary Forest, an Oil Palm Plantation and a Paddy Field in Riparian Areas of the Kerian River Basin, Perak, Malaysia

    PubMed Central

    Azman, Nur Munira; Latip, Nurul Salmi Abdul; Sah, Shahrul Anuar Mohd; Akil, Mohd Abdul Muin Md; Shafie, Nur Juliani; Khairuddin, Nurul Liyana

    2011-01-01

    The diversity and the feeding guilds of birds in three different habitats (secondary forest, oil palm plantation and paddy field) were investigated in riparian areas of the Kerian River Basin (KRB), Perak, Malaysia. Point-count observation and mist-netting methods were used to determine bird diversity and abundance. A total of 132 species of birds from 46 families were recorded in the 3 habitats. Species diversity, measured by Shannon’s diversity index, was 3.561, 3.183 and 1.042 in the secondary forest, the paddy field and the oil palm plantation, respectively. The vegetation diversity and the habitat structure were important determinants of the number of bird species occurring in an area. The relative abundance of the insectivore, insectivore-frugivore and frugivore guilds was greater in the forest than in the monoculture plantation. In contrast, the relative abundance of the carnivore, granivore and omnivore guilds was higher in the plantation. The results of the study show that the conversion of forest to either oil palm plantation or paddy fields produced a decline in bird diversity and changes in the distribution of bird feeding guilds. PMID:24575217

  5. Assessing the potential impact of fly ash amendments on Indian paddy field with special emphasis on growth, yield, and grain quality of three rice cultivars.

    PubMed

    Singh, Anupama; Sarkar, Abhijit; Agrawal, S B

    2012-08-01

    Proper disposal and/or recycling of different industrial waste materials have long been recognized as a prime environmental concern throughout the world, and fly ash is major amongst them. In the present study, we tried to assess the feasibilities of possible effective and safe utilization of fly ash as soil amendment in Indian paddy field and its impact on rice plants, especially at growth and yield level. Our results showed that certain doses of fly ash amendments have significantly improved the physico-chemical and mineralogical properties of paddy field soil, and at lower level of amendments, fly ash induced the growth performances of three rice cultivars too. Grain yield and grain quality also responded similarly as per the growth responses. However, differential cultivar response was observed accordingly, and cultivar Sugandha-3 showed higher yield as compared with cultivars Sambha and Saryu-52. Based on the observed results, it was concluded that up to a certain level, fly ash amendments could be beneficial for Indian paddy field and can be utilized as feasible management strategy for the disposal of this major industrial waste. PMID:21901311

  6. Seasonal and diurnal variations of atmospheric PAHs and OCPs in a suburban paddy field, South China: Impacts of meteorological parameters and sources

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Li, Qilu; Wang, Shaorui; Wang, Yujie; Luo, Chunling; Li, Jun; Zhang, Gan

    2015-07-01

    The atmospheric contaminations of polycyclic aromatic hydrocarbons (PAHs), hexachlorocyclohexanes (HCHs), and DDTs have been extensively monitored for decades, but contaminations in agricultural paddy fields have rarely been reported. We measured the atmospheric PAH, HCH, and DDT constituents during different rice growth stages in a suburban paddy field in South China. Diurnal variations were found in the atmospheric concentrations of PAHs and HCHs, but not for DDTs. Additional nocturnal emissions and meteorological conditions, such as low nocturnal stable atmospheric boundary layers, may be mainly responsible for the higher PAH and HCH levels at night, respectively. Atmospheric concentrations of PAH, HCH, and DDT constituents varied with rice growth stage, but no regular seasonal variation was found, suggesting that rice growth has no significant influence on the atmospheric concentrations of these chemicals. A correlation analysis suggested that meteorological parameters, such as temperature, precipitation, mixing layer height, or wind speed, may directly or indirectly affect the air concentrations of PAHs, HCHs, and DDTs. Source apportionment showed that atmospheric PAHs, HCHs, and DDTs in the paddy field originated from mixed sources, and the contribution of each source varied with time. The isomer ratio of fluoranthene/(fluoranthene + pyrene) may result in an invalid diagnosis of PAHs.

  7. [Characteristics of CO2, CH4 and N2O emissions from winter-fallowed paddy fields in hilly area of South China].

    PubMed

    Liu, Hui; Zhao, Ping; Sun, Gu-chou; Lin, Yong-biao; Rao, Xing-quan; Wang, Yue-si

    2007-01-01

    With closed static chamber and modified gas chromatograph (HP5890 II), the in situ measurements were made on the CO2, CH4 and N2O emissions from winter-fallowed paddy fields in the hilly area of South China. Gas samples were taken simultaneously from the fields with and without rice stubble. The results showed that both of the fields had the peak value of CO2 flux in the late afternoon. In the fields with and without rice stubble, the CH4 flux was positive in the day time while negative in the night, and the N2O flux in the day time was 1.79 and 1.58 times as much as that in the night, respectively. The diurnal average CO2 flux in the field with rice stubble was significantly higher than that in bare field (P < 0.05). Correlation analysis demonstrated that the CO2 flux in winter-fallowed paddy fields had significant correlations with soil temperature, aboveground temperature, and air temperature, suggesting that temperature was the main factor affecting the CO2 emission from rice field after harvesting. During the observation time (from 2003-11-10 to 2004-01-18), the average CO2, CH4 and N2O fluxes in the field with rice stubble were (180.69 +/- 21.21) mg x m(-2) x h(-1), (-0.04 +/- 0.01) mg x m(-2) x h(-1) and (21.26 +/- 19.31) microg x m(-2) x h(-1), respectively. Compared with bare field, the CO2 flux in the field with rice stubble was 13.06% higher, CH4 absorption increased by 50%, while N2O flux was 60.75% lower. It was concluded that the winter fallowed paddy field in hilly area of South China was the source of atmospheric CO2 and N2O, and the sink of atmospheric CH4. PMID:17396500

  8. Diversity of bacteriophages infecting Xanthomonas oryzae pv. oryzae in paddy fields and its potential to control bacterial leaf blight of rice.

    PubMed

    Chae, Jong-Chan; Hung, Nguyen Bao; Yu, Sang-Mi; Lee, Ha Kyung; Lee, Yong Hoon

    2014-06-28

    Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a very serious disease in rice-growing regions of the world. In spite of their economic importance, there are no effective ways of protecting rice plants from this disease. Bacteriophages infecting Xoo affect the population dynamics of the pathogen and consequently the occurrence of the disease. In this study, we investigated the diversity, host range, and infectivity of Xoo phages, and their use as a bicontrol agent on BLB was tested. Among the 34 phages that were isolated from floodwater in paddy fields, 29 belonged to the Myoviridae family, which suggests that the dominant phage in the ecosystem was Myoviridae. The isolated phages were classified into two groups based on plaque size produced on the lawn of Xoo. In general, there was a negative relationship between plaque size and host range, and interestingly the phages having a narrow host range had low efficiency of infectivity. The deduced protein sequence analysis of htf genes indicated that the gene was not a determinant of host specificity. Although the difference in host range and infectivity depending on morphotype needs to be addressed, the results revealed deeper understanding of the interaction between the phages and Xoo strains in floodwater and damp soil environments. The phage mixtures reduced the occurrence of BLB when they were treated with skim milk. The results indicate that the Xoo phages could be used as an alternative control method to increase the control efficacy and reduce the use of agrochemicals. PMID:24651644

  9. A three-year experiment confirms continuous immobilization of cadmium and lead in contaminated paddy field with biochar amendment.

    PubMed

    Bian, Rongjun; Joseph, Stephen; Cui, Liqiang; Pan, Genxing; Li, Lianqing; Liu, Xiaoyu; Zhang, Afeng; Rutlidge, Helen; Wong, Singwei; Chia, Chee; Marjo, Chris; Gong, Bin; Munroe, Paul; Donne, Scott

    2014-05-15

    Heavy metal contamination in croplands has been a serious concern because of its high health risk through soil-food chain transfer. A field experiment was conducted in 2010-2012 in a contaminated rice paddy in southern China to determine if bioavailability of soil Cd and Pb could be reduced while grain yield was sustained over 3 years after a single soil amendment of wheat straw biochar. Contaminated biochar particles were separated from the biochar amended soil and microscopically analyzed to help determine where, and how, metals were immobilized with biochar. Biochar soil amendment (BSA) consistently and significantly increased soil pH, total organic carbon and decreased soil extractable Cd and Pb over the 3 year period. While rice plant tissues' Cd content was significantly reduced, depending on biochar application rate, reduction in plant Pb concentration was found only in root tissue. Analysis of the fresh and contaminated biochar particles indicated that Cd and Pb had probably been bonded with the mineral phases of Al, Fe and P on and around and inside the contaminated biochar particle. Immobilization of the Pb and Cd also occurred to cation exchange on the porous carbon structure. PMID:24685528

  10. Effect of Different Fertilizer Application on the Soil Fertility of Paddy Soils in Red Soil Region of Southern China

    PubMed Central

    Dong, Wenyi; Zhang, Xinyu; Wang, Huimin; Dai, Xiaoqin; Sun, Xiaomin; Qiu, Weiwen; Yang, Fengting

    2012-01-01

    Appropriate fertilizer application is an important management practice to improve soil fertility and quality in the red soil regions of China. In the present study, we examined the effects of five fertilization treatments [these were: no fertilizer (CK), rice straw return (SR), chemical fertilizer (NPK), organic manure (OM) and green manure (GM)] on soil pH, soil organic carbon (SOC), total nitrogen (TN), C/N ratio and available nutrients (AN, AP and AK) contents in the plowed layer (020 cm) of paddy soil from 1998 to 2009 in Jiangxi Province, southern China. Results showed that the soil pH was the lowest with an average of 5.33 units in CK and was significantly higher in NPK (5.89 units) and OM (5.63 units) treatments (P<0.05). The application of fertilizers have remarkably improved SOC and TN values compared with the CK, Specifically, the OM treatment resulted in the highest SOC and TN concentrations (72.5% and 51.2% higher than CK) and NPK treatment increased the SOC and TN contents by 22.0% and 17.8% compared with CK. The average amounts of C/N ratio ranged from 9.66 to 10.98 in different treatments, and reached the highest in OM treatment (P<0.05). During the experimental period, the average AN and AP contents were highest in OM treatment (about 1.6 and 29.6 times of that in the CK, respectively) and second highest in NPK treatment (about 1.2 and 20.3 times of that in the CK). Unlike AN and AP, the highest value of AK content was observed in NPK treatments with 38.10 mgkg?1. Thus, these indicated that organic manure should be recommended to improve soil fertility in this region and K fertilizer should be simultaneously applied considering the soil K contents. Considering the long-term fertilizer efficiency, our results also suggest that annual straw returning application could improve soil fertility in this trial region. PMID:23028550

  11. Surfactant dependent self-organization of Co3O4 nanowires on Ni foam for high performance supercapacitors: from nanowire microspheres to nanowire paddy fields

    NASA Astrophysics Data System (ADS)

    Zhang, Xuan; Zhao, Yongqing; Xu, Cailing

    2014-03-01

    Different surfactants were used in a typical hydrothermal process for controlling the morphology of the Co3O4 nanowire superstructure on Ni foam. It is easy for the Co3O4 nanowires to self-organize into nanowire microspheres on Ni foam in the absence of surfactants. And the nanowire microspheres gradually unfold into nanowire paddy fields with the addition of nonionic, cationic and anionic surfactants, respectively. The results of BET and electrochemical measurements show that the specific surface area and capacitance first decrease and then increase with the change in the Co3O4 superstructure morphology. Among these electrodes, the Co3O4 electrode with paddy like nanowires shows an outstanding specific capacitance of 1217.4 F g-1 and areal specific capacitance as high as 6087 mF cm-2 at 0.7 A g-1 with high mass loading (5 mg cm-2), good power capability (showing a high specific capacitance of 835.1 F g-1 (4176 mF cm-2) at 5 A g-1), excellent cycling stability and high columbic efficiency (~100%). This exceptional performance is benefited from the almost monodispersed nanowire morphology and high specific surface area (121.4 m2 g-1). At the same time, the asymmetric supercapacitor, employing the Co3O4 electrode with paddy-like nanowires as the positive electrode and the activated carbon electrode as the negative electrode, was successfully assembled. It shows a high specific energy and good long-term electrochemical stability. All these impressive results demonstrate that the Co3O4 electrode with paddy-like nanowires is promising for practical applications in supercapacitors.Different surfactants were used in a typical hydrothermal process for controlling the morphology of the Co3O4 nanowire superstructure on Ni foam. It is easy for the Co3O4 nanowires to self-organize into nanowire microspheres on Ni foam in the absence of surfactants. And the nanowire microspheres gradually unfold into nanowire paddy fields with the addition of nonionic, cationic and anionic surfactants, respectively. The results of BET and electrochemical measurements show that the specific surface area and capacitance first decrease and then increase with the change in the Co3O4 superstructure morphology. Among these electrodes, the Co3O4 electrode with paddy like nanowires shows an outstanding specific capacitance of 1217.4 F g-1 and areal specific capacitance as high as 6087 mF cm-2 at 0.7 A g-1 with high mass loading (5 mg cm-2), good power capability (showing a high specific capacitance of 835.1 F g-1 (4176 mF cm-2) at 5 A g-1), excellent cycling stability and high columbic efficiency (~100%). This exceptional performance is benefited from the almost monodispersed nanowire morphology and high specific surface area (121.4 m2 g-1). At the same time, the asymmetric supercapacitor, employing the Co3O4 electrode with paddy-like nanowires as the positive electrode and the activated carbon electrode as the negative electrode, was successfully assembled. It shows a high specific energy and good long-term electrochemical stability. All these impressive results demonstrate that the Co3O4 electrode with paddy-like nanowires is promising for practical applications in supercapacitors. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06734c

  12. Effects of raising frogs and putting pest-killing lamps in paddy fields on the prevention of rice pests and diseases

    NASA Astrophysics Data System (ADS)

    Teng, Qing; Hu, Xue-Feng; Luo, Fan; Cao, Ming-Yang

    2014-05-01

    Frogs in paddy fields become less and less due to applying large amounts of pesticides and human hunting for a long time, which causes the aggravation of rice pests and diseases. A field experiment was carried out in the suburb of Shanghai to study the effects of artificially raising frogs and putting frequency oscillation pest-killing lamps in paddy fields on the prevention of rice pests and diseases. The field experiment includes three treatments. Treatment I: 150 frogs, each 20 g in weight, per 100 m2 were put in the fields; Treatment II: a frequency oscillation pest-killing lamp was put in the fields; Treatment III: no frogs and pest-killing lamps were put in the fields. All the experimental fields were operated based on the organic faming system. The amount of organic manure, 7500 kg/hm2, was applied to the fields as base fertilizer before sowing in early June, 2013. No any chemical fertilizers and pesticides were used during the entire period of rice growth. Each treatment is in triplicate and each plot is 67 m2 in area. The results are as follows: (1) During the entire growth period, the incidences of rice pests and diseases with Treatment I and II are significantly lower than those with CK (Treatment III). The incidence of chilo suppressalis with Treatment I, II and III is 0, 0.46% and 1.69%, respectively; that of cnaphalocrocis medinalis is 7.67%, 6.62% and 10.10%, respectively; that of rice sheath blight is 0, 11.11% and 5.43%, respectively; that of rice planthopper is 4.25 per hill, 5.75 per hill and 11 per hill, respectively. (2) The grain yield of the three treatments is significantly different. That of Treatment I, II and III is 5157.73 kg/hm2, 4761.60 kg/hm2 and 3645.14kg/hm2 on average, respectively. (3) Affected by frog activities, the contents of NH4-N, available P and available K in the soil with Treatment I are significantly raised. All the above suggest that artificially raising frogs in paddy fields could effectively prevent rice pests and diseases, especially reduce the incidences of rice sheath blight and chilo suppressalis, and setting pest-killing lamps could also effectively control rice pests, but not rice sheath blight, which contribute to the increase of grain yield largely. Moreover, the activity of frogs in paddy fields could improve soil fertility and increase bio-diversity. Acknowledgements: This work was supported by the National Natural Science Foundation of China (No. 41130526).

  13. [Effects of controlled release nitrogen fertilizer on surface water N dynamics and its runoff loss in double cropping paddy fields in Dongtinghu Lake area].

    PubMed

    Ji, Xiong-Hui; Zheng, Sheng-Xian; Lu, Yan-Hong; Liao, Yu-Lin

    2007-07-01

    By using leakage pond to simulate the double cropping paddy fields in Dongtinghu Lake area, this paper studied the effects of urea (CF) and controlled release nitrogen fertilizer (CRNF) on the dynamics of surface water pH, electrical conductivity (EC), total nitrogen (TN), ammonia nitrogen (NH4(+)-N) and nitrate nitrogen (NO3(-)-N) and the runoff loss of TN in alluvial sandy loamy paddy soil and purple calcareous clayed paddy soil, the two main paddy soils in this area. The results showed that after applying urea, the surface water TN and NH4(+)-N concentrations reached the peak at the 1st and 3rd day, respectively, and decreased rapidly then. Surface water NO3(-)-N concentration was very low, though it showed a little raise at the 3rd to 7th day after applying urea in purple calcareous clayed paddy soil. In early rice field, surface water pH rose gradually within 15 days after applying urea, while in late rice field, it did within 3 days. EC kept consistent with the dynamics of NH4(+)-N. CRNF, especially 70% N CRNF, gave rise to distinctly lower surface water pH, EC, and TN and NH4(+)-N concentrations within 15 days after application, but NO3- concentration rose slightly at late growth stages, compared with urea application. The monitoring of TN runoff loss indicated that during double cropping rice growth season, the loss amount of TN under urea application was 7.70 kg x hm(-2), accounting for 2.57% of applied urea-N. The two runoff events occurred within 20 days after urea application contributed significantly to the TN runoff loss. CRNF application resulted in a significantly lower TN concentration in runoff water from the 1st runoff event occurred within 10 days of its application, and thereafter, the total TN runoff loss for CRNF and 70% N CRNF application was decreased by 24.5% and 27.2%, respectively, compared with urea application. PMID:17886631

  14. Effect of timing of joint application of hydroquinone and dicyandiamide on nitrous oxide emission from irrigated lowland rice paddy field.

    PubMed

    Li, Xianglan; Zhang, Guangbin; Xu, Hua; Cai, Zucong; Yagi, Kazuyuki

    2009-06-01

    A field experiment was conducted to study the effect of timing of joint application of urease inhibitor hydroquinone (HQ) and nitrification inhibitor dicyandiamide (DCD) on N(2)O emission from irrigated lowland rice paddy field. Four treatments including Treatment CK (the control with urea alone), HQ/DCD-1 (application of HQ and DCD together with fertilizer before transplanting), HQ/DCD-2 (HQ and DCD with fertilizer at tillering stage) and HQ/DCD-3 (HQ and DCD with fertilizer at panicle initiation stage) were designed and implemented separately during rice growth period. Seasonal peaks of N(2)O flux occurred during midseason drainage and significant negative correlation between N(2)O flux and water layer depth was observed (r=-0.69 to -0.75, P<0.01). Mean N(2)O flux was the highest in the control with urea alone, while joint addition of HQ and DCD with urea lowered mean N(2)O flux considerably (P<0.05). Total N(2)O emission during rice growth season in Treatment CK, HQ/DCD-1, HQ/DCD-2 and HQ/DCD-3 was 3.90, 2.98, 1.73 and 3.23kgN(2)O-N ha(-1), respectively. Application of HQ and DCD together with basal fertilizer, tillering fertilizer and panicle initiation fertilizer decreased the total N(2)O emission by 24%, 56% and 17%, respectively, while increased grain yield by 10%, 18% and 6%, respectively. Effect of application of inhibitors on N(2)O emission during the continuous period from incorporation of HQ and DCD to rice harvest was also studied, where results indicating that the highest inhibiting efficiency of inhibitors on N(2)O emission was recorded when HQ and DCD applied with fertilizer at tillering stage. PMID:19269003

  15. Analysis of Spatial Variability in a Korean Paddy Field Using Median Polish Detrending

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is developing interest in precision agriculture in Korea, despite the fact that typical fields are less than 1 ha in size. Describing within-field variability in typical Korean production settings is a fundamental first step toward determining the size of management zones and the inter-relatio...

  16. Bacterial diversity and bioaugmentation in floodwater of a paddy field in the presence of the herbicide molinate.

    PubMed

    Barreiros, Luisa; Manaia, Clia M; Nunes, Olga C

    2011-04-01

    This work aimed at studying variations on the diversity and composition of the bacterial community of a rice paddy field floodwater, subjected to conventional management, namely by using the herbicide molinate. The promotion of the herbicide biodegradation either by the autochthonous microbiota or by a bioaugmentation process was also assessed. This study comprehended four sampling campaigns at key dates of the farming procedures (seeding, immediately and 6 days after application of the herbicide molinate, and after synthetic fertilization) and the subsequent physic-chemical and microbiological characterization (pH, DOC and molinate contents, total cells, cultivable bacteria and DGGE profiling) of the samples. Multivariate analysis of the DGGE profiles showed temporal variations in the bacterial community structure and the Shannon's index values indicated that the bacterial diversity reached its minimum at the molinate application day. The highest bacterial diversity coincided with the periods with undetectable concentrations of the herbicide, although microcosm assays suggested that other factors than molinate may have been responsible for the decrease of the bacterial diversity. The ability of autochthonous microorganisms to degrade molinate and the influence of the herbicide on the bacterial community composition were assessed in microcosm assays using floodwater collected at the same dates. Given molinate was not degraded by autochthonous microorganisms, and considering it represents an environmental contaminant, bioaugmentation microcosms were assayed aiming the assessment of the feasibility of a bioremediation process to clean contaminated floodwater. A molinate-mineralizing culture, previously isolated, promoted molinate removal, induced alterations in the autochthonous bacterial community structure and diversity, and was undetected after 7 days of incubation, suggesting the feasibility of the process. PMID:20862524

  17. Evidence for the cooccurrence of nitrite-dependent anaerobic ammonium and methane oxidation processes in a flooded paddy field.

    PubMed

    Shen, Li-Dong; Liu, Shuai; Huang, Qian; Lian, Xu; He, Zhan-Fei; Geng, Sha; Jin, Ren-Cun; He, Yun-Feng; Lou, Li-Ping; Xu, Xiang-Yang; Zheng, Ping; Hu, Bao-Lan

    2014-12-01

    Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two of the most recent discoveries in the microbial nitrogen cycle. In the present study, we provide direct evidence for the cooccurrence of the anammox and n-damo processes in a flooded paddy field in southeastern China. Stable isotope experiments showed that the potential anammox rates ranged from 5.6 to 22.7 nmol N2 g(-1) (dry weight) day(-1) and the potential n-damo rates varied from 0.2 to 2.1 nmol CO2 g(-1) (dry weight) day(-1) in different layers of soil cores. Quantitative PCR showed that the abundance of anammox bacteria ranged from 1.0 10(5) to 2.0 10(6) copies g(-1) (dry weight) in different layers of soil cores and the abundance of n-damo bacteria varied from 3.8 10(5) to 6.1 10(6) copies g(-1) (dry weight). Phylogenetic analyses of the recovered 16S rRNA gene sequences showed that anammox bacteria affiliated with "Candidatus Brocadia" and "Candidatus Kuenenia" and n-damo bacteria related to "Candidatus Methylomirabilis oxyfera" were present in the soil cores. It is estimated that a total loss of 50.7 g N m(-2) per year could be linked to the anammox process, which is at intermediate levels for the nitrogen flux ranges of aerobic ammonium oxidation and denitrification reported in wetland soils. In addition, it is estimated that a total of 0.14 g CH4 m(-2) per year could be oxidized via the n-damo process, while this rate is at the lower end of the aerobic methane oxidation rates reported in wetland soils. PMID:25261523

  18. Evidence for the Cooccurrence of Nitrite-Dependent Anaerobic Ammonium and Methane Oxidation Processes in a Flooded Paddy Field

    PubMed Central

    Shen, Li-dong; Liu, Shuai; Huang, Qian; Lian, Xu; He, Zhan-fei; Geng, Sha; Jin, Ren-cun; He, Yun-feng; Lou, Li-ping; Xu, Xiang-yang; Zheng, Ping

    2014-01-01

    Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two of the most recent discoveries in the microbial nitrogen cycle. In the present study, we provide direct evidence for the cooccurrence of the anammox and n-damo processes in a flooded paddy field in southeastern China. Stable isotope experiments showed that the potential anammox rates ranged from 5.6 to 22.7 nmol N2 g?1 (dry weight) day?1 and the potential n-damo rates varied from 0.2 to 2.1 nmol CO2 g?1 (dry weight) day?1 in different layers of soil cores. Quantitative PCR showed that the abundance of anammox bacteria ranged from 1.0 105 to 2.0 106 copies g?1 (dry weight) in different layers of soil cores and the abundance of n-damo bacteria varied from 3.8 105 to 6.1 106 copies g?1 (dry weight). Phylogenetic analyses of the recovered 16S rRNA gene sequences showed that anammox bacteria affiliated with Candidatus Brocadia and Candidatus Kuenenia and n-damo bacteria related to Candidatus Methylomirabilis oxyfera were present in the soil cores. It is estimated that a total loss of 50.7 g N m?2 per year could be linked to the anammox process, which is at intermediate levels for the nitrogen flux ranges of aerobic ammonium oxidation and denitrification reported in wetland soils. In addition, it is estimated that a total of 0.14 g CH4 m?2 per year could be oxidized via the n-damo process, while this rate is at the lower end of the aerobic methane oxidation rates reported in wetland soils. PMID:25261523

  19. Methylomonas koyamae sp. nov., a type I methane-oxidizing bacterium from floodwater of a rice paddy field.

    PubMed

    Ogiso, Takuya; Ueno, Chihoko; Dianou, Dayri; Huy, Tran Van; Katayama, Arata; Kimura, Makoto; Asakawa, Susumu

    2012-08-01

    A novel methane-oxidizing bacterium, strain Fw12E-Y(T), was isolated from floodwater of a rice paddy field in Japan. Cells of strain Fw12E-Y(T) were Gram-negative, motile rods with a single polar flagellum and type I intracytoplasmic membrane arrangement. The strain grew only on methane or methanol as sole carbon and energy source. It was able to grow at 10-40 C (optimum 30 C), at pH 5.5-7.0 (optimum 6.5) and with 0-0.1% (w/w) NaCl (no growth above 0.5% NaCl). 16S rRNA gene sequence analysis showed that strain Fw12E-Y(T) is related most closely to members of the genus Methylomonas, but at low levels of similarity (95.0-95.4%). Phylogenetic analysis of pmoA and mxaF genes indicated that the strain belongs to the genus Methylomonas (97 and 92?% deduced amino acid sequence identities to Methylomonas methanica S1(T), respectively). The DNA G+C content of strain Fw12E-Y(T) was 57.1 mol%. Chemotaxonomic data regarding the major quinone (MQ-8) and major fatty acids (C(16:1) and C(14:0)) also supported its affiliation to the genus Methylomonas. Based on phenotypic, genomic and phylogenetic data, strain Fw12E-Y(T) is considered to represent a novel species of the genus Methylomonas, for which the name Methylomonas koyamae sp. nov. is proposed. The type strain is Fw12E-Y(T) (?=?JCM 16701(T)?=?NBRC 105905(T)?=?NCIMB 14606(T)). PMID:21984674

  20. From tidal wetland to paddy rice fields - Changes in soil microbial communities during 2000 years of rice cultivation

    NASA Astrophysics Data System (ADS)

    Bannert, Andrea; Kleineidam, Kristina; Frenzel, Peter; Ho, Adrian; Schloter, Michael

    2010-05-01

    In many areas of China tidal wetlands have been converted into agricultural land for lowland rice cultivation. However, the consequences and effects on soil microbial communities are poorly understood. Therefore, we investigated bacterial and archaeal communities involved in nitrification and denitrification based on diversity and abundance pattern of the corresponding functional genes in a tidal wetland and two paddy soils cultivated for 50 years respectively 2000 years with rice. The abundances of all measured genes increased from the tidal wetland to the 2000 years paddy soil in reference to one gram of soil due to a significant increase of the microbial biomass. When relating the functional gene copies to the extracted microbial biomass highest copy numbers were observed in the paddy soil with 50 years of rice cultivation history with exception of the archaeal nitrification gene amoA. T-RFLP data of the archaeal amoA gene and the bacterial denitrification gene nosZ revealed significant differences in community composition in the three investigated soils. Overall, our results indicate clear changes in abundance and diversity pattern of microbial communities participating in nitrogen cycling during rice paddy evolution.

  1. RADIOMETRIC ESTIMATION OF SOIL PROPERTIES USING MULTIPLE IMAGE SENSORS IN RICE PADDY AND DRYLAND FIELDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An efficient way to detect spatial differences in crop and soil conditions at field scale is through image-based remote sensing. We report on three studies investigating the estimation of soil properties using bare-soil images. First, the ability of image data to estimate soil chemical property leve...

  2. Paddy-field contamination with 134Cs and 137Cs due to Fukushima Dai-ichi Nuclear Power Plant accident and soil-to-rice transfer coefficients.

    PubMed

    Endo, Satoru; Kajimoto, Tsuyoshi; Shizuma, Kiyoshi

    2013-02-01

    The transfer coefficient (TF) from soil to rice plants of (134)Cs and (137)Cs in the form of radioactive deposition from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011 was investigated in three rice paddy fields in Minami-Soma City. Rice crops were planted in the following May and harvested at the end of September. Soil cores of 30-cm depth were sampled from rice-planted paddy fields to measure (134)Cs and (137)Cs radioactivity at 5-cm intervals. (134)Cs and (137)Cs radioactivity was also measured in rice ears (rice with chaff), straws and roots. The rice ears were subdivided into chaff, brown rice, polished rice and rice bran, and the (134)Cs and (137)Cs radioactivity concentration of each plant part was measured to calculate the respective TF from the soil. The TF of roots was highest at 0.48 0.10 in the field where the (40)K concentration in the soil core was relatively low, in comparison with TF values of 0.31 and 0.38 in other fields. Similar trends could be found for the TF of whole rice plants, excluding roots. The TF of rice ears was relatively low at 0.019-0.026. The TF of chaff, rice bran, brown rice and polished rice was estimated to be 0.049, 0.10-0.16, 0.013-0.017 and 0.005-0.013, respectively. PMID:23103577

  3. Paddy-field contamination with 134Cs and 137Cs due to Fukushima Dai-ichi Nuclear Power Plant accident and soil-to-rice transfer coefficients.

    TOXLINE Toxicology Bibliographic Information

    Endo S; Kajimoto T; Shizuma K

    2013-02-01

    The transfer coefficient (TF) from soil to rice plants of (134)Cs and (137)Cs in the form of radioactive deposition from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011 was investigated in three rice paddy fields in Minami-Soma City. Rice crops were planted in the following May and harvested at the end of September. Soil cores of 30-cm depth were sampled from rice-planted paddy fields to measure (134)Cs and (137)Cs radioactivity at 5-cm intervals. (134)Cs and (137)Cs radioactivity was also measured in rice ears (rice with chaff), straws and roots. The rice ears were subdivided into chaff, brown rice, polished rice and rice bran, and the (134)Cs and (137)Cs radioactivity concentration of each plant part was measured to calculate the respective TF from the soil. The TF of roots was highest at 0.48 0.10 in the field where the (40)K concentration in the soil core was relatively low, in comparison with TF values of 0.31 and 0.38 in other fields. Similar trends could be found for the TF of whole rice plants, excluding roots. The TF of rice ears was relatively low at 0.019-0.026. The TF of chaff, rice bran, brown rice and polished rice was estimated to be 0.049, 0.10-0.16, 0.013-0.017 and 0.005-0.013, respectively.

  4. Optimizing grain yields reduces CH4 emissions from rice paddy fields.

    PubMed

    Denier Van Der Gon, H A C; Kropff, M J; Van Breemen, N; Wassmann, R; Lantin, R S; Aduna, E; Corton, T M; Van Laar, H H

    2002-09-17

    Microbial production in anoxic wetland rice soils is a major source of atmospheric CH4 the most important non-CO2 greenhouse gas. Much higher CH4 emissions from well managed irrigated rice fields in the wet than in the dry season could not be explained by seasonal differences in temperature. We hypothesized that high CH4 emissions in the wet season are caused by low grain to biomass ratios. In a screenhouse experiment, removing spikelets to reduce the plants' capacity to store photosynthetically fixed C in grains increased CH4 emissions, presumably via extra C inputs to the soil. Unfavorable conditions for spikelet formation in the wet season may similarly explain high methane emissions. The observed relationship between reduced grain filling and CH4 emission provides opportunities to mitigate CH4 emissions by optimizing rice productivity. PMID:12189212

  5. The Effects of Rape Residue Mulching on Net Global Warming Potential and Greenhouse Gas Intensity from No-Tillage Paddy Fields

    PubMed Central

    Zhang, Zhi-Sheng; Cao, Cou-Gui; Guo, Li-Jin; Li, Cheng-Fang

    2014-01-01

    A field experiment was conducted to provide a complete greenhouse gas (GHG) accounting for global warming potential (GWP), net GWP, and greenhouse gas intensity (GHGI) from no-tillage (NT) paddy fields with different amounts of oilseed rape residue mulch (0, 3000, 4000, and 6000?kg dry matter (DM)?ha?1) during a rice-growing season after 3 years of oilseed rape-rice cultivation. Residue mulching treatments showed significantly more organic carbon (C) density for the 020?cm soil layer at harvesting than no residue treatment. During a rice-growing season, residue mulching treatments sequestered significantly more organic C from 687?kg?C?ha?1?season?1 to 1654?kg?C?ha?1?season?1 than no residue treatment. Residue mulching significantly increased emissions of CO2 and N2O but decreased CH4 emissions. Residue mulching treatments significantly increased GWP by 930% but significantly decreased net GWP by 3371% and GHGI by 3572% relative to no residue treatment. These results suggest that agricultural economic viability and GHG mitigation can be achieved simultaneously by residue mulching on NT paddy fields in central China. PMID:25140329

  6. Durability of Drainage Improvement by Combination of Main Drain and Trench Drains with Vertical Drains in Clayey Field Converted from Paddy to Upland Use

    NASA Astrophysics Data System (ADS)

    Adachi, Kazuhide; Ohno, Satoshi; Furuhata, Masami; Ogura, Chikara; Tanimoto, Takeshi

    The drainage efficiency of a subsurface drainage system for avoidance of standing water on the plow pan of clayey field was evaluated. A subsurface drainage system with a main drain and orthogonally adjoined rice husk trench drains joined by vertical rice husk drains was constructed on a test plot and compared to an identical control plot of paddy field converted to upland use under soybean cultivation. The ratio of total underdrain discharge to rainfall in the improved plot greatly increased over two years compared to that in a control plot. In the improved plot, the peak underdrain discharge per hour associated with some heavy rainfalls was around 3 mm/h in the first year but decreased to about 2 mm/h in the second year. By improving drainage in the paddy field, standing water on the plow pan was quickly eliminated after rain events and the period of flooding on the plow pan during the soybean growing season was greatly reduced. However, underdrain discharge in the improved plot decreased greatly in the third year to be at the same level as in the control plot, and rain water flooded the plow pan for extended periods of time.

  7. Evaluation of allelopathic potential and quantification of momilactone A,B from rice hull extracts and assessment of inhibitory bioactivity on paddy field weeds.

    PubMed

    Chung, Ill Min; Kim, Jung Tae; Kim, Seung-Hyun

    2006-04-01

    Rice (Oryza sativa L.) hull extracts were used in a bioassay to evaluate the allelopathic potential of rice on the germination and growth of barnyard grass (Echinochloa crus-galli P. Beauv. var. oryzicola Ohwi), to quantify momilactone A and B levels in rice hull germplasm and to assess the inhibitory bioactivity of momilactone A and B as a potential natural source of herbicide for weed control in paddy fields. Four varieties of weeds including E. crus-galli P. Beauv. var. oryzicola Ohwi, Monochoria vaginalis var. plantaginea, Scirpus juncoides, and Eleocharis kuroguwai were tested in the paddy field. Of 99 rice varieties, the top five including Noindari exhibited inhibition effects greater than 50% in average inhibition of dry weight (AIDW). Noindari among them exerted the strongest effect (55.6%). The next five in the ranking exhibited inhibition effects of greater than 40%. Also, 46 varieties had inhibition effects between 20 and 40%, and 29 varieties had inhibition effects greater than 10%. Fourteen varieties had very low inhibitory effects (less than 10%), the lowest of which was Heunbe (4.7%). These varieties showed a mean inhibition of 19.8% for germination rate (GR), 9.9% for germination percentage (GP), 16.6% for leaf dry weight (LDW), 38.9% for straw dry weight (SDW), and 26.8% for root dry weight (RDW). Rice varieties were classified into six categories based on their total momilactones (TMs) (momilactone A + momilactone B). The highest level of momilactone A was found in the Baekna rice variety (34.7 microg g(-1)), and Baekgwangok contained the highest level of momilactone B (37.8 microg g(-1)). In allelopathic potential with genetic properties and morphological characteristics, the total inhibition rate (TIR) was 18.3% for Korean rice varieties, 19.0% for middle maturing varieties, 17.8% for colorless hull varieties, 18.3% for awn varieties, and 19.0% for colorless awn varieties. In addition, Korean varieties showed higher TMs (4.5 microg g(-1)) as compared with varieties that were late maturing (4.4 microg g(-1)), had colorless hulls (4.1 microg g(-1)), awns (4.7 microg g(-1)), and colorless awns (4.8 microg g(-1)). Momilactone A levels were generally higher than momilactone B levels. Total inhibition rates on barnyard grass correlated with average inhibitions of germination (AIG) (r2 = 0.62***), AIDW (r2 = 0.92***), and were affected by the inhibition rate of GP (r2 = 0.57***). Regions of origin for rice varieties correlated with the AIG (r2 = -0.23***), and maturing time showed a positive correlation with SDW (r2 = 0.15**) and RDW (r2 = 0.19**). Levels of momilactones were also correlated with the region of origin (r2 = -0.32***), maturing time (r2 = 0.13***), and awns (momilactone A, r2 = 0.23***; momilactone B, r2 = 0.14**), suggesting that rice varieties with awns, Korean varieties, and varieties with later maturing times contain higher levels of momilactone. Also, the investigation of the momilactone A and B bioactivity (0, 250, 500, 1000, 2000, and 4000 g a.i./ha) for weed control in paddy fields indicated that momilactones A and B exhibited no toxicity (0 in all concentrations) against rice plants, and the inhibitory bioactivity on weeds with momilactone A was higher than that of momilactone B. When compared with no momilactone control, the highest inhibitory effect (50%) on E. crus-galli P. Beauv. var. oryzicola Ohwi was shown on the 14th day after the application of momiactone A. The inhibitory effect increased with the concentration of the compound from 250 to 4000 g a.i./ha. Furthermore, momilactone A showed greater suppression than momliactone B toward toward E. crus-galli P. Beauv. var. oryzicola Ohwi, M. vaginalis var. plantaginea, S. juncoides, and E. kuroguwai. In broad weed species, momilactone A showed the highest inhibitory effect (90% in 4000 g a.i./ha) on S. juncoides, 14 days after the application as compared with no momilactone control. Further studies on allelopathic effects and momilactones from the germplasm of rice varieties using genetic properties and morphological characterist

  8. Mapping paddy rice planting areas through time series analysis of MODIS land surface temperature and vegetation index data

    NASA Astrophysics Data System (ADS)

    Zhang, Geli; Xiao, Xiangming; Dong, Jinwei; Kou, Weili; Jin, Cui; Qin, Yuanwei; Zhou, Yuting; Wang, Jie; Menarguez, Michael Angelo; Biradar, Chandrashekhar

    2015-08-01

    Knowledge of the area and spatial distribution of paddy rice is important for assessment of food security, management of water resources, and estimation of greenhouse gas (methane) emissions. Paddy rice agriculture has expanded rapidly in northeastern China in the last decade, but there are no updated maps of paddy rice fields in the region. Existing algorithms for identifying paddy rice fields are based on the unique physical features of paddy rice during the flooding and transplanting phases and use vegetation indices that are sensitive to the dynamics of the canopy and surface water content. However, the flooding phenomena in high latitude area could also be from spring snowmelt flooding. We used land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor to determine the temporal window of flooding and rice transplantation over a year to improve the existing phenology-based approach. Other land cover types (e.g., evergreen vegetation, permanent water bodies, and sparse vegetation) with potential influences on paddy rice identification were removed (masked out) due to their different temporal profiles. The accuracy assessment using high-resolution images showed that the resultant MODIS-derived paddy rice map of northeastern China in 2010 had a high accuracy (producer and user accuracies of 92% and 96%, respectively). The MODIS-based map also had a comparable accuracy to the 2010 Landsat-based National Land Cover Dataset (NLCD) of China in terms of both area and spatial pattern. This study demonstrated that our improved algorithm by using both thermal and optical MODIS data, provides a robust, simple and automated approach to identify and map paddy rice fields in temperate and cold temperate zones, the northern frontier of rice planting.

  9. [Effects of combined applications of pig manure and chemical fertilizers on CH4 and N2O emissions and their global warming potentials in paddy fields with double-rice cropping].

    PubMed

    Wang, Cong; Shen, Jian-Lin; Zheng, Liang; Liu, Jie-Yun; Qin, Hong-Ling; Li, Yong; Wu, Jin-Shui

    2014-08-01

    A field experiment was carried out to study the effects of combined applications of pig manure and chemical fertilizers on CH4 and N2O emissions, which were measured using the static chamber/gas chromatography method, and their global warming potentials in typical paddy fields with double-rice cropping in Hunan province. The results showed that the combined applications of pig manure and chemical fertilizers did not change the seasonal patterns of CH4 and N2O emissions from paddy soils, but significantly changed the magnitudes of CH4 and N2O fluxes in rice growing seasons as compared with sole application of chemical fertilizers. During the two rice growing seasons, the cumulative CH4 emissions for the pig manure and chemical nitrogen (N) fertilizer each contributing to 50% of the total applied N (1/2N + PM) treatment were higher than those for the treatments of no N fertilizer (ON), half amount of chemical N fertilizer (1/2N) and 100% chemical N fertilizer (N) by 54.83%, 33.85% and 43.30%, respectively (P < 0.05), whilst the cumulative N2O emissions for the 1/2N + PM treatment were decreased by 67.50% compared with N treatment, but increased by 129.43% and 119.23% compared with ON and 1/2N treatments, respectively (P < 0.05). CH4 was the dominant contributor to the global warming potential (GWP) in both rice growing seasons, which contributed more than 99% to the integrated GWP of CH4 and N2O emissions for all the four treatments. Both GWP and yield-scaled GWP for the treatment of 1/2N + PM were significantly higher than the other three treatments. The yield-scaled GWP for the treatment of 1/2N + PM was higher than those for the N, 1/2N and ON treatments by 58.21%, 26.82% and 20. 63%, respectively. Therefore, combined applications of pig manure and chemical fertilizers in paddy fields would increase the GWP of CH4 and N2O emissions during rice growing seasons and this effect should be considered in regional greenhouse gases emissions inventory. PMID:25338388

  10. Trace analysis of pesticides in paddy field water by direct injection using liquid chromatography-quadrupole-linear ion trap-mass spectrometry.

    PubMed

    Pareja, Luca; Martnez-Bueno, M J; Cesio, Vernica; Heinzen, Horacio; Fernndez-Alba, A R

    2011-07-29

    A multiresidue method was developed for the quantification and confirmation of 70 pesticides in paddy field water. After its filtration, water was injected directly in a liquid chromatograph coupled to a hybrid triple quadrupole-linear ion trap-mass spectrometer (QqLIT). The list of target analytes included organophosphates, phenylureas, sulfonylureas, carbamates, conazoles, imidazolinones and others compounds widely used in different countries where rice is cropped. Detection and quantification limits achieved were in the range from 0.4 to 80 ng L(-1) and from 2 to 150 ng L(-1), respectively. Correlation coefficients for the calibration curves in the range 0.1-50 ?g L(-1) were higher than 0.99 except for diazinon (0.1-25 ?g L(-1)). Only 9 pesticides presented more than 20% of signal suppression/enhancement, no matrix effect was observed in the studied conditions for the rest of the target pesticides. The method developed was used to investigate the occurrence of pesticides in 59 water samples collected in paddy fields located in Spain and Uruguay. The study shows the presence of bensulfuron methyl, tricyclazole, carbendazim, imidacloprid, tebuconazole and quinclorac in a concentration range from 0.08 to 7.20 ?g L(-1). PMID:21397903

  11. Net ecosystem exchange, gross primary production, and ecosystem respiration of carbon dioxide during barley growing season in rice-barley paddy field of Korea

    NASA Astrophysics Data System (ADS)

    Jung, M.; Shim, K.; Min, S.; Kim, Y.; Kim, S.; So, K.

    2013-12-01

    This study was conducted to measure carbon dioxide exchange between customarily cultivated rice-barley double cropping paddy field and the atmosphere during barley growing season (October 2012 and June 2013) and to estimate carbon dioxide fluxes using agro-meteorological factors (temperature, net radiation etc. ) and barley biomass. The carbon dioxide fluxes were quantified by eddy covariance technique in paddy fields with rice-barley double cropping system, located at the Gimje flux site in the southwestern coast of Korea. The total values of net ecosystem carbon dioxide exchange (NEE), gross primary production (GPP), and ecosystem respiration (Re) were -100.6, 782.7, and 682.5 g C m-2 during barley growing season, respectively. The NEE was tended to keep between 0 and 5 g C m-2 d-1 from sowing date (Oct. 21, 2012) to winter rest stage (Dec. 3, 2012 to Feb. 22, 2013), and gradually decreased in tillering stage (Feb. 23, 2013 to May 5, 2013) with its maximum around heading date, and then started to increase in ripening stage (May 6, 2013 to Jun. 8, 2013). The soil temperature was strongly correlated with the Re (r2=0.86), while the net radiation showed the weak relationship with the GPP during the emergence, seedling, and winter rest stage. The aboveground biomass of barley was significantly correlated with the values of NEE (r2=0.79), GPP (r2=0.83), and Re (r2=0.77), respectively.

  12. In situ field application of electrokinetic remediation for an As-, Cu-, and Pb-contaminated rice paddy site using parallel electrode configuration.

    PubMed

    Jeon, Eun-Ki; Jung, Ji-Min; Ryu, So-Ri; Baek, Kitae

    2015-10-01

    The applicability of an in situ electrokinetic process with a parallel electrode configuration was evaluated to treat an As-, Cu-, and Pb-contaminated paddy rice field in full scale (width, 17 m; length, 12.2 m; depth, 1.6 m). A constant voltage of 100 V was supplied and electrodes were spaced 2 m apart. Most As, Cu, and Pb were bound to Fe oxide and the major clay minerals in the test site were kaolinite and muscovite. The electrokinetic system removed 48.7, 48.9, and 54.5 % of As, Cu, and Pb, respectively, from the soil during 24 weeks. The removal of metals in the first layer (0-0.4 m) was higher than that in the other three layers because it was not influenced by groundwater fluctuation. Fractionation analysis showed that As and Pb bound to amorphous Fe and Al oxides decreased mainly, and energy consumption was 1.2 kWh/m(3). The standard deviation of metal concentration in the soil was much higher compared to the hexagonal electrode configuration because of a smaller electrical active area; however, the electrode configuration removed similar amounts of metals compared to the hexagonal system. From these results, it was concluded that the electrokinetic process could be effective at remediating As-, Cu-, and Pb-contaminated paddy rice field in situ. PMID:26032450

  13. Mapping paddy rice planting area in wheat-rice double-cropped areas through integration of Landsat-8 OLI, MODIS, and PALSAR images

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Xiao, Xiangming; Qin, Yuanwei; Dong, Jinwei; Zhang, Geli; Kou, Weili; Jin, Cui; Zhou, Yuting; Zhang, Yao

    2015-05-01

    As farmland systems vary over space and time (season and year), accurate and updated maps of paddy rice are needed for studies of food security and environmental problems. We selected a wheat-rice double-cropped area from fragmented landscapes along the rural-urban complex (Jiangsu Province, China) and explored the potential utility of integrating time series optical images (Landsat-8, MODIS) and radar images (PALSAR) in mapping paddy rice planting areas. We first identified several main types of non-cropland land cover and then identified paddy rice fields by selecting pixels that were inundated only during paddy rice flooding periods. These key temporal windows were determined based on MODIS Land Surface Temperature and vegetation indices. The resultant paddy rice map was evaluated using regions of interest (ROIs) drawn from multiple high-resolution images, Google Earth, and in-situ cropland photos. The estimated overall accuracy and Kappa coefficient were 89.8% and 0.79, respectively. In comparison with the National Land Cover Data (China) from 2010, the resultant map better detected changes in the paddy rice fields and revealed more details about their distribution. These results demonstrate the efficacy of using images from multiple sources to generate paddy rice maps for two-crop rotation systems.

  14. Mapping paddy rice planting area in wheat-rice double-cropped areas through integration of Landsat-8 OLI, MODIS, and PALSAR images.

    PubMed

    Wang, Jie; Xiao, Xiangming; Qin, Yuanwei; Dong, Jinwei; Zhang, Geli; Kou, Weili; Jin, Cui; Zhou, Yuting; Zhang, Yao

    2015-01-01

    As farmland systems vary over space and time (season and year), accurate and updated maps of paddy rice are needed for studies of food security and environmental problems. We selected a wheat-rice double-cropped area from fragmented landscapes along the rural-urban complex (Jiangsu Province, China) and explored the potential utility of integrating time series optical images (Landsat-8, MODIS) and radar images (PALSAR) in mapping paddy rice planting areas. We first identified several main types of non-cropland land cover and then identified paddy rice fields by selecting pixels that were inundated only during paddy rice flooding periods. These key temporal windows were determined based on MODIS Land Surface Temperature and vegetation indices. The resultant paddy rice map was evaluated using regions of interest (ROIs) drawn from multiple high-resolution images, Google Earth, and in-situ cropland photos. The estimated overall accuracy and Kappa coefficient were 89.8% and 0.79, respectively. In comparison with the National Land Cover Data (China) from 2010, the resultant map better detected changes in the paddy rice fields and revealed more details about their distribution. These results demonstrate the efficacy of using images from multiple sources to generate paddy rice maps for two-crop rotation systems. PMID:25965027

  15. Mapping paddy rice planting area in wheat-rice double-cropped areas through integration of Landsat-8 OLI, MODIS, and PALSAR images

    PubMed Central

    Wang, Jie; Xiao, Xiangming; Qin, Yuanwei; Dong, Jinwei; Zhang, Geli; Kou, Weili; Jin, Cui; Zhou, Yuting; Zhang, Yao

    2015-01-01

    As farmland systems vary over space and time (season and year), accurate and updated maps of paddy rice are needed for studies of food security and environmental problems. We selected a wheat-rice double-cropped area from fragmented landscapes along the rural–urban complex (Jiangsu Province, China) and explored the potential utility of integrating time series optical images (Landsat-8, MODIS) and radar images (PALSAR) in mapping paddy rice planting areas. We first identified several main types of non-cropland land cover and then identified paddy rice fields by selecting pixels that were inundated only during paddy rice flooding periods. These key temporal windows were determined based on MODIS Land Surface Temperature and vegetation indices. The resultant paddy rice map was evaluated using regions of interest (ROIs) drawn from multiple high-resolution images, Google Earth, and in-situ cropland photos. The estimated overall accuracy and Kappa coefficient were 89.8% and 0.79, respectively. In comparison with the National Land Cover Data (China) from 2010, the resultant map better detected changes in the paddy rice fields and revealed more details about their distribution. These results demonstrate the efficacy of using images from multiple sources to generate paddy rice maps for two-crop rotation systems. PMID:25965027

  16. Changes of paddy rice planting areas in Northeastern Asia from 1986 to 2014 based on Landsat data

    NASA Astrophysics Data System (ADS)

    Dong, J.; Xiao, X.; Kou, W.; Qin, Y.; Wang, J.; Zhang, G.; Jin, C.; Zhou, Y.; Menarguez, M. A.; Moore, B., III

    2014-12-01

    Paddy rice is an important cereal crop and main grain source for more than half of the global human population. However, knowledge about its area and spatial pattern is still limited due to large changes in agriculture in different regions; for example, higher latitude areas underwent increase (e.g., northeastern China) and decrease (e.g., South Korea) of paddy rice planting areas due to climatic warming, urbanization and other drivers. It is necessary to track paddy rice planting area changes in these regions in the past decades. We developed a pixel- and phenology-based image analysis system, Landsat-RICE, to map the paddy rice by using Landsat imagery. The algorithm was based on the unique physical and spectral characteristics of paddy rice fields during the flooding and transplanting phases. First, Landsat images are preprocessed and time series vegetation indices (NDVI, EVI, and LSWI) are generated. Second, MODIS Land Surface Temperature (LST) data were used to define thermal plant growing season (0 oC, 5 oC and 10 oC), which provides a guide for selection of Landsat images within the period of flooding and transplanting. Third, several non-cropland land cover maps (e.g., permanent water bodies, built-up and barren lands, sparsely vegetated lands, and evergreen vegetation) are produced through analysis of Landsat-based vegetation indices within the plant growing season and combined as a mask. Fourthly, vegetation index data within the time window of flooded and rice transplanting were analyzed to identify flood/transplanting signals. Finally, the maps of paddy rice planting areas were generated through overlying the results from Step 3 and 4. Paddy rice planting area changes were investigated in some hotspots of Northeastern Asia from 1986 to 2014 at 30-m spatial resolution and 5-year interval. This study has demonstrated that our newly developed Landsat-Rice system is robust and effective for tracking paddy rice changes in cold temperate and temperate zones.

  17. Simulation of global warming potential (GWP) from rice fields in the Tai-Lake region, China by coupling 1:50,000 soil database with DNDC model

    NASA Astrophysics Data System (ADS)

    Zhang, Liming; Yu, Dongsheng; Shi, Xuezheng; Weindorf, David C.; Zhao, Limin; Ding, Weixin; Wang, Hongjie; Pan, Jianjun; Li, Changsheng

    Quantifying greenhouse gas (GHG) emissions from wetland ecosystems is a relatively new issue in global climate change studies. China has approximately 22% of the world's rice paddies and 38% of the world's rice production, which are crucial to accurately estimate the global warming potential (GWP) at regional scale. This paper reports an application of a biogeochemical model (DeNitrification and DeComposition or DNDC) for quantifying GWP from rice fields in the Tai-Lake region of China. For this application, DNDC is linked to a 1:50,000 soil database, which was derived from 1107 paddy soil profiles compiled during the Second National Soil Survey of China in the 1980-1990s. The simulated results show that the 2.34 Mha of paddy soil cultivated in rice-wheat rotation in the Tai-Lake region emitted about -1.48 Tg C, 0.84 Tg N and 5.67 Tg C as CO 2, N 2O, and CH 4 respectively, with a cumulative GWP of 565 Tg CO 2 equivalent from 1982 to 2000. As for soil subgroups, the highest GWP (26,900 kg CO 2 equivalent ha -1 yr -1) was linked to gleyed paddy soils accounting for about 4.4% of the total area of paddy soils. The lowest GWP (5370 kg CO 2 equivalent ha -1 yr -1) was associated with submergenic paddy soils accounting for about 0.32% of the total area of paddy soils. The most common soil in the area was hydromorphic paddy soils, which accounted for about 53% of the total area of paddy soils with a GWP of 12,300 kg CO 2 equivalent ha -1 yr -1. On a regional basis, the annual averaged GWP in the polder, Tai-Lake plain, and alluvial plain soil regions was distinctly higher than that in the low mountainous and Hilly soil regions. As for administrative areas, the average annual GWP of counties in Shanghai city was high. Conversely, the average annual GWP of counties in Jiangsu province was low. The high variability in soil properties throughout the Tai-Lake region is important and affects the net greenhouse gas emissions. Therefore, the use of detailed soil data sets with high-resolution digital soil maps is essential to improve the accuracy of GWP estimates with process-based models at regional and national scales.

  18. Effects of Tillage and Nitrogen Fertilizers on CH4 and CO2 Emissions and Soil Organic Carbon in Paddy Fields of Central China

    PubMed Central

    Zhi-Kui, Kou; Zhi-Sheng, Zhang; Jin-Ping, Wang; Ming-Li, Cai; Cou-Gui, Cao

    2012-01-01

    Quantifying carbon (C) sequestration in paddy soils is necessary to help better understand the effect of agricultural practices on the C cycle. The objective of the present study was to assess the effects of tillage practices [conventional tillage (CT) and no-tillage (NT)] and the application of nitrogen (N) fertilizer (0 and 210 kg N ha?1) on fluxes of CH4 and CO2, and soil organic C (SOC) sequestration during the 2009 and 2010 rice growing seasons in central China. Application of N fertilizer significantly increased CH4 emissions by 13%66% and SOC by 21%94% irrespective of soil sampling depths, but had no effect on CO2 emissions in either year. Tillage significantly affected CH4 and CO2 emissions, where NT significantly decreased CH4 emissions by 10%36% but increased CO2 emissions by 22%40% in both years. The effects of tillage on the SOC varied with the depth of soil sampling. NT significantly increased the SOC by 7%48% in the 05 cm layer compared with CT. However, there was no significant difference in the SOC between NT and CT across the entire 020 cm layer. Hence, our results suggest that the potential of SOC sequestration in NT paddy fields may be overestimated in central China if only surface soil samples are considered. PMID:22574109

  19. Effects of winter cover crops straws incorporation on CH4 and N2O emission from double-cropping paddy fields in southern China.

    PubMed

    Tang, Hai-Ming; Xiao, Xiao-Ping; Tang, Wen-Guang; Wang, Ke; Sun, Ji-Min; Li, Wei-Yan; Yang, Guang-Li

    2014-01-01

    Residue management in cropping systems is believed to improve soil quality. However, the effects of residue management on methane (CH4) and nitrous oxide (N2O) emissions from paddy field in Southern China have not been well researched. The emissions of CH4 and N2O were investigated in double cropping rice (Oryza sativa L.) systems with straw returning of different winter cover crops by using the static chamber-gas chromatography technique. A randomized block experiment with three replications was established in 2004 in Hunan Province, China, including rice-rice-ryegrass (Lolium multiflorum L.) (Ry-R-R), rice-rice-Chinese milk vetch (Astragalus sinicus L.) (Mv-R-R) and rice-rice with winter fallow (Fa-R-R). The results showed that straw returning of winter crops significantly increased the CH4 emission during both rice growing seasons when compared with Fa-R-R. Ry-R-R plots had the largest CH4 emissions during the early rice growing season with 14.235 and 15.906 g m(-2) in 2012 and 2013, respectively, when Ry-R-R plots had the largest CH4 emission during the later rice growing season with 35.673 and 38.606 g m(-2) in 2012 and 2013, respectively. The Ry-R-R and Mv-R-R also had larger N2O emissions than Fa-R-R in both rice seasons. When compared to Fa-R-R, total N2O emissions in the early rice growing season were increased by 0.05 g m(-2) in Ry-R-R and 0.063 g m(-2) in Mv-R-R in 2012, and by 0.058 g m(-2) in Ry-R-R and 0.068 g m(-2) in Mv-R-R in 2013, respectively. Similar result were obtained in the late rice growing season, and the total N2O emissions were increased by 0.104 g m(-2) in Ry-R-R and 0.073 g m(-2) in Mv-R-R in 2012, and by 0.108 g m(-2) in Ry-R-R and 0.076 g m(-2) in Mv-R-R in 2013, respectively. The global warming potentials (GWPs) from paddy fields were ranked as Ry-R-R>Mv-R-R>Fa-R-R. As a result, straw returning of winter cover crops has significant effects on increase of CH4 and N2O emission from paddy field in double cropping rice system. PMID:25271923

  20. Effects of Winter Cover Crops Straws Incorporation on CH4 and N2O Emission from Double-Cropping Paddy Fields in Southern China

    PubMed Central

    Tang, Hai-Ming; Xiao, Xiao-Ping; Tang, Wen-Guang; Wang, Ke; Sun, Ji-Min; Li, Wei-Yan; Yang, Guang-Li

    2014-01-01

    Residue management in cropping systems is believed to improve soil quality. However, the effects of residue management on methane (CH4) and nitrous oxide (N2O) emissions from paddy field in Southern China have not been well researched. The emissions of CH4 and N2O were investigated in double cropping rice (Oryza sativa L.) systems with straw returning of different winter cover crops by using the static chamber-gas chromatography technique. A randomized block experiment with three replications was established in 2004 in Hunan Province, China, including rice–rice–ryegrass (Lolium multiflorum L.) (Ry-R-R), rice–rice–Chinese milk vetch (Astragalus sinicus L.) (Mv-R-R) and rice–rice with winter fallow (Fa-R-R). The results showed that straw returning of winter crops significantly increased the CH4 emission during both rice growing seasons when compared with Fa-R-R. Ry-R-R plots had the largest CH4 emissions during the early rice growing season with 14.235 and 15.906 g m−2 in 2012 and 2013, respectively, when Ry-R-R plots had the largest CH4 emission during the later rice growing season with 35.673 and 38.606 g m−2 in 2012 and 2013, respectively. The Ry-R-R and Mv-R-R also had larger N2O emissions than Fa-R-R in both rice seasons. When compared to Fa-R-R, total N2O emissions in the early rice growing season were increased by 0.05 g m−2 in Ry-R-R and 0.063 g m−2 in Mv-R-R in 2012, and by 0.058 g m−2 in Ry-R-R and 0.068 g m−2 in Mv-R-R in 2013, respectively. Similar result were obtained in the late rice growing season, and the total N2O emissions were increased by 0.104 g m−2 in Ry-R-R and 0.073 g m−2 in Mv-R-R in 2012, and by 0.108 g m−2 in Ry-R-R and 0.076 g m−2 in Mv-R-R in 2013, respectively. The global warming potentials (GWPs) from paddy fields were ranked as Ry-R-R>Mv-R-R>Fa-R-R. As a result, straw returning of winter cover crops has significant effects on increase of CH4 and N2O emission from paddy field in double cropping rice system. PMID:25271923

  1. Effects of winter covering crop residue incorporation on CH₄ and N₂O emission from double-cropped paddy fields in southern China.

    PubMed

    Tang, Haiming; Xiao, Xiaoping; Tang, Wenguang; Wang, Ke; Sun, Jimin; Li, Weiyan; Yang, Guangli

    2015-08-01

    Residue management in cropping systems is useful to improve soil quality. However, the studies on the effects of residue management on methane (CH4) and nitrous oxide (N2O) emission from paddy field in southern China are few. Therefore, the emissions of CH4 and N2O were investigated in double cropping rice (Oryza sativa L.) systems with different winter covering crops using the static chamber-gas chromatography technique to assess the effects of different covering crops on the emissions of greenhouse gases. The experiment was established in 2004 in Hunan Province, China. Three winter cropping systems were used: rice-rice-rape (Brassica napus L.) (T1), rice-rice-potato with straw mulching (Solanum tuberosum L.) (T2), and rice-rice with winter fallow (CK). A randomized block design was adopted in plots, with three replications. The results showed that T2 plots had the largest CH4 emissions during the early and late rice growing season with 12.506 and 32.991 g m(-2), respectively. When compared to CK, total N2O emissions in the early rice growth period and the emissions of the gas increased by 0.013 g m(-2) in T1 and 0.045 g m(-2) in T2, respectively. Similar results were obtained in the late rice growth period; the total N2O emissions increased by 0.027 g m(-2) in T1 and 0.084 g m(-2) in T2, respectively. The mean value of global warming potentials (GWPs) of CH4 and N2O emissions over 100 years was in the order of T2 > T1 > CK, which indicated CK and T1 was significantly lower than T2 (P < 0.05). This suggests that adoption of T1 would be beneficial for greenhouse gas emission mitigation and could be a good option cropping pattern in double rice cropped regions. PMID:25913315

  2. Characterization and risk assessment of polychlorinated biphenyls in soils and rice tissues in a suburban paddy field of the Pearl River Delta, South China.

    PubMed

    Li, Qilu; Wang, Yan; Luo, Chunling; Li, Jun; Zhang, Gan

    2015-08-01

    We investigated the concentration and composition of polychlorinated biphenyls (PCBs) in paddy soils and rice tissues and the associated potential health risks in the urban agricultural areas of the Pearl River Delta (PRD), South China. The results indicated that highly chlorinated PCBs were more prominent in soil when the concentrations of low-molecular-weight PCBs were relatively high in rice plants. There was a trend of decreasing PCB concentrations with soil depth and a significant correlation between PCBs and the total organic carbon or total nitrogen concentration in section soils. The PCB concentrations followed the order of root > leaf > stem > grain. Although the dioxin toxicity equivalency values and estimated daily intake levels (based direct and indirect consumption) were lower than in other seriously contaminated regions, there is still a need to monitor PCB pollution in urban agriculture because of the PCB emissions from capacitor storage following the rapid urbanization experienced in the PRD. PMID:25847439

  3. Using DET and DGT probes (ferrihydrite and titanium dioxide) to investigate arsenic concentrations in soil porewater of an arsenic-contaminated paddy field in Bangladesh.

    PubMed

    Garnier, Jean-Marie; Garnier, Jrmie; Jzquel, Didier; Angeletti, Bernard

    2015-12-01

    Arsenic concentration in the pore water of paddy fields (Csoln) irrigated with arsenic-rich groundwater is a key parameter in arsenic uptake by rice. Pore water extracts from cores and in situ deployment of DET and DGT probes were used to measure the arsenic concentration in the pore water. Ferrihydrite (Fe) and titanium dioxide (Ti) were used as DGT binding agents. Six sampling events during different growing stages of the rice, inducing different biogeochemical conditions, were performed in one rice field. A time series of DGT experiments allow the determination of an in situ arsenic diffusion coefficient in the diffusive gel (3.3410(-6) cm(2) s(-1)) needed to calculate the so-called CDGT(Fe) and CDGT(Ti) concentrations. Over 3 days of a given sampling event and for cores sampled at intervals smaller than 50 cm, great variability in arsenic Csoln concentrations between vertical profiles was observed, with maxima of concentrations varying from 690 to 2800 ?g L(-1). Comparisons between arsenic measured Csol and CDET and calculated CDGT(Fe) and CDGT(Ti) concentrations show either, in a few cases, roughly similar vertical profiles, or in other cases, significantly different profiles. An established iron oxyhydroxide precipitation in the DET gel may explain why measured arsenic CDET concentrations occasionally exceeded Csoln. The large spread in results suggests limitations to the use of DET and type of DGT probes used here for similarly representing the spatio-temporal variations of arsenic content in soil pore water in specific environmental such as paddy soils. PMID:26225738

  4. Temporal patterns and source apportionment of nitrate-nitrogen leaching in a paddy field at Kelantan, Malaysia.

    PubMed

    Hussain, Hazilia; Yusoff, Mohd Kamil; Ramli, Mohd Firuz; Abd Latif, Puziah; Juahir, Hafizan; Zawawi, Mohamed Azwan Mohammed

    2013-11-15

    Nitrate-nitrogen leaching from agricultural areas is a major cause for groundwater pollution. Polluted groundwater with high levels of nitrate is hazardous and cause adverse health effects. Human consumption of water with elevated levels of NO3-N has been linked to the infant disorder methemoglobinemia and also to non-Hodgkin's disease lymphoma in adults. This research aims to study the temporal patterns and source apportionment of nitrate-nitrogen leaching in a paddy soil at Ladang Merdeka Ismail Mulong in Kelantan, Malaysia. The complex data matrix (128 x 16) of nitrate-nitrogen parameters was subjected to multivariate analysis mainly Principal Component Analysis (PCA) and Discriminant Analysis (DA). PCA extracted four principal components from this data set which explained 86.4% of the total variance. The most important contributors were soil physical properties confirmed using Alyuda Forecaster software (R2 = 0.98). Discriminant analysis was used to evaluate the temporal variation in soil nitrate-nitrogen on leaching process. Discriminant analysis gave four parameters (hydraulic head, evapotranspiration, rainfall and temperature) contributing more than 98% correct assignments in temporal analysis. DA allowed reduction in dimensionality of the large data set which defines the four operating parameters most efficient and economical to be monitored for temporal variations. This knowledge is important so as to protect the precious groundwater from contamination with nitrate. PMID:24511695

  5. Effects of free-air CO2 enrichment (FACE) and soil warming on CH4 emission from a rice paddy field: impact assessment and stoichiometric evaluation

    NASA Astrophysics Data System (ADS)

    Tokida, T.; Fumoto, T.; Cheng, W.; Matsunami, T.; Adachi, M.; Katayanagi, N.; Matsushima, M.; Okawara, Y.; Nakamura, H.; Okada, M.; Sameshima, R.; Hasegawa, T.

    2010-09-01

    Paddy fields are an important source of atmospheric CH4, the second most important greenhouse gas. There is a strong concern that the increasing atmospheric CO2 concentration ([CO2]) and global warming are further stimulating CH4 emissions, but the magnitude of this stimulation varies substantially by study, and few open-field evaluations have been conducted. Here we report results obtained at a Japanese rice free-air CO2 enrichment (FACE) site under water and soil temperature elevation during two growing seasons. Our objectives were to evaluate the effects of high [CO2] (ambient + 200 ?mol mol-1) and elevated soil temperature (+ 2 C) on CH4 emissions under completely open-field conditions. We found about 80% enhancement in total seasonal emissions by the additive effects of FACE and warming, indicating a strong positive feedback effect of global warming. The enhancement in CH4 emission from the FACE-effect alone (+ 26%) was statistically non-significant (P = 0.19). Nevertheless, observed positive correlations between CH4 emissions and rice biomass agreed well with previous studies, suggesting that higher photosynthesis led to greater rhizodeposition, which then acted as substrates for methanogenesis. Soil warming increased the emission by 44% (P < 0.001), which was equivalent to a Q10 of 5.5. Increased rice biomass by warming could only partly explain the enhanced CH4 emissions, but stoichiometric analysis of the electron budget indicated that even a moderate enhancement in organic matter decomposition due to soil warming can cause a large increase in CH4 production under conditions where Fe(III) reduction, which was little affected by soil warming, dominates electron-accepting processes. At later rice growth stages, advanced root senescence due to elevated temperature probably provided more substrate for methanogenesis. Our stoichiometric evaluation showed that in situ Fe reduction characteristics and root turnover in response to elevated temperature should be understood to correctly predict future CH4 emissions from paddy fields under a changing climate. Challenges remain for determination of in situ root-exudation rate and its response to FACE and warming.

  6. Effects of free-air CO2 enrichment (FACE) and soil warming on CH4 emission from a rice paddy field: impact assessment and stoichiometric evaluation

    NASA Astrophysics Data System (ADS)

    Tokida, T.; Fumoto, T.; Cheng, W.; Matsunami, T.; Adachi, M.; Katayanagi, N.; Matsushima, M.; Okawara, Y.; Nakamura, H.; Okada, M.; Sameshima, R.; Hasegawa, T.

    2010-03-01

    Paddy fields are an important source of atmospheric CH4, the second most important greenhouse gas. There is a strong concern that the increasing atmospheric CO2 concentration ([CO2]) and global warming are further stimulating CH4 emissions, but the magnitude of this stimulation varies substantially by study, and few open-field evaluations have been conducted. Here we report results obtained at a Japanese rice free-air CO2 enrichment (FACE) site under water and soil temperature elevation during two growing seasons. Our objectives were to evaluate the effects of high [CO2] (ambient+200 ?mol mol-1) and elevated soil temperature (+2 C) on CH4 emissions under completely open-field conditions. We found about 80% enhancement in total seasonal emissions by the additive effects of FACE and warming, indicating a strong positive feedback effect of global warming. The enhancement in CH4 emission (+26%, P = 0.19) from the effect of FACE alone was similar to that in rice biomass, suggesting that higher photosynthesis led to greater rhizodeposition, providing substrates for methanogenesis. Soil warming increased the emission by 44% (P < 0.001), which was equivalent to a Q10 of 5.5. Increased rice biomass by warming could only partly explain the enhanced CH4 emissions, but stoichiometric analysis of the electron budget indicated that even a moderate enhancement in organic matter decomposition due to soil warming can cause a large increase in CH4 production under conditions where Fe(III) reduction, which was little affected by soil warming, dominates electron-accepting processes. At later rice growth stages, advanced root senescence due to elevated temperature probably provided more substrate for methanogenesis. Our stoichiometric evaluation showed that in situ Fe reduction characteristics and root turnover in response to elevated temperature should be understood to correctly predict future CH4 emissions from paddy fields under a changing climate. Challenges remain for determination of in situ root-exudation rate and its response to FACE and warming.

  7. Dissolved carbon and nitrogen dynamics in paddy fields under different water management practices and implications on green-house gas emissions

    NASA Astrophysics Data System (ADS)

    Miniotti, Eleonora; Said-Pullicino, Daniel; Bertora, Chiara; Pelissetti, Simone; Sacco, Dario; Grignani, Carlo; Lerda, Cristina; Romani, Marco; Celi, Luisella

    2013-04-01

    The alternation of oxidizing and reducing conditions in paddy soils results in considerable complexity in the biogeochemical cycling of elements and their interactions, influencing important soil processes. Water management practices may play an important role in controlling the loss of nutrients from rice paddies to surface and subsurface waters, as well as soil organic matter (SOM) stabilization and the emission of green-house gases (GHG) such as methane and nitrous oxide. The aim of this study was therefore to evaluate the interaction between changes in soil redox conditions and element cycling in temperate paddy soils as a function of different water management practices. The research was carried out within an experimental platform (1.2 ha) located at the Rice Research Center of Ente Nazionale Risi (Castello d'Agogna, PV, NW Italy) where three water management practices are being compared with two plots for each treatment. These included (i) rice cultivation under traditional submerged conditions (FLD); (ii) seeding under dry soil conditions and flooding delayed by about 40 days (DRY); (iii) seeding under dry soil conditions and rotational irrigation (IRR). Surface and subsurface (25, 50 and 75 cm) water samples were collected at regular intervals over the cropping season from V-notch weirs and porous ceramic suction cups installed in each plot, and subsequently analyzed for DOC, SUVA, Fe(II), ammonium and nitrate-N. Moreover, methane and nitrous oxide fluxes were measured in situ by the closed-chamber technique. DOC concentrations in soil solutions were generally higher in FLD and DRY treatments with respect to IRR throughout the cropping season. Higher DOC contents after field flooding in FLD and DRY treatments also corresponded with greater concentrations of reduced Fe, higher SUVA values, lower Eh values and higher pH values, suggesting that desorption of more aromatic, mineral-associated SOM could be responsible for the observed increase in DOC. These trends were not observed in the IRR treatment. The differences in DOC contents and in Eh trend between treatments could possibly explain the increasing trend in cumulative methane emissions in the order IRR<field study show that alternative water management practices may have important implications on nutrient availability, fertilizer efficiency, losses of DOC and nitrates to surface and subsurface waters, soil C stocks as well as GHG emissions. Suggesting alternative management practices therefore requires a holistic evaluation of the extent of all the processes involved. This research was partly supported by the Italian Ministry of Agriculture, Food and Forestry within the project POLORISO.

  8. Ammonia volatilization from a paddy field following applications of urea: rice plants are both an absorber and an emitter for atmospheric ammonia.

    PubMed

    Hayashi, Kentaro; Nishimura, Seiichi; Yagi, Kazuyuki

    2008-02-15

    Ammonia (NH(3)) volatilization from a paddy field following applications of urea was measured. Two lysimeters of Gray Lowland soil with a pH (H(2)O) of 5.7 were used for the experiment. Urea was applied at a rate of 50 kg N ha(-1) by incorporation as the basal fertilization (BF) and at rates of 30 and 10 kg N ha(-1) by top-dressing as the first (SF1) and second (SF2) supplemental fertilizations, respectively. Two wind tunnels per lysimeter were installed just after BF; one was transplanted with rice plants (PR plot), and the other was without rice plants (NR plot). Weak volatilization was observed at the PR plots after BF. By contrast, strong volatilization was observed at the PR plots after SF1 with a maximum flux of 150 g N ha(-1) h(-1); however, almost no volatilization was observed after SF2. The NH(3) volatilization loss accounted for 2.1%, 20.9%, 0.5%, and 8.2% of the applied urea at each application, BF, SF1, SF2, and the total application, respectively, for which only the net fluxes as volatilization were accumulated. The NH(3) volatilization fluxes from the paddy water surface (F(vol)) at the NR plots were estimated using a film model for its verification. After confirmation of good correlation, the film model was applied to estimate F(vol) at the PR plots. The NH(3) exchange fluxes by rice plants (F(ric)) were obtained by subtracting F(vol) from the observed net NH(3) flux. The derived F(ric) showed that the rice plants emitted NH(3) remarkably just after SF1 when a relatively high rate of urea was applied, although they absorbed atmospheric NH(3) in the other periods. In conclusion, rice plants are essentially an absorber of atmospheric NH(3); however, they turn into an emitter of NH(3) under excess nutrition of ammoniacal nitrogen. PMID:18054067

  9. A Rice Gene for Microbial Symbiosis, Oryza sativa CCaMK, Reduces CH4 Flux in a Paddy Field with Low Nitrogen Input

    PubMed Central

    Bao, Zhihua; Watanabe, Aya; Sasaki, Kazuhiro; Okubo, Takashi; Tokida, Takeshi; Liu, Dongyan; Ikeda, Seishi; Imaizumi-Anraku, Haruko; Asakawa, Susumu; Sato, Tadashi; Mitsui, Hisayuki

    2014-01-01

    Plants have mutualistic symbiotic relationships with rhizobia and fungi by the common symbiosis pathway, of which Ca2+/calmodulin-dependent protein kinase (encoded by CCaMK) is a central component. Although Oryza sativa CCaMK (OsCCaMK) is required for fungal accommodation in rice roots, little is known about the role of OsCCaMK in rice symbiosis with bacteria. Here, we report the effect of a Tos17-induced OsCCaMK mutant (NE1115) on CH4 flux in low-nitrogen (LN) and standard-nitrogen (SN) paddy fields compared with wild-type (WT) Nipponbare. The growth of NE1115 was significantly decreased compared with that of the WT, especially in the LN field. The CH4 flux of NE1115 in the LN field was significantly greater (156 to 407% in 2011 and 170 to 816% in 2012) than that of the WT, although no difference was observed in the SN field. The copy number of pmoA (encodes methane monooxygenase in methanotrophs) was significantly higher in the roots and rhizosphere soil of the WT than in those of NE1115. However, the mcrA (encodes methyl coenzyme M reductase in methanogens) copy number did not differ between the WT and NE1115. These results were supported by a 13C-labeled CH4-feeding experiment. In addition, the natural abundance of 15N in WT shoots (3.05) was significantly lower than in NE1115 shoots (3.45), suggesting greater N2 fixation in the WT because of dilution with atmospheric N2 (0.00). Thus, CH4 oxidation and N2 fixation were simultaneously activated in the root zone of WT rice in the LN field and both processes are likely controlled by OsCCaMK. PMID:24441161

  10. [Straw return to rice paddy: soil carbon sequestration and increased methane emission].

    PubMed

    Lu, Fei; Wang, Xiao-Ke; Han, Bing; Ouyang, Zhi-Yun; Zheng, Hua

    2010-01-01

    Based on the long-term datasets of soil organic matter content and the observation data of rice paddies' methane (CH4) emission collected from the agricultural experiment stations across the country, the rice paddies in China were divided into single cropping and double cropping regions. The soil carbon sequestration potential of straw return in three types of rice paddies in the two regions, i. e., single cropping rice paddies, upland/paddy alternated rice paddies, and double cropping rice paddies, was evaluated, based on the datasets of soil organic matter content; and the total CH4 emission from rice paddies without straw return was estimated, with reference to the experimental data of paddies' CH4 emission and by the method of mean emission coefficient. The total CH4 emission from our paddies after straw return and the global warming potential of the increased CH4 emission were also estimated by using the related methods and parameters given by IPCC. It was estimated that the full popularization of straw return to China's rice paddies would sequester 10.48 Tg x a(-1) of C, and the contribution to the global warming mitigation was 38.43 Tg CO2-eqv x a(-1). In the meanwhile, the CH4 emission from our rice paddies would be increased from 5.796 Tg x a(-1) to 9.114 Tg x a(-1), and the increased 3.318 Tg x a(-1) of CH4 emission would lead to a global warming potential of 82.95 Tg CO2 -eqv x a(-1), which was 2.158 times of the mitigation from carbon sequestration in rice paddies. Therefore, the increased CH4 emission due to straw return should be regarded as an important greenhouse gas leakage, since it could greatly offset the mitigation benefits of soil carbon sequestration in China's rice paddies. PMID:20387430

  11. Quantification and modelling of water flow in rain-fed paddy fields in NE Thailand: Evidence of soil salinization under submerged conditions by artesian groundwater

    NASA Astrophysics Data System (ADS)

    Hammecker, Claude; Maeght, Jean-Luc; Grnberger, Olivier; Siltacho, Siwaporn; Srisruk, Kriengsak; Noble, Andrew

    2012-08-01

    SummaryWater flow and solute transport in soils forms an essential part in many groundwater hydrology studies. This is especially true for Northeast Thailand, where the agricultural land is affected by the soil salinity, which is a widespread and an increasing phenomenon affecting 25% of the agricultural land. Salinization appears as scattered discrete patches of 10-100 m2 in the lowlands, illustrated by white efflorescences during the dry season and bare soil during the cropping season. A field study was undertaken in farm plots to measure the water flow and solute transport within the soil surface and the vadose zone, both inside and outside a saline patch. The water flow was measured on the soil surface with lysimeters and infiltration rings, and was derived in the soil from the hydraulic gradients measured with tensiometers placed at different depths. The salt transport was evaluated with water traps also placed at different depths, where the soil water's electrical conductivity was measured throughout the rainy season. Field study results demonstrated that the accumulation of saline solutions in rain fed paddy fields, occurred mainly during the rainy season while the soil surface remained flooded. During this period the saline water table rose towards the soil surface independently of infiltration into the soil. It happened in specific places where the compacted soil layer, generally ubiquitous in the area at a depth of 40-50 cm, is interrupted. Therefore salinity appeareds in discret points as patches. Artesian upward flow already described in this area (Haworth et al., 1966; Williamson et al., 1989; Imaizumi et al., 2002) is most probably responsible for this water table rise, thereby affecting crop productivity. Numerical modelling of water flow using HYDRUS-3D further supported these results and showed that managing the depth of flooding within the plot can significantly reduce the outbreak of these saline plumes.

  12. Responses of methanogen mcrA genes and their transcripts to an alternate dry/wet cycle of paddy field soil.

    PubMed

    Ma, Ke; Conrad, Ralf; Lu, Yahai

    2012-01-01

    Intermittent drainage can substantially reduce methane emission from rice fields, but the microbial mechanisms remain poorly understood. In the present study, we determined the rates of methane production and emission, the dynamics of ferric iron and sulfate, and the abundance of methanogen mcrA genes (encoding the alpha subunit of methyl coenzyme M reductase) and their transcripts in response to alternate dry/wet cycles in paddy field soil. We found that intermittent drainage did not affect the growth of rice plants but significantly reduced the rates of both methane production and emission. The dry/wet cycles also resulted in shifts of soil redox conditions, increasing the concentrations of ferric iron and sulfate in the soil. Quantitative PCR analysis revealed that both mcrA gene copies and mcrA transcripts significantly decreased after dry/wet alternation compared to continuous flooding. Correlation and regression analyses showed that the abundance of mcrA genes and transcripts positively correlated with methane production potential and soil water content and negatively correlated with the concentrations of ferric iron and sulfate in the soil. However, the transcription of mcrA genes was reduced to a greater extent than the abundance of mcrA genes, resulting in very low mcrA transcript/gene ratios after intermittent drainage. Furthermore, terminal restriction fragment length polymorphism analysis revealed that the composition of methanogenic community remained stable under dry/wet cycles, whereas that of metabolically active methanogens strongly changed. Collectively, our study demonstrated a stronger effect of intermittent drainage on the abundance of mcrA transcripts than of mcrA genes in rice field soil. PMID:22101043

  13. Influence of nitrogen loading and plant nitrogen assimilation on nitrogen leaching and N?O emission in forage rice paddy fields fertilized with liquid cattle waste.

    PubMed

    Riya, Shohei; Zhou, Sheng; Kobara, Yuso; Sagehashi, Masaki; Terada, Akihiko; Hosomi, Masaaki

    2015-04-01

    Livestock wastewater disposal onto rice paddy fields is a cost- and labor-effective way to treat wastewater and cultivate rice crops. We evaluated the influence of nitrogen loading rates on nitrogen assimilation by rice plants and on nitrogen losses (leaching and N2O emission) in forage rice fields receiving liquid cattle waste (LCW). Four forage rice fields were subjected to nitrogen loads of 107, 258, 522, and 786 kg N ha(-1) (N100, N250, N500, and N750, respectively) using basal fertilizer (chemical fertilizer) (50 kg N ha(-1)) and three LCW topdressings (each 57-284 kg N ha(-1)). Nitrogen assimilated by rice plants increased over time. However, after the third topdressing, the nitrogen content of the biomass did not increase in any treatment. Harvested aboveground biomass contained 93, 60, 33, and 31 % of applied nitrogen in N100, N250, N500, and N750, respectively. The NH4 (+) concentration in the pore water at a depth of 20 cm was less than 1 mg N L(-1) in N100, N250, and N500 throughout the cultivation period, while the NH4 (+) concentration in N750 increased to 3 mg N L(-1) after the third topdressing. Cumulative N2O emissions ranged from -0.042 to 2.39 kg N ha(-1); the highest value was observed in N750, followed by N500. In N750, N2O emitted during the final drainage accounted for 80 % of cumulative N2O emissions. This study suggested that 100-258 kg N ha(-1) is a recommended nitrogen loading rate for nitrogen recovery by rice plants without negative environmental impacts such as groundwater pollution and N2O emission. PMID:25388561

  14. Responses of Methanogen mcrA Genes and Their Transcripts to an Alternate Dry/Wet Cycle of Paddy Field Soil

    PubMed Central

    Ma, Ke; Conrad, Ralf

    2012-01-01

    Intermittent drainage can substantially reduce methane emission from rice fields, but the microbial mechanisms remain poorly understood. In the present study, we determined the rates of methane production and emission, the dynamics of ferric iron and sulfate, and the abundance of methanogen mcrA genes (encoding the alpha subunit of methyl coenzyme M reductase) and their transcripts in response to alternate dry/wet cycles in paddy field soil. We found that intermittent drainage did not affect the growth of rice plants but significantly reduced the rates of both methane production and emission. The dry/wet cycles also resulted in shifts of soil redox conditions, increasing the concentrations of ferric iron and sulfate in the soil. Quantitative PCR analysis revealed that both mcrA gene copies and mcrA transcripts significantly decreased after dry/wet alternation compared to continuous flooding. Correlation and regression analyses showed that the abundance of mcrA genes and transcripts positively correlated with methane production potential and soil water content and negatively correlated with the concentrations of ferric iron and sulfate in the soil. However, the transcription of mcrA genes was reduced to a greater extent than the abundance of mcrA genes, resulting in very low mcrA transcript/gene ratios after intermittent drainage. Furthermore, terminal restriction fragment length polymorphism analysis revealed that the composition of methanogenic community remained stable under dry/wet cycles, whereas that of metabolically active methanogens strongly changed. Collectively, our study demonstrated a stronger effect of intermittent drainage on the abundance of mcrA transcripts than of mcrA genes in rice field soil. PMID:22101043

  15. Effects of fertilization on microbial abundance and emissions of greenhouse gases (CH4 and N2O) in rice paddy fields.

    PubMed

    Fan, Xianfang; Yu, Haiyang; Wu, Qinyan; Ma, Jing; Xu, Hua; Yang, Jinghui; Zhuang, Yiqing

    2016-02-01

    This study is to explore effects of nitrogen application and straw incorporation on abundance of relevant microbes and CH 4 and N2O fluxes in a midseason aerated rice paddy field. Fluxes of CH 4 and N2O were recorded, and abundance of relevant soil microbial functional genes was determined during rice-growing season in a 6-year-long fertilization experiment field in China. Results indicate that application of urea significantly changed the functional microbial composition, while the influence of straw incorporation was not significant. Application of urea significantly decreased the gene abundances of archaeal amoA and mcrA, but it significantly increased the gene abundances of bacterial amoA. CH 4 emission was significantly increased by fresh straw incorporation. Incorporation of burnt straw tended to increase CH 4 emission, while the urea application had no obvious effect on CH 4 emission. N2O emission was significantly increased by urea application, while fresh or burnt straw incorporation tended to decrease N2O emission. The functional microbial composition did not change significantly over time, although the abundances of pmoA, archaeal amoA, nirS, and nosZ genes changed significantly. The change of CH 4 emission showed an inverse trend with the one of the N2O emissions over time. To some extent, the abundance of some functional genes in this study can explain CH 4 and N2O emissions. However, the correlation between CH 4 and N2O emissions and the abundance of related functional genes was not significant. Environmental factors, such as soil Eh, may be more related to CH 4 and N2O emissions. PMID:26811747

  16. Estimation of Actual Crop ET of Paddy Using the Energy Balance Model SMARET and Validation with Field Water Balance Measurements and a Crop Growth Model (ORYZA)

    NASA Astrophysics Data System (ADS)

    Nallasamy, N. D.; Muraleedharan, B. V.; Kathirvel, K.; Narasimhan, B.

    2014-12-01

    Sustainable management of water resources requires reliable estimates of actual evapotranspiration (ET) at fine spatial and temporal resolution. This is significant in the case of rice based irrigation systems, one of the major consumers of surface water resources and where ET forms a major component of water consumption. However huge tradeoff in the spatial and temporal resolution of satellite images coupled with lack of adequate number of cloud free images within a growing season act as major constraints in deriving ET at fine spatial and temporal resolution using remote sensing based energy balance models. The scale at which ET is determined is decided by the spatial and temporal scale of Land Surface Temperature (LST) and Normalized Difference Vegetation Index (NDVI), which form inputs to energy balance models. In this context, the current study employed disaggregation algorithms (NL-DisTrad and DisNDVI) to generate time series of LST and NDVI images at fine resolution. The disaggregation algorithms aimed at generating LST and NDVI at finer scale by integrating temporal information from concurrent coarse resolution data and spatial information from a single fine resolution image. The temporal frequency of the disaggregated images is further improved by employing composite images of NDVI and LST in the spatio-temporal disaggregation method. The study further employed half-hourly incoming surface insolation and outgoing long wave radiation obtained from the Indian geostationary satellite (Kalpana-1) to convert the instantaneous ET into daily ET and subsequently to the seasonal ET, thereby improving the accuracy of ET estimates. The estimates of ET were validated with field based water balance measurements carried out in Gadana, a subbasin predominated by rice paddy fields, located in Tamil Nadu, India.

  17. The Extraction Model of Paddy Rice Information Based on GF-1 Satellite WFV Images.

    PubMed

    Yang, Yan-jun; Huang, Yan; Tian, Qing-jiu; Wang, Lei; Geng, Jun; Yang, Ran-ran

    2015-11-01

    In the present, using the characteristics of paddy rice at different phenophase to identify it by remote sensing images is an efficient way in the information extraction. According to the remarkably properties of paddy rice different from other vegetation, which the surface of paddy fields is with a large number of water in the early stage, NDWI (normalized difference water index) which is used to extract water information can reasonably be applied in the extraction of paddy rice at the early stage of the growth. And using NDWI ratio of two phenophase can expand the difference between paddy rice and other surface features, which is an important part for the extraction of paddy rice with high accuracy. Then using the variation of NDVI (normalized differential vegetation index) in different phenophase can further enhance accuracy of paddy rice information extraction. This study finds that making full advantage of the particularity of paddy rice in different phenophase and combining two indices (NDWI and NDVI) associated with paddy rice can establish a reasonable, accurate and effective extraction model of paddy rice. This is also the main way to improve the accuracy of paddy rice extraction. The present paper takes Lai'an in Anhui Province as the research area, and rice as the research object. It constructs the extraction model of paddy rice information using NDVI and NDWI between tillering stage and heading stage. Then the model was applied to GF1-WFV remote sensing image on July 12, 2013 and August 30, 2013. And it effectively extracted out of paddy rice distribution in Lai'an and carried on the mapping. At last, the result of extraction was verified and evaluated combined with field investigation data in the study area. The result shows that using the extraction model can quickly and accurately obtain the distribution of rice information, and it has the very good universality. PMID:26978945

  18. Organophosphorus and Carbamate Pesticide Residues Detected in Water Samples Collected from Paddy and Vegetable Fields of the Savar and Dhamrai Upazilas in Bangladesh

    PubMed Central

    Chowdhury, Md. Alamgir Zaman; Banik, Sanjoy; Uddin, Borhan; Moniruzzaman, Mohammed; Karim, Nurul; Gan, Siew Hua

    2012-01-01

    Several types of organophosphorous and carbamate pesticides have been used extensively by the farmers in Bangladesh during the last few decades. Twenty seven water samples collected from both paddy and vegetable fields in the Savar and Dhamrai Upazilas in Bangladesh were analyzed to determine the occurrence and distribution of organo-phosphorus (chlorpyrifos, malathion and diazinon) and carbamate (carbaryl and carbofuran) pesticide residues. A high performance liquid chromatograph instrument equipped with a photodiode array detector was used to determine the concentrations of these pesticide residues. Diazinon and carbofuran were detected in water samples collected from Savar Upazila at 0.9 μg/L and 198.7 μg/L, respectively. Malathion was also detected in a single water sample at 105.2 μg/L from Dhamrai Upazila. Carbaryl was the most common pesticide detected in Dhamrai Upazila at 14.1 and 18.1 μg/L, while another water sample from Dhamrai Upazila was contaminated with carbofuran at 105.2 μg/L. Chlorpyrifos was not detected in any sample. Overall, the pesticide residues detected were well above the maximum acceptable levels of total and individual pesticide contamination, at 0.5 and 0.1 μg/L, respectively, in water samples recommended by the European Economic Community (Directive 98/83/EC). The presence of these pesticide residues may be attributed by their intense use by the farmers living in these areas. Proper handling of these pesticides should be ensured to avoid direct or indirect exposure to these pesticides. PMID:23202689

  19. Effects of elevated ozone concentration on CH4 and N2O emission from paddy soil under fully open-air field conditions.

    PubMed

    Tang, Haoye; Liu, Gang; Zhu, Jianguo; Kobayashi, Kazuhiko

    2015-04-01

    We investigated the effects of elevated ozone concentration (E-O3) on CH4 and N2O emission from paddies with two rice cultivars: an inbred Indica cultivar Yangdao 6 (YD6) and a hybrid one II-you 084 (IIY084), under fully open-air field conditions in China. A mean 26.7% enhancement of ozone concentration above the ambient level (A-O3) significantly reduced CH4 emission at tillering and flowering stages leading to a reduction of seasonal integral CH4 emission by 29.6% on average across the two cultivars. The reduced CH4 emission is associated with O3-induced reduction in the whole-plant biomass (-13.2%), root biomass (-34.7%), and maximum tiller number (-10.3%), all of which curbed the carbon supply for belowground CH4 production and its release from submerged soil to atmosphere. Although no significant difference was detected between the cultivars in the CH4 emission response to E-O3, a larger decrease in CH4 emission with IIY084 (-33.2%) than that with YD6 (-7.0%) was observed at tillering stage, which may be due to the larger reduction in tiller number in IIY084 by E-O3. Additionally, E-O3 reduced seasonal mean NOx flux by 5.7% and 11.8% with IIY084 and YD6, respectively, but the effects were not significant statistically. We found that the relative response of CH4 emission to E-O3 was not significantly different from those reported in open-top chamber experiments. This study has thus confirmed that increasing ozone concentration would mitigate the global warming potential of CH4 and suggested consideration of the feedback mechanism between ozone and its precursor emission into the projection of future ozone effects on terrestrial ecosystem. PMID:25403809

  20. Seasonal parameter extraction of paddy rice fields in West Java using multi-temporal MODIS imagery datasets

    NASA Astrophysics Data System (ADS)

    Sianturi, Riswan S.; Nieuwenhuis, Willem; Jetten, V. G.

    2015-10-01

    Continuous monitoring on farming practices is urgently needed provided the challenges faced by rice fields. Information of seasonal parameters supplies crucial inputs for monitoring rice fields as well as improving other applications, such as biomass monitoring, yield estimation, integrated pest management, irrigation water management, and precision farming. We extracted the heading stages using multi-temporal MODerate resolution Imaging Spectroradiometer (MODIS) imageries in rice fields in northern districts of West Java, Indonesia. The spatial distribution of the heading stages in the whole year suggests complex cropping pattern of rice fields in West Java. The monthly average of EVI shows that green waves move northward as the results of stipulated cropping calendar. The Root Mean Square Error (RMSE) for the heading stages is 12.77 days. The heading stages periods of most rice fields are from the middle of February to the middle of March and from the middle of June to the middle of July for rendeng and gadu, consecutively. The findings provide timely and cost effective information for monitoring rice fields.

  1. Impact of six transgenic Bacillus thuringiensis rice lines on four nontarget thrips species attacking rice panicles in the paddy field.

    PubMed

    Akhtar, Z R; Tian, J C; Chen, Y; Fang, Q; Hu, C; Peng, Y F; Ye, G Y

    2013-02-01

    As a key component of ecological risk assessments, nontarget effects of Bacillus thuringiensis (Bt) rice have been tested under laboratory and field conditions for various organisms. A 2-yr field experiment was conducted to observe the nontarget effects of six transgenic rice lines (expressing the Cry1Ab or fused protein of Cry1Ab and Cry1Ac) on four nontarget thrips species including Frankliniella intonsa (Trybom), F. tenuicornis (Uzel), Haplothrips aculeatus (F.), and H. tritici (Kurd), as compared with their rice parental control lines. Two sampling methods including the beat plate and plastic bag method were used to monitor the population densities of the four thrips species for 2 yr. The results showed that the seasonal average densities of four tested thrips species in Bt rice plots were significantly lower than or very similar to those in the non-Bt rice plots depending on rice genotypes, sampling methods, and years. Among all six tested Bt rice lines, transgenic B1 and KMD2 lines suppressed the population of these tested thrips species the most. Our results indicate that the tested Bt rice lines are unlikely to result in high population pressure of thrips species in comparison with non-Bt rice. In some cases, Bt rice lines could significantly suppress thrips populations in the rice ecosystem. In addition, compatibility of Bt rice, with rice host plant resistance to nontarget sucking pests is also discussed within an overall integrated pest management program for rice. PMID:23339799

  2. Comparison of three models for simulating N2O emissions from paddy fields under water-saving irrigation

    NASA Astrophysics Data System (ADS)

    Wu, Xiarui; Zhang, Ao

    2014-12-01

    N2O emissions simulated by WNMM, DAYCENT and Crop-DNDC models were compared to the observed data sets from rice-wheat rotation systems under water-saving irrigation at Kunshan City, Jiangsu Province, China. On the basis of the correlation and paired t-test for evaluation, the simulation of N2O emission by Crop-DNDC and WNMM models provided better agreement with the observed data than by DAYCENT model. The daily time step, Crop-DNDC model was consistently the best for predicting daily N2O emissions (R2 = 0.892, n = 28, p > 0.05), and WNMM model performed better (R2 = 0.87, n = 28, p > 0.05). The Crop-DNDC model simulated the seasonal cumulative N2O emissions were the closest to the measured value of 1.07 kg N ha-1, and WNMM and DAYCENT models predicted 8.4% and 15.0% more N2O emissions than that in field experiments. The three models predicted well the seasonal cycle of soil temperature, soil moisture and could provide reliable estimations. The simulation of daily average soil temperature at 10 cm were consistently with the field observed data, which by Crop-DNDC (R2 = 0.92, n = 67, p > 0.05) and WNMM (R2 = 0.91, n = 67, p > 0.05). The comparison of observed to simulated results indicated that soil WFPS was simulated by Crop-DNDC (R2 = 0.52, n = 50, p > 0.05), WNMM (R2 = 0.56, n = 50, p > 0.05) and DAYCENT (R2 = 0.37, n = 50, p > 0.05). Accurate simulation of soil moisture, soil temperature and accurate partitioning of gaseous nitrogen loss into NO, N2O and N2 are challenges for all models.

  3. Further understanding of nitrous oxide emission from paddy fields under rice/wheat rotation in south China

    NASA Astrophysics Data System (ADS)

    Zhao, Xu; Min, Ju; Wang, Shenqiang; Shi, Weiming; Xing, Guangxi

    2011-06-01

    This paper reported the quantitative contribution of three important dry-wet cycles to N2O emission in annual rotation, and compared N2O emission patterns during rice and wheat seasons affected by diverse causes-induced dry-wet cycles based on in situ measurements for 2 consecutive years (from 2007 to 2009). Results showed that 50-70% of the annual N2O emission was emitted during wheat season and 30-50% during rice season. During rice seasons, greatest flux occurred immediately after preflooding at the start of rice season, accompanied by peaks of NO3- concentrations in soil water. N2O emission during the preflooding period contributed 80-84% of seasonal emission, far higher than 7.6-8.4% released during midseason aeration and 5.0-7.4% during drainage period. Variation of N2O emission in wheat season was much greater than that in rice season. In the Taihu lake region, controlled water management determined emissions of N2O in rice season, whereas variation of natural precipitation and temperature determined N2O emission pattern during wheat season.

  4. Observation and Modeling of Heat, Water and Carbon Dioxide Fluxes upon The Paddy Field for Development of The Numerical Integrate Agro-Ecosystem Simulator

    NASA Astrophysics Data System (ADS)

    Kim, W.; Komori, D.; Yokozawa, M.; Kanae, S.; Oki, T.

    2006-12-01

    The spatiotemporal fluctuation of water resources according to land use and climate changes have a demoralizing influence upon the potential area and the feasible period for paddy cultivation. To understand the syndrome, an agroecohydrological model which is considered both the characteristics of the cultivate method and the changes of land use around themselves or those upstream is indispensable. In consequence, the development of the Numerical Integrate Agro-Ecosystem Simulator (NIAES) which is based on a land surface model (LSM) and a real time monitoring and simulation system (RTMASS) has been explored. As a first step, some candidate LSMs are tested, validated and modified for NIAES model with micrometeorological flux tower data (Jun 2005 to May 2006) at Sukhothai in Thailand. The simulated trend of heat, water and carbon dioxide (CO2) fluxes are valid during the cultivate period of paddy (LAI > 2), but are disagree with those of measurements during the watering and the early period (LAI <= 2). The disagreements suggest that the paddy water is considered as an important parameter and the soil water conductivity is also estimated as a temporal variable in the LSMs to explain the land surface process of heat, water and CO2. During the non-cultivate period, the clear estimation of parameters for substituted grass type and the precise simulation of dewfall for dawn were key points to understand the characteristics of those fluxes in Indochina peninsula.

  5. Models for Estimating the Physical Properties of Paddy Soil Using Visible and Near Infrared Reflectance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Gholizadeh, A.; Amin, M. S. M.; Bor?vka, L.; Saberioon, M. M.

    2014-07-01

    A fast and convenient soil analytical technique is needed for soil quality assessment and precision soil management. The main objective of this study was to evaluate the ability of visible (Vis) and near-infrared (NIR) refl ectance spectroscopy to predict paddy soil properties in a typical Malaysian paddy fi eld. To assess the utility of spectroscopy for soil physical characteristics (bulk density, moisture content, clay, silt and sand) prediction, 118 soil samples were used for laboratory analysis and optical measurement in the Vis-NIR region using an analytical spectral device (ASD) FieldSpec spectroradiometer (350-2500 nm). The Savitzky-Golay algorithm and stepwise multiple linear regression (SMLR) were then applied to preprocess, model, and predict the properties on the basis of their spectral refl ectance within the Vis-NIR range. One-third of the samples (40 samples) were withheld for validation purposes. The study revealed that Vis and NIR spectroscopy calibration models for all the measured soil physical characteristics provided a good fi t (R2 > 0.78); hence Vis and NIR (specifi cally NIR refl ectance) can be considered to be a reliable tool to assess soil physical properties of Malaysian paddy fi elds. The results of this study could contribute signifi cantly to developing site-specifi c management.

  6. Greenhouse gas emission consequences of large-scale changes in water management of China's rice paddies during 1980-2000

    NASA Astrophysics Data System (ADS)

    Li, C.; Qiu, J.; Frolking, S.; Xiao, X.; Salas, W.; Moore, B.; Boles, S.; Huang, Y.; Sass, R.

    2003-04-01

    In China, midseason paddy drainage, which reduces growing season methane fluxes and enhances growing season nitrous oxide fluxes, was first implemented in the early 1980s, and has gradually replaced continuous flooding in much of the paddy rice area. We constructed a prediction rice paddy methane and nitrous oxide emissions in China using the DNDC biogeochemical model. Results of continuous flooding and midseason drainage simulations for all paddy fields in China (about 30 million ha) were combined with regional scenarios for the timing of the transition from continuous flooding to predominantly mid-season drainage to generate estimates of total methane (CH_4) and nitrous oxide (N_2O) flux for 1980-2000. By shifting from continuous flooding to midseason drainage management, we estimate that total N_2O emissions from the rice paddies in China increased by about 0.17 Tg N_2O-N yr-1 due to the stimulated nitrification and denitrification, while CH_4 emissions decreased by about 4.5 Tg CH_4-C yr-1 due to increased soil aeration. Simulated net carbon loss in paddy soils was about 0.65 Tg C yr-1 due to elevated decomposition. On a 100-year time frame, CH_4 has a global warming potential (GWP) 23 times that of CO_2, and N_2O has a GWP 296 times that of CO_2. The total GWP impact (2000 vs. 1980) of shifting to predominantly mid-season paddy drainage was -0.138 Pg CO_2-equiv yr-1 from methane, +0.077 Pg CO_2-equiv yr-1 from nitrous oxide and +0.0024 Pg CO_2 yr-1 from soil C loss, for a total GWP impact of -0.059 Pg CO_2-equiv yr-1. The results imply that more than half of the GWP benefit of decreased CH_4 emissions was offset, primarily by increases in N_2O emissions, and to a small degree by soil C loss.

  7. Open magnetic fields in active regions

    NASA Technical Reports Server (NTRS)

    Svestka, Z.; Solodyna, C. V.; Howard, R.; Levine, R. H.

    1977-01-01

    Soft X-ray images and magnetograms of several active regions and coronal holes are examined which support the interpretation that some of the dark X-ray gaps seen between interconnecting loops and inner cores of active regions are foot points of open field lines inside the active regions. Characteristics of the investigated dark gaps are summarized. All the active regions with dark X-ray gaps at the proper place and with the correct polarity predicted by global potential extrapolation of photospheric magnetic fields are shown to be old active regions, indicating that field opening is accomplished only in a late phase of active-region development. It is noted that some of the observed dark gaps probably have nothing in common with open fields, but are either due to the decreased temperature in low-lying portions of interconnecting loops or are the roots of higher and less dense or cooler loops.

  8. Mapping of arsenic pollution with reference to paddy cultivation in the middle Indo-Gangetic Plains.

    PubMed

    Srivastava, Pankaj Kumar; Singh, Manvi; Gupta, Manjul; Singh, Nandita; Kharwar, Ravindra Nath; Tripathi, Rudra Deo; Nautiyal, Chandra Shekhar

    2015-04-01

    A detailed field study was carried out to monitor (i) the arsenic contents in irrigation groundwater and paddy soil and (ii) the accumulation of arsenic in the roots and grains of different paddy varieties grown in the arsenic-contaminated middle Indo-Gangetic Plains of Northern India. Results showed the highest arsenic contamination in the irrigation groundwater (312?gl(-1)) and in paddy soil (35mgkg(-1)) values that were significantly exceeded the recommended threshold values of 100?gl(-1) (EU) and 20mgkg(-1) (FAO), respectively. The paddy soil arsenic content ranged from 3 to 35mgkg(-1) with a mean value of 15mgkg(-1). The soil arsenic content was found to be influenced by the soil texture, carbon, macronutrients, phosphorus, sulfur, hydrolases, and oxidoreductases properties of the paddy soils as revealed in the principal component analyses. Higher root accumulation (>10mgkg(-1)) of arsenic was observed in 6 of the 17 paddy varieties grown in the study area. The range of arsenic content accumulated in the paddy roots was 4.1 to 16.2mgkg(-1) dry weight (dw) and in the grains 0.179 to 0.932mgkg(-1) dw. Out of 17 paddy varieties, eight had 0?>?.55mgkg(-1) grain arsenic content and were found unsafe for subsistence maximum daily tolerable dietary intake (MTDI) by human beings according to the regulatory standards. PMID:25796519

  9. Understanding transitions in rice paddy extent and management in the Vietnamese Mekong River Delta using Landsat data

    NASA Astrophysics Data System (ADS)

    Kontgis, C. P.; Schneider, A.; Ozdogan, M.

    2014-12-01

    Rice is a staple food crop for the majority of the world's population, yet paddy fields are threatened by urban expansion, climate change, and degraded agricultural land. For example, Vietnam, the second largest exporter of rice globally, grows most of its rice in the Mekong River Delta at the country's southern tip, yet this low-lying and heavily populated area is proving susceptible to land cover changes in the area. To properly monitor and manage the rice crops in this region, remote sensing of satellite imagery has been particularly useful; however, most efforts to map regional paddy area utilize coarse resolution MODIS or AVHRR data since the high temporal resolution of these datasets can overcome missing data issues due to clouds. Here, we aim to map the landscape using finer-scale Landsat data by generating dense time stacks over multiple growing seasons. First, we exploit dense stacks of data for circa 2000 and circa 2010 to classify rice using vegetation trajectories (EVI and NDWI). Next, these pixel-based rice maps are combined with image-based segments (generated using the open-source Mean-shift region-growing segmentation algorithm, which has been proven to optimally identify clusters within an image) to generate a polygon-based rice map using the majority rule. Results show that this method can map rice paddy agriculture with over 90% accuracy at a much finer spatial resolution than has ever been produced. Finally, this work also aims to differentiate between double- and triple-cropped rice paddies in the region, again by exploiting EVI trajectories, in an effort to determine how management practices have changed over the decade-long study period. Increasing the number of annual cropping cycles over the area can lead to soil degradation and lower yields per harvest, albeit larger total annual yields, so monitoring these practices is vital to understanding the sustainability of these agricultural systems.

  10. Paddy soil cracks: characteristics and their impact on preferential flow

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongbin; Peng, Xinhua

    2015-04-01

    Paddy soils with harrowing and puddling easily crack under alternate flooding and drying cycles (AFD). These cracks in paddy field may become pathways of preferential flow, improving water infiltration and increasing the pollution risk of groundwater. The objectives of this study were to investigate the 2D and 3D characteristics of soil cracks in paddy fields; and to determine their impacts on preferential flow. Two paddy fields, one cultivated for 20 years (YPF) and the other cultivated for more than 100 years (OPF), were subjected to either alternate flooding and drying (AFD) or continuous flooding (CF) during rice growing season. After the harvest of late rice crop, soil surface cracks were recorded using digital camera; and 3D structure of soil cracks was scanned by computed tomography (CT). The characteristics of 2D and 3D soil cracks were quantified with the aid of image analysis. The influence of soil cracks on preferential flow was characterized by tension infiltrometer, dye tracer and ion breakthrough curve. Our main results in this study were summed up as follows: under AFD condition, for the 2D soil cracks, the YPF presented 10 fold more cracks in quantity but these cracks were finer and more complicated as compared to those generated in the OPF. The results of CT scanning showed that the presence of soil cracks under the AFD increased average macropore length but decreased the number of macropores significantly, and it also changed macropore size distribution and macropore area density distribution with soil depth. The 3D structures of soil cracks were complicated but can be quantified using CT. The depth of soil cracks in young paddy field (7.58 cm) was smaller than that in old paddy field (9.34 cm), but soil cracks in both fields did not reach the plough pan (about 15 cm). Soil cracks significantly increased soil hydraulic conductivity. They serviced as pathways for preferential flow only in plow layer, as evidenced by a large dyed area above plough pan but a small area below it. Both the shape of BTCs and fitting parameters demonstrated that soil cracks did not increase preferential flow below plow pan because they did not perforate through the dense plow pan. This study demonstrates that soil cracks in paddy fields significantly affect macropore structure but their impact on preferential flow may be poor when they do not penetrate through the plow pan.

  11. Solubility and Leaching Risks of Organic Carbon in Paddy Soils as Affected by Irrigation Managements

    PubMed Central

    Yang, Shihong; Wei, Qi; Gao, Xiaoli

    2013-01-01

    Influence of nonflooding controlled irrigation (NFI) on solubility and leaching risk of soil organic carbon (SOC) were investigated. Compared with flooding irrigation (FI) paddies, soil water extractable organic carbon (WEOC) and dissolved organic carbon (DOC) in NFI paddies increased in surface soil but decreased in deep soil. The DOC leaching loss in NFI field was 63.3?kg C ha?1, reduced by 46.4% than in the FI fields. It indicated that multi-wet-dry cycles in NFI paddies enhanced the decomposition of SOC in surface soils, and less carbon moved downward to deep soils due to less percolation. That also led to lower SOC in surface soils in NFI paddies than in FI paddies, which implied that more carbon was released into the atmosphere from the surface soil in NFI paddies. Change of solubility of SOC in NFI paddies might lead to potential change in soil fertility and sustainability, greenhouse gas emission, and bioavailability of trace metals or organic pollutants. PMID:23935423

  12. Paddy soil — A suitable target for monitoring heavy metal pollution by magnetic proxies

    NASA Astrophysics Data System (ADS)

    Yan, H. T.; Hu, S. Y.; Blaha, U.; Rösler, W.; Duan, X. M.; Appel, E.

    2011-10-01

    A preliminary magnetic study around Meishan steel mill in Nanjing (SE China) was carried out combining geochemical analysis with scanning electron microscopy (SEM) to prove that paddy soil can be a suitable target for environmental study on heavy metal pollution. Magnetic background investigation showed a strong variation in this area due to different land uses and soil types. Magnetic susceptibilities (MS) measured on forest soils are much higher than in paddy fields, and values below 20 cm of the soil surface in forest with parent material of Xiashu loess are several times higher than in paddy soil with parent material of fluvisol. Measurements on vertical profiles show that paddy soil has a very low and stable magnetic background with mass-specific MS around 15 × 10 - 8 m 3 kg - 1 . A strong enhancement of MS values is found in the upper ~ 20 cm of paddy soil predominated by multidomain and pseudo single domain magnetite. However, relatively low S-ratios (0.57 to 0.85) reveal a significant contribution of imperfect anti-ferromagnetic minerals. Detailed research on a paddy soil core at site C719 near the steel mill indicates strong correlation between magnetic mineral concentration-related parameters (χ, ARM, SIRM) and heavy metal concentrations of Cu, Pb and Zn. In addition, typical anthropogenic Fe-spherules are detected in top paddy soil by means of SEM, which indicates that the increase of susceptibility in upper soil is mainly caused by steel mill emission. Mapping of MS in paddy fields across the steel mill area shows a decrease of MS with the distance to the major emission zone. Positive correlation between χ and Zn is found by measuring surface soil samples around the steel mill. Because of low background and high homogeneity of the ~ 20 cm uppermost mixing layer paddy fields are especially suitable for magnetic surface mapping of heavy metal pollution.

  13. Enzyme dynamics in paddy soils of the rice district (NE Italy) under different cropping patterns

    NASA Astrophysics Data System (ADS)

    Bini, Claudio; Nadimi-Goki, Mandana; Kato, Yoichi; Fornasier, Flavio; Wahsha, Mohammad; Spiandorello, Massimo

    2014-05-01

    The recent widespread interest on soil enzymes is due to the need to develop sensitive indicators of soil quality that reflect the effects of land management on soil and assist land managers in promoting long-term sustainability of terrestrial ecosystems. The activities of six important enzymes involved in C, N, P, and S cycling were investigated in a paddy soil from the Veneto region, Italy, in four different rotation systems (rice-rice-rice: R-R-R; soya-rice-rice: S-R-R; fallow-rice: F-R; pea-soya-rice: P-S-R) with three replications in April (after field preparation, field moist condition), June (after seedling, waterlogged soil condition), August (after tillering stage of rice, waterlogged soil condition) and October (after rice harvesting, drained soil condition) over the 2012 growing season. Our results demonstrated that enzyme activities varied with rotation systems and growth stages in paddy soil. Compared with field moist soil, drained soil condition resulted in a significant increase (P < 0.05) of β-glucosidase, arylsulfatase, alkaline and acid phosphatases, leucine aminopeptidase (except of fallow-rice), and chitinase activities in all rotations, while compared with drained soil, early waterlogging (in month of June) significantly decreased (P moist soil> late waterlogged>early waterlogged. There was an inhibitory effect of waterlogging (except P-S-R rotation) for both alkaline and acid phosphatases due to high pH and redox conditions. However, the response of enzymes to waterlogging differed with the chemical species and the cropping pattern. The best rotation system for chitinase, leucine aminopeptidase and β-glucosidase activity (C and N cycles) proved R-R-R, while for arylsulfatase, alkaline and acid phosphatases (P and S cycles) it was the S-R-R. Key Words: enzyme activity, paddy soil, Crop Rotation System, Italy __ Corresponding Author: Mandana Nadimi-Goki, Tel.: +39 3891356251 E-mail address: mandy.nadimi@gmail.com

  14. Annual Changes of Paddy Rice Planting Areas in Northeastern Asia from MODIS images in 2000-2014

    NASA Astrophysics Data System (ADS)

    Xiao, X.; Zhang, G.; Dong, J.; Menarguez, M. A.; Kou, W.; Jin, C.; Qin, Y.; Zhou, Y.; Wang, J.; Moore, B., III

    2014-12-01

    Knowledge of the area and spatial distribution of paddy rice is important for assessment of food security, management of water resources, estimation of greenhouse gas (methane) emissions, and understanding avian influenza virus transmission. Over the past two decades, paddy rice cultivation has expanded northward in temperate and cold temperate zones, particularly in Northeastern China. There is a need to quantify and map changes in paddy rice planting areas in Northeastern Asia (Japan, North and South Korea, and northeast China) at annual interval. We developed a pixel- and phenology-based image analysis system, MODIS-RICE, to map the paddy rice in Northeastern Asia by using multi-temporal MODIS thermal and surface reflectance imagery. Paddy rice fields during the flooding and transplanting phases have unique physical and spectral characteristics, which make it possible for the development of an automated and robust algorithm to track flooding and transplanting phases of paddy rice fields over time. In this presentation, we will show the MODIS-based annual maps of paddy rice planting area in the Northeastern Asia from 2000-2014 (500-m spatial resolution). Accuracy assessments using high-resolution images show that the resultant paddy rice map of Northeastern Asia had a comparable accuracy to the existing products, including 2010 Landsat-based National Land Cover Dataset (NLCD) of China, the 2010 RapidEye-based paddy rice map in North Korea, and the 2010 AVNIR-2-based National Land Cover Dataset in Japan in terms of both area and spatial pattern of paddy rice. This study has demonstrated that our novel MODIS-Rice system, which use both thermal and optical MODIS data over a year, are simple and robust tools to identify and map paddy rice fields in temperate and cold temperate zones.

  15. The large-scale distribution of ammonia oxidizers in paddy soils is driven by soil pH, geographic distance, and climatic factors.

    PubMed

    Hu, Hang-Wei; Zhang, Li-Mei; Yuan, Chao-Lei; Zheng, Yong; Wang, Jun-Tao; Chen, Deli; He, Ji-Zheng

    2015-01-01

    Paddy soils distribute widely from temperate to tropical regions, and are characterized by intensive nitrogen fertilization practices in China. Mounting evidence has confirmed the functional importance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in soil nitrification, but little is known about their biogeographic distribution patterns in paddy ecosystems. Here, we used barcoded pyrosequencing to characterize the effects of climatic, geochemical and spatial factors on the distribution of ammonia oxidizers from 11 representative rice-growing regions (75-1945 km apart) of China. Potential nitrification rates varied greatly by more than three orders of magnitude, and were significantly correlated with the abundances of AOA and AOB. The community composition of ammonia oxidizer was affected by multiple factors, but changes in relative abundances of the major lineages could be best predicted by soil pH. The alpha diversity of AOA and AOB displayed contrasting trends over the gradients of latitude and atmospheric temperature, indicating a possible niche separation between AOA and AOB along the latitude. The Bray-Curtis dissimilarities in ammonia-oxidizing community structure significantly increased with increasing geographical distance, indicating that more geographically distant paddy fields tend to harbor more dissimilar ammonia oxidizers. Variation partitioning analysis revealed that spatial, geochemical and climatic factors could jointly explain majority of the data variation, and were important drivers defining the ecological niches of AOA and AOB. Our findings suggest that both AOA and AOB are of functional importance in paddy soil nitrification, and ammonia oxidizers in paddy ecosystems exhibit large-scale biogeographic patterns shaped by soil pH, geographic distance, and climatic factors. PMID:26388866

  16. The large-scale distribution of ammonia oxidizers in paddy soils is driven by soil pH, geographic distance, and climatic factors

    PubMed Central

    Hu, Hang-Wei; Zhang, Li-Mei; Yuan, Chao-Lei; Zheng, Yong; Wang, Jun-Tao; Chen, Deli; He, Ji-Zheng

    2015-01-01

    Paddy soils distribute widely from temperate to tropical regions, and are characterized by intensive nitrogen fertilization practices in China. Mounting evidence has confirmed the functional importance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in soil nitrification, but little is known about their biogeographic distribution patterns in paddy ecosystems. Here, we used barcoded pyrosequencing to characterize the effects of climatic, geochemical and spatial factors on the distribution of ammonia oxidizers from 11 representative rice-growing regions (75–1945 km apart) of China. Potential nitrification rates varied greatly by more than three orders of magnitude, and were significantly correlated with the abundances of AOA and AOB. The community composition of ammonia oxidizer was affected by multiple factors, but changes in relative abundances of the major lineages could be best predicted by soil pH. The alpha diversity of AOA and AOB displayed contrasting trends over the gradients of latitude and atmospheric temperature, indicating a possible niche separation between AOA and AOB along the latitude. The Bray–Curtis dissimilarities in ammonia-oxidizing community structure significantly increased with increasing geographical distance, indicating that more geographically distant paddy fields tend to harbor more dissimilar ammonia oxidizers. Variation partitioning analysis revealed that spatial, geochemical and climatic factors could jointly explain majority of the data variation, and were important drivers defining the ecological niches of AOA and AOB. Our findings suggest that both AOA and AOB are of functional importance in paddy soil nitrification, and ammonia oxidizers in paddy ecosystems exhibit large-scale biogeographic patterns shaped by soil pH, geographic distance, and climatic factors. PMID:26388866

  17. Methane and Nitrous Oxide Emissions Reduced Following Conversion of Rice Paddies to Inland Crab-Fish Aquaculture in Southeast China.

    PubMed

    Liu, Shuwei; Hu, Zhiqiang; Wu, Shuang; Li, Shuqing; Li, Zhaofu; Zou, Jianwen

    2016-01-19

    Aquaculture is an important source of atmospheric methane (CH4) and nitrous oxide (N2O), while few direct flux measurements are available for their regional and global source strength estimates. A parallel field experiment was performed to measure annual CH4 and N2O fluxes from rice paddies and rice paddy-converted inland crab-fish aquaculture wetlands in southeast China. Besides N2O fluxes dependent on water/sediment mineral N and CH4 fluxes related to water chemical oxygen demand, both CH4 and N2O fluxes from aquaculture were related to water/sediment temperature, sediment dissolved organic carbon, and water dissolved oxygen concentration. Annual CH4 and N2O fluxes from inland aquaculture averaged 0.37 mg m(-2) h(-1) and 48.1 ?g m(-2) h(-1), yielding 32.57 kg ha(-1) and 2.69 kg N2O-N ha(-1), respectively. The conversion of rice paddies to aquaculture significantly reduced CH4 and N2O emissions by 48% and 56%, respectively. The emission factor for N2O was estimated to be 0.66% of total N input in the feed or 1.64 g N2O-N kg(-1) aquaculture production in aquaculture. The conversion of rice paddies to inland aquaculture would benefit for reconciling greenhouse gas mitigation and agricultural income increase as far as global warming potentials and net ecosystem economic profits are of concomitant concern. Some agricultural practices such as better aeration and feeding, and fallow season dredging would help to lower CH4 and N2O emissions from inland aquaculture. More field measurements from inland aquaculture are highly needed to gain an insight into national and global accounting of CH4 and N2O emissions. PMID:26669815

  18. Anaerobic ammonia oxidation in a fertilized paddy soil

    PubMed Central

    Zhu, Guibing; Wang, Shanyun; Wang, Yu; Wang, Chaoxu; Risgaard-Petersen, Nils; Jetten, Mike SM; Yin, Chengqing

    2011-01-01

    Evidence for anaerobic ammonium oxidation in a paddy field was obtained in Southern China using an isotope-pairing technique, quantitative PCR assays and 16S rRNA gene clone libraries, along with nutrient profiles of soil cores. A paddy field with a high load of slurry manure as fertilizer was selected for this study and was shown to contain a high amount of ammonium (6.2–178.8 mg kg−1). The anaerobic oxidation of ammonium (anammox) rates in this paddy soil ranged between 0.5 and 2.9 nmolN per gram of soil per hour in different depths of the soil core, and the specific cellular anammox activity observed in batch tests ranged from 2.9 to 21 fmol per cell per day. Anammox contributed 4–37% to soil N2 production, the remainder being due to denitrification. The 16S rRNA gene sequences of surface soil were closely related to the anammox bacteria ‘Kuenenia', ‘Anammoxoglobus' and ‘Jettenia'. Most of the anammox 16S rRNA genes retrieved from the deeper soil were affiliated to ‘Brocadia'. The retrieval of mainly bacterial amoA sequences in the upper part of the paddy soil indicated that nitrifying bacteria may be the major source of nitrite for anammox bacteria in the cultivated horizon. In the deeper oxygen-limited parts, only archaeal amoA sequences were found, indicating that archaea may produce nitrite in this part of the soil. It is estimated that a total loss of 76 g N m−2 per year is linked to anammox in the paddy field. PMID:21593796

  19. Development of a method for estimating total CH4 emission from rice paddies in Japan using the DNDC-Rice model.

    PubMed

    Katayanagi, Nobuko; Fumoto, Tamon; Hayano, Michiko; Takata, Yusuke; Kuwagata, Tsuneo; Shirato, Yasuhito; Sawano, Shinji; Kajiura, Masako; Sudo, Shigeto; Ishigooka, Yasushi; Yagi, Kazuyuki

    2016-03-15

    Methane (CH4) is a greenhouse gas, and paddy fields are one of its main anthropogenic emission sources. To mitigate this emission based on effective management measures, CH4 emission from paddy fields must be quantified at a national scale. In Japan, country-specific emission factors have been applied since 2003 to estimate national CH4 emission from paddy fields. However, this method cannot account for the effects of weather conditions and temporal variability of nitrogen fertilizer and organic matter application rates; thus, the estimated emission is highly uncertain. To improve the accuracy of national-scale estimates, we calculated country-specific emission factors using the DeNitrification-DeComposition-Rice (DNDC-Rice) model. First, we calculated CH4 emission from 1981 to 2010 using 986 datasets that included soil properties, meteorological data, and field management data. Using the simulated site-specific emission, we calculated annual mean emission for each of Japan's seven administrative regions, two water management regimes (continuous flooding and conventional mid-season drainage), and three soil drainage rates (slow, moderate, and fast). The mean emission was positively correlated with organic carbon input to the field, and we developed linear regressions for the relationships among the regions, water management regimes, and drainage rates. The regression results were within the range of published observation values for site-specific relationships between CH4 emission and organic carbon input rates. This suggests that the regressions provide a simplified method for estimating CH4 emission from Japanese paddy fields, though some modifications can further improve the estimation accuracy. PMID:26802630

  20. Effect of rice husk gasification residue application on herbicide behavior in micro paddy lysimeter.

    PubMed

    Ok, Junghun; Pisith, Sok; Watanabe, Hirozumi; Thuyet, Dang Quoc; Boulange, Julien; Takagi, Kazuhiro

    2015-06-01

    Effects of rice husk gasification residues (RHGR) application on the fate of herbicides, butachlor and pyrazosulfuron-ethyl, in paddy water were investigated using micro paddy lysimeters (MPLs). The dissipation of both herbicides in paddy water was faster in the RHGR treated MPL than in the control MPL. The average concentrations of butachlor and pyrazosulfuron-ethyl in paddy water in the lysimeter treated with RHGR during 21 days were significantly reduced by 51% and 48%, respectively, as compared to those in the lysimeter without RHGR application. The half-lives (DT50) of butachlor in paddy water for control and treatment were 3.1 and 2.3 days respectively, and these values of pyrazosulfuron-ethyl were 3.0 and 2.2 days, respectively. Based on this study, RHGR application in rice paddy environment is an alternative method to reduce the concentration of herbicide in paddy field water and consequently to reduce potential pollution to aquatic environment. PMID:25763539

  1. Polar Field Reversals and Active Region Decay

    NASA Astrophysics Data System (ADS)

    Petrie, Gordon; Ettinger, Sophie

    2015-07-01

    We study the relationship between polar field reversals and decayed active region magnetic flux. Photospheric active region flux is dispersed by differential rotation and turbulent diffusion, and is transported poleward by meridional flows and diffusion. We summarize the published evidence from observation and modeling of the influence of meridional flow variations and decaying active region flux's spatial distribution, such as the Joy's law tilt angle. Using NSO Kitt Peak synoptic magnetograms covering cycles 21-24, we investigate in detail the relationship between the transport of decayed active region flux to high latitudes and changes in the polar field strength, including reversals in the magnetic polarity at the poles. By means of stack plots of low- and high-latitude slices of the synoptic magnetograms, the dispersal of flux from low to high latitudes is tracked, and the timing of this dispersal is compared to the polar field changes. In the most abrupt cases of polar field reversal, a few activity complexes (systems of active regions) are identified as the main cause. The poleward transport of large quantities of decayed trailing-polarity flux from these complexes is found to correlate well in time with the abrupt polar field changes. In each case, significant latitudinal displacements were found between the positive and negative flux centroids of the complexes, consistent with Joy's law bipole tilt with trailing-polarity flux located poleward of leading-polarity flux. The activity complexes of the cycle 21 and 22 maxima were larger and longer-lived than those of the cycle 23 and 24 maxima, and the poleward surges were stronger and more unipolar and the polar field changes larger and faster. The cycle 21 and 22 polar reversals were dominated by only a few long-lived complexes whereas the cycle 23 and 24 reversals were the cumulative effects of more numerous, shorter-lived regions. We conclude that sizes and lifetimes of activity complexes are key to understanding the diversity of polar reversals.

  2. Microbial lipids in Paddy Soils of the Yangtze Area

    NASA Astrophysics Data System (ADS)

    Mueller-Niggemann, Cornelia; Bannert, Andrea; Schloter, Michael; Cao, Zhihong; Schwark, Lorenz

    2010-05-01

    Geobiochemical studies of rice paddy soils and their effect on the global carbon cycle are of paramount importance. Paddy soils comprise manmade wetlands because soil flooding is a prerequisite for lowland rice cultivation. Except for sulphate-rich substrates, rice growth is not very sensitive to soil conditions prevailing prior to conversion of marine tidal flat sediments to paddy cultivation. Thus, soil management practices, such as artificial submergence or drainage, ploughing and puddling (i.e. ploughing a submerged soil), manuring, liming, and fertilization, are the major driving factors of paddy soil development. Soil organic matter (SOM) decomposition and humification proceeds in hydromorphic soils at a slower rate than in well-drained, aerated soils. Rice paddy soils thus also represent a suitable model system to study fundamental aspects of redox sensitive soil processes. These processes are of special interest because in flooded rice fields the anaerobic fermentation of SOM leads to the release of methane and to denitrification losses of inorganic nitrogen. Here we present results from a chronosequence study of paddy soils with different and well known starting dates of cultivation, in the Zhejiang province (Yangtze River delta) by land reclamation through the building of protective dikes over the past 2000 years. We here describe the biomarker geochemistry of six paddy soils that developed on marine tidal sediments and where cultivation started 50, 100, 300, 700, 1000 or 2000 years before present. As reference substrates recent marine and lacustrine sediments were selected. The differentiation of the lipid biomass was achieved by investigating glycerol dialkyl glycerol tetraethers (GDGT). These specific organic geochemical biomarkers allow for determining the abundance of fossil microbial consortia (archaea and bacteria input) into paddy soils, justified by the diversity of the archaeal and bacterial cell membrane constituents. The dominant proportion of the GDGT in soils and in the lacustrine sediment derived from bacterial branched isoalkane tetraethers (BIT) as described previously for dry-land soils [1]. Only the marine sediment contained significant amounts of isoprenoidal GDGT originating from eury- and crenarchaeota. This result contradicted our expectation that methanogenic euryarchaeota thriving in paddy soils should lead to high abundances of isoprenoidal GDGT, in particular calarchaeol. Additionally we compared concentration of isoprenoidal GDGT cell membrane lipids with the number of ammonia monooxygenase gene copies from ammonia-oxidizing archaea and bacteria (AOA and AOB amoA) determinated by phylogenetic analysis. Concentration of the isoprenoidal tetraether lipid crenarchaeol (ng per g of soil) correlated with the abundance of archaeal amoA gene copies (copies per g of soil). This agrees with a dominance of ammonia-oxidizing archaea (AOA) over ammonia-oxidizing bacteria (AOB) in paddy soil nitrification as previously shown for a variety of terrestrial soil types [2]. The distribution patterns of GDGTs revealed that microbial lipids have been converted from marine to paddy signatures within a period of only 50 years. [1] Weijers J.W.H., et al. (2007) Geochim. Cosmochim. Acta 71, 703-71 [2] Leininger S., et al. (2006) Nature 442, 806-809

  3. Polar Field Reversals and Active Region Decay

    NASA Astrophysics Data System (ADS)

    Petrie, Gordon; Ettinger, Sophie

    2015-04-01

    We study the relationship between polar field reversals and decayed active region magnetic flux. Photospheric active region flux is dispersed by differential rotation and turbulent diffusion, and is transported poleward by meridional flows and diffusion. Using NSO Kitt Peak synoptic magnetograms, we investigate in detail the relationship between the transport of decayed active region flux to high latitudes and changes in the polar field strength, including reversals in the magnetic polarity at the poles. By means of stack plots of low- and high-latitude slices of the synoptic magnetograms, the dispersal of flux from low to high latitudes is tracked, and the timing of this dispersal is compared to the polar field changes. In the most abrupt cases of polar field reversal, a few activity complexes (systems of active regions) are identified as the main cause. The poleward transport of large quantities of decayed lagging-polarity flux from these complexes is found to correlate well in time with the abrupt polar field changes. In each case, significant latitudinal displacements were found between the positive and negative flux centroids of the complexes, consistent with Joy's law bipole tilt with lagging-polarity flux located poleward of leading-polarity flux. This work is carried out through the National Solar Observatory Summer Research Assistantship (SRA) Program. The National Solar Observatory is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.

  4. Assessing nitrification and denitrification in a paddy soil with different water dynamics and applied liquid cattle waste using the ?N isotopic technique.

    PubMed

    Zhou, Sheng; Sakiyama, Yukina; Riya, Shohei; Song, Xiangfu; Terada, Akihiko; Hosomi, Masaaki

    2012-07-15

    Using livestock wastewater for rice production in paddy fields can remove nitrogen and supplement the use of chemical fertilizers. However, paddy fields have complicated water dynamics owing to varying characteristics and would influence nitrogen removal through nitrification followed by denitrification. Quantification of nitrification and denitrification is of great importance in assessing the influence of water dynamics on nitrogen removal in paddy fields. In this study, nitrification and nitrate reduction rates with different water dynamics after liquid cattle waste application were evaluated, and the in situ denitrification rate was determined directly using the (15)N isotopic technique in a laboratory experiment. A significant linear regression correlation between nitrification and the nitrate reduction rate was observed and showed different regression coefficients under different water dynamics. The regression coefficient in the continuously flooded paddy soil was higher than in the drained-reflooded paddy soil, suggesting that nitrate would be consumed faster in the flooded paddy soil. However, nitrification was limited and the maximum rate was only 13.3 ?g Ng(-1)day(-1) in the flooded paddy soil with rice plants, which limited the supply of nitrate. In contrast, the drained-reflooded paddy soil had an enhanced nitrification rate up to 56.8 ?g Ng(-1)day(-1), which was four times higher than the flooded paddy soil and further stimulated nitrate reduction rates. Correspondingly, the in situ denitrification rates determined directly in the drained-reflooded paddy soil ranged from 5 to 1035 mg Nm(-2)day(-1), which was higher than the continuously flooded paddy soil (from 5 to 318 mg Nm(-2)day(-1)) during the vegetation period. The nitrogen removal through denitrification accounted for 38.9% and 9.9% of applied nitrogen in the drained-reflooded paddy soil and continuously flooded paddy soil, respectively. PMID:22634555

  5. Fly ash application in nutrient poor agriculture soils: impact on methanotrophs population dynamics and paddy yields.

    PubMed

    Singh, Jay Shankar; Pandey, Vimal Chandra

    2013-03-01

    There are reports that the application of fly ash, compost and press mud or a combination thereof, improves plant growth, soil microbial communities etc. Also, fly ash in combination with farmyard manure or other organic amendments improves soil physico-chemical characteristics, rice yield and microbial processes in paddy fields. However, the knowledge about the impact of fly ash inputs alone or in combination with other organic amendments on soil methanotrophs number in paddy soils is almost lacking. We hypothesized that fly ash application at lower doses in paddy agriculture soil could be a potential amendment to elevate the paddy yields and methanotrophs number. Here we demonstrate the impact of fly ash and press mud inputs on number of methanotrophs, antioxidants, antioxidative enzymatic activities and paddy yields at agriculture farm. The impact of amendments was significant for methanotrophs number, heavy metal concentration, antioxidant contents, antioxidant enzymatic activities and paddy yields. A negative correlation was existed between higher doses of fly ash-treatments and methanotrophs number (R(2)=0.833). The content of antioxidants and enzymatic activities in leaves of higher doses fly ash-treated rice plants increased in response to stresses due to heavy metal toxicity, which was negatively correlated with rice grain yield (R(2)=0.944) and paddy straw yield (R(2)=0.934). A positive correlation was noted between heavy metals concentrations and different antioxidant and enzymatic activities across different fly ash treated plots.The data of this study indicate that heavy metal toxicity of fly ash may cause oxidative stress in the paddy crop and the antioxidants and related enzymes could play a defensive role against phytotoxic damages. We concluded that fly ash at lower doses with press mud seems to offer the potential amendments to improving soil methanotrophs population and paddy crop yields for the nutrient poor agriculture soils. PMID:23260239

  6. The specific role of fungal community structure on soil aggregation and carbon sequestration: results from long-term field study in a paddy soil

    NASA Astrophysics Data System (ADS)

    Murugan, Rajasekaran; Kumar, Sanjay

    2015-04-01

    Soil aggregate stability is a crucial soil property that affects soil biota, biogeochemical processes and C sequestration. The relationship between soil aggregate stability and soil C cycling is well known but the influence of specific fungal community structure on this relationship is largely unknown in paddy soils. The aim of the present study was to evaluate the long-term fertilisation (mineral fertiliser-MIN; farmyard manure-FYM; groundnut oil cake-GOC) effects on soil fungal community shifts associated with soil aggregates under rice-monoculture (RRR) and rice-legume-rice (RLR) systems. Fungal and bacterial communities were characterized using phospholipid fatty acids, and glucosamine and muramic acid were used as biomarkers for fungal and bacterial residues, respectively. Microbial biomass C and N, fungal biomass and residues were significantly higher in the organic fertiliser treatments than in the MIN treatment, for all aggregate sizes under both crop rotation systems. In general, fungal/bacterial biomass ratio and fungal residue C/bacterial residue C ratio were significantly higher in macroaggregate fractions (> 2000 and 250-2000 μm) than in microaggregate fractions (53-250 and <53 μm). In both crop rotation systems, the long-term application of FYM and GOC led to increased accumulation of saprotrophic fungi (SF) in aggregate fractions > 2000 μm. In contrast, we found that arbuscular mycorrhizal fungi (AMF) was surprisingly higher in aggregate fractions > 2000 μm than in aggregate fraction 250-2000 μm under MIN treatment. The RLR system showed significantly higher AMF biomass and fungal residue C/ bacterial residue C ratio in both macroaggregate fractions compared to the RRR system. The strong relationships between SF, AMF and water stable aggregates shows the specific contribution of fungi community on soil aggregate stability. Our results highlight the fact that changes within fungal community structure play an important role in shaping the soil aggregate stability and C sequestration in tropical agricultural ecosystems.

  7. Magnetic Field Strengths in Photodissociation Regions

    NASA Astrophysics Data System (ADS)

    Balser, Dana S.; Anish Roshi, D.; Jeyakumar, S.; Bania, T. M.; Montet, Benjamin T.; Shitanishi, J. A.

    2016-01-01

    We measure carbon radio recombination line (RRL) emission at 5.3 {{GHz}} toward four H ii regions with the Green Bank Telescope to determine the magnetic field strength in the photodissociation region (PDR) that surrounds the ionized gas. Roshi suggests that the non-thermal line widths of carbon RRLs from PDRs are predominantly due to magneto-hydrodynamic waves, thus allowing the magnetic field strength to be derived. We model the PDR with a simple geometry and perform the non-LTE radiative transfer of the carbon RRL emission to solve for the PDR physical properties. Using the PDR mass density from these models and the carbon RRL non-thermal line width we estimate total magnetic field strengths of B? 100{--}300 ? {{G}} in W3 and NGC 6334A. Our results for W49 and NGC 6334D are less well constrained with total magnetic field strengths between B? 200{--}1000 ? {{G}}. H i and OH Zeeman measurements of the line of sight magnetic field strength ({B}{{los}}), taken from the literature, are between a factor of ? 0.5{--}1 of the lower bound of our carbon RRL magnetic field strength estimates. Since | {B}{{los}}| ?slant B, our results are consistent with the magnetic origin of the non-thermal component of carbon RRL widths.

  8. Vector Magnetic Field in Emerging Flux Regions

    NASA Astrophysics Data System (ADS)

    Schmieder, B.; Pariat, E.

    A crucial phase in magnetic flux emergence is the rise of magnetic flux tubes through the solar photosphere, which represents a severe transition between the very different environments of the solar interior and corona. Multi-wavelength observations with Flare Genesis, TRACE, SoHO, and more recently with the vector magnetographs at THEMIS and Hida (DST) led to the following conclusions. The fragmented magnetic field in the emergence region - with dipped field lines or bald patches - is directly related with Ellerman bombs, arch filament systems, and overlying coronal loops. Measurements of vector magnetic fields have given evidence that undulating "serpentine" fields are present while magnetic flux tubes cross the photosphere. See the sketch below, and for more detail see Pariat et al. (2004, 2007); Watanabe et al. (2008):

  9. [Dimensional fractal of post-paddy wheat root architecture].

    PubMed

    Chen, Xin-xin; Ding, Qi-shuo; Li, Yi-nian; Xue, Jin-lin; Lu, Ming-zhou; Qiu, Wei

    2015-06-01

    To evaluate whether crop rooting system was directionally dependent, a field digitizer was used to measure post-paddy wheat root architectures. The acquired data was transferred to Pro-E, in which virtual root architecture was reconstructed and projected to a series of planes each separated in 10 apart. Fractal dimension and fractal abundance of root projections in all the 18 planes were calculated, revealing a distinctive architectural distribution of wheat root in each direction. This strongly proved that post-paddy wheat root architecture was directionally dependent. From seedling to turning green stage, fractal dimension of the 18 projections fluctuated significantly, illustrating a dynamical root developing process in the period. At the jointing stage, however, fractal indices of wheat root architecture resumed its regularity in each dimension. This wheat root architecture recovered its dimensional distinctness. The proposed method was applicable for precision modeling field state root distribution in soil. PMID:26572023

  10. Geoid for Austria - Regional gravity FIELD improved

    NASA Astrophysics Data System (ADS)

    Rieser, Daniel; Pock, Christian; Mayer-Gürr, Torsten; Kühtreiber, Norbert

    2013-04-01

    The project 'Geoid for Austria - Regional gravity FIELD improved' (GARFIELD) is a current initiative for the generation of a new high-quality gravity field solution for the Austrian region, which overcomes the inconsistencies between previous geoid solutions and geoid heights from GPS/leveling campaigns. The optimum combination of the complementary data types of satellite observations and all available terrestrial gravity field measurements in Austria and neighbouring countries will be essential. The Least Squares Collocation (LSC) approach will serve as reference method for the gravity field computation. In this context, GOCE gradients should be used as in-situ observations. Alternatively to LSC, a Gauss-Markov model with parametrization as Radial Basis Functions will be implemented. For a successful data combination, the Remove-Compute-Restore technique will be revised to avoid a double consideration of the topographic masses when performing long- and short-wavelength signal reductions. This contribution should give an overview about methods, developments and the current status of the project GARFIELD.

  11. Focal region fields of distorted reflectors

    NASA Technical Reports Server (NTRS)

    Buris, N. E.; Kauffman, J. F.

    1988-01-01

    The problem of the focal region fields scattered by an arbitrary surface reflector under uniform plane wave illumination is solved. The physical optics (PO) approximation is used to calculate the current induced on the reflector. The surface of the reflector is described by a number of triangular domain-wise 5th degree bivariate polynomials. A 2-dimensional Gaussian quadrature is employed to numerically evaluate the integral expressions of the scattered fields. No Freshnel or Fraunhofer zone approximations are made. The relation of the focal fields problem to surface compensation techniques and other applications are mentioned. Several examples of distorted parabolic reflectors are presented. The computer code developed is included, together with instructions on its usage.

  12. 21 CFR 882.4700 - Neurosurgical paddie.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Neurosurgical paddie. 882.4700 Section 882.4700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Surgical Devices 882.4700 Neurosurgical paddie. (a)...

  13. Uncultivated Methylocystis Species in Paddy Soil Include Facultative Methanotrophs that Utilize Acetate.

    PubMed

    Leng, Lingqin; Chang, Jiali; Geng, Kan; Lu, Yahai; Ma, Ke

    2015-07-01

    Methanotrophs are crucial in regulating methane emission from rice field systems. Type II methanotrophs in particular are often observed in high abundance in paddy soil. Some cultivated species of Methylocystis are able to grow on acetate in the absence of methane. We hypothesize that the dominant type II methanotrophs in paddy soil might facultatively utilize acetate for growth, which we evaluate in the present study. The measurement of methane oxidation rates showed that the methanotrophic activity in paddy soil was inhibited by the addition of acetate compared to the continuous supplementation of methane, but the paddy soil maintained the methane oxidation capacity and recovered following methane supplementation. Terminal restriction fragment length polymorphism analysis (T-RFLP) combined with cloning and sequencing of pmoA genes showed that Methylocystis was enriched after incubation with added acetate, while the type I methanotrophs Methylocaldum/Methylococcus and Methylobacter were enriched by methane supplementation. A comparison of pmoA sequences obtained in this study with those in the public database indicated that they were globally widespread in paddy soils or in associated with rice roots. Furthermore, we performed stable isotope probing (SIP) of pmoA messenger RNA (mRNA) to investigate the assimilation of (13)C-acetate by paddy soil methanotrophs. RNA-SIP revealed that Methylocystis-related methanotrophs which shared the same genotype of the above enriched species were significantly labelled. It indicates that these methanotrophs actively assimilated the labelled acetate in paddy soil. Altogether, these results suggested that uncultivated Methylocystis species are facultative methanotrophs utilizing acetate as a secondary carbon source in paddy soil. PMID:25475784

  14. Isolation and characterization of methane utilizing bacteria from wetland paddy ecosystem.

    PubMed

    Jhala, Y K; Vyas, R V; Shelat, H N; Patel, H K; Patel, H K; Patel, K T

    2014-06-01

    Methylotrophic bacteria which are known to utilize C1 compounds including methane. Research during past few decades increased the interest in finding out novel genera of methane degrading bacteria to efficiently utilize methane to decrease global warming effect. Moreover, evaluation of certain known plant growth promoting strains for their methane degrading potential may open up a new direction for multiple utility of such cultures. In this study, efficient methylotrophic cultures were isolated from wetland paddy fields of Gujarat. From the overall morphological, biochemical and molecular characterization studies, the isolates were identified and designated as Bacillus aerius AAU M 8; Rhizobium sp. AAU M 10; B. subtilis AAU M 14; Paenibacillus illinoisensis AAU M 17 and B. megaterium AAU M 29. Gene specific PCR analysis of the isolates, P. illinoisensis, B. aerius, Rhizobium sp. and B. subtilis showed presence of pmoA gene encoding ? subunit particulate methane monooxygenase cluster. B. megaterium, P. illinoisensis, Rhizobium sp. and Methylobacterium extrorquens showed presence of mmoX gene encoding ? subunit of the hydroxylase component of the soluble methane monooxygenase cluster. P. illinoisensis and Rhizobium sp. showed presence mxaF gene encoding ? subunit region of methanol dehydrogenase gene cluster showing that both isolates are efficient utilizers of methane. To the best of our knowledge, this is the first time report showing presence of methane degradation enzymes and genes within the known PGPB group of organisms from wet land paddy agro-ecosystem, which is considered as one of the leading methane producer. PMID:24469547

  15. Basin-wide Projection for Paddy Irrigation in Monsoon Asia Based on a Distributed Hydrological Model and Climate Change Scenarios

    NASA Astrophysics Data System (ADS)

    Kudo, R.; Masumoto, T.; Yoshida, T.; Horikawa, N.

    2010-12-01

    1. Introduction A large amount of water in Monsoon Asia is used for rice paddy, and the mechanism of water use varies widely by region. Agricultural water exerts a great influence on the hydrological cycle in river basins and modeling of this process is crucial to understand the hydrological cycle especially in areas where irrigated agriculture is dominant. Such agricultural water uses, however, were not fully combined in the previous runoff models, although this process is essential for assessing the impact of climate change on agriculture in Monsoon Asia. In this study, impact assessment of climate change on paddy field irrigation was carried out in the Seki River basin located in the northern part of Japan, using a distributed hydrological model incorporating various paddy water uses. 2. Distributed hydrological model incorporating various agricultural water uses The model used in this study consists of four sub-models, such as evapotranspiration, cropping pattern/area, agricultural water use, and runoff, so that it enables to estimate cropping area, paddy water requirements, actual intake at main irrigation facilities at any point of the basin, in addition to actual evapotranspiration, soil water content, runoff amount that are normally calculated by many prevailing runoff models. A target basin is divided into 1km-messhed cells and each cell contains the ratio of 5 land-use category as forest, rain-fed paddy, irrigated paddy, upland field and water area. Irrigation and crop patterns are also set as agricultural practices in each cell, and then irrigation amount and actual evapotranspiration can be estimated according to cropping stage and soil moisture. 3. Climate change scenarios and its bias correction Future climate scenarios simulated by MIROC (SRES-A1B), which is one of the GCMs developed by CCSR/NIES/FRCGC in Japan, were used as input data into the hydrological model. Coarse resolution by GCM was nested into 1km resolution by a simple linear interpolation. Bias correction was carried out by a statistical method for the meteorological elements such as precipitation, temperature, relative humidity and wind velocity which were calculated by MIROC. Furthermore, monthly daily-maximum precipitation as extreme events was corrected with the Gumbel distribution. 4. Results and discussion The results in this study are as follows: 1) Snow water equivalence during the winter season will decrease by global warming in near future (2046-2065) and the end of 21th century (2081-2100). As a result, this will lead to a decrease in snowmelt runoff in early spring. 2) Agricultural intake at the Itakura head works would decrease especially on May and June owing to the decrease in snowmelt runoff mentioned above. 3) The agricultural water would not be supplied in lower part of irrigated area sufficiently, while increasing in evapotranspiration from paddy field. Therefore, this may result in imbalance of agricultural water in these areas.4) The distributed hydrological model incorporating various agricultural water uses can foretell detailed impacts of climate change on irrigation as well as that of discharge.

  16. Mass absorption efficiency of light absorbing organic aerosols from source region of paddy-residue burning emissions in the Indo-Gangetic Plain

    NASA Astrophysics Data System (ADS)

    Srinivas, B.; Rastogi, N.; Sarin, M. M.; Singh, A.; Singh, D.

    2016-01-01

    The mass absorption efficiency (MAE) of light absorbing water-soluble organics, representing a significant fraction of brown carbon (BrC), has been studied in fine mode aerosols (PM2.5) from a source region (Patiala: 30.2 °N, 76.3 °E) of biomass burning emissions (BBEs) in the Indo-Gangetic Plain (IGP). The mass absorption coefficient of BrC at 365 nm (babs-365), assessed from absorption spectra of aqueous extracts, exhibits significant linear relationship with water-soluble organic carbon (WSOC) for day (R2 = 0.37) and night time (R2 = 0.77) samples; and slope of regression lines provides a measure of MAE of BrC (daytime: ∼0.75 m2 g-1 and night time: 1.13 m2 g-1). A close similarity in the temporal variability of babs-365 (for BrC) and K+ in all samples suggests their common source from BBEs. The babs-365 of BrC follows a power law (babs-λ ≈ λ-α; where α = angstrom exponent) and averages around 5.2 ± 2.0 M m-1 (where M = 10-6). A significant decrease in the MAE of BrC from the source region (this study) to the downwind oceanic region (over Bay of Bengal, Srinivas and Sarin, 2013) could be attributed to relative increase in the contribution of non-absorbing WSOC and/or photo-bleaching of BrC during long-range atmospheric transport. The atmospheric radiative forcing due to BrC over the study site accounts for ∼40% of that from elemental carbon (EC).

  17. Development of an Improved Irrigation Subroutine in SWAT to Simulate the Hydrology of Rice Paddy Grown under Submerged Conditions

    NASA Astrophysics Data System (ADS)

    Muraleedharan, B. V.; Kathirvel, K.; Narasimhan, B.; Nallasamy, N. D.

    2014-12-01

    Soil Water Assessment Tool (SWAT) is a basin scale, distributed hydrological model commonly used to predict the effect of management decisions on the hydrologic response of watersheds. Hydrologic response is decided by the various components of water balance. In the case of watersheds located in south India as well as in several other tropical countries around the world, paddy is one of the dominant crop controlling the hydrologic response of a watershed. Hence, the suitability of SWAT in replicating the hydrology of paddy fields needs to be verified. Rice paddy fields are subjected to flooding method of irrigation, while the irrigation subroutines in SWAT are developed to simulate crops grown under non flooding conditions. Moreover irrigation is represented well in field scale models, while it is poorly represented within watershed models like SWAT. Reliable simulation of flooding method of irrigation and hydrology of the fields will assist in effective water resources management of rice paddy fields which are one of the major consumers of surface and ground water resources. The current study attempts to modify the irrigation subroutine in SWAT so as to simulate flooded irrigation condition. A field water balance study was conducted on representative fields located within Gadana, a subbasin located in Tamil Nadu (southern part of India) and dominated by rice paddy based irrigation systems. The water balance of irrigated paddy fields simulated with SWAT was compared with the water balance derived by rice paddy based crop growth model named ORYZA. The variation in water levels along with the soil moisture variation predicted by SWAT was evaluated with respect to the estimates derived from ORYZA. The water levels were further validated with field based water balance measurements taken on a daily scale. It was observed that the modified irrigation subroutine was able to simulate irrigation of rice paddy within SWAT in a realistic way compared to the existing method.

  18. Biogeochemical Typing of Paddy Field by a Data-Driven Approach Revealing Sub-Systems within a Complex Environment - A Pipeline to Filtrate, Organize and Frame Massive Dataset from Multi-Omics Analyses

    PubMed Central

    Ogawa, Diogo M. O.; Moriya, Shigeharu; Tsuboi, Yuuri; Date, Yasuhiro; Prieto-da-Silva, Álvaro R. B.; Rádis-Baptista, Gandhi; Yamane, Tetsuo; Kikuchi, Jun

    2014-01-01

    We propose the technique of biogeochemical typing (BGC typing) as a novel methodology to set forth the sub-systems of organismal communities associated to the correlated chemical profiles working within a larger complex environment. Given the intricate characteristic of both organismal and chemical consortia inherent to the nature, many environmental studies employ the holistic approach of multi-omics analyses undermining as much information as possible. Due to the massive amount of data produced applying multi-omics analyses, the results are hard to visualize and to process. The BGC typing analysis is a pipeline built using integrative statistical analysis that can treat such huge datasets filtering, organizing and framing the information based on the strength of the various mutual trends of the organismal and chemical fluctuations occurring simultaneously in the environment. To test our technique of BGC typing, we choose a rich environment abounding in chemical nutrients and organismal diversity: the surficial freshwater from Japanese paddy fields and surrounding waters. To identify the community consortia profile we employed metagenomics as high throughput sequencing (HTS) for the fragments amplified from Archaea rRNA, universal 16S rRNA and 18S rRNA; to assess the elemental content we employed ionomics by inductively coupled plasma optical emission spectroscopy (ICP-OES); and for the organic chemical profile, metabolomics employing both Fourier transformed infrared (FT-IR) spectroscopy and proton nuclear magnetic resonance (1H-NMR) all these analyses comprised our multi-omics dataset. The similar trends between the community consortia against the chemical profiles were connected through correlation. The result was then filtered, organized and framed according to correlation strengths and peculiarities. The output gave us four BGC types displaying uniqueness in community and chemical distribution, diversity and richness. We conclude therefore that the BGC typing is a successful technique for elucidating the sub-systems of organismal communities with associated chemical profiles in complex ecosystems. PMID:25330259

  19. Biogeochemical typing of paddy field by a data-driven approach revealing sub-systems within a complex environment--a pipeline to filtrate, organize and frame massive dataset from multi-omics analyses.

    PubMed

    Ogawa, Diogo M O; Moriya, Shigeharu; Tsuboi, Yuuri; Date, Yasuhiro; Prieto-da-Silva, lvaro R B; Rdis-Baptista, Gandhi; Yamane, Tetsuo; Kikuchi, Jun

    2014-01-01

    We propose the technique of biogeochemical typing (BGC typing) as a novel methodology to set forth the sub-systems of organismal communities associated to the correlated chemical profiles working within a larger complex environment. Given the intricate characteristic of both organismal and chemical consortia inherent to the nature, many environmental studies employ the holistic approach of multi-omics analyses undermining as much information as possible. Due to the massive amount of data produced applying multi-omics analyses, the results are hard to visualize and to process. The BGC typing analysis is a pipeline built using integrative statistical analysis that can treat such huge datasets filtering, organizing and framing the information based on the strength of the various mutual trends of the organismal and chemical fluctuations occurring simultaneously in the environment. To test our technique of BGC typing, we choose a rich environment abounding in chemical nutrients and organismal diversity: the surficial freshwater from Japanese paddy fields and surrounding waters. To identify the community consortia profile we employed metagenomics as high throughput sequencing (HTS) for the fragments amplified from Archaea rRNA, universal 16S rRNA and 18S rRNA; to assess the elemental content we employed ionomics by inductively coupled plasma optical emission spectroscopy (ICP-OES); and for the organic chemical profile, metabolomics employing both Fourier transformed infrared (FT-IR) spectroscopy and proton nuclear magnetic resonance (1H-NMR) all these analyses comprised our multi-omics dataset. The similar trends between the community consortia against the chemical profiles were connected through correlation. The result was then filtered, organized and framed according to correlation strengths and peculiarities. The output gave us four BGC types displaying uniqueness in community and chemical distribution, diversity and richness. We conclude therefore that the BGC typing is a successful technique for elucidating the sub-systems of organismal communities with associated chemical profiles in complex ecosystems. PMID:25330259

  20. A Preliminary Study to Forecast Japanese Encephalitis Vector Abundance in Paddy Growing Area, with the Aid of Radar Satellite Images.

    PubMed

    Raju, K Hari Kishan; Sabesan, Shanmugavelu; Rajavel, Aladu Ramakrishnan; Subramanian, Swaminathan; Natarajan, Ramalingam; Thenmozhi, Velayutham; Tyagi, Brij Kishore; Jambulingam, Purushothaman

    2016-02-01

    Vector mosquitoes of Japanese encephalitis (JE) breed mostly in rice fields, and human cases occur scattered over extended rural rice-growing areas. From this, one may surmise an ecological connection with the irrigation facilities and paddy cultivation. Furthermore, it has been hypothesized that a particular stage of paddy growth is a premonitory sign that can lead to a markedly increased population of the vector mosquitoes. The present study aimed to forecast the vector abundance by monitoring the paddy growth using remote sensing and geographical information systems. The abundance of the JE vector Culex tritaeniorhynchus peaked when the paddy crop was at its heading stage and dipped when the crop reached the maturing stage. A significant positive correlation was observed between paddy growth and adult density (r = 0.73, p < 0.008). The sigma naught values (σ0) derived from satellite images of paddy fields ranged from -18.3 (during transplantation stage) to approximately -10 (during the noncultivation period). A significant positive correlation was observed between σ0 and paddy growth stages (r = 0.87, p < 0.05) and adult vector density (r = 0.74, p = 0.04). The σ0 value observed during the vegetative and flowering stages of paddy growth ranged from -17.6 to -17.16, at which period the vector density started building up. This could be the spectral signature that denotes the "risk," following which a high vector abundance is expected during heading stage of the paddy. PMID:26824289

  1. Environmental controls over methyl halide emissions from rice paddies

    NASA Astrophysics Data System (ADS)

    Redeker, K. R.; Cicerone, R. J.

    2004-03-01

    This paper examines primary controlling factors that affect methyl halide emissions from rice paddy ecosystems. Observations of four cultivars under multiple growth conditions during studies in commercial fields and the University of California, Irvine, greenhouse lead to the conclusion that daily emissions of methyl halides are primarily determined by the growth stage of the rice plant, with the exception that methyl chloride emissions show no clear seasonal pattern. Methyl chloride emissions appear to be more from the paddy water and/or soil as opposed to the plants; however, in soils with high chloride content, these emissions appear to peak during the reproductive phase. Strong secondary influences include air temperature, soil halide concentration, and soil pore water saturation. The cultivars studied had statistically separate seasonally integrated emissions. Irradiant light and aboveground biomass appear to have little effect on emissions. Emissions of methyl chloride, methyl bromide, and methyl iodide are estimated to be 3.5, 2.3, and 48 mg/m2/yr, or 5.3, 3.5, and 72 Gg/yr, from rice paddies globally.

  2. Impacts of climate change on paddy rice yield in a temperate climate.

    PubMed

    Kim, Han-Yong; Ko, Jonghan; Kang, Suchel; Tenhunen, John

    2013-02-01

    The crop simulation model is a suitable tool for evaluating the potential impacts of climate change on crop production and on the environment. This study investigates the effects of climate change on paddy rice production in the temperate climate regions under the East Asian monsoon system using the CERES-Rice 4.0 crop simulation model. This model was first calibrated and validated for crop production under elevated CO2 and various temperature conditions. Data were obtained from experiments performed using a temperature gradient field chamber (TGFC) with a CO2 enrichment system installed at Chonnam National University in Gwangju, Korea in 2009 and 2010. Based on the empirical calibration and validation, the model was applied to deliver a simulated forecast of paddy rice production for the region, as well as for the other Japonica rice growing regions in East Asia, projecting for years 2050 and 2100. In these climate change projection simulations in Gwangju, Korea, the yield increases (+12.6 and+22.0%) due to CO2 elevation were adjusted according to temperature increases showing variation dependent upon the cultivars, which resulted in significant yield decreases (-22.1% and -35.0%). The projected yields were determined to increase as latitude increases due to reduced temperature effects, showing the highest increase for any of the study locations (+24%) in Harbin, China. It appears that the potential negative impact on crop production may be mediated by appropriate cultivar selection and cultivation changes such as alteration of the planting date. Results reported in this study using the CERES-Rice 4.0 model demonstrate the promising potential for its further application in simulating the impacts of climate change on rice production from a local to a regional scale under the monsoon climate system. PMID:23504792

  3. [Microbial metabolism in typical flooded paddy soils ].

    PubMed

    Cai, Yuanfeng; Wu, Yucheng; Wang, Shuwei; Yan, Xiaoyuan; Zhu, Yongguan; Jia, Zhongjun

    2014-09-01

    [OBJECTIVE] The object of this study is to reveal the composition of active microorganism and their metabolic activities in flooded paddy soils with long-term fertilization ( Mineral nitrogen, phosphorus, and potassium, NPK) and without fertilizer (Control check, CK) by environmental transcriptomics. [METHODS] Flooded soil microcosms were incubated in the laboratory for two weeks, then total RNA were extracted from the soil for transcriptome sequencing. Resulting fastq files were uploaded to the Metagenomics Analysis Server (MG-RAST) for taxonomic analysis, gene annotation and function classification. [RESULTS] Transcripts from diverse active microorganism, including bacteria ( > 95% ) , archaea, eukaryotes and viruses, were detected in both flooded paddy soils of CK and NPK treatments. Most of the transcripts (active genes) of bacteria and archaea were derived from Proteobacteria (more than 50% of total bacterial transcripts) and Thaumarchaaeota (about 70% of total archaeal transcripts ) respectively in both treatments. Transcriptional activity of Acidobacteria in NPK treatment paddy soil was significantly higher than that in CK treatment paddy soil. As for other phyla of bacteria and archaea, there were no significant differences of transcriptional activity of them between CK and NPK treatment paddy soils. The highest expressed gene in both CK and NPK treatment paddy soils is ABC transporter encoding gene which related to the transmembrane transport of substances. Based on gene function category of COG (Clusters of Orthologous Genes), Subsystem and KEGG (Kyoto Encyclopedia of Genes and Genomes) database, we found that the main metabolic activities of microorganisms in both CK and NPK treatment paddy soils were related to energy production and conversion, carbohydrate metabolism, protein metabolism and amino acid metabolism, and the dominant KEGG pathways were oxidative phosphorylation and aminoacyl-tRNA biosynthesis. [ CONCLUSION] Composition of active microorganism in CK and NPK treatment paddy soils was generally similar, except Acidobacteria whose transcriptional activity was significantly different between these two treatment paddy soils. It was also very similar between CK and NPK treatment paddy soils considering the metabolic activities of microorganisms in them, for dominant metabolic processes in these two soils were both related to energy obtaining and protein metabolism. So, dominant metabolic activities of microorganism in flooded paddy soils used in this study were not altered significantly under long - term inorganic fertilization. PMID:25522592

  4. Detection of fumonisin producing Fusarium verticillioides in paddy (Oryza sativa L.) using polymerase chain reaction (PCR)

    PubMed Central

    Maheshwar, P.K.; Moharram, S. Ahmed; Janardhana, G.R.

    2009-01-01

    The study reports the occurrence of fumonisin producing Fusarium verticillioides in 90 samples of stored paddy (Oryza sativa L.) collected from different geographical regions of Karnataka, India. Fumonisin producing F. verticillioides was identified based on micromorphological characteristics and PCR using two sets of primers. One set of primers was F. verticillioides species specific, which selectively amplified the intergenic space region of rDNA. The other set of primers was specific to fumonisin producing F. verticillioides. Eight paddy samples were positive for F. verticillioides. Eleven isolates obtained from these samples were capable of producing fumonisin. PMID:24031332

  5. The estimation of rice paddy yield with GRAMI crop model and Geostationary Ocean Color Imager (GOCI) image over South Korea

    NASA Astrophysics Data System (ADS)

    Yeom, J. M.; Kim, H. O.

    2014-12-01

    In this study, we estimated the rice paddy yield with moderate geostationary satellite based vegetation products and GRAMI model over South Korea. Rice is the most popular staple food for Asian people. In addition, the effects of climate change are getting stronger especially in Asian region, where the most of rice are cultivated. Therefore, accurate and timely prediction of rice yield is one of the most important to accomplish food security and to prepare natural disasters such as crop defoliation, drought, and pest infestation. In the present study, GOCI, which is world first Geostationary Ocean Color Image, was used for estimating temporal vegetation indices of the rice paddy by adopting atmospheric correction BRDF modeling. For the atmospheric correction with LUT method based on Second Simulation of the Satellite Signal in the Solar Spectrum (6S), MODIS atmospheric products such as MOD04, MOD05, MOD07 from NASA's Earth Observing System Data and Information System (EOSDIS) were used. In order to correct the surface anisotropy effect, Ross-Thick Li-Sparse Reciprocal (RTLSR) BRDF model was performed at daily basis with 16day composite period. The estimated multi-temporal vegetation images was used for crop classification by using high resolution satellite images such as Rapideye, KOMPSAT-2 and KOMPSAT-3 to extract the proportional rice paddy area in corresponding a pixel of GOCI. In the case of GRAMI crop model, initial conditions are determined by performing every 2 weeks field works at Chonnam National University, Gwangju, Korea. The corrected GOCI vegetation products were incorporated with GRAMI model to predict rice yield estimation. The predicted rice yield was compared with field measurement of rice yield.

  6. Characterizing Spatiotemporal Dynamics of Methane Emissions from Rice Paddies in Northeast China from 1990 to 2010

    PubMed Central

    Zhang, Yuan; Su, Shiliang; Zhang, Feng; Shi, Runhe; Gao, Wei

    2012-01-01

    Background Rice paddies have been identified as major methane (CH4) source induced by human activities. As a major rice production region in Northern China, the rice paddies in the Three-Rivers Plain (TRP) have experienced large changes in spatial distribution over the recent 20 years (from 1990 to 2010). Consequently, accurate estimation and characterization of spatiotemporal patterns of CH4 emissions from rice paddies has become an pressing issue for assessing the environmental impacts of agroecosystems, and further making GHG mitigation strategies at regional or global levels. Methodology/Principal Findings Integrating remote sensing mapping with a process-based biogeochemistry model, Denitrification and Decomposition (DNDC), was utilized to quantify the regional CH4 emissions from the entire rice paddies in study region. Based on site validation and sensitivity tests, geographic information system (GIS) databases with the spatially differentiated input information were constructed to drive DNDC upscaling for its regional simulations. Results showed that (1) The large change in total methane emission that occurred in 2000 and 2010 compared to 1990 is distributed to the explosive growth in amounts of rice planted; (2) the spatial variations in CH4 fluxes in this study are mainly attributed to the most sensitive factor soil properties, i.e., soil clay fraction and soil organic carbon (SOC) content, and (3) the warming climate could enhance CH4 emission in the cool paddies. Conclusions/Significance The study concluded that the introduction of remote sensing analysis into the DNDC upscaling has a great capability in timely quantifying the methane emissions from cool paddies with fast land use and cover changes. And also, it confirmed that the northern wetland agroecosystems made great contributions to global greenhouse gas inventory. PMID:22235268

  7. Diversity and abundance of arsenic biotransformation genes in paddy soils from southern China.

    PubMed

    Zhang, Si-Yu; Zhao, Fang-Jie; Sun, Guo-Xin; Su, Jian-Qiang; Yang, Xiao-Ru; Li, Hu; Zhu, Yong-Guan

    2015-04-01

    Microbe-mediated arsenic (As) biotransformation in paddy soils determines the fate of As in soils and its availability to rice plants, yet little is known about the microbial communities involved in As biotransformation. Here, we revealed wide distribution, high diversity, and abundance of arsenite (As(III)) oxidase genes (aioA), respiratory arsenate (As(V)) reductase genes (arrA), As(V) reductase genes (arsC), and As(III) S-adenosylmethionine methyltransferase genes (arsM) in 13 paddy soils collected across Southern China. Sequences grouped with As biotransformation genes are mainly from rice rhizosphere bacteria, such as some Proteobacteria, Gemmatimonadales, and Firmicutes. A significant correlation of gene abundance between arsC and arsM suggests that the two genes coexist well in the microbial As resistance system. Redundancy analysis (RDA) indicated that soil pH, EC, total C, N, As, and Fe, C/N ratio, SO4(2-)-S, NO3(-)-N, and NH4(+)-N were the key factors driving diverse microbial community compositions. This study for the first time provides an overall picture of microbial communities involved in As biotransformation in paddy soils, and considering the wide distribution of paddy fields in the world, it also provides insights into the critical role of paddy fields in the As biogeochemical cycle. PMID:25738639

  8. Soil amendments and cultivar selection can improve rice yield in salt-influenced (tsunami-affected) paddy fields in Sri Lanka.

    PubMed

    Reichenauer, Thomas G; Panamulla, Sunil; Subasinghe, Siripala; Wimmer, Bernhard

    2009-10-01

    The tsunami disaster in the Indian Ocean in December 2004 caused devastation of agricultural soils by salt water over wide areas. Many rice fields located close to the coast were affected by the flood of seawater. Electric conductivity (EC) of soils in tsunami-affected rice fields was found to be higher compared to unaffected fields 2 years after the tsunami. Four soil amendments (gypsum, dolomite, cinnamon ash and rice-husk-charcoal) were tested for their influence on improving the yield parameters of rice grown in a tsunami-affected and a non-affected area. Yield parameters were compared with an untreated control of the same cultivar (AT362) and with a salt resistant rice variety (AT354). The salt resistant variety had the highest grain yield. The two amendments gypsum and rice-husk-charcoal led to an increase in grain yield compared to the untreated control, whereas dolomite and cinnamon ash had no significant effect on grain yield. PMID:19255858

  9. Impact of Rice Paddy Areas Decrease on Local Climate over Taiwan

    NASA Astrophysics Data System (ADS)

    Lo, M. H.; Wen, W. H.; Chen, C. C.

    2014-12-01

    Agricultural irrigation practice is one of the important anthropogenic processes in the land surface modeling. Irrigation can decrease local surface temperature with alternating surface energy partitioning. Rice paddy is the major food crop in Asian monsoon region and rice is grown under flooded conditions during the growing season; hence, the rice paddy can be considered as an open water body, which has more impacts on the surface energy budget than other cropland does. In this study, we explore how the rice paddy area changes affect Taiwan's regional climate from both observational data and numerical modeling exercise. The Weather Research and Forecasting (WRF) model is utilized to explore impacts of rice paddy area changes on the regional climate, and energy and water budget changes. In addition, temperature datasets from six automatic weather stations in the northern Taiwan and two stations in the southern Taiwan are analyzed in this study to explore how the Daily Temperature Range (DTR) changes with the decreased rice paddy areas. Previous studies show that due to the urban heat island effect, aerosol direct and indirect effects, and global warming, the DTR has decreased in the past 4 decades observed from most of the weather stations around Taiwan. However, the declined rice paddy area may increase the DTR with higher Bowen ratio during the daytime. Preliminary results show that DTR is decreased in weather stations near the urban area, but increased in weather stations near fallow areas in the past 20 years. It shows that different land use changes may have opposite impacts on local and regional climate.

  10. Aerenchyma and an Inducible Barrier to Radial Oxygen Loss Facilitate Root Aeration in Upland, Paddy and Deep‐water Rice (Oryza sativa L.)

    PubMed Central

    COLMER, T. D.

    2003-01-01

    The present study evaluated waterlogging tolerance, root porosity and radial O2 loss (ROL) from the adventitious roots, of seven upland, three paddy, and two deep‐water genotypes of rice (Oryza sativa L.). Upland types, with the exception of one genotype, were as tolerant of 30 d soil waterlogging as the paddy and deep‐water types. In all but one of the 12 genotypes, the number of adventitious roots per stem increased for plants grown in waterlogged, compared with drained, soil. When grown in stagnant deoxygenated nutrient solution, genotypic variation was evident for root porosity and rates of ROL, but there was no overall difference between plants from the three cultural types. Adventitious root porosity increased from 20–26 % for plants grown in aerated solution to 29–41 % for plants grown in stagnant solution. Growth in stagnant solution also induced a ‘tight’ barrier to ROL in the basal regions of adventitious roots of five of the seven upland types, all three paddy types, and the two deep‐water types. The enhanced porosity provided a low resistance pathway for O2 movement to the root tip, and the barrier to ROL in basal zones would have further enhanced longitudinal O2 diffusion towards the apex, by diminishing losses to the rhizosphere. The plasticity in root physiology, as described above, presumably contributes to the ability of rice to grow in diverse environments that differ markedly in soil waterlogging, such as drained upland soils as well as waterlogged paddy fields. PMID:12509350

  11. Environmental profile of paddy rice cultivation with different straw management.

    PubMed

    Fusi, Alessandra; Bacenetti, Jacopo; Gonzlez-Garca, Sara; Vercesi, Annamaria; Bocchi, Stefano; Fiala, Marco

    2014-10-01

    Italy is the most important European country in terms of paddy rice production. North Italian districts such as Vercelli, Pavia, Novara, and Milano are known as some of the world's most advanced rice cultivation sites. In 2013 Italian rice cultivation represented about 50% of all European rice production by area, and paddy fields extended for over 216,000 ha. Cultivation of rice involves different agricultural activities which have environmental impacts mainly due to fossil fuels and agrochemical requirements as well as the methane emission associated with the fermentation of organic material in the flooded rice fields. In order to assess the environmental consequences of rice production in the District of Vercelli, the cultivation practices most frequently carried out were inventoried and evaluated. The general approach of this study was not only to gather the inventory data for rice production and quantify their environmental impacts, but also to identify the key environmental factors where special attention must be paid. Life Cycle Assessment methodology was applied in this study from a cradle-to-farm gate perspective. The environmental profile was analyzed in terms of seven different impact categories: climate change, ozone depletion, human toxicity, terrestrial acidification, freshwater eutrophication, marine eutrophication, and fossil depletion. Regarding straw management, two different scenarios (burial into the soil of the straw versus harvesting) were compared. The analysis showed that the environmental impact was mainly due to field emissions, the fuel consumption needed for the mechanization of field operations, and the drying of the paddy rice. The comparison between the two scenarios highlighted that the collection of the straw improves the environmental performance of rice production except that for freshwater eutrophication. To improve the environmental performance of rice production, solutions to save fossil fuel and reduce the emissions from fertilizers (leaching, volatilization) as well as methane emissions should be implemented. PMID:25038430

  12. Methanogenic Pathway and Fraction of CH4 Oxidized in Paddy Fields: Seasonal Variation and Effect of Water Management in Winter Fallow Season

    PubMed Central

    Zhang, Guangbin; Liu, Gang; Zhang, Yi; Ma, Jing; Xu, Hua; Yagi, Kazuyuki

    2013-01-01

    A 2-year field and incubation experiment was conducted to investigate ?13C during the processes of CH4 emission from the fields subjected to two water managements (flooding and drainage) in the winter fallow season, and further to estimate relative contribution of acetate to total methanogenesis (Fac) and fraction of CH4 oxidized (Fox) based on the isotopic data. Compared with flooding, drainage generally caused CH4, either anaerobically or aerobically produced, depleted in 13C. There was no obvious difference between the two in transport fractionation factor (?transport) and ?13C-value of emitted CH4. CH4 emission was negatively related to its ?13C-value in seasonal variation (P<0.01). Acetate-dependent methanogenesis in soil was dominant (6070%) in the late season, while drainage decreased Fac-value by 510%. On roots however, CH4 was mostly produced through H2/CO2 reduction (60100%) over the season. CH4 oxidation mainly occurred in the first half of the season and roughly 1090% of the CH4 was oxidized in the rhizosphere. Drainage increased Fox-value by 515%, which is possibly attributed to a significant decrease in production while no simultaneous decrease in oxidation. Around 3070% of the CH4 was oxidized at the soil-water interface when CH4 in pore water was released into floodwater, although the amount of CH4 oxidized therein might be negligible relative to that in the rhizosphere. CH4 oxidation was also more important in the first half of the season in lab conditions and about 550% of the CH4 was oxidized in soil while almost 100% on roots. Drainage decreased Fox-value on roots by 15% as their CH4 oxidation potential was highly reduced. The findings suggest that water management in the winter fallow season substantially affects Fac in the soil and Fox in the rhizosphere and roots rather than Fac on roots and Fox at the soil-water interface. PMID:24069259

  13. Methanogenic pathway and fraction of CH(4) oxidized in paddy fields: seasonal variation and effect of water management in winter fallow season.

    PubMed

    Zhang, Guangbin; Liu, Gang; Zhang, Yi; Ma, Jing; Xu, Hua; Yagi, Kazuyuki

    2013-01-01

    A 2-year field and incubation experiment was conducted to investigate ?(13)C during the processes of CH4 emission from the fields subjected to two water managements (flooding and drainage) in the winter fallow season, and further to estimate relative contribution of acetate to total methanogenesis (Fac ) and fraction of CH4 oxidized (Fox ) based on the isotopic data. Compared with flooding, drainage generally caused CH4, either anaerobically or aerobically produced, depleted in (13)C. There was no obvious difference between the two in transport fractionation factor (?transport ) and ?(13)C-value of emitted CH4. CH4 emission was negatively related to its ?(13)C-value in seasonal variation (P<0.01). Acetate-dependent methanogenesis in soil was dominant (60-70%) in the late season, while drainage decreased Fac -value by 5-10%. On roots however, CH4 was mostly produced through H2/CO2 reduction (60-100%) over the season. CH4 oxidation mainly occurred in the first half of the season and roughly 10-90% of the CH4 was oxidized in the rhizosphere. Drainage increased Fox -value by 5-15%, which is possibly attributed to a significant decrease in production while no simultaneous decrease in oxidation. Around 30-70% of the CH4 was oxidized at the soil-water interface when CH4 in pore water was released into floodwater, although the amount of CH4 oxidized therein might be negligible relative to that in the rhizosphere. CH4 oxidation was also more important in the first half of the season in lab conditions and about 5-50% of the CH4 was oxidized in soil while almost 100% on roots. Drainage decreased Fox -value on roots by 15% as their CH4 oxidation potential was highly reduced. The findings suggest that water management in the winter fallow season substantially affects Fac in the soil and Fox in the rhizosphere and roots rather than Fac on roots and Fox at the soil-water interface. PMID:24069259

  14. Elevated ground-level O3 negatively influences paddy methanogenic archaeal community.

    PubMed

    Feng, Youzhi; Lin, Xiangui; Yu, Yongchang; Zhang, Huayong; Chu, Haiyan; Zhu, Jianguo

    2013-01-01

    The current knowledge regarding the effect of global climate change on rice-paddy methane (CH4) emissions is incomplete, partly because information is limited concerning the mechanism of the microbial response to elevated ground-level ozone (O3). A field experiment was conducted in the China Ozone Free-Air Concentration Enrichment facility in a rice-wheat rotation system to investigate the responses of methanogenic archaeal communities to elevated ground-level O3 by culture-independent and -reliant approaches. We found that elevated ground-level O3 inhibited methanogenic activity and influenced the composition of paddy methanogenic communities, reducing the abundance and diversity of paddy methanogens by adversely affecting dominant groups, such as aceticlastic Methanosaeta, especially at the rice tillering stage. Our results indicated that continuously elevated ground-level O3 would negatively influence paddy methanogenic archaeal communities and its critical ecological function. These findings will contribute to a comprehensive understanding of the responses and feedbacks of paddy ecosystems to global climate change. PMID:24217205

  15. Elevated ground-level O3 negatively influences paddy methanogenic archaeal community

    PubMed Central

    Feng, Youzhi; Lin, Xiangui; Yu, Yongchang; Zhang, Huayong; Chu, Haiyan; Zhu, Jianguo

    2013-01-01

    The current knowledge regarding the effect of global climate change on rice-paddy methane (CH4) emissions is incomplete, partly because information is limited concerning the mechanism of the microbial response to elevated ground-level ozone (O3). A field experiment was conducted in the China Ozone Free-Air Concentration Enrichment facility in a rice–wheat rotation system to investigate the responses of methanogenic archaeal communities to elevated ground-level O3 by culture-independent and -reliant approaches. We found that elevated ground-level O3 inhibited methanogenic activity and influenced the composition of paddy methanogenic communities, reducing the abundance and diversity of paddy methanogens by adversely affecting dominant groups, such as aceticlastic Methanosaeta, especially at the rice tillering stage. Our results indicated that continuously elevated ground-level O3 would negatively influence paddy methanogenic archaeal communities and its critical ecological function. These findings will contribute to a comprehensive understanding of the responses and feedbacks of paddy ecosystems to global climate change. PMID:24217205

  16. Towards Global Simulation of Irrigation in a Land Surface Model: Multiple Cropping and Rice Paddy in Southeast Asia

    NASA Technical Reports Server (NTRS)

    Beaudoing, Hiroko Kato; Rodell, Matthew; Ozdogan, Mutlu

    2010-01-01

    Agricultural land use significantly influences the surface water and energy balances. Effects of irrigation on land surface states and fluxes include repartitioning of latent and sensible heat fluxes, an increase in net radiation, and an increase in soil moisture and runoff. We are working on representing irrigation practices in continental- to global-scale land surface simulation in NASA's Global Land Data Assimilation System (GLDAS). Because agricultural practices across the nations are diverse, and complex, we are attempting to capture the first-order reality of the regional practices before achieving a global implementation. This study focuses on two issues in Southeast Asia: multiple cropping and rice paddy irrigation systems. We first characterize agricultural practices in the region (i.e., crop types, growing seasons, and irrigation) using the Global data set of monthly irrigated and rainfed crop areas around the year 2000 (MIRCA2000) dataset. Rice paddy extent is identified using remote sensing products. Whether irrigated or rainfed, flooded fields need to be represented and treated explicitly. By incorporating these properties and processes into a physically based land surface model, we are able to quantify the impacts on the simulated states and fluxes.

  17. Central Region Library Field Records Collection

    USGS Multimedia Gallery

    The USGS Denver Library, Field Records Collection is an archive of unpublished field notes, maps, correspondence, manuscripts, analysis reports, and other data created or collected by USGS Geologic Discipline scientists during field studies and other project work. Materials in the collection represe...

  18. [Effects of Water and Nitrogenous Fertilizer Coupling on CH4 and N2O Emission from Double-Season Rice Paddy Field].

    PubMed

    Fu, Zhi-qiang; Long, Pan; Liu, Yi-yi; Zhong, Juan; Long, Wen-fei

    2015-09-01

    To provide support for the efficient use of water and fertilizer technology to double-season rice cultivation, water and fertilizer coupling mode was applied in this research, including two irrigation methods and four N levels. The irrigation methods were flood irrigation and intermittent irrigation, while four N levels were high-N, middle-N, low-N and none-N. Field experiment was conducted to study the effect of water and fertilizer coupling mode on CH4 and N2O emission. The results showed that the accumulated CH4 emissions were significantly reduced by intermittent irrigation, in comparison with flood irrigation, the reduction in early rice season were from 13. 18 kg.hm-2 to 87. 90 kg.hm-2, and were from 74. 48 kg.hm-2 to 131. 07 kg.hm-2 in late rice season, with a rate of 24. 4% -67. 4% and 42. 5% -65. 5% respectively; whereas the accumulated N20 emissions were increased, the increment were from 0. 03 kg.hm-2 to 0. 24 kg.hm-2 in early rice season and from 0. 35 kg.hm-2 to 1. 53 kg.hm-2 in late rice season when compared flood irrigation, increased by 6.2% -18. 3% and 40.2% - 80.9% respectively. On the whole, intermittent irrigation reduces the warming potential of greenhouse gases (GWP), which were decreased by 18. 8% to 58. 6% in early rice season and by 34. 4% to 60. 1% in late rice season, and the reduction of total GWP were from 2 388 to 4 151 kg. hm-2 (CO2 eq), with a rate of 41% -54% . Through correlation analysis it found that CH4 emissions from soil were significantly related with soil solution Eh and solution CH4 concentration. In comparison with the flood irrigation, the application of intermittent irrigation in double-season rice cultivation was conducive to CH4 reduction, though the increase came in N2O, but the GWPs were significantly reduced. Comprehensively, intermittent irrigation matching with middle-N is more benefit to double-season rice cultivation. PMID:26717700

  19. Effect of no-tillage and tillage on the ecology of mite, Acarina (Oribatida) in two different farming systems of paddy field in Cachar district of Assam.

    PubMed

    Singh, Leimapokpam Amarjit; Ray, D C

    2015-01-01

    The present investigation was carried out in Cachar district of Assam over a period of one year (January 2011 - December 2011) to understand the seasonal ecology of Acarina (Oribatida) in rice (Oryza sativa L.) cultivated fields. Population of Oribatida was found to be maximum during August 2011, both in no-tillage (6.32 ± 0.66 No./m2 x 100(2)) and tillage (5.30 ± 0.71 No./M2 x 100(2)) sites in Dorgakona area whereas the peak was recorded during August 2011, both in no-tillage (5.38 ± 0.75 No./m(2) x 100(2)) and tillage (4.69 ± 0.77 No./m2 x 100(2)) in Durby area of study sites. Least population was encountered during January 2011, in both no-tillage (0.98 ± 0.28 ± No./m2 x 100(2)) and tillage (0.98 ± 0.30 No/m2 x 100(2)) sites in Dorgakona area whereas the same was found during November 2011 in no-tillage (0.57 ± 0.31 No.m/2 x 100(2)) and in February 2011 in tillage (0.45 ± 0.21 No./m2 x 100(2)) sites of Durby area. Linear regression analysis with all the environmental variables showed positive and significant influence on the population dynamics whereas relative humidity (R2 = 0.26 p > 0.05) in Dorgakona no-tillage and tillage (R2 = 0.19 P > 0.05) sites and relative humidity in tillage site (R2 = 0.27 P > 0.05) in Durby area showed no influence. Multiple regression analysis showed that the combined effect of climatic variables having a significant influence (p < 0.05) on the oribatid mite population in no-tillage and tillage systems in both the study sites. Rainfall, relative humidity and temperature facilitated the soil moisture, microbial activity and litter decomposition, which in turn may favour the reproduction and growth rate of the species. Among microclimatic conditions all the parameters showed positive and significant influence (P < 0.05) on the population in no-tillage and tillage system on both the sites except pH which showed negative correlation with the population. One way ANOVA revealed significant difference (F = 6.53, P < 0.01) of the Oribatid population between the systems. PMID:26536810

  20. Natural Occurrence of Toxigenic Fusarium proliferatum on Paddy (Oryza sativa L.) in Karnataka, India

    PubMed Central

    Maheshwar, Pavagada Krishnamurthy; Janardhana, Gottravalli Ramanayaka

    2010-01-01

    Contamination of paddy seeds (rice with husk) by Fusarium species can cause spoilage and subsequent production of mycotoxins, especially fumonisins that affect human and animal health. A mycological study was conducted to evaluate the natural occurrence of fumonisin B1 produced by Fusarium proliferatum on paddy grown in different geographic regions of Karnataka (India). A total of 65 isolates of F. proliferatum from paddy samples were analysed by polymerase chain reaction (PCR). One set of primers, Fp3-F and Fp4-R was employed to identify the species F. proliferatum, and another set of primers, FUM1 was employed to determine the fumonisin producing ability of the isolates. All 65 isolates of F. proliferatum scored positive with both set of primers, producing amplified products of the expected sizes. Furthermore, thin layer chromatography (TLC) analysis detected fumonisin B1 (FB1) in all of the PCR positive isolates of F. proliferatum. PMID:24575185

  1. Phylogenetically distinct phylotypes modulate nitrification in a paddy soil.

    PubMed

    Zhao, Jun; Wang, Baozhan; Jia, Zhongjun

    2015-05-01

    Paddy fields represent a unique ecosystem in which regular flooding occurs, allowing for rice cultivation. However, the taxonomic identity of the microbial functional guilds that catalyze soil nitrification remains poorly understood. In this study, we provide molecular evidence for distinctly different phylotypes of nitrifying communities in a neutral paddy soil using high-throughput pyrosequencing and DNA-based stable isotope probing (SIP). Following urea addition, the levels of soil nitrate increased significantly, accompanied by an increase in the abundance of the bacterial and archaeal amoA gene in microcosms subjected to SIP (SIP microcosms) during a 56-day incubation period. High-throughput fingerprints of the total 16S rRNA genes in SIP microcosms indicated that nitrification activity positively correlated with the abundance of Nitrosospira-like ammonia-oxidizing bacteria (AOB), soil group 1.1b-like ammonia-oxidizing archaea (AOA), and Nitrospira-like nitrite-oxidizing bacteria (NOB). Pyrosequencing of 13C-labeled DNA further revealed that 13CO2 was assimilated by these functional groups to a much greater extent than by marine group 1.1a-associated AOA and Nitrobacter-like NOB. Phylogenetic analysis demonstrated that active AOB communities were closely affiliated with Nitrosospira sp. strain L115 and the Nitrosospira multiformis lineage and that the 13C-labeled AOA were related to phylogenetically distinct groups, including the moderately thermophilic "Candidatus Nitrososphaera gargensis," uncultured fosmid 29i4, and acidophilic "Candidatus Nitrosotalea devanaterra" lineages. These results suggest that a wide variety of microorganisms were involved in soil nitrification, implying physiological diversification of soil nitrifying communities that are constantly exposed to environmental fluctuations in paddy fields. PMID:25724959

  2. Phylogenetically Distinct Phylotypes Modulate Nitrification in a Paddy Soil

    PubMed Central

    Zhao, Jun; Wang, Baozhan

    2015-01-01

    Paddy fields represent a unique ecosystem in which regular flooding occurs, allowing for rice cultivation. However, the taxonomic identity of the microbial functional guilds that catalyze soil nitrification remains poorly understood. In this study, we provide molecular evidence for distinctly different phylotypes of nitrifying communities in a neutral paddy soil using high-throughput pyrosequencing and DNA-based stable isotope probing (SIP). Following urea addition, the levels of soil nitrate increased significantly, accompanied by an increase in the abundance of the bacterial and archaeal amoA gene in microcosms subjected to SIP (SIP microcosms) during a 56-day incubation period. High-throughput fingerprints of the total 16S rRNA genes in SIP microcosms indicated that nitrification activity positively correlated with the abundance of Nitrosospira-like ammonia-oxidizing bacteria (AOB), soil group 1.1b-like ammonia-oxidizing archaea (AOA), and Nitrospira-like nitrite-oxidizing bacteria (NOB). Pyrosequencing of 13C-labeled DNA further revealed that 13CO2 was assimilated by these functional groups to a much greater extent than by marine group 1.1a-associated AOA and Nitrobacter-like NOB. Phylogenetic analysis demonstrated that active AOB communities were closely affiliated with Nitrosospira sp. strain L115 and the Nitrosospira multiformis lineage and that the 13C-labeled AOA were related to phylogenetically distinct groups, including the moderately thermophilic “Candidatus Nitrososphaera gargensis,” uncultured fosmid 29i4, and acidophilic “Candidatus Nitrosotalea devanaterra” lineages. These results suggest that a wide variety of microorganisms were involved in soil nitrification, implying physiological diversification of soil nitrifying communities that are constantly exposed to environmental fluctuations in paddy fields. PMID:25724959

  3. A comparison of methane emissions following rice paddies conversion to crab-fish farming wetlands in southeast China.

    PubMed

    Hu, Zhiqiang; Wu, Shuang; Ji, Cheng; Zou, Jianwen; Zhou, Quansuo; Liu, Shuwei

    2016-01-01

    Rice paddies and aquaculture wetlands are typical agricultural wetlands that constitute one of the important sources of atmospheric methane (CH4). Traditional transplanted rice paddies have been experiencing conversion to pond aquaculture wetlands for pursuing higher economic benefits over the past decades in southeast China. A parallel field experiment was carried out to compare CH4 emissions from a transplanted rice paddy and its converted crab-fish farming wetland in southeast China. Over the rice-growing season, CH4 fluxes averaged 1.86mgm(-2)h(-1) from rice paddies, and 1.14 and 0.50mgm(-2)h(-1) for the treatments with or without aquatic vegetation present in the crab-fish farming wetlands, respectively. When averaged across the treatments, seasonal CH4 emissions from crab-fish framing wetlands were 52% lower than those from rice paddies. The CH4 fluxes were negatively related to water dissolved oxygen (DO) concentration but positively related to soil/sediment dissolved organic carbon (DOC) content in crab-fish farming wetlands. Dependence of CH4 fluxes on DO or DOC was intensified by the aquatic vegetation presence. By extrapolating the present CH4 emission rate with the current rice paddy-converted aquaculture cultivation area, the seasonal CH4 emissions from inland aquaculture wetlands during the critical farming stage (20 June to 18 October) were estimated to be 33.6Ggha(-1) in southeast China in 2012. Rice paddies conversion to crab-fish farming wetlands might have reduced CH4 emissionsby 22-54 % in mainland China. Results of this study suggest that the conversion of transplanted rice paddies to crab-fish aquaculture wetlands for higher economic benefits would also lead to a lower ecosystem CH4 release rate. PMID:26374545

  4. STOCHASTIC METHODOLOGY FOR REGIONAL WIND FIELD MODELING

    EPA Science Inventory

    Three-dimensional regional scale (1000 km) air quality simulation models require hourly inputs of U and V wind components for each vertical layer of the model and for each grid cell in the horizontal. he standard North American meteorological observation network is used to derive...

  5. Radiocesium sorption in relation to clay mineralogy of paddy soils in Fukushima, Japan.

    PubMed

    Nakao, Atsushi; Ogasawara, Sho; Sano, Oki; Ito, Toyoaki; Yanai, Junta

    2014-01-15

    Relationships between Radiocesium Interception Potential (RIP) and mineralogical characteristics of the clay fraction isolated from 97 paddy soils (Hama-dori, n = 25; Naka-dori, n = 36; Aizu, n = 36) in Fukushima Prefecture, Japan were investigated to clarify the mineralogical factors controlling the (137)Cs retention ability of soils (half-life 30.1 y). Of all the fission products released by the Fukushima accident, (137)Cs is the most important long-term contributor to the environmental contamination. The RIP, a quantitative index of the (137)Cs retention ability, was determined for the soil clays. The composition of clay minerals in the soil clays was estimated from peak areas obtained using X-ray diffraction (XRD) analyses. The predominant clay mineral was smectite in soils from Hama-dori and Aizu, while this was variable for those from Naka-dori. Native K content of the soil clays was found to be an indicator of the amount of micaceous minerals. The average RIP for the 97 soil clays was 7.8 mol kg(-1), and ranged from 2.4 mol kg(-1) to 19.4 mol kg(-1). The RIP was significantly and positively correlated with native K content for each of the geographical regions, Hama-dori (r = 0.76, p < 0.001), Naka-dori (r = 0.43, p < 0.05), and Aizu (r = 0.76, P < 0.001), while it was not related to the relative abundance of smectite. The linear relationship between RIP and native K content not only indicate a large contribution of micaceous minerals to the (137)Cs retention ability of the soil clays, but also could be used to predict the (137)Cs retention ability of soil clays for other paddy fields in Fukushima and other areas. PMID:24055668

  6. Global rain-fed, irrigated, and paddy croplands: A new high resolution map derived from remote sensing, crop inventories and climate data

    NASA Astrophysics Data System (ADS)

    Salmon, J. Meghan; Friedl, Mark A.; Frolking, Steve; Wisser, Dominik; Douglas, Ellen M.

    2015-06-01

    Irrigation accounts for 70% of global water use by humans and 33-40% of global food production comes from irrigated croplands. Accurate and timely information related to global irrigation is therefore needed to manage increasingly scarce water resources and to improve food security in the face of yield gaps, climate change and extreme events such as droughts, floods, and heat waves. Unfortunately, this information is not available for many regions of the world. This study aims to improve characterization of global rain-fed, irrigated and paddy croplands by integrating information from national and sub-national surveys, remote sensing, and gridded climate data sets. To achieve this goal, we used supervised classification of remote sensing, climate, and agricultural inventory data to generate a global map of irrigated, rain-fed, and paddy croplands. We estimate that 314 million hectares (Mha) worldwide were irrigated circa 2005. This includes 66 Mha of irrigated paddy cropland and 249 Mha of irrigated non-paddy cropland. Additionally, we estimate that 1047 Mha of cropland are managed under rain-fed conditions, including 63 Mha of rain-fed paddy cropland and 985 Mha of rain-fed non-paddy cropland. More generally, our results show that global mapping of irrigated, rain-fed, and paddy croplands is possible by combining information from multiple data sources. However, regions with rapidly changing irrigation or complex mixtures of irrigated and non-irrigated crops present significant challenges and require more and better data to support high quality mapping of irrigation.

  7. Microbial phototrophic fixation of atmospheric CO2 in China subtropical upland and paddy soils

    NASA Astrophysics Data System (ADS)

    Ge, Tida; Wu, Xiaohong; Chen, Xiaojuan; Yuan, Hongzhao; Zou, Ziying; Li, Baozhen; Zhou, Ping; Liu, Shoulong; Tong, Chengli; Brookes, Phil; Wu, Jinshui

    2013-07-01

    Autotrophic microorganisms, which can fix atmospheric CO2 to synthesize organic carbon, are numerous and widespread in soils. However, the extent and the mechanism of CO2 fixation in soils remain poorly understood. We incubated five upland and five paddy soils from subtropical China in an enclosed, continuously 14CO2-labeled, atmosphere and measured 14CO2 incorporated into soil organic matter (SOC14) and microbial biomass (MBC14) after 110 days. The five upland soils supported dominant crops soils (maize, wheat, sweet potato, and rapeseed) in the region, while all paddy soils were cultivated in a regime consisting of permanently-flooded double-cropping rice cultivation. The upland and paddy soils represented typical soil types (fluvisols and ultisols) and three landforms (upland, hill, and low mountain), ranging in total carbon from low (<10 g kg-1 soil organic carbon) to medium (10-20 g kg-1) to high (>20 g kg-1). Substantial amounts of 14CO2 were fixed into SOC14 (mean 20.1 7.1 mg C kg-1 in upland soil, 121.1 6.4 mg C kg-1 in paddy soil) in illuminated soils (12 h light/12 h dark), whereas no 14C was fixed in soils incubated in continuous darkness. We concluded that the microbial CO2 fixation was almost entirely phototrophic rather than chemotrophic. The rate of SOC14 synthesis was significantly higher in paddy soils than in upland soils. The SOC14 comprised means of 0.15 0.01% (upland) and 0.65 0.03% (paddy) of SOC. The extent of 14C immobilized as MBC14 and that present as dissolved organic C (DOC14) differed between soil types, accounting for 15.69-38.76% and 5.54-18.37% in upland soils and 15.57-40.03% and 3.67-7.17% of SOC14 in paddy soils, respectively. The MBC14/MBC and DOC14/DOC were 1.76-5.70% and 1.69-5.17% in the upland soils and 4.23-28.73% and 5.65-14.30% in the paddy soils, respectively. Thus, the newly-incorporated C stimulated the dynamics of DOC and MBC more than the dynamics of SOC. The SOC14 and MBC14 concentrations were highly significantly correlated (r = 0.946; P < 0.0001). We conclude that CO2 uptake by phototrophic soil microorganisms can contribute significantly to carbon assimilation in soil, and so warrants further future study.

  8. Seasonal variations in methane flux and [delta][sup 13]CH[sub 4] values for rice paddies in Japan and their implications

    SciTech Connect

    Tyler, S.C.; Cicerone, R.J. ); Brailsford, G.W. ); Yagi, K.; Minami, K. )

    1994-03-01

    An important source of methane to the atmosphere is from rice paddy fields. This paper presents isotopic data and interpretations from two seasons of measurements of rice paddy methane flux from fields located in Japan. Possible causes for the variation in the stable carbon isotopic signal of methane throughout the growing season are suggested. The consequences for developing a global isotopic atmospheric methane budget are also discussed. 54 refs., 3 figs., 2 tabs.

  9. Magnetic and velocity fields of active regions

    NASA Astrophysics Data System (ADS)

    Choudhary, D. P.; Gosain, S.

    We have observed about 15 active regions on the Sun, with the Advanced Stokes Polarimeter and Dick Dunn Telescope at NSO/SP to map the Stokes parameters in the photospheric Fe 6302.5 and chromospheric Mg i 5173 lines, during 1999-2002. The observations are corrected for dark current, gain, instrumental polarization and cross-talk using ASP pipeline. The wavelength calibration is carried out using the O_2 telluric line 6302 which is also present in the observations. The photospheric and chromospheric longitudinal magnetograms are made from the Stokes V profiles, which were inter-calibrated with the Kitt Peak magnetograms. The plasma motions are inferred from the line bisector measurements at different positions of the spectral line. In this paper we present the height dependence of Doppler velocity scatter plots of a sunspot in the photospheric Fe i 6302 line.

  10. Community structure and soil pH determine chemoautotrophic carbon dioxide fixation in drained paddy soils.

    PubMed

    Long, Xi-En; Yao, Huaiying; Wang, Juan; Huang, Ying; Singh, Brajesh K; Zhu, Yong-Guan

    2015-06-16

    Previous studies suggested that microbial photosynthesis plays a potential role in paddy fields, but little is known about chemoautotrophic carbon fixers in drained paddy soils. We conducted a microcosm study using soil samples from five paddy fields to determine the environmental factors and quantify key functional microbial taxa involved in chemoautotrophic carbon fixation. We used stable isotope probing in combination with phospholipid fatty acid (PLFA) and molecular approaches. The amount of microbial (13)CO2 fixation was determined by quantification of (13)C-enriched fatty acid methyl esters and ranged from 21.28 to 72.48 ng of (13)C (g of dry soil)(-1), and the corresponding ratio (labeled PLFA-C:total PLFA-C) ranged from 0.06 to 0.49%. The amount of incorporationof (13)CO2 into PLFAs significantly increased with soil pH except at pH 7.8. PLFA and high-throughput sequencing results indicated a dominant role of Gram-negative bacteria or proteobacteria in (13)CO2 fixation. Correlation analysis indicated a significant association between microbial community structure and carbon fixation. We provide direct evidence of chemoautotrophic C fixation in soils with statistical evidence of microbial community structure regulation of inorganic carbon fixation in the paddy soil ecosystem. PMID:25989872

  11. Elevated CO2 facilitates C and N accumulation in a rice paddy ecosystem.

    PubMed

    Guo, Jia; Zhang, Mingqian; Wang, Xiaowen; Zhang, Weijian

    2015-03-01

    Elevated CO2 can stimulate wetland carbon (C) and nitrogen (N) exports through gaseous and dissolved pathways, however, the consequent influences on the C and N pools are still not fully known. Therefore, we set up a free-air CO2 enrichment experiment in a paddy field in Eastern China. After five year fumigation, we studied C and N in the plant-water-soil system. The results showed: (1) elevated CO2 stimulated rice aboveground biomass and N accumulations by 19.1% and 12.5%, respectively. (2) Elevated CO2 significantly increased paddy soil TOC and TN contents by 12.5% and 15.5%, respectively in the 0-15 cm layer, and 22.7% and 26.0% in the 15-30 cm soil layer. (3) Averaged across the rice growing period, elevated CO2 greatly increased TOC and TN contents in the surface water by 7.6% and 11.4%, respectively. (4) The TOC/TN ratio and natural ?15N value in the surface soil showed a decreasing trend under elevated CO2. The above results indicate that elevated CO2 can benefit C and N accumulation in paddy fields. Given the similarity between the paddies and natural wetlands, our results also suggest a great potential for long-term C and N accumulation in natural wetlands under future climate patterns. PMID:25766010

  12. Wake Fields in the Super B Factory Interaction Region

    SciTech Connect

    Weathersby, Stephen; Novokhatski, Alexander; /SLAC

    2011-06-02

    The geometry of storage ring collider interaction regions present an impedance to beam fields resulting in the generation of additional electromagnetic fields (higher order modes or wake fields) which affect the beam energy and trajectory. These affects are computed for the Super B interaction region by evaluating longitudinal loss factors and averaged transverse kicks for short range wake fields. Results indicate at least a factor of 2 lower wake field power generation in comparison with the interaction region geometry of the PEP-II B-factory collider. Wake field reduction is a consderation in the Super B design. Transverse kicks are consistent with an attractive potential from the crotch nearest the beam trajectory. The longitudinal loss factor scales as the -2.5 power of the bunch length. A factor of 60 loss factor reduction is possible with crotch geometry based on an intersecting tubes model.

  13. Fate of pesticides in combined paddy rice-fish pond farming systems in northern Vietnam.

    PubMed

    Anyusheva, Maria; Lamers, Marc; La, Nguyen; Nguyen, Van Vien; Streck, Thilo

    2012-01-01

    During the last decades, high population growth and export-oriented economics in Vietnam have led to a tremendous intensification of rice production, which in turn has significantly increased the amount of pesticides applied in rice cropping systems. Since pesticides are toxic by design, there is a natural concern on the impact of their presence in the environment on human health and environmental quality. The present study was designed to examine the water regime and fate of pesticides (fenitrothion, dimethoate) during two consecutive rice crop seasons in combined paddy rice-fish pond farming systems in northern Vietnam. Major results revealed that 5 and 41% (dimethoate), and 1 and 17% (fenitrothion) of the applied mass of pesticides were lost from the paddy field to the adjacent fish pond during spring and summer crop seasons, respectively. The decrease of pesticide concentration in paddy surface water was very rapid with dissipation half-life values of 0.3 to 0.8 and 0.2 d for dimethoate and fenitrothion, respectively. Key factors controlling the transport of pesticides were water solubility and paddy water management parameters, such as hydraulic residence time and water holding period. Risk assessment indicates that the exposure to toxic levels of pesticides for aquaculture (, ) is significant, at least shortly after pesticide application. PMID:22370414

  14. Are Symbiotic Methanotrophs Key Microbes for N Acquisition in Paddy Rice Root?

    PubMed

    Minamisawa, Kiwamu; Imaizumi-Anraku, Haruko; Bao, Zhihua; Shinoda, Ryo; Okubo, Takashi; Ikeda, Seishi

    2016-03-26

    The relationships between biogeochemical processes and microbial functions in rice (Oryza sativa) paddies have been the focus of a large number of studies. A mechanistic understanding of methane-nitrogen (CH4-N) cycle interactions is a key unresolved issue in research on rice paddies. This minireview is an opinion paper for highlighting the mechanisms underlying the interactions between biogeochemical processes and plant-associated microbes based on recent metagenomic, metaproteomic, and isotope analyses. A rice symbiotic gene, relevant to rhizobial nodulation and mycorrhization in plants, likely accommodates diazotrophic methanotrophs or the associated bacterial community in root tissues under low-N fertilizer management, which may permit rice plants to acquire N via N2 fixation. The amount of N fixed in rice roots was previously estimated to be approximately 12% of plant N based on measurements of (15)N natural abundance in a paddy field experiment. Community analyses also indicate that methanotroph populations in rice roots are susceptible to environmental conditions such as the microclimate of rice paddies. Therefore, CH4 oxidation by methanotrophs is a driving force in shaping bacterial communities in rice roots grown in CH4-rich environments. Based on these findings, we propose a hypothesis with unanswered questions to describe the interplay between rice plants, root microbiomes, and their biogeochemical functions (CH4 oxidation and N2 fixation). PMID:26960961

  15. Effect of Drying on Heavy Metal Fraction Distribution in Rice Paddy Soil

    PubMed Central

    Qi, Yanbing; Huang, Biao; Darilek, Jeremy Landon

    2014-01-01

    An understanding of how redox conditions affect soil heavy metal fractions in rice paddies is important due to its implications for heavy metal mobility and plant uptake. Rice paddy soil samples routinely undergo oxidation prior to heavy metal analysis. Fraction distribution of Cu, Pb, Ni, and Cd from paddy soil with a wide pH range was investigated. Samples were both dried according to standard protocols and also preserved under anaerobic conditions through the sampling and analysis process and heavy metals were then sequentially extracted for the exchangeable and carbonate bound fraction (acid soluble fraction), iron and manganese oxide bound fraction (reducible fraction), organic bound fraction (oxidizable fraction), and residual fraction. Fractions were affected by redox conditions across all pH ranges. Drying decreased reducible fraction of all heavy metals. Curesidual fraction, Pboxidizable fraction, Cdresidual fraction, and Niresidual fraction increased by 25%, 33%, 35%, and >60%, respectively. Pbresidual fraction, Niacid soluble fraction, and Cdoxidizable fraction decreased 33%, 25%, and 15%, respectively. Drying paddy soil prior to heavy metal analysis overestimated Pb and underestimated Cu, Ni, and Cd. In future studies, samples should be stored after injecting N2 gas to maintain the redox potential of soil prior to heavy metal analysis, and investigate the correlation between heavy metal fraction distribution under field conditions and air-dried samples. PMID:24823670

  16. Influence of the nonexchangeable potassium of mica on radiocesium uptake by paddy rice.

    PubMed

    Eguchi, Tetsuya; Ohta, Takeshi; Ishikawa, Tetsuya; Matsunami, Hisaya; Takahashi, Yoshihiko; Kubo, Katashi; Yamaguchi, Noriko; Kihou, Nobuharu; Shinano, Takuro

    2015-09-01

    A pot cultivation experiment was conducted to elucidate the influence of the nonexchangeable potassium (K) of mica on radiocesium ((137)Cs) uptake by paddy rice (Oryza sativa L. cv. Koshihikari), and to evaluate the potential of mica application as a countermeasure to reduce radiocesium transfer from soil to paddy rice. The increase in the exchangeable K concentrations of soils, measured before planting, due to mica (muscovite, biotite, and phlogopite) application was negligible. However, in trioctahedral mica (biotite and phlogopite)-treated soil, the release of nonexchangeable K from the mica interlayer maintained the soil-solution K at a higher level during the growing season in comparison to the control, and consequently decreased the (137)Cs transfer factor for brown rice (TF). The sodium tetraphenylboron (TPB)-extractable K concentration of the soils, measured before planting, was strongly negatively correlated with the TF, whereas the exchangeable K concentration of the soils, also measured before planting, was not correlated with the TF. Therefore, we conclude that TPB-extractable K is more reliable than exchangeable K as a basis of fertilizer recommendations for radiocesium-contaminated paddy fields. Phlogopite-treated soils exhibited higher TPB-extractable K concentrations and lower TF values than biotite-treated soils. We thus conclude that phlogopite application is an effective countermeasure to reduce radiocesium uptake in paddy rice. PMID:26026983

  17. Effect of drying on heavy metal fraction distribution in rice paddy soil.

    PubMed

    Qi, Yanbing; Huang, Biao; Darilek, Jeremy Landon

    2014-01-01

    An understanding of how redox conditions affect soil heavy metal fractions in rice paddies is important due to its implications for heavy metal mobility and plant uptake. Rice paddy soil samples routinely undergo oxidation prior to heavy metal analysis. Fraction distribution of Cu, Pb, Ni, and Cd from paddy soil with a wide pH range was investigated. Samples were both dried according to standard protocols and also preserved under anaerobic conditions through the sampling and analysis process and heavy metals were then sequentially extracted for the exchangeable and carbonate bound fraction (acid soluble fraction), iron and manganese oxide bound fraction (reducible fraction), organic bound fraction (oxidizable fraction), and residual fraction. Fractions were affected by redox conditions across all pH ranges. Drying decreased reducible fraction of all heavy metals. Curesidual fraction, Pboxidizable fraction, Cdresidual fraction, and Niresidual fraction increased by 25%, 33%, 35%, and >60%, respectively. Pbresidual fraction, Niacid soluble fraction, and Cdoxidizable fraction decreased 33%, 25%, and 15%, respectively. Drying paddy soil prior to heavy metal analysis overestimated Pb and underestimated Cu, Ni, and Cd. In future studies, samples should be stored after injecting N2 gas to maintain the redox potential of soil prior to heavy metal analysis, and investigate the correlation between heavy metal fraction distribution under field conditions and air-dried samples. PMID:24823670

  18. Are Symbiotic Methanotrophs Key Microbes for N Acquisition in Paddy Rice Root?

    PubMed Central

    Minamisawa, Kiwamu; Imaizumi-Anraku, Haruko; Bao, Zhihua; Shinoda, Ryo; Okubo, Takashi; Ikeda, Seishi

    2016-01-01

    The relationships between biogeochemical processes and microbial functions in rice (Oryza sativa) paddies have been the focus of a large number of studies. A mechanistic understanding of methane–nitrogen (CH4–N) cycle interactions is a key unresolved issue in research on rice paddies. This minireview is an opinion paper for highlighting the mechanisms underlying the interactions between biogeochemical processes and plant-associated microbes based on recent metagenomic, metaproteomic, and isotope analyses. A rice symbiotic gene, relevant to rhizobial nodulation and mycorrhization in plants, likely accommodates diazotrophic methanotrophs or the associated bacterial community in root tissues under low-N fertilizer management, which may permit rice plants to acquire N via N2 fixation. The amount of N fixed in rice roots was previously estimated to be approximately 12% of plant N based on measurements of 15N natural abundance in a paddy field experiment. Community analyses also indicate that methanotroph populations in rice roots are susceptible to environmental conditions such as the microclimate of rice paddies. Therefore, CH4 oxidation by methanotrophs is a driving force in shaping bacterial communities in rice roots grown in CH4-rich environments. Based on these findings, we propose a hypothesis with unanswered questions to describe the interplay between rice plants, root microbiomes, and their biogeochemical functions (CH4 oxidation and N2 fixation). PMID:26960961

  19. Relation between the active region magnetic field and solar flares

    NASA Astrophysics Data System (ADS)

    Podgorny, A. I.; Podgorny, I. M.; Meshalkina, N. S.

    2013-11-01

    A weak active region (NOAA 11158) appeared on the solar disk near the eastern limb. This region increased rapidly and, having reached the magnetic flux higher than 1022 Mx, produced an X-class flare. Only weak field variations at individual points were observed during the flare. An analysis of data with a resolution of 45 s did not indicate any characteristic features in the photospheric field dynamics during the flare. When the flux became higher than 3 1022 Mx, active region NOAA 10720 produced six X-class flares. The field remained quiet during these flares. An increase in the magnetic flux above 1022 Mx is a necessary, but not sufficient, condition for the appearance of powerful flares. Simple active regions do not produce flares. A flare originates only when the field distribution in an active region is complex and lines of polarity inversion have a complex shape. Singular lines of the magnetic field can exist only above such active regions. The current sheets, in the magnetic field of which the solar flare energy is accumulated, originate in the vicinity of these lines.

  20. Agricultural Field in the Great Plains Region of Montana

    USGS Multimedia Gallery

    Agricultural fields and an abandoned farmstead in eastern Montana in the Great Plains region. The Great Plains region of the United States has experienced significant land-use change since European settlement, with vast swaths of grasslands converted to agricultural lands. Access to water, technolog...

  1. Mapping Crop Residue Cover at Field to Regional Scales

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of crop residues in agricultural fields is an important consideration for reducing soil erosion and increasing soil organic C. Current methods of quantifying crop residue cover are inadequate for characterizing the spatial variability of residue cover within fields or across large regions...

  2. Investigating Arsenic Mobilization Mechanisms as well as Complexation Between Arsenic and Polysulfides Associated With a Bangladeshi Rice Paddy

    NASA Astrophysics Data System (ADS)

    Lin, T.; Kampalath, R.; Jay, J.

    2009-12-01

    The presence of arsenic in the groundwater has led to the largest environmental poisoning in history. Although it is a worldwide issue that affects numerous countries, including Taiwan, Bangladesh, India, China, Mexico, Peru, Australia, and the United States, the issue is of greatest concern in the West Bengal region. In the Ganges Delta, as many as 2 million people are diagnosed with arsenicosis each year. The World Health Organization (WHO) estimates 200,000 to 270,000 arsenic-induced cancer-related deaths in Bangladesh alone. More than 100 million people in the country consume groundwater that exceeds the WHO limit as 50% of the 8 million wells contain groundwater with more than 10 ?g/L. Despite the tragic public health implications of this problem, we do not yet have a complete answer to the question of why dissolved arsenic concentrations are so high in the groundwater of the Ganges Delta. Since 1999, we have been intensively studying a field site in Munshiganj, Bangladesh with extremely high levels of arsenic in groundwater (up to 1.2 mg/L). Sediment cores were collected from two locations at the field site: 1) the rice paddy and 2) edge of a nearby irrigation pond. Recharge from irrigation ponds have recently been hypothesized to be an important site of arsenic mobilization. Recent work has proposed mineral dissolution under phosphorus-limited conditions as an important mechanism for arsenic mobilization. Using microcosms with paddy and pond sediment, we are comparing arsenic release via this mechanism with that resulting from reduction of iron hydroxides at our site. Concurrently, we are looking at enhanced solubility of As in the presence of polysulfides as the effects of elemental sulfur on As solubility have not been well researched. We hypothesize that the presence of elemental sulfur, and consequent formation of polysulfides, will substantially increase the solubility of orpiment in sulfidic water and that sorption of these complexes will significantly affect the mobility of these species of As in groundwater. We have shown substantial (order of magnitude) increases in metal solubility in bottle in the presence of elemental sulfur and sulfide compared to bottles in the presence of the same concentration of sulfide alone. This is presumably attributable to metal-polysulfide complexation. Further experiments measuring solubility over a range of pH and sulfide levels are necessary to model the data and determine complexation constants. By elucidating As mobilization mechanisms at an experimental rice paddy, this work could ultimately lead to solutions that minimize As exposure in critical populations.

  3. Ground cover rice production systems increase soil carbon and nitrogen stocks at regional scale

    NASA Astrophysics Data System (ADS)

    Liu, M.; Dannenmann, M.; Lin, S.; Saiz, G.; Yan, G.; Yao, Z.; Pelster, D. E.; Tao, H.; Sippel, S.; Tao, Y.; Zhang, Y.; Zheng, X.; Zuo, Q.; Butterbach-Bahl, K.

    2015-08-01

    Rice production is increasingly limited by water scarcity. Covering paddy rice soils with films (so-called ground cover rice production system: GCRPS) can significantly reduce water demand as well as overcome temperature limitations at the beginning of the growing season, which results in greater grain yields in relatively cold regions and also in those suffering from seasonal water shortages. However, it has been speculated that both increased soil aeration and temperature under GCRPS result in lower soil organic carbon and nitrogen stocks. Here we report on a regional-scale experiment conducted in Shiyan, a typical rice-producing mountainous area of China. We sampled paired adjacent paddy and GCRPS fields at 49 representative sites. Measured parameters included soil carbon (C) and nitrogen (N) stocks (to 1 m depth), soil physical and chemical properties, δ15N composition of plants and soils, potential C mineralization rates, and soil organic carbon (SOC) fractions at all sampling sites. Root biomass was also quantified at one intensively monitored site. The study showed that: (1) GCRPS increased SOC and N stocks 5-20 years following conversion from traditional paddy systems; (2) there were no differences between GCRPS and paddy systems in soil physical and chemical properties for the various soil depths, with the exception of soil bulk density; (3) GCRPS increased above-ground and root biomass in all soil layers down to a 40 cm depth; (4) δ15N values were lower in soils and plant leaves indicating lower NH3 volatilization losses from GCRPS than in paddy systems; and (5) GCRPS had lower C mineralization potential than that observed in paddy systems over a 200-day incubation period. Our results suggest that GCRPS is an innovative production technique that not only increases rice yields using less irrigation water, but that it also increases SOC and N stocks.

  4. Modeling the effect of rainfall intensity on soil-water nutrient exchange in flooded rice paddies and implications for nitrate fertilizer runoff to the Oita River in Japan

    NASA Astrophysics Data System (ADS)

    Higashino, Makoto; Stefan, Heinz G.

    2014-11-01

    This paper examines the effect of rainfall intensity on nutrient exchange at the soil-water interface of rice paddy fields and the implications to nitrate runoff to the Oita River. The Oita River Basin on Kyushu Island in Japan covers 650 km2 of which 11% are used for agriculture (rice). During the monsoon season in June/July, the heavily fertilized paddy fields are flooded and large amounts of NO3-N are discharged to the Oita River. A model has been developed for the NO3-N release in the rice paddy fields. The model focuses on the effect of rainfall intensity. It assumes that in addition to increased surface runoff and infiltration, the monsoon rain enhances pore water flow and causes nitrate release from the soil by dynamic pressure fluctuations at the soil/water interface. The magnitude of NO3-N release from paddy fields is described by the simulated soil/water exchange velocity (W) which increases with rising rainfall intensity and hydraulic conductivity, and is on the order of 10-2 to 10-6 cm/s. When the river flow rises due to precipitation (monsoon), the NO3-N load rises almost proportionately to the river discharge, and with little delay. Measured unit NO3-N loads in the Oita River per day and m2 of paddy fields were nearly proportional to precipitation intensity R (R1.042) and so were modeled unit NO3-N release rates in the paddy fields (R1.095). This result suggests that raindrop-induced pumping is an important if not crucial process that enhances NO3-N runoff from rice paddy fields. An implication is that the nutrient loading of surface water bodies may grow as the occurrence of extreme rainfall events increases with climate change.

  5. Efficiency evaluation for remediating paddy soil contaminated with cadmium and arsenic using water management, variety screening and foliage dressing technologies.

    PubMed

    Liao, Guojian; Wu, Qianhua; Feng, Renwei; Guo, Junkang; Wang, Ruigang; Xu, Yingming; Ding, Yongzhen; Fan, Zhilian; Mo, Liangyu

    2016-04-01

    Paddy soils in many regions of China have been seriously polluted by multiple heavy metals or metalloids, such as arsenic (As), cadmium (Cd) and lead (Pb). In order to ensure the safety of food and take full advantage of the limited farmland resources of China, exploring an effective technology to repair contaminated soils is urgent and necessary. In this study, three technologies were employed, including variety screening, water management and foliage dressing, to assess their abilities to reduce the accumulation of Cd and As in the grains of different rice varieties, and meanwhile monitor the related yields. The results of variety screening under insufficient field drying condition showed that the As and Cd contents in the grains of only four varieties [Fengliangyouxiang 1 (P6), Zhongzheyou 8 (P7), Guangliangyou 1128 (P10), Y-liangyou 696 (P11)] did not exceed their individual national standard. P6 gained a relatively high grain yield but accumulated less As and Cd in the grains despite of the relatively high As and Cd concentrations in the rhizosphere soil. However, long-playing field drying in water management trial significantly increased Cd but decreased As content in the grains of all tested three varieties including P6, suggesting an important role of water supply in controlling the accumulation of grain As and Cd. Selenium (Se) showed a stronger ability than silicon (Si) to reduce As and Cd accumulation in the grains of Fengliangyou 4 (P2) and Teyou 524 (P13), and keep the yields. The results of this study suggest that combined application of water management and foliage dressing may be an efficient way to control As and Cd accumulation in the grains of paddy rice exposing to As- and Cd-contaminated soils. PMID:26807822

  6. Mineralization of metsulfuron-methyl in Chinese paddy soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A laboratory study was conducted to investigate the mineralization of metsulfuron-methyl (MSM) in paddy soils in response to soil moisture, temperature and soil properties. The results indicated that MSM mineralization was relatively limited in the paddy soils when soil temperature was low. Only 2.2...

  7. Relationship between Birkeland current regions, particle precipitation, and electric fields

    NASA Technical Reports Server (NTRS)

    De La Beaujardiere, O.; Watermann, J.; Newell, P.; Rich, F.

    1993-01-01

    The relationship of the large-scale dayside Birkeland currents to large-scale particle precipitation patterns, currents, and convection is examined using DMSP and Sondrestrom radar observations. It is found that the local time of the mantle currents is not limited to the longitude of the cusp proper, but covers a larger local time extent. The mantle currents flow entirely on open field lines. About half of region 1 currents flow on open field lines, consistent with the assumption that the region 1 currents are generated by the solar wind dynamo and flow within the surface that separates open and closed field lines. More than 80 percent of the Birkeland current boundaries do not correspond to particle precipitation boundaries. Region 2 currents extend beyond the plasma sheet poleward boundary; region 1 currents flow in part on open field lines; mantle currents and mantle particles are not coincident. On most passes when a triple current sheet is observed, the convection reversal is located on closed field lines.

  8. The Twist and Tilt of Active Region Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Holder, Z. A.; McMullen, R. A.; Canfield, R. C.; Howard, R. F.; Pevtsov, A. A.

    2002-05-01

    We combine two large datasets to study the formation of the overall twist that is present in solar active-region magnetic fields. For purposes of discussion, we adopt a simplified model in which the magnetic flux bundles that form active regions start as axisymmetric toroids, without intrinsic twist, and rise in Ω -shaped loops through the convection zone, acquiring writhe through the effect of the Coriolis force on the large-scale flows within them, as well as buffeting by turbulent convection. The tilt of active regions with respect to the equator is an observable manifestation of such writhe, at photospheric levels. Owing to magnetic helicity conservation, we expect this tilt to be related to twist of the fields of these same regions. Using Mees Solar Observatory active-region vector magnetograms and Mount Wilson Observatory full-disk longitudinal magnetograms, we have measured both the tilt (Mount Wilson) and twist (Mees) of their magnetic fields, on active-region scales. This dataset clearly shows two well-known phenomena, Joy's law and the hemispheric handedness rule. In this paper we present the relationship between twist and tilt and estimate the extent to which that relationship is due to a mutual dependence of tilt and twist on latitude. We then compare our observational results to the simplified model.

  9. Magnetic Fields in the Star Forming Region S88B

    NASA Astrophysics Data System (ADS)

    Sarma, A. P.; Brogan, C. L.; Bourke, T.; Troland, T. H.; Crutcher, R. M.; Myers, P. C.

    2004-12-01

    We present VLA OH Zeeman observations of the star forming region S88B at 1665 and 1667 MHz. We have combined data from the B and C configurations of the VLA, in order to obtain a high resolution map of the magnetic field (4 arcsec resolution). The line-of-sight field is observed to increase from about 100 microG in the southwest to about 300 microG in the northeast. We shall use our results to examine the importance of the magnetic field in providing support to the cloud.

  10. Zoning of the Circumpolar Region after the potential fields character

    NASA Astrophysics Data System (ADS)

    Litvinova, T.; Kashubin, S.; Petrov, O.

    2012-04-01

    Basic digital maps of the magnetic anomaly and gravity fields of Arctic, compiled as a part of the international project [Gaina et al., 2011], were updated in the Russian part of the region in 2010-2011. Zoning of anomalous potential fields in Arctic using updated Russian digital mapping projects was made. Main tasks are: 1 - substantiation of the types and boundaries of geological structures in the Circumpolar Region after the character of magnetic anomaly and gravity fields; 2 - analysis and comparison of the magnetic anomaly and gravity fields within the Arctic Basin and its continental margins in order to reveal similarities in the character of potential fields and tectonic structures. Analysis was performed visually using GIS ESRI ArcMap v.9.3. Previously, all digital materials on anomalous magnetic field and anomalous gravity field were compiled into a single project jointly with auxiliary materials: geological map, map of surface topography and ocean depths, map of sedimentary cover, map of crustal thickness, and fragments of different-scale tectonic maps available for the Circumpolar Region. When delineating areas, the following ranking system (in decreasing order) was accepted: anomalous province, anomalous area, and anomalous district. Anomalous provinces represent the largest areas of anomalous fields, characterized by a common morphostructural plan. Typically, they correspond to global objects, such as continents, oceans or their considerable parts. Anomalous areas within the provinces correspond to major territories with their own specific features (first of all, they differ from each other in amplitude-frequency characteristics and in anomaly configuration), but at the same time preserving main features within the distinguished area. In the tectonic sense, they correspond to regional geological elements such as platforms, oceanic basins, large folded areas, etc. Anomalous districts within anomalous areas correspond to groups of anomalies presumably of the same origin, and therefore have similar characteristics. In the tectonic sense, they correspond to geological objects such as shields, plates, individual fold belts, sedimentary basins, etc. The following features are taken as a basis for anomalous fields typification: field morphostructure, intensity, and anomaly sign. Digital coding of six types of anomalous fields morphostructures and six types of combinations of intensity and anomaly sign is proposed. As a result of this work, an integrated scheme of potential fields zoning in the Circumpolar Arctic linked with the tectonic zoning scheme was created.

  11. Transformation of marine sediment to paddy soil: Primary marine, lacustrine, and land plant lipids

    NASA Astrophysics Data System (ADS)

    Mueller-Niggemann, Cornelia; Cao, Zhihong; Schwark, Lorenz

    2010-05-01

    More than fifty percent of the world's population feeds on rice. The continuous population increase and urban sprawl leads to an ever-increasing demand for new rice cultivation area, in particular China. For centuries suitable coastal areas in China have been exploited for land reclamation, i.e. conversion of coastal marine and lacustrine marshlands into rice paddy fields. Flooded rice paddies are considered one of the major biogenic sources of methane into the atmospheric. Methane is thought to be about 30 times more efficient as greenhouse gas, when compared to carbon dioxide. Overall, rice fields are assumed to contribute app. 10-25% to global CH4 production. It is thus paramount importance to study the effects of increasing rice cultivation and land reclamation in China. For global carbon cycle investigation, it is crucial whether paddy soils, due to their large extent and higher carbon turnover, serve as carbon (CO2) sinks or sources. Here we present results from a chronosequence study of paddy soils with different and well known starting dates of cultivation, in the Zhejiang province (Yangtze River delta) by land reclamation through the building of protective dikes over the past 2000 years. Two end members of natural sediments subjected to land reclamation, a marine tidal mudflat in the Yangtze delta and a coastal lake, represent the substrate on which the paddy soil evolution started. Dike systems were constructed 2000, 1000, 700, 300, 100, and 50 years before present. We are thus able to follow the evolution of rice paddy soils developed on marine sediments using eight well defined tie-points. This chronosequence is then used for assessing the relative proportion of primary marine or lacustrine organic matter preserved in present day soils and to identify the amount and composition of organic matter added since cultivation started. Paddy soil management introduces rice plants debris and exudates as well as rice-associated microbial biomass (covered in a separate contribution) into soils. Management practises involve burning of rice straw on fields, thus adding biomass combustion residues that either may be particularly stable (e.g. PAH) or highly reactive (alkenes resulting from dehydration of alcohols). Bulk parameters reveal that the five field replicates taken at each site are highly compatible, with standard deviations usually between 0.1 to 5.0 % depending on site and/or parameter. This is better than expected and proves that the samples are representative for each cropping site. The n- and isoalkane composition also proved to be very systematic and reproducible. The marine end-member shows a broad n-alkane envelope from nC13 to nC40, with a maximum of nC31 and low abundance of nC17 and nC32+ alkanes. The lacustrine site also reveals a broad n-alkane envelope and a maximum of nC31 but shows higher relative abundance of nC17, nC23 and nC25 alkanes in addition to a C20-HBI. These biomarkers for aquatic macrophytes and diatoms were also found in minor proportions in paddy soils due to flooding with lacustrine water. Paddy n-alkane patterns were dominated by nC29 which systematically increased in abundance for older paddy soils. Paddy soil n-alkane patterns from the chronosequence are similar and related to the marine pattern. Combustion of rice straw on the field is a common management practise for nutrient return to soils. A rice straw ash sample collected in the field revealed a series of nC13 to nC37 n-alkane/alkene doublets with low odd over even predominance. As no alkenes were found in paddy soils, very fast diagenetic conversion of reactive alkenes must occur. Soil organic matter and aliphatics content increased six fold over a cultivation time of 2000 years, identifying paddies as CO2 sinks in the global carbon cycle.

  12. Differential assemblage of functional units in paddy soil microbiomes.

    PubMed

    Kim, Yongkyu; Liesack, Werner

    2015-01-01

    Flooded rice fields are not only a global food source but also a major biogenic source of atmospheric methane. Using metatranscriptomics, we comparatively explored structural and functional succession of paddy soil microbiomes in the oxic surface layer and anoxic bulk soil. Cyanobacteria, Fungi, Xanthomonadales, Myxococcales, and Methylococcales were the most abundant and metabolically active groups in the oxic zone, while Clostridia, Actinobacteria, Geobacter, Anaeromyxobacter, Anaerolineae, and methanogenic archaea dominated the anoxic zone. The protein synthesis potential of these groups was about 75% and 50% of the entire community capacity, respectively. Their structure-function relationships in microbiome succession were revealed by classifying the protein-coding transcripts into core, non-core, and taxon-specific transcripts based on homologous gene distribution. The differential expression of core transcripts between the two microbiomes indicated that structural succession is primarily governed by the cellular ability to adapt to the given oxygen condition, involving oxidative stress, nitrogen/phosphorus metabolism, and fermentation. By contrast, the non-core transcripts were expressed from genes involved in the metabolism of various carbon sources. Among those, taxon-specific transcripts revealed highly specialized roles of the dominant groups in community-wide functioning. For instance, taxon-specific transcripts involved in photosynthesis and methane oxidation were a characteristic of the oxic zone, while those related to methane production and aromatic compound degradation were specific to the anoxic zone. Degradation of organic matters, antibiotics resistance, and secondary metabolite production were detected to be expressed in both the oxic and anoxic zones, but by different taxonomic groups. Cross-feeding of methanol between members of the Methylococcales and Xanthomonadales was suggested by the observation that in the oxic zone, they both exclusively expressed homologous genes encoding methanol dehydrogenase. Our metatranscriptomic analysis suggests that paddy soil microbiomes act as complex, functionally coordinated assemblages whose taxonomic composition is governed by the prevailing habitat factors and their hierarchical importance for community succession. PMID:25898319

  13. Differential Assemblage of Functional Units in Paddy Soil Microbiomes

    PubMed Central

    Kim, Yongkyu; Liesack, Werner

    2015-01-01

    Flooded rice fields are not only a global food source but also a major biogenic source of atmospheric methane. Using metatranscriptomics, we comparatively explored structural and functional succession of paddy soil microbiomes in the oxic surface layer and anoxic bulk soil. Cyanobacteria, Fungi, Xanthomonadales, Myxococcales, and Methylococcales were the most abundant and metabolically active groups in the oxic zone, while Clostridia, Actinobacteria, Geobacter, Anaeromyxobacter, Anaerolineae, and methanogenic archaea dominated the anoxic zone. The protein synthesis potential of these groups was about 75% and 50% of the entire community capacity, respectively. Their structure-function relationships in microbiome succession were revealed by classifying the protein-coding transcripts into core, non-core, and taxon-specific transcripts based on homologous gene distribution. The differential expression of core transcripts between the two microbiomes indicated that structural succession is primarily governed by the cellular ability to adapt to the given oxygen condition, involving oxidative stress, nitrogen/phosphorus metabolism, and fermentation. By contrast, the non-core transcripts were expressed from genes involved in the metabolism of various carbon sources. Among those, taxon-specific transcripts revealed highly specialized roles of the dominant groups in community-wide functioning. For instance, taxon-specific transcripts involved in photosynthesis and methane oxidation were a characteristic of the oxic zone, while those related to methane production and aromatic compound degradation were specific to the anoxic zone. Degradation of organic matters, antibiotics resistance, and secondary metabolite production were detected to be expressed in both the oxic and anoxic zones, but by different taxonomic groups. Cross-feeding of methanol between members of the Methylococcales and Xanthomonadales was suggested by the observation that in the oxic zone, they both exclusively expressed homologous genes encoding methanol dehydrogenase. Our metatranscriptomic analysis suggests that paddy soil microbiomes act as complex, functionally coordinated assemblages whose taxonomic composition is governed by the prevailing habitat factors and their hierarchical importance for community succession. PMID:25898319

  14. Magnetic Field Modeling of Complex, Flare Productive Active Regions

    NASA Astrophysics Data System (ADS)

    Millholland, S. C.; Savcheva, A. S.; DeLuca, E. E.

    2014-12-01

    We present models and analysis of the magnetic field structure of three sigmoidal active regions (ARs). Sigmoids, forward or backward S-shaped EUV and X-ray emissions in the corona, are relevant as predictors of eruptive events such as flares and Coronal Mass Ejections. The regions were modeled using the Flux Rope Insertion Method, in which flux ropes, held in equilibrium by an overlying potential arcade, represent the sigmoids. The flux rope paths were inserted into a potential field following the filaments observed in 304. The models were then relaxed into a nonlinear force free (NLFFF) state using a magnetofrictional relaxation process. The first region studied is NOAA AR 12017, which produced an X1.0 flare at 2014/03/29 17:35. The second is NOAA AR 11283, which erupted with an X2.1 flare at 2011/09/06 22:12. For these regions, we show detailed comparisons of Quasi-Separatrix Layer (QSL) maps and observed flare ribbons. The slow evolution of an unstable solution at the time of the eruption produces a set of QSL solutions. Comparison of the photospheric mapping of the QSL with the flare ribbons will be a good measure of how well we have captured the magnetic structure of the particle acceleration region with our simple NLFFF models. The third is NOAA AR 11093. This region was a double decker filament composed of two branches over the same polarity inversion line. At 2010/08/07 17:55, the upper filament erupted with an M1.0 flare. This is the first time a double decker flux rope region has been modeled using these techniques. We show the interaction of the two inserted flux ropes and the evolution of the region through a series of NLFFF solutions to the evolving photospheric magnetic field. This work has been funded by the NSF-REU solar physics program at Smithsonian Astrophysical Observatory, grant number AGS-1263241.

  15. Positron extraction to an electromagnetic field free region

    NASA Astrophysics Data System (ADS)

    Cooke, D. A.; Barandun, G.; Vergani, S.; Brown, B.; Rubbia, A.; Crivelli, P.

    2016-01-01

    We describe a scheme for high efficiency (? 90%) extraction of 50 ns positron bunches from a buffer gas trap in an electromagnetic field free region. The positrons are time bunched to approximately 1 ns (FWHM) and focussed to less than 1 mm (?). The target is kept at ground potential which is an advantage for many applications. The results compare well with SIMION simulations.

  16. REGIONAL AIR POLLUTION STUDY: LAMBERT FIELD GRAPHICAL WEATHER SUMMARY

    EPA Science Inventory

    A graphical summary of National Weather Service (NWS) 3-hour weather observations from Lambert Field Airport, St. Louis, Missouri has been prepared for use by individuals involved in the analysis and application of Regional Air Pollution Study (RAPS) data. It is intended as a ref...

  17. Identification and isolation of active N2O reducers in rice paddy soil.

    PubMed

    Ishii, Satoshi; Ohno, Hiroki; Tsuboi, Masahiro; Otsuka, Shigeto; Senoo, Keishi

    2011-12-01

    Dissolved N(2)O is occasionally detected in surface and ground water in rice paddy fields, whereas little or no N(2)O is emitted to the atmosphere above these fields. This indicates the occurrence of N(2)O reduction in rice paddy fields; however, identity of the N(2)O reducers is largely unknown. In this study, we employed both culture-dependent and culture-independent approaches to identify N(2)O reducers in rice paddy soil. In a soil microcosm, N(2)O and succinate were added as the electron acceptor and donor, respectively, for N(2)O reduction. For the stable isotope probing (SIP) experiment, (13)C-labeled succinate was used to identify succinate-assimilating microbes under N(2)O-reducing conditions. DNA was extracted 24 ?h after incubation, and heavy and light DNA fractions were separated by density gradient ultracentrifugation. Denaturing gradient gel electrophoresis and clone library analysis targeting the 16S rRNA and the N(2)O reductase gene were performed. For culture-dependent analysis, the microbes that elongated under N(2)O-reducing conditions in the presence of cell-division inhibitors were individually captured by a micromanipulator and transferred to a low-nutrient medium. The N(2)O-reducing ability of these strains was examined by gas chromatography/mass spectrometry. Results of the SIP analysis suggested that Burkholderiales and Rhodospirillales bacteria dominated the population under N(2)O-reducing conditions, in contrast to the control sample (soil incubated with only (13)C-succinate). Results of the single-cell isolation technique also indicated that the majority of the N(2)O-reducing strains belonged to the genera Herbaspirillum (Burkholderiales) and Azospirillum (Rhodospirillales). In addition, Herbaspirillum strains reduced N(2)O faster than Azospirillum strains. These results suggest that Herbaspirillum spp. may have an important role in N(2)O reduction in rice paddy soils. PMID:21677691

  18. Current helicity and magnetic field anisotropy in solar active regions

    NASA Astrophysics Data System (ADS)

    Xu, H.; Stepanov, R.; Kuzanyan, K.; Sokoloff, D.; Zhang, H.; Gao, Y.

    2015-12-01

    The electric current helicity density ? =< ? _{ijk}b_i{partial b_k/partial x_j}rangle contains six terms, where bi are components of the magnetic field. Due to the observational limitations, only four of the above six terms can be inferred from solar photospheric vector magnetograms. By comparing the results for simulation we distinguished the statistical difference of above six terms for isotropic and anisotropic cases. We estimated the relative degree of anisotropy for three typical active regions and found that it is of order 0.8 which means the assumption of local isotropy for the observable current helicity density terms is generally not satisfied for solar active regions. Upon studies of the statistical properties of the anisotropy of magnetic field of solar active regions with latitudes and with evolution in the solar cycle, we conclude that the consistency of that assumption of local homogeneity and isotropy requires further analysis in the light of our findings.

  19. The Spatial Region of Photoionization in a Strong Laser Field

    NASA Astrophysics Data System (ADS)

    Bauer, J. H.

    2008-10-01

    In the framework of the Keldysh-Faisal-Reiss theory in the velocity gauge we investigate the magnitude of the space region, where photoionization in a strong laser field takes place. We find substantial differences between the short-range and the long-range (Coulomb) potentials, and between linear and circular polarizations of incident radiation. It appears that only for the initial state in the Coulomb potential the region of space, where ionization is held, expands significantly with increasing intensity for a typical optical frequency and non-relativistic but strong circularly polarized laser field. As a result of our considerations, we suggest to modify the idea of Reiss and Krainov of a certain simple Coulomb correction to the Volkov wave function. We show that photoionization rate calculated for the H(1s) atom, using our approach, is in better agreement with other theoretical results for moderately strong circularly polarized laser field.

  20. Sources of atmospheric methane - Measurements in rice paddies and a discussion

    NASA Technical Reports Server (NTRS)

    Cicerone, R. J.; Shetter, J. D.

    1981-01-01

    Field measurements of methane fluxes from rice paddies, fresh water lakes, and saltwater marshes have been made to infer estimates of the size of these sources of atmospheric methane. The rice-paddy measurements, the first of their kind, show that the principal means of methane escape is through the plants themselves as opposed to transport across the water-air interface via bubbles or molecular diffusion. Nitrogen-fertilized plants release much more methane than unfertilized plants but even these measured rates are only one fourth as large as those inferred earlier by Koyama (1963, 1964) and on which all global extrapolations have been based to date. Measured methane fluxes from lakes and marshes are also compared to similar earlier data and it is found that extant data and flux-measurement methods are insufficient for reliable global extrapolations.

  1. Differential contributions of ammonia oxidizers and nitrite oxidizers to nitrification in four paddy soils.

    PubMed

    Wang, Baozhan; Zhao, Jun; Guo, Zhiying; Ma, Jing; Xu, Hua; Jia, Zhongjun

    2015-05-01

    Rice paddy fields are characterized by regular flooding and nitrogen fertilization, but the functional importance of aerobic ammonia oxidizers and nitrite oxidizers under unique agricultural management is poorly understood. In this study, we report the differential contributions of ammonia-oxidizing archaea (AOA), bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to nitrification in four paddy soils from different geographic regions (Zi-Yang (ZY), Jiang-Du (JD), Lei-Zhou (LZ) and Jia-Xing (JX)) that are representative of the rice ecosystems in China. In urea-amended microcosms, nitrification activity varied greatly with 11.9, 9.46, 3.03 and 1.43??g NO3(-)-N?g(-1) dry weight of soil per day in the ZY, JD, LZ and JX soils, respectively, over the course of a 56-day incubation period. Real-time quantitative PCR of amoA genes and pyrosequencing of 16S rRNA genes revealed significant increases in the AOA population to various extents, suggesting that their relative contributions to ammonia oxidation activity decreased from ZY to JD to LZ. The opposite trend was observed for AOB, and the JX soil stimulated only the AOB populations. DNA-based stable-isotope probing further demonstrated that active AOA numerically outcompeted their bacterial counterparts by 37.0-, 10.5- and 1.91-fold in (13)C-DNA from ZY, JD and LZ soils, respectively, whereas AOB, but not AOA, were labeled in the JX soil during active nitrification. NOB were labeled to a much greater extent than AOA and AOB, and the addition of acetylene completely abolished the assimilation of (13)CO2 by nitrifying populations. Phylogenetic analysis suggested that archaeal ammonia oxidation was predominantly catalyzed by soil fosmid 29i4-related AOA within the soil group 1.1b lineage. Nitrosospira cluster 3-like AOB performed most bacterial ammonia oxidation in the ZY, LZ and JX soils, whereas the majority of the (13)C-AOB in the JD soil was affiliated with the Nitrosomona communis lineage. The (13)C-NOB was overwhelmingly dominated by Nitrospira rather than Nitrobacter. A significant correlation was observed between the active AOA/AOB ratio and the soil oxidation capacity, implying a greater advantage of AOA over AOB under microaerophilic conditions. These results suggest the important roles of soil physiochemical properties in determining the activities of ammonia oxidizers and nitrite oxidizers. PMID:25303715

  2. Differential contributions of ammonia oxidizers and nitrite oxidizers to nitrification in four paddy soils

    PubMed Central

    Wang, Baozhan; Zhao, Jun; Guo, Zhiying; Ma, Jing; Xu, Hua; Jia, Zhongjun

    2015-01-01

    Rice paddy fields are characterized by regular flooding and nitrogen fertilization, but the functional importance of aerobic ammonia oxidizers and nitrite oxidizers under unique agricultural management is poorly understood. In this study, we report the differential contributions of ammonia-oxidizing archaea (AOA), bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to nitrification in four paddy soils from different geographic regions (Zi-Yang (ZY), Jiang-Du (JD), Lei-Zhou (LZ) and Jia-Xing (JX)) that are representative of the rice ecosystems in China. In urea-amended microcosms, nitrification activity varied greatly with 11.9, 9.46, 3.03 and 1.43 μg NO3−-N g−1 dry weight of soil per day in the ZY, JD, LZ and JX soils, respectively, over the course of a 56-day incubation period. Real-time quantitative PCR of amoA genes and pyrosequencing of 16S rRNA genes revealed significant increases in the AOA population to various extents, suggesting that their relative contributions to ammonia oxidation activity decreased from ZY to JD to LZ. The opposite trend was observed for AOB, and the JX soil stimulated only the AOB populations. DNA-based stable-isotope probing further demonstrated that active AOA numerically outcompeted their bacterial counterparts by 37.0-, 10.5- and 1.91-fold in 13C-DNA from ZY, JD and LZ soils, respectively, whereas AOB, but not AOA, were labeled in the JX soil during active nitrification. NOB were labeled to a much greater extent than AOA and AOB, and the addition of acetylene completely abolished the assimilation of 13CO2 by nitrifying populations. Phylogenetic analysis suggested that archaeal ammonia oxidation was predominantly catalyzed by soil fosmid 29i4-related AOA within the soil group 1.1b lineage. Nitrosospira cluster 3-like AOB performed most bacterial ammonia oxidation in the ZY, LZ and JX soils, whereas the majority of the 13C-AOB in the JD soil was affiliated with the Nitrosomona communis lineage. The 13C-NOB was overwhelmingly dominated by Nitrospira rather than Nitrobacter. A significant correlation was observed between the active AOA/AOB ratio and the soil oxidation capacity, implying a greater advantage of AOA over AOB under microaerophilic conditions. These results suggest the important roles of soil physiochemical properties in determining the activities of ammonia oxidizers and nitrite oxidizers. PMID:25303715

  3. Efficacy of Aquatain, a Monomolecular Film, for the Control of Malaria Vectors in Rice Paddies

    PubMed Central

    Bukhari, Tullu; Takken, Willem; Githeko, Andrew K.; Koenraadt, Constantianus J. M.

    2011-01-01

    Background Rice paddies harbour a large variety of organisms including larvae of malaria mosquitoes. These paddies are challenging for mosquito control because their large size, slurry and vegetation make it difficult to effectively apply a control agent. Aquatain, a monomolecular surface film, can be considered a suitable mosquito control agent for such breeding habitats due to its physical properties. The properties allow Aquatain to self-spread over a water surface and affect multiple stages of the mosquito life cycle. Methodology/Principal Findings A trial based on a pre-test/post-test control group design evaluated the potential of Aquatain as a mosquito control agent at Ahero rice irrigation scheme in Kenya. After Aquatain application at a dose of 2 ml/m2 on rice paddies, early stage anopheline larvae were reduced by 36%, and late stage anopheline larvae by 16%. However, even at a lower dose of 1 ml/m2 there was a 93.2% reduction in emergence of anopheline adults and 69.5% reduction in emergence of culicine adults. No pupation was observed in treated buckets that were part of a field bio-assay carried out parallel to the trial. Aquatain application saved nearly 1.7 L of water in six days from a water surface of 0.2 m2 under field conditions. Aquatain had no negative effect on rice plants as well as on a variety of non-target organisms, except backswimmers. Conclusions/Significance We demonstrated that Aquatain is an effective agent for the control of anopheline and culicine mosquitoes in irrigated rice paddies. The agent reduced densities of aquatic larval stages and, more importantly, strongly impacted the emergence of adult mosquitoes. Aquatain also reduced water loss due to evaporation. No negative impacts were found on either abundance of non-target organisms, or growth and development of rice plants. Aquatain, therefore, appears a suitable mosquito control tool for use in rice agro-ecosystems. PMID:21738774

  4. Chromospheric magnetic fields of an active region filament

    NASA Astrophysics Data System (ADS)

    Xu, Z.; Solanki, S.; Lagg, A.

    2012-06-01

    Vector magnetic fields of an active region filament are co-spatially and co-temporally mapped in photosphere and upper chromosphere, by using spectro-polarimetric observations made by Tenerife Infrared Polarimeter (TIP II) at the German Vacuum Tower Telescope (VTT). A Zeeman-based ME inversion is performed on the full Stokes vectors of both the photospheric Si I 1082.7 nm and the chromospheric He I 1083.0 nm lines. We found that the strong magnetic fields, with the field strength of 600 - 800 G in the He I line formation height, are not uncommon among AR filaments. But such strong magnetic field is not always found in AR filaments.

  5. Regional United States electric field and GIC hazard impacts (Invited)

    NASA Astrophysics Data System (ADS)

    Gannon, J. L.; Balch, C. C.; Trichtchenko, L.

    2013-12-01

    Geomagnetically Induced Currents (GICs) are primarily driven by impulsive geomagnetic disturbances created by the interaction between the Earth's magnetosphere and sharp velocity, density, and magnetic field enhancements in the solar wind. However, the magnitude of the induced electric field response at the ground level, and therefore the resulting hazard to the bulk power system, is determined not only by magnetic drivers, but also by the underlying geology. Convolution techniques are used to calculate surface electric fields beginning from the spectral characteristics of magnetic field drivers and the frequency response of the local geology. Using these techniques, we describe historical scenarios for regions across the United States, and the potential impact of large events on electric power infrastructure.

  6. Observed pre flare characteristics of active region magnetic fields

    NASA Astrophysics Data System (ADS)

    Yurchyshyn, V.

    I will present data and results on observations of flare-related magnetic conditions in solar active regions The following topics will be discussed Static non-potential magnetic characteristics before flares such as magnetic gradients shear and twist 2 spatio-temporal dynamics of the photospheric magnetic flux such as flows and flux emergence 3 evolution of magnetic structures leading to and following flares A special attention will be payed to new approaches to quantify complexity of the photospheric magnetic fields in terms of intermittency magnetic power spectra and probability distribution functions Discovered correlation between the parameters and the flare activity in active regions provides new insights into understanding of the nature of magnetic coupling between the sub-photospheric layers where the magnetic field is generated and the corona where eruptions occur

  7. Chiral Effective Field Theory in the $\\Delta$-resonance region

    SciTech Connect

    Vladimir Pascalutsa

    2006-09-18

    I discuss the problem of constructing an effective low-energy theory in the vicinity of a resonance or a bound state. The focus is on the example of the $\\Delta(1232)$, the lightest resonance in the nucleon sector. Recent developments of the chiral effective-field theory in the $\\Delta$-resonance region are briefly reviewed. I conclude with a comment on the merits of the manifestly covariant formulation of chiral EFT in the baryon sector.

  8. Ground cover rice production system facilitates soil carbon and nitrogen stocks at regional scale

    NASA Astrophysics Data System (ADS)

    Liu, M.; Dannenmann, M.; Lin, S.; Saiz, G.; Yan, G.; Yao, Z.; Pelster, D.; Tao, H.; Sippel, S.; Tao, Y.; Zhang, Y.; Zheng, X.; Zuo, Q.; Butterbach-Bahl, K.

    2015-02-01

    Rice production is increasingly challenged by irrigation water scarcity, however covering paddy rice soils with films (ground cover rice production system: GCRPS) can significantly reduce water demand as well as overcome temperature limitations at the beginning of the vegetation period resulting in increased grain yields in colder regions of rice production with seasonal water shortages. It has been speculated that the increased soil aeration and temperature under GCRPS may result in losses of soil organic carbon and nitrogen stocks. Here we report on a regional scale experiment, conducted by sampling paired adjacent Paddy and GCRPS fields at 49 representative sites in the Shiyan region, which is typical for many mountainous areas across China. Parameters evaluated included soil C and N stocks, soil physical and chemical properties, potential carbon mineralization rates, fractions of soil organic carbon and stable carbon isotopic composition of plant leaves. Furthermore, root biomass was quantified at maximum tillering stage at one of our paired sites. Against expectations the study showed that: (1) GCRPS significantly increased soil organic C and N stocks 5-20 years following conversion of production systems, (2) there were no differences between GCRPS and Paddy in soil physical and chemical properties for the various soil depths with the exception of soil bulk density, (3) GCRPS had lower mineralization potential for soil organic C compared with Paddy over the incubation period, (4) GCRPS showed lower ?15N in the soils and plant leafs indicating less NH3 volatilization in GCRPS than in Paddy; and (5) GCRPS increased yields and root biomass in all soil layers down to 40 cm depth. Our results suggest that GCRPS is an innovative rice production technique that not only increases yields using less irrigation water, but that it also is environmentally beneficial due to increased soil C and N stocks at regional scale.

  9. Effects of soil spatial resolution on quantifying CH4 and N2O emissions from rice fields in the Tai Lake region of China by DNDC model

    NASA Astrophysics Data System (ADS)

    Yu, D. S.; Yang, H.; Shi, X. Z.; Warner, E. D.; Zhang, L. M.; Zhao, Q. G.

    2011-06-01

    Fourteen grid data sets of different cell resolutions were generated, from 0.5 × 0.5 km to 64 × 64 km, to estimate CH4 and N2O emissions from paddy soils in the Tai Lake region of China using the Denitrification-Decomposition (DNDC) model. The grids were derived from a polygon-based data set (1:50,000 digital soil map/database), which was the most detailed soil database for the region. Comparison of simulated CH4 and N2O concentrations from input of the 14 grid data sets with the original polygon data demonstrated (1) no distinct variability (relative errors <5%) of the results when grid data sets of cell size ≤2 km were used as input for the DNDC model; (2) slight variability (<10%) in the results when grid data sets with cell size in the range of 2 to 8 km were used as input; and (3) distinct variability (>10%) in the results when grid data sets with cell size of >8 km were applied as input. A grid data set with a cell size of 8 km was found to be optimal based on accuracy and computational efficiency of DNDC simulations. The results can be used as a guideline for optimizing field sampling strategies for locations where there is a lack of or insufficient soil data, whereby soil data can be collected through sampling in cell centers of designed grid frames.

  10. Locating source regions of precursory seismo-electric fields and the mechanism generating electric field variations

    NASA Astrophysics Data System (ADS)

    Takahashi, Kozo; Fujinawa, Yukio

    1993-04-01

    Electrodes consisting of a steel pipe in a deep borehole and a grounded wire surrounding the borehole were constructed to measure vertical electric fields, whereas conventional electrodes measure horizontal fields. Three years of monitoring showed that the anomalous variations in vertical underground electric fields preceding earthquakes and volcanic eruptions are much clearer than the variations in horizontal fields. The data also showed that there is much less man-made noise in the vertical fields. To determine whether these observed anomalies are forerunners of seismic disturbance, a system developed to locate precisely the source regions of underground vertical electric fields or volcanic tremors has been continuously operated. The system uses three or more time lags calculated by cross-correlating the electric fields or volcanic tremors recorded at four, or more, monitoring stations. If this system reveals the intensity distributions of the sources, prediction of imminent earthquakes and volcanic eruptions will become possible. To explain the mechanisms by which precursory electric field variations are generated, a model is proposed in which the electric field variations are generated by Earth current variations caused by increased electric conductivity in source regions before an earthquake. The conductivity is increased by free electrons and positive holes created on the fresh fracture surfaces caused by microcracks that occur before rock failure in the Earth's crust. The model can explain precursory electrical phenomena which are observed not only in the field before an earthquake but also in the laboratory before rock failure.

  11. Phase unwrapping using region-based markov random field model.

    PubMed

    Dong, Ying; Ji, Jim

    2010-01-01

    Phase unwrapping is a classical problem in Magnetic Resonance Imaging (MRI), Interferometric Synthetic Aperture Radar and Sonar (InSAR/InSAS), fringe pattern analysis, and spectroscopy. Although many methods have been proposed to address this problem, robust and effective phase unwrapping remains a challenge. This paper presents a novel phase unwrapping method using a region-based Markov Random Field (MRF) model. Specifically, the phase image is segmented into regions within which the phase is not wrapped. Then, the phase image is unwrapped between different regions using an improved Highest Confidence First (HCF) algorithm to optimize the MRF model. The proposed method has desirable theoretical properties as well as an efficient implementation. Simulations and experimental results on MRI images show that the proposed method provides similar or improved phase unwrapping than Phase Unwrapping MAx-flow/min-cut (PUMA) method and ZpM method. PMID:21096819

  12. A Simple Evaluation of Soil Quality of Waterlogged Purple Paddy Soils with Different Productivities

    PubMed Central

    Liu, Zhanjun; Zhou, Wei; Lv, Jialong; He, Ping; Liang, Guoqing; Jin, Hui

    2015-01-01

    Evaluation of soil quality can be crucial for designing efficient farming systems and ensuring sustainable agriculture. The present study aimed at evaluating the quality of waterlogged purple paddy soils with different productivities in Sichuan Basin. The approach involved comprehensive analyses of soil physical and chemical properties, as well as enzyme activities and microbial community structure measured by phospholipid fatty acid analysis (PLFA). A total of 36 soil samples were collected from four typical locations, with 12 samples representing high productivity purple paddy soil (HPPS), medium productivity purple paddy soil (MPPS) and low productivity purple paddy soil (LPPS), respectively. Most measured soil properties showed significant differences (P ≤ 0.05) among HPPS, MPPS and LPPS. Pearson correlation analysis and principal component analysis were used to identify appropriate soil quality indicators. A minimum data set (MDS) including total nitrogen (TN), available phosphorus (AP), acid phosphatase (ACP), total bacteria (TB) and arbuscular mycorrhizal fungi was established and accounted for 82.1% of the quality variation among soils. A soil quality index (SQI) was developed based on the MDS method, whilst HPPS, MPPS and LPPS received mean SQI scores of 0.725, 0.536 and 0.425, respectively, with a ranking of HPPS > MPPS > LPPS. HPPS showed relatively good soil quality characterized by optimal nutrient availability, enzymatic and microbial activities, but the opposite was true of LPPS. Low levels of TN, AP and soil microbial activities were considered to be the major constraints limiting the productivity in LPPS. All soil samples collected were rich in available N, K, Si and Zn, but deficient in available P, which may be the major constraint for the studied regions. Managers in our study area should employ more appropriate management in the LPPS to improve its rice productivity, and particularly to any potential limiting factor. PMID:25997107

  13. Dynamic nuclear polarization in the hyperfine-field-dominant region

    NASA Astrophysics Data System (ADS)

    Lee, Seong-Joo; Shim, Jeong Hyun; Kim, Kiwoong; Yu, Kwon Kyu; Hwang, Seong-min

    2015-06-01

    Dynamic nuclear polarization (DNP) allows measuring enhanced nuclear magnetic resonance (NMR) signals. Though the efficiency of DNP has been known to increase at low fields, the usefulness of DNP has not been throughly investigated yet. Here, using a superconducting quantum interference device-based NMR system, we performed a series of DNP experiments with a nitroxide radical and measured DNP spectra at several magnetic fields down to sub-microtesla. In the DNP spectra, the large overlap of two peaks having opposite signs results in net enhancement factors, which are significantly lower than theoretical expectations [30] and nearly invariant with respect to magnetic fields below the Earth's field. The numerical analysis based on the radical's Hamiltonian provides qualitative explanations of such features. The net enhancement factor reached 325 at maximum experimentally, but our analysis reveals that the local enhancement factor at the center of the rf coil is 575, which is unaffected by detection schemes. We conclude that DNP in the hyperfine-field-dominant region yields sufficiently enhanced NMR signals at magnetic fields above 1 μ T.

  14. Dynamic nuclear polarization in the hyperfine-field-dominant region.

    PubMed

    Lee, Seong-Joo; Shim, Jeong Hyun; Kim, Kiwoong; Yu, Kwon Kyu; Hwang, Seong-min

    2015-06-01

    Dynamic nuclear polarization (DNP) allows measuring enhanced nuclear magnetic resonance (NMR) signals. Though the efficiency of DNP has been known to increase at low fields, the usefulness of DNP has not been throughly investigated yet. Here, using a superconducting quantum interference device-based NMR system, we performed a series of DNP experiments with a nitroxide radical and measured DNP spectra at several magnetic fields down to sub-microtesla. In the DNP spectra, the large overlap of two peaks having opposite signs results in net enhancement factors, which are significantly lower than theoretical expectations and nearly invariant with respect to magnetic fields below the Earth's field. The numerical analysis based on the radical's Hamiltonian provides qualitative explanations of such features. The net enhancement factor reached 325 at maximum experimentally, but our analysis reveals that the local enhancement factor at the center of the rf coil is 575, which is unaffected by detection schemes. We conclude that DNP in the hyperfine-field-dominant region yields sufficiently enhanced NMR signals at magnetic fields above 1 ?T. PMID:25955437

  15. E region electric field dependence of the solar activity

    NASA Astrophysics Data System (ADS)

    Denardini, C. M.; Moro, J.; Resende, L. C. A.; Chen, S. S.; Schuch, N. J.; Costa, J. E. R.

    2015-10-01

    We have being studying the zonal and vertical E region electric field components inferred from the Doppler shifts of type 2 echoes (gradient drift irregularities) detected with the 50 MHz backscatter coherent radar set at São Luis, Brazil (SLZ, 2.3°S, 44.2°W) during the solar cycle 24. In this report we present the dependence of the vertical and zonal components of this electric field with the solar activity, based on the solar flux F10.7. For this study we consider the geomagnetically quiet days only (Kp ≤ 3+). A magnetic field-aligned-integrated conductivity model was developed for proving the conductivities, using the IRI-2007, the MISIS-2000, and the IGRF-11 models as input parameters for ionosphere, neutral atmosphere, and Earth magnetic field, respectively. The ion-neutron collision frequencies of all the species are combined through the momentum transfer collision frequency equation. The mean zonal component of the electric field, which normally ranged from 0.19 to 0.35 mV/m between the 8 and 18 h (LT) in the Brazilian sector, show a small dependency with the solar activity. Whereas the mean vertical component of the electric field, which normally ranges from 4.65 to 10.12 mV/m, highlights the more pronounced dependency of the solar flux.

  16. Soil physicochemical and biological properties of paddy-upland rotation: a review.

    PubMed

    Zhou, Wei; Lv, Teng-Fei; Chen, Yong; Westby, Anthony P; Ren, Wan-Jun

    2014-01-01

    Paddy-upland rotation is an unavoidable cropping system for Asia to meet the increasing demand for food. The reduction in grain yields has increased the research interest on the soil properties of rice-based cropping systems. Paddy-upland rotation fields are unique from other wetland or upland soils, because they are associated with frequent cycling between wetting and drying under anaerobic and aerobic conditions; such rotations affect the soil C and N cycles, make the chemical speciation and biological effectiveness of soil nutrient elements varied with seasons, increase the diversity of soil organisms, and make the soil physical properties more difficult to analyze. Consequently, maintaining or improving soil quality at a desirable level has become a complicated issue. Therefore, fully understanding the soil characteristics of paddy-upland rotation is necessary for the sustainable development of the system. In this paper, we offer helpful insight into the effect of rice-upland combinations on the soil chemical, physical, and biological properties, which could provide guidance for reasonable cultivation management measures and contribute to the improvement of soil quality and crop yield. PMID:24995366

  17. Microbial community analysis in rice paddy soils irrigated by acid mine drainage contaminated water.

    PubMed

    Sun, Min; Xiao, Tangfu; Ning, Zengping; Xiao, Enzong; Sun, Weimin

    2015-03-01

    Five rice paddy soils located in southwest China were selected for geochemical and microbial community analysis. These rice fields were irrigated with river water which was contaminated by Fe-S-rich acid mine drainage. Microbial communities were characterized by high-throughput sequencing, which showed 39 different phyla/groups in these samples. Among these phyla/groups, Proteobacteria was the most abundant phylum in all samples. Chloroflexi, Acidobacteria, Nitrospirae, and Bacteroidetes exhibited higher relative abundances than other phyla. A number of rare and candidate phyla were also detected. Moreover, canonical correspondence analysis suggested that pH, sulfate, and nitrate were significant factors that shaped the microbial community structure. In addition, a wide diversity of Fe- and S-related bacteria, such as GOUTA19, Shewanella, Geobacter, Desulfobacca, Thiobacillus, Desulfobacterium, and Anaeromyxobacter, might be responsible for biogeochemical Fe and S cycles in the tested rice paddy soils. Among the dominant genera, GOUTA19 and Shewanella were seldom detected in rice paddy soils. PMID:25408313

  18. Abundance, composition and activity of denitrifier communities in metal polluted paddy soils

    PubMed Central

    Liu, Yuan; Liu, Yongzhuo; Zhou, Huimin; Li, Lianqing; Zheng, Jinwei; Zhang, Xuhui; Zheng, Jufeng; Pan, Genxing

    2016-01-01

    Denitrification is one of the most important soil microbial processes leading to the production of nitrous oxide (N2O). The potential changes with metal pollution in soil microbial community for N2O production and reduction are not well addressed. In this study, topsoil samples were collected both from polluted and non-polluted rice paddy fields and denitrifier communities were characterized with molecular fingerprinting procedures. All the retrieved nirK sequences could be grouped into neither α- nor β- proteobacteria, while most of the nosZ sequences were affiliated with α-proteobacteria. The abundances of the nirK and nosZ genes were reduced significantly in the two polluted soils. Thus, metal pollution markedly affected composition of both nirK and nosZ denitrifiers. While the total denitrifying activity and N2O production rate were both reduced under heavy metal pollution of the two sites, the N2O reduction rate showed no significant change. These findings suggest that N2O production activity could be sensitive to heavy metal pollution, which could potentially lead to a decrease in N2O emission in polluted paddies. Therefore, metal pollution could have potential impacts on soil N transformation and thus on N2O emission from paddy soils. PMID:26739424

  19. Abundance, composition and activity of denitrifier communities in metal polluted paddy soils.

    PubMed

    Liu, Yuan; Liu, Yongzhuo; Zhou, Huimin; Li, Lianqing; Zheng, Jinwei; Zhang, Xuhui; Zheng, Jufeng; Pan, Genxing

    2016-01-01

    Denitrification is one of the most important soil microbial processes leading to the production of nitrous oxide (N2O). The potential changes with metal pollution in soil microbial community for N2O production and reduction are not well addressed. In this study, topsoil samples were collected both from polluted and non-polluted rice paddy fields and denitrifier communities were characterized with molecular fingerprinting procedures. All the retrieved nirK sequences could be grouped into neither ?- nor ?- proteobacteria, while most of the nosZ sequences were affiliated with ?-proteobacteria. The abundances of the nirK and nosZ genes were reduced significantly in the two polluted soils. Thus, metal pollution markedly affected composition of both nirK and nosZ denitrifiers. While the total denitrifying activity and N2O production rate were both reduced under heavy metal pollution of the two sites, the N2O reduction rate showed no significant change. These findings suggest that N2O production activity could be sensitive to heavy metal pollution, which could potentially lead to a decrease in N2O emission in polluted paddies. Therefore, metal pollution could have potential impacts on soil N transformation and thus on N2O emission from paddy soils. PMID:26739424

  20. Abundance, composition and activity of denitrifier communities in metal polluted paddy soils

    NASA Astrophysics Data System (ADS)

    Liu, Yuan; Liu, Yongzhuo; Zhou, Huimin; Li, Lianqing; Zheng, Jinwei; Zhang, Xuhui; Zheng, Jufeng; Pan, Genxing

    2016-01-01

    Denitrification is one of the most important soil microbial processes leading to the production of nitrous oxide (N2O). The potential changes with metal pollution in soil microbial community for N2O production and reduction are not well addressed. In this study, topsoil samples were collected both from polluted and non-polluted rice paddy fields and denitrifier communities were characterized with molecular fingerprinting procedures. All the retrieved nirK sequences could be grouped into neither α- nor β- proteobacteria, while most of the nosZ sequences were affiliated with α-proteobacteria. The abundances of the nirK and nosZ genes were reduced significantly in the two polluted soils. Thus, metal pollution markedly affected composition of both nirK and nosZ denitrifiers. While the total denitrifying activity and N2O production rate were both reduced under heavy metal pollution of the two sites, the N2O reduction rate showed no significant change. These findings suggest that N2O production activity could be sensitive to heavy metal pollution, which could potentially lead to a decrease in N2O emission in polluted paddies. Therefore, metal pollution could have potential impacts on soil N transformation and thus on N2O emission from paddy soils.

  1. Soil Physicochemical and Biological Properties of Paddy-Upland Rotation: A Review

    PubMed Central

    Lv, Teng-Fei; Chen, Yong; Westby, Anthony P.; Ren, Wan-Jun

    2014-01-01

    Paddy-upland rotation is an unavoidable cropping system for Asia to meet the increasing demand for food. The reduction in grain yields has increased the research interest on the soil properties of rice-based cropping systems. Paddy-upland rotation fields are unique from other wetland or upland soils, because they are associated with frequent cycling between wetting and drying under anaerobic and aerobic conditions; such rotations affect the soil C and N cycles, make the chemical speciation and biological effectiveness of soil nutrient elements varied with seasons, increase the diversity of soil organisms, and make the soil physical properties more difficult to analyze. Consequently, maintaining or improving soil quality at a desirable level has become a complicated issue. Therefore, fully understanding the soil characteristics of paddy-upland rotation is necessary for the sustainable development of the system. In this paper, we offer helpful insight into the effect of rice-upland combinations on the soil chemical, physical, and biological properties, which could provide guidance for reasonable cultivation management measures and contribute to the improvement of soil quality and crop yield. PMID:24995366

  2. Identification of active denitrifiers in rice paddy soil by DNA- and RNA-based analyses.

    PubMed

    Yoshida, Megumi; Ishii, Satoshi; Fujii, Daichi; Otsuka, Shigeto; Senoo, Keishi

    2012-01-01

    Denitrification occurs markedly in rice paddy fields; however, few microbes that are actively involved in denitrification in these environments have been identified. In this study, we used a laboratory soil microcosm system in which denitrification activity was enhanced. DNA and RNA were extracted from soil at six time points after enhancing denitrification activity, and quantitative PCR and clone library analyses were performed targeting the 16S rRNA gene and denitrification functional genes (nirS, nirK and nosZ) to clarify which microbes are actively involved in denitrification in rice paddy soil. Based on the quantitative PCR results, transcription levels of the functional genes agreed with the denitrification activity, although gene abundance did not change at the DNA level. Diverse denitrifiers were detected in clone library analysis, but comparative analysis suggested that only some of the putative denitrifiers, especially those belonging to the orders Neisseriales, Rhodocyclales and Burkholderiales, were actively involved in denitrification in rice paddy soil. PMID:22972387

  3. Potential Contribution of Anammox to Nitrogen Loss from Paddy Soils in Southern China

    PubMed Central

    Yang, Xiao-Ru; Li, Hu; Nie, San-An; Su, Jian-Qiang; Weng, Bo-Sen; Zhu, Gui-Bing; Yao, Huai-Ying; Gilbert, Jack A.

    2014-01-01

    The anaerobic oxidation of ammonium (anammox) process has been observed in diverse terrestrial ecosystems, while the contribution of anammox to N2 production in paddy soils is not well documented. In this study, the anammox activity and the abundance and diversity of anammox bacteria were investigated to assess the anammox potential of 12 typical paddy soils collected in southern China. Anammox bacteria related to “Candidatus Brocadia” and “Candidatus Kuenenia” and two novel unidentified clusters were detected, with “Candidatus Brocadia” comprising 50% of the anammox population. The prevalence of the anammox was confirmed by the quantitative PCR results based on hydrazine synthase (hzsB) genes, which showed that the abundance ranged from 1.16 × 104 to 9.65 × 104 copies per gram of dry weight. The anammox rates measured by the isotope-pairing technique ranged from 0.27 to 5.25 nmol N per gram of soil per hour in these paddy soils, which contributed 0.6 to 15% to soil N2 production. It is estimated that a total loss of 2.50 × 106 Mg N per year is linked to anammox in the paddy fields in southern China, which implied that ca. 10% of the applied ammonia fertilizers is lost via the anammox process. Anammox activity was significantly correlated with the abundance of hzsB genes, soil nitrate concentration, and C/N ratio. Additionally, ammonia concentration and pH were found to be significantly correlated with the anammox bacterial structure. PMID:25416768

  4. [Effects of different fertilizer species on carbon and nitrogen leaching in a reddish paddy soil].

    PubMed

    Liu, Xi-Yu; Zou, Jing-Dong; Xu, Li-Li; Zhang, Xin-Yu; Yang, Feng-Ting; Dai, Xiao-Qin; Wang, Zhong-Qiang; Sun, Xiao-Min

    2014-08-01

    Enhanced fertilization could decrease nitrogen utilization rate and increase carbon and nitrogen leaching, leading to water pollution in agricultural ecosystem. A long-term field experiment had been established on a reddish paddy soil of Qianyanzhou Ecological Experimental Station (114 degrees 53'E, 26 degrees 48'N) in Jiangxi Province in 1998. Soil solution samples were collected by clay tube and vacuum pump. Four fertilizer species treatments were selected: control with no fertilizer (CK), straw return (ST), nitrogen, phosphorus and potassium mineral fertilizers (NPK) and pig manure (OM), aiming to evaluate the effects of different species of fertilizer on carbon and nitrogen leaching in a double rice cropping system. The results showed that: (1) ammonium nitrogen (NH4(+) -N) was the major type of N in soil leachate in reddish paddy soil. The application of NPK could significantly increase the ammonium nitrogen concentration (1.2 mg x L(-1) +/- 0.1 mg x L(-1)) compared with the CK, ST and OM treatments, and the application of OM could significantly increase the dissolved organic carbon (DOC) concentration (27.3 mg x L(-1) +/- 1.6 mg x L(-1)) in soil leachate. The carbon and nitrogen leaching were more notable in the vegetative growth stage than the reproductive growth stage of rice (P < 0.05); (2) the long-term application of NPK and OM increased the NH4(+) -N, DOC, soil organic carbon (SOC) and total nitrogen (TN) contents. The NPK was best beneficial to improve TN contents and OM to improve SOC contents. (3) The DOC contents in soil leachate and SOC in paddy soil had a positive correlation (P < 0.01), while NH4(+) -N contents in soil leachate and TN contents in paddy soil had a positive correlation (P < 0.01). PMID:25338383

  5. Potential contribution of anammox to nitrogen loss from paddy soils in Southern China.

    PubMed

    Yang, Xiao-Ru; Li, Hu; Nie, San-An; Su, Jian-Qiang; Weng, Bo-Sen; Zhu, Gui-Bing; Yao, Huai-Ying; Gilbert, Jack A; Zhu, Yong-Guan

    2015-02-01

    The anaerobic oxidation of ammonium (anammox) process has been observed in diverse terrestrial ecosystems, while the contribution of anammox to N2 production in paddy soils is not well documented. In this study, the anammox activity and the abundance and diversity of anammox bacteria were investigated to assess the anammox potential of 12 typical paddy soils collected in southern China. Anammox bacteria related to "Candidatus Brocadia" and "Candidatus Kuenenia" and two novel unidentified clusters were detected, with "Candidatus Brocadia" comprising 50% of the anammox population. The prevalence of the anammox was confirmed by the quantitative PCR results based on hydrazine synthase (hzsB) genes, which showed that the abundance ranged from 1.16 10(4) to 9.65 10(4) copies per gram of dry weight. The anammox rates measured by the isotope-pairing technique ranged from 0.27 to 5.25 nmol N per gram of soil per hour in these paddy soils, which contributed 0.6 to 15% to soil N2 production. It is estimated that a total loss of 2.50 10(6) Mg N per year is linked to anammox in the paddy fields in southern China, which implied that ca. 10% of the applied ammonia fertilizers is lost via the anammox process. Anammox activity was significantly correlated with the abundance of hzsB genes, soil nitrate concentration, and C/N ratio. Additionally, ammonia concentration and pH were found to be significantly correlated with the anammox bacterial structure. PMID:25416768

  6. Stability of soil organic matter accumulated under long-term use as a rice paddy

    NASA Astrophysics Data System (ADS)

    Nakahara, Shiko; Zou, Ping; Ando, Ho; Fu, Jianrong; Cao, Zhihong; Nakamura, Toshio; Sugiura, Yuki; Watanabe, Akira

    2016-01-01

    To understand the mechanism responsible for the enhanced accumulation of soil organic matter (SOM) under long-term use as a rice paddy, soil samples from the plow layer from 16 fields that have been used for irrigated rice production from 5 to 2000 years in the Hangzhou Bay, China, were analyzed. The humin in silt/clay particles was isolated as a representative relatively stable SOM pool, and isotopic signatures (δ13C, δ15N, and 14C concentration), 13C nuclear magnetic resonance (NMR) spectra, and biodegradability in an incubation were examined. The amounts of C and N in the bulk soil, silt/clay, and silt/clay-humin increased with increasing period of use as a rice paddy within the east and west zones, respectively. The degree of humification determined for humic acids indicated that the progression of humification did not contribute to the accumulation of C beyond 100 years. The δ15N of silt/clay-humin suggested an increase in organic N derived from chemical fertilizer or recent biological fixation with increasing amount of this fraction. The 14C concentration showed a negative correlation with the amount of silt/clay-humin C. The structural property with regard to 13C NMR spectra and biodegradability of the silt/clay-humin remained constant with the length of use as a rice paddy or 14C concentration. These results suggest that the larger C or N accumulation in the soils with a longer rice paddy history can be attributed to an enhancement in the accumulation of recently generated SOM rather than the stable accumulation of humus over the years.

  7. Assessing energy efficiencies and greenhouse gas emissions under bioethanol-oriented paddy rice production in northern Japan.

    PubMed

    Koga, Nobuhisa; Tajima, Ryosuke

    2011-03-01

    To establish energetically and environmentally viable paddy rice-based bioethanol production systems in northern Japan, it is important to implement appropriately selected agronomic practice options during the rice cultivation step. In this context, effects of rice variety (conventional vs. high-yielding) and rice straw management (return to vs. removal from the paddy field) on energy inputs from fuels and consumption of materials, greenhouse gas emissions (fuel and material consumption-derived CO(2) emissions as well as paddy soil CH(4) and N(2)O emissions) and ethanol yields were assessed. The estimated ethanol yield from the high-yielding rice variety, "Kita-aoba" was 2.94 kL ha(-1), a 32% increase from the conventional rice variety, "Kirara 397". Under conventional rice production in northern Japan (conventional rice variety and straw returned to the paddy), raising seedlings, mechanical field operations, transportation of harvested unhulled brown rice and consumption of materials (seeds, fertilizers, biocides and agricultural machinery) amounted to 28.5 GJ ha(-1) in energy inputs. The total energy input was increased by 14% by using the high-yielding variety and straw removal, owing to increased requirements for fuels in harvesting and transporting harvested rice as well as in collecting, loading and transporting rice straw. In terms of energy efficiency, the variation among rice variety and straw management scenarios regarding rice varieties and rice straw management was small (28.5-32.6 GJ ha(-1) or 10.1-14.0 MJ L(-1)). Meanwhile, CO(2)-equivalent greenhouse gas emissions varied considerably from scenario to scenario, as straw management had significant impacts on CH(4) emissions from paddy soils. When rice straw was incorporated into the soil, total CO(2)-equivalent greenhouse gas emissions for "Kirara 397" and "Kita-aoba" were 25.5 and 28.2 Mg CO(2) ha(-1), respectively; however, these emissions were reduced notably for the two varieties when rice straw was removed from the paddy fields in an effort to mitigate CH(4) emissions. Thus, rice straw removal avers itself a key practice with respect to lessening the impacts of greenhouse gas emissions in paddy rice-based ethanol production systems in northern Japan. More crucially, the rice straw removed is available for ethanol production and generation of heat energy with a biomass boiler, all elements required for biomass-to-ethanol transformation steps including saccharification, fermentation and distillation. This indicates opportunities for further improvement in energy efficiency and reductions in greenhouse gas emissions under whole rice plant-based bioethanol production systems. PMID:21126818

  8. A theory for generation of the paired region 1 and region 2 field-aligned currents

    NASA Astrophysics Data System (ADS)

    Yamamoto, Takashi; Inoue, S.; Nishitani, N.; Ozaki, M.; Meng, C.-I.

    1996-12-01

    We present a new theoretical model for generation of a pair of region 1 and region 2 field-aligned currents (FACs) under the condition of a southward interplanetary magnetic field. On the basis of the satellite observations it is assumed that the hot (>1 keV) plasma particles are distributed in a magnetic shell connected to two ovals of diffuse auroras on the northern and southern polar ionospheres. The hot plasma population contained in this magnetic shell having several degrees of latitude in width is called the hot plasma torus (HPT). It is proposed that the region 1/region 2 FACs can be generated as a result of natural distortion of the HPT due to the solar wind convection. When the interplanetary magnetic field has a southward component, i.e., the IMF Bz is negative, the solar wind flow across open geomagnetic field lines gives rise to electric field convection patterns over the polar caps, which are modeled as twin vortex cells with antisunward flows in the center of the polar caps. The convection thus driven by the solar wind is referred to as the solar wind convection. If it were not for an EB convection flow, the HPT would be shaped such that the HPT particles are contained in the ``magnetic drift shells,'' which are tangent to the averaged total magnetic drift velocity. In the presence of the solar wind convection the configuration of the HPT will be deformed from the magnetic drift shells. Because of the distortion of the HPT the pressure gradient in the HPT gains a component parallel to the magnetic drift. Therefore the HPT can be polarized because of oppositely directed magnetic drifts of the HPT electrons and protons: the high-latitude and low-latitude sides of the HPT on the eveningside are negative and positive, respectively, and the polarity is reversed on the morningside. The resulting pattern of large-scale field-aligned currents due to the polarization of the HPT is consistent with the observations of region 1 and region 2 FACs. Moreover, provided that the solar wind acts as a voltage generator in the interaction with the open field lines, as a long-term characteristic of the paired region 1 and region 2 FACs we can obtain the relationship between the FAC intensity and the ionospheric conductivity both the region 1 and region 2 intensities increase linearly with the Pederson conductivity, while the proportionality constant for the region 2 FAC is smaller than that for the region 1 FAC. Our predicted relation for geomagnetic quiet conditions quantitatively agrees with the regression lines between the current intensities and the Pedersen conductivities obtained on the basis of Magsat satellite observations by Fujii and Iijima [1987].

  9. Magnetic fields in star-forming regions - Observations

    NASA Technical Reports Server (NTRS)

    Heiles, Carl; Goodman, Alyssa A.; Mckee, Christopher F.; Zweibel, Ellen G.

    1993-01-01

    We review the observational aspects of magnetic fields in dense, star-forming regions. First we discuss ways to observe the field. These include direct methods, which consist of the measurement of both linear and circular polarization of spectral line and continuum radiation; and indirect methods, consisting of the angular distribution of H2O masers on the sky and the measurement of ambipolar diffusion. Next we discuss selected observational results, focusing on detailed discussions of a small number of points rather than a generalized discussion that covers the waterfront. We discuss the Orion/BN-KL region in detail, both on the small and large scales. Next we discuss the derivation of the complete magnetic vector, including both the systematic and fluctuating component, from a large sample of Zeeman and linear polarization measurements for the L204 dark cloud. We examine the virial theorem as it applies to dark clouds in general and one dark cloud, Barnard 1, in particular. We critically discuss the numerous claims for alignment of cloud structural features with the plane-of-the-sky component of the magnetic field, and find that many of these have not been definitively established.

  10. Magnetic field configuration in a flaring active region

    NASA Astrophysics Data System (ADS)

    Palacios, J.; Balmaceda, L. A.; Vieira, L. E.

    2015-10-01

    The Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) provides continuous monitoring of the Sun's vector magnetic field through full-disk photospheric data with both high cadence and high spatial resolution. Here we investigate the evolution of AR 11249 from March 6 to March 7, 2012. We make use of HMI Stokes imaging, SDO/SHARPs, the HMI magnetic field line-of-sight (LOS) maps and the transverse components of the magnetic field as well as LOS velocity maps in order to detect regions with significant flux emergence and/or cancellation. In addition, we apply the Local Correlation Tracking (LCT) technique to the total and signed magnetic flux data and derive maps of horizontal velocity. From this analysis, we were able to pinpoint localized shear regions (and a shear channel) where penumbrae and pore formation areas, with strong linear polarization signals, are stretched and squeezed, showing also important downflows and upflows. We have also utilized Hinode/SP data and compared them to the HMI-SHARPs and the HMI-Stokes spectrograms. The aforementioned shear channel seems to correspond well with the X-class flare main channel of March 7 2012, as observed in AIA/SDO 171, 304 and 1600 Å.

  11. Effects of sulfate and selenite on mercury methylation in a mercury-contaminated rice paddy soil under anoxic conditions.

    PubMed

    Wang, Yongjie; Dang, Fei; Zhong, Huan; Wei, Zhongbo; Li, Ping

    2016-03-01

    Biogeochemical cycling of sulfur and selenium (Se) could play an important role in methylmercury (MeHg) dynamics in soil, while their potential effects on MeHg production in rice paddy soil are less understood. The main objective of this study was to explore the effects of sulfate and selenite on net MeHg production in contaminated rice paddy soil, characterized with massive MeHg production and thus MeHg accumulation in rice. A series of microcosm incubation experiments were conducted using a contaminated paddy soil amended with sulfate and/or selenite, in which sulfate-reducing bacteria were mainly responsible for MeHg production. Our results demonstrated that sulfate addition reduced solid and dissolved MeHg levels in soils by ≤18 and ≤25 %, respectively. Compared to sulfate, selenite was more effective in inhibiting net MeHg production, and the inhibitory effect depended largely on amended selenite doses. Moreover, sulfate input played a dual role in affecting Hg-Se interactions in soil, which could be explained by the dynamics of sulfate under anoxic conditions. Therefore, the effects of sulfate and selenium input should be carefully considered when assessing risk of Hg in anoxic environments (e.g., rice paddy field and wetland). PMID:26520099

  12. Videomagnetograph studies of solar magnetic fields. II - Field changes in an active region

    NASA Technical Reports Server (NTRS)

    Schoolman, S. A.

    1973-01-01

    Using the Caltech videomagnetograph, we obtained a 6.5-hr movie of the magnetic fields in a young active region. The major contribution to the short term magnetic evolution of the region was provided by many discrete magnetic points which move in apparently random directions with typical velocities of 0.4 - 1.0 km/sec. The majority of these features appear to be footpoints of new EFR's, which emerge at an observed rate of one to two per hour. The pattern of the motions suggests that the magnetic evolution of a growing region cannot be principally due to photospheric convective cells.

  13. Fine structure of the magnetic field in active regions

    NASA Astrophysics Data System (ADS)

    Pustilnik, Lev; Beskrovnaya, Nina; Ikhsanov, Nazar

    High-resolution observations with SOHO, SDO, TRACE, HINODE suggest that the solar magnetic field in active regions has a complicated fine structure. There is a large number of thin magnetic arcs extended from the photosphere to corona with almost constant cross-section. We explore a possibility to model the complex of interacting arcs in terms of a dynamical percolating network. A transition of the system into flaring can be triggered by the flute instability of prominences and/or coronal condensations. We speculate around an assumption that the energy release in active regions is governed by the same scenario as dynamical current percolation through a random resistors network in which the saltatory conduction is controlled by a local current level.

  14. Measurements of the E region neutral wind field

    NASA Technical Reports Server (NTRS)

    Cogger, L. L.; Murphree, J. S.; Tepley, C. A.; Meriwether, J. W., Jr.

    1985-01-01

    The neutral E-region wind field was measured at Calgary, Canada (51 N, 114 N) during 75 nights in 1982. Observations of the Doppler shift of the 5577-A emission line of atomic oxygen using a Fabry-Perot interferometer were converted to horizontal wind vectors. From the analysis of the data, four categories of wind characteristics were identified. In order of increasing magnetic activity these categories are: (1) wind field mostly variable in space and time; (2) predominantly equatorward flow throughout the night, (3) predominantly poleward flow throughout the night and (4) north-westward flow before midnight and southward after midnight. The wind magnitude was also variable and on some disturbed days exceeded 200 m/s.

  15. Plasma Equilibrium in a Magnetic Field with Stochastic Regions

    SciTech Connect

    J.A. Krommes and Allan H. Reiman

    2009-04-23

    The nature of plasma equilibrium in a magnetic field with stochastic regions is examined. It is shown that the magnetic differential equation that determines the equilibrium Pfirsch-Schluter currents can be cast in a form similar to various nonlinear equations for a turbulent plasma, allowing application of the mathematical methods of statistical turbulence theory. An analytically tractable model, previously studied in the context of resonance-broadening theory, is applied with particular attention paid to the periodicity constraints required in toroidal configurations. It is shown that even a very weak radial diffusion of the magnetic field lines can have a significant effect on the equilibrium in the neighborhood of the rational surfaces, strongly modifying the near-resonant Pfirsch-Schluter currents. Implications for the numerical calculation of 3D equilibria are discussed

  16. Neptune's polar cusp region - Observations and magnetic field analysis

    NASA Technical Reports Server (NTRS)

    Lepping, R. P.; Burlaga, L. F.; Lazarus, A. J.; Vasyliunas, V. M.; Szabo, A.; Steinberg, J.; Ness, N. F.; Krimigis, S. M.

    1992-01-01

    This paper confirms and extends the results of Szabo et al. (1991) (which demonstrated some similarities of the Neptune's polar cusp region to the earth's cusp), but uses a different approach requiring plasma and vector magnetic field quantities. In addition, various MHD properties of the cusp-magnetopause boundary, which separates the cusp from the magnetosheath allowing thermal anisotropy, are obtained, including the magnetopause (MP) normal, mass, and normal momentum flux, the boundary speed (and thickness), and their relationships. Results demonstrate that the MP velocity is composed of two components: a propagation speed and the other component consistent with the rotational motion of the magnetosphere.

  17. Analysis of supersonic combustion flow fields with embedded subsonic regions

    NASA Technical Reports Server (NTRS)

    Dash, S.; Delguidice, P.

    1972-01-01

    The viscous characteristic analysis for supersonic chemically reacting flows was extended to include provisions for analyzing embedded subsonic regions. The numerical method developed to analyze this mixed subsonic-supersonic flow fields is described. The boundary conditions are discussed related to the supersonic-subsonic and subsonic-supersonic transition, as well as a heuristic description of several other numerical schemes for analyzing this problem. An analysis of shock waves generated either by pressure mismatch between the injected fluid and surrounding flow or by chemical heat release is also described.

  18. Adiabatic theory in regions of strong field gradients. [in magnetosphere

    NASA Technical Reports Server (NTRS)

    Whipple, E. C.; Northrop, T. G.; Birmingham, T. J.

    1986-01-01

    The theory for the generalized first invariant for adiabatic motion of charged particles in regions where there are large gradients in magnetic or electric fields is developed. The general condition for an invariant to exist in such regions is that the potential well in which the particle oscillates change its shape slowly as the particle drifts. It is shown how the Kruskal (1962) procedure can be applied to obtain expressions for the invariant and for drift velocities that are asymptotic in a smallness parameter epsilon. The procedure is illustrated by obtaining the invariant and drift velocities for particles traversing a perpendicular shock, and the generalized invariant is compared with the magnetic moment, and the drift orbits with the actual orbits, for a particular case. In contrast to the magnetic moment, the generalized first invariant is better for large gyroradii (large kinetic energies) than for small gyroradii. Expressions for the invariant when an electrostatic potential jump is imposed across the perpendicular shock, and when the particle traverses a rotational shear layer with a small normal component of the magnetic field are given.

  19. Plant available silicon in South-east Asian rice paddy soils - relevance of agricultural practice and of abiotic factors

    NASA Astrophysics Data System (ADS)

    Marxen, A.; Klotzbücher, T.; Vetterlein, D.; Jahn, R.

    2012-12-01

    Background Silicon (Si) plays a crucial role in rice production. Si content of rice plants exceeds the content of other major nutrients such as nitrogen, phosphorous or potassium. Recent studies showed that in some environments external supply of Si can enhance the growth of rice plants. Rice plants express specific Si transporters to absorb Si from soil solutions in form of silicic acid, which precipitates in tissue cells forming amorphous silica bodies, called phytoliths. The phytoliths are returned to soils with plant residues. They might be a main source of plant available silicic acid in soils. Aims In this study we assess the effects of rice paddy cultivation on the stocks of `reactive` Si fractions in mineral topsoils of rice paddy fields in contrasting landscapes. The `reactive` Si fractions are presumed to determine the release of plant-available silicic acid in soils. We consider the relevance of abiotic factors (mineral assemblage; soil weathering status) and agricultural practice for these fractions. Agricultural practices, which were assumed to affect the stocks of `reactive` Si were (i) the usage of different rice varieties (which might differ in Si demand), (ii) straw residue management (i.e., whether straw residues are returned to the fields or removed and used e.g. as fodder), and (iii) yield level and number of crops per year. Material and methods Soils (top horizon of about 0-20 cm depth) were sampled from rice paddy fields in 2 mountainous and 5 lowland landscapes of contrasting geologic conditions in Vietnam and the Philippines. Ten paddy fields were sampled per landscape. The rice paddy management within landscapes differed when different farmers and/or communities managed the fields. We analysed the following fractions of `reactive` Si in the soils: acetate-extractable Si (dissolved and easily exchangeable Si), phosphate-extractable Si (adsorbed Si), oxalate extractable Si (Si associated with poorly-ordered sesquioxides), NaOH extractable Si (amorphous Si), and biogenic Si bodies (`phytoliths`). Thereby extractions with phosphate, oxalate, and NaOH were conducted sequentially. Results and conclusions First results from the two highland landscapes show that the stocks of `reactive` Si fractions differ considerably within the landscapes (i.e., by a factor of up to 3). The differences between landscapes are, however, even more pronounced (factors of 3-8), which can be attributed to differences in the weathering status of the soils. Our preliminary conclusion is that soil weathering status is the main determinant of the stocks of `reactive` Si in paddy topsoils. Agricultural practice can, however, also exert significant effects. In landscapes with highly weathered soils, the sustained supply of Si to rice plants might therefore largely depend on appropriate agricultural practices.

  20. Microbial communities play important roles in modulating paddy soil fertility.

    PubMed

    Luo, Xuesong; Fu, Xiaoqian; Yang, Yun; Cai, Peng; Peng, Shaobing; Chen, Wenli; Huang, Qiaoyun

    2016-01-01

    We studied microbial communities in two paddy soils, which did not receive nitrogen fertilization and were distinguished by the soil properties. The two microbial communities differed in the relative abundance of gram-negative bacteria and total microbial biomass. Variability in microbial communities between the two fields was related to the levels of phosphorus and soil moisture. Redundancy analysis for individual soils showed that the bacterial community dynamics in the high-yield soil were significantly correlated with total carbon, moisture, available potassium, and pH, and those in the low-yield cores were shaped by pH, and nitrogen factors. Biolog Eco-plate data showed a more active microbial community in the high yield soil. The variations of enzymatic activities in the two soils were significantly explained by total nitrogen, total potassium, and moisture. The enzymatic variability in the low-yield soil was significantly explained by potassium, available nitrogen, pH, and total carbon, and that in the high-yield soil was partially explained by potassium and moisture. We found the relative abundances of Gram-negative bacteria and Actinomycetes partially explained the spatial and temporal variations of soil enzymatic activities, respectively. The high-yield soil microbes are probably more active to modulate soil fertility for rice production. PMID:26841839

  1. Microbial communities play important roles in modulating paddy soil fertility

    NASA Astrophysics Data System (ADS)

    Luo, Xuesong; Fu, Xiaoqian; Yang, Yun; Cai, Peng; Peng, Shaobing; Chen, Wenli; Huang, Qiaoyun

    2016-02-01

    We studied microbial communities in two paddy soils, which did not receive nitrogen fertilization and were distinguished by the soil properties. The two microbial communities differed in the relative abundance of gram-negative bacteria and total microbial biomass. Variability in microbial communities between the two fields was related to the levels of phosphorus and soil moisture. Redundancy analysis for individual soils showed that the bacterial community dynamics in the high-yield soil were significantly correlated with total carbon, moisture, available potassium, and pH, and those in the low-yield cores were shaped by pH, and nitrogen factors. Biolog Eco-plate data showed a more active microbial community in the high yield soil. The variations of enzymatic activities in the two soils were significantly explained by total nitrogen, total potassium, and moisture. The enzymatic variability in the low-yield soil was significantly explained by potassium, available nitrogen, pH, and total carbon, and that in the high-yield soil was partially explained by potassium and moisture. We found the relative abundances of Gram-negative bacteria and Actinomycetes partially explained the spatial and temporal variations of soil enzymatic activities, respectively. The high-yield soil microbes are probably more active to modulate soil fertility for rice production.

  2. Microbial communities play important roles in modulating paddy soil fertility

    PubMed Central

    Luo, Xuesong; Fu, Xiaoqian; Yang, Yun; Cai, Peng; Peng, Shaobing; Chen, Wenli; Huang, Qiaoyun

    2016-01-01

    We studied microbial communities in two paddy soils, which did not receive nitrogen fertilization and were distinguished by the soil properties. The two microbial communities differed in the relative abundance of gram-negative bacteria and total microbial biomass. Variability in microbial communities between the two fields was related to the levels of phosphorus and soil moisture. Redundancy analysis for individual soils showed that the bacterial community dynamics in the high-yield soil were significantly correlated with total carbon, moisture, available potassium, and pH, and those in the low-yield cores were shaped by pH, and nitrogen factors. Biolog Eco-plate data showed a more active microbial community in the high yield soil. The variations of enzymatic activities in the two soils were significantly explained by total nitrogen, total potassium, and moisture. The enzymatic variability in the low-yield soil was significantly explained by potassium, available nitrogen, pH, and total carbon, and that in the high-yield soil was partially explained by potassium and moisture. We found the relative abundances of Gram-negative bacteria and Actinomycetes partially explained the spatial and temporal variations of soil enzymatic activities, respectively. The high-yield soil microbes are probably more active to modulate soil fertility for rice production. PMID:26841839

  3. Modelling the fate of pesticides in paddy rice-fish pond farming system in Northern Vietnam

    NASA Astrophysics Data System (ADS)

    Lamers, M.; Nguyen, N.; Streck, T.

    2012-04-01

    During the last decade rice production in Vietnam has tremendously increased due to the introduction of new high yield, short duration rice varieties and an increased application of pesticides. Since pesticides are toxic by design, there is a natural concern on the possible impacts of their presence in the environment on human health and environment quality. In North Vietnam, lowland and upland rice fields were identified to be a major non-point source of agrochemical pollution to surface and ground water, which are often directly used for domestic purposes. Field measurements, however, are time consuming, costly and logistical demanding. Hence, quantification, forecast and risk assessment studies are hampered by a limited amount of field data. One potential way to cope with this shortcoming is the use of process-based models. In the present study we developed a model for simulating short-term pesticide dynamics in combined paddy rice field - fish pond farming systems under the specific environmental conditions of south-east Asia. Basic approaches and algorithms to describe the key underlying biogeochemical processes were mainly adopted from the literature to assure that the model reflects the current standard of scientific knowledge and commonly accepted theoretical background. The model was calibrated by means of the Gauss-Marquardt-Levenberg algorithm and validated against measured pesticide concentrations (dimethoate and fenitrothion) during spring and summer rice crop season 2008, respectively, of a paddy field - fish pond system typical for northern Vietnam. First simulation results indicate that our model is capable to simulate the fate of pesticides in such paddy - fish pond farming systems. The model efficiency for the period of calibration, for example, was 0.97 and 0.95 for dimethoate and fenitrothion, respectively. For the period of validation, however, the modeling efficiency slightly decreased to 0.96 and 0.81 for dimethoate and fenitrothion, respectively. In our presentation we will picture key model features and algorithms and demonstrate that our model provides a useful and appropriate tool for analyzing and quantifying the transport and behavior of pesticides in paddy rice farming systems.

  4. Baseline soil variation is a major factor in arsenic accumulation in Bengal Delta paddy rice.

    PubMed

    Lu, Ying; Adomako, Eureka E; Solaiman, A R M; Islam, M Rafiqul; Deacon, Claire; Williams, P N; Rahman, G K M M; Meharg, Andrew A

    2009-03-15

    Factors responsible for paddy soil arsenic accumulation in the tubewell irrigated systems of the Bengal Delta were investigated. Baseline (i.e., nonirrigated) and paddy soils were collected from 30 field systems across Bangladesh. For each field, soil sampled at dry season (Boro) harvest i.e., the crop cycle irrigated with tubewell water, was collected along a 90 m transect away from the tubewell irrigation source. Baseline soil arsenic levels ranged from 0.8 to 21. mg/kg, with lower values found on the Pliestocene Terrace around Gazipur (average, 1.6 +/- 0.2 mg/kg), and higher levels found in Holecene sediment tracts of Jessore and Faridpur (average, 6.6 +/- 1.0 mg/kg). Two independent approaches were used to assess the extent of arsenic build-up in irrigated paddy soils. First, arsenic build-up in paddy soil at the end of dry season production (irrigated - baseline soil arsenic) was regressed against number of years irrigated and tubewell arsenic concentration. Years of irrigation was not significant (P = 0.711), indicating no year-on-year arsenic build-up, whereas tubewell As concentration was significant (P = 0.008). The second approach was analysis of irrigated soils for 20 fields over 2 successive years. For nine of the fields there was a significant (P < 0.05) decrease in soil arsenic from year 1 to 2, one field had a significant increase, whereas there was no change for the remaining 10. Over the dry season irrigation cycle, soil arsenic built-up in soils at a rate dependent on irrigation tubewell water, 35* (tubewell water concentration in mg/kg, triple bond mg/L). Grain arsenic rises steeply at low soil/shoot arsenic levels, plateauing out at concentratations. Baseline soil arsenic at Faridpur sites corresponded to grain arsenic levels at the start of this saturation phase. Therefore, variation in baseline levels of soil arsenic leads to a large range in grain arsenic. Where sites have high baseline soil arsenic, further additional arsenic from irrigation water only leads to a gradual increase in grain arsenic concentration. PMID:19368163

  5. A Distributed Water Circulation Model Incorporating Large Irrigation Schemes for Paddy Areas

    NASA Astrophysics Data System (ADS)

    Yoshida, T.; Masumoto, T.; Kudo, R.; Horikawa, N.

    2010-12-01

    Water intake for paddy irrigation in Japan accounts for approximately 70% of total intake. Spatial and temporal variation of precipitation and river flow changes, likely to be caused by climate changes, directly affect paddy irrigation and its management schemes. Previous studies show that potential water stresses were estimated in the framework of grid-based distributed water circulation models, in which water availability and demand were roughly compared in large-scale grids of 10~100km. However, in mid and small-scale basins, where we carry out impact assessment studies of 1~10km grids, we need schemes to couple the irrigation intake and its allocation, because agricultural water is highly dependent on human decision making processes. Then, we have developed a model that couples natural hydrological behaviors of a basin and artificial irrigation systems. A distributed water circulation model, which explains natural hydrological behaviors of a basin, consists of approximately 1km square gridded meshes. Infiltration and saturation-excess flow and water requirements of irrigated paddy fields on any grid are calculated. The generated surface flow is routed by a kinematic wave equation so that daily flow rate can be calculated at any point of interest. The core of the model is water allocation and management scheme that exploit the spatial database of irrigation facilities and beneficiary areas. This analysis consists of new modeled plane for irrigation, which is calculated independently from the surface plain of the distributed water circulation model. Following the configuration of the water allocation and management schemes, the model is coupled with the distributed water circulation model. The reservoir operation scheme is an algorithm to determine the reservoir releases for irrigation based on requirement and flow rate at downstream diversion weirs. Diversion weirs intake water from associated rivers at the maximum rate, if water is available. The integrated model is applied to the Seki River Basin, a representative basin in which irrigated paddies are dominant. The paddy area in the basin is 17 % of the total catchment area. The calculation is carried out from 2002 to 2007. The calculated discharges closely agree with the observed discharges at the outlet of the catchment, the relative error of which is 27%. In addition, the model depicts the reservoir releases additional supply to meet the requirements of the diversion weirs. Water intake at the most upstream diversion weir is stabilized by released water, while intake at the other 2 weirs are more variable. While the daily upstream intake is 22mm, the actual supplies of irrigation to paddies are estimated as 12mm/d. This is partially due to a loss through the distribution process, which account for 15% of total intake. In addition, approximately 50% of intake returns to channels as a surplus, which will be utilized in downstream paddies. The integration of the water allocation and management schemes into the distributed water circulation model enabled us to evaluate both rivers and irrigation systems. The model we present here may be applied to quantitatively evaluate the potential impact on human activities of changing hydrologic cycles such as climate changes.

  6. Do microorganism stoichiometric alterations affect carbon sequestration in paddy soil subjected to phosphorus input?

    PubMed

    Zhang, ZhiJian; Li, HongYi; Hu, Jiao; Li, Xia; He, Qiang; Tian, GuangMing; Wang, Hang; Wang, ShunYao; Wang, Bei

    2015-04-01

    Ecological stoichiometry provides a powerful tool for integrating microbial biomass stoichiometry with ecosystem processes, opening far-reaching possibilities for linking microbial dynamics to soil carbon (C) metabolism in response to agricultural nutrient management. Despite its importance to crop yield, the role of phosphorus (P) with respect to ecological stoichiometry and soil C sequestration in paddy fields remains poorly understood, which limits our ability to predict nutrient-related soil C cycling. Here, we collected soil samples from a paddy field experiment after seven years of superphosphate application along a gradient of 0, 30, 60, and 90 (P-0 through P-90, respectively) kg.ha-1.yr-1 in order to evaluate the role of exogenous P on soil C sequestration through regulating microbial stoichiometry. P fertilization increased soil total organic C and labile organic C by 1-14% and 4-96%, respectively, while rice yield is a function of the activities of soil β-1,4-glucosidase (BG), acid phosphatase (AP), and the level of available soil P through a stepwise linear regression model. P input induced C limitation, as reflected by decreases in the ratios of C:P in soil and microbial biomass. An eco-enzymatic ratio indicating microbial investment in C vs. P acquisition, i.e., ln(BG): ln(AP), changed the ecological function of microbial C acquisition, and was stoichiometrically related to P input. This mechanism drove a shift in soil resource availability by increasing bacterial community richness and diversity, and stimulated soil C sequestration in the paddy field by enhancing C-degradation-related bacteria for the breakdown of plant-derived carbon sources. Therefore, the decline in the C:P stoichiometric ratio of soil microorganism biomass under P input was beneficial for soil C sequestration, which offered a "win-win" relationship for the maximum balance point between C sequestration and P availability for rice production in the face of climate change. PMID:26214930

  7. The prominence-corona transition region in transverse magnetic fields

    NASA Astrophysics Data System (ADS)

    Chuideri Drago, Franca; Engvold, Oddbjorn; Jensen, Eberhart

    1992-05-01

    A model is developed to analyze the emissions from the prominence-corona transition region (PCTR), and comparisons are made with observational data to assess the heating mechanism in the PCTR. The cool matter of the quiescent filaments is assumed to be organized into magnetic flux loops in the hot coronal cavity gas. The lower layers of the PCTR are theorized to be heated by the dissipation of Alfven waves since the heating caused by the divergence of transverse conduction is not consistent with EUV and UV emissions. The temperature gradient of the high-temperature layers is determined by the balance of radiative cooling and conductive heating with magnetic fields minimizing thermal conduction. The model offers an explanation for the difference in observed EUV brightnesses at the limb and on the disk caused by the angle between the filaments and the line of sight.

  8. Drying characteristics of paddy in an integrated dryer.

    PubMed

    Manikantan, M R; Barnwal, P; Goyal, R K

    2014-04-01

    Drying characteristics of paddy (long grain variety PR-118 procured from PAU, Ludhiana) in an integrated dryer using single as well as combined heating source was studied at different air temperatures. The integrated dryer comprises three different air heating sources such as solar, biomass and electrical. Drying of paddy occurred in falling rate period. It was observed that duration of drying of paddy from 22 to 13% moisture content (w.b.) was 5-9h depending upon the source of energy used. In order to select a suitable drying curve, six thin layer-drying models (Newton, Page, Modified Page, Henderson and Pabis, Logarithmic and Wang and Singh) were fitted to the experimental moisture ratio data. Among the mathematical models investigated, Wang and Singh model best described the drying behaviour of paddy using solar, biomass and combined heating sources with highest coefficient of determination (r (2)) values and least chi-square, ? (2), mean bias error (MBE) and root mean square error (RMSE) values. However, Page model adequately described the drying behavior of paddy using electrical heating source. PMID:24741181

  9. Methane emission from single cropping rice paddies amended different manures

    SciTech Connect

    Du Daodeng; Tao Zhan

    1996-12-31

    Methane emission fluxes were determined from single cropping rice paddies amended with different manures through a productively comparative experiment. The average fluxes in the whole growth season ranged from 3.92 to 10.96 mg/m{sup 2}.hr. The compost amended paddies gave the highest emission fluxes of 10.26 mg/m{sup 2}.hr, while the fluxes from the other manure amended paddies ranked as follows: horse dung biogas digester sediment 10.02, chemical fertilizer only 8.81, nightsoil biogas sediment 7.76, chicken dropping biogas digester sediment 4.48 and pig dung biogas digester sediment 3.92 mg/m{sup 2}.hr. The latter 3 sediments gave the significant less ({alpha} < 0.05) fluxes than compost. The highest fluxes peaks of all treated paddies appeared unanimously between the stages of the midtillering and the earing, with a half of total CH{sub 4} emissions were produced in this period which could be chosen as the key period for control of CH{sub 4} emission from the single cropping rice paddies. The positive correlation of the fluxes with the temperatures in 5 cm soil layers and the negative correlation of the fluxes with the rice yields, the soil N and P{sub 2}O{sub 5} contents were also observed.

  10. Magnetic field measurements in and above a limb active region

    NASA Astrophysics Data System (ADS)

    Philip, Judge

    2013-07-01

    We analyze spectropolarimetric data of a limb active region (NOAA 11302) obtained on September 22nd 2011 using the Facility Infrared Spectrometer (FIRS) at the Dunn Solar Telescope (DST). Stokes profiles including lines of Si I 1028.7 nm and He I 1083 nm were obtained in three scans over a 45"x75" area. Simultaneous narrow band Ca II K and G-band intensity data were acquired with a cadence of 5s at the DST. The He I data show not only typical active region polarization signatures, but also signatures in plumes -- cool post flare loops -- which extend many Mm into the corona across the visible limb. The plumes have remarkably uniform brightness, and the plume plasma is significantly Doppler shifted as it drains from the corona. Using carefully constructed observing and calibration sequences and applying Principal Component Analysis to remove instrumental artifacts, we achieved a polarization sensitivity approaching 0.02%. With this sensitivity we attempt to diagnose the vector magnetic fields and plasma properties of chromospheric and cool coronal material in and above NOAA 11302. Inversions using various radiative transfer models in the HAZEL code are remarkably consistent with the idea that plume spectra are formed in a simple, slab-like geometry, but that the ``disk'' spectra are formed under more traditional models (Milne-Eddington). The inverted magnetic data of He I lines are compared with photospheric inversions of DST Si I and Fe I data from the Solar Dynamics Observatory.

  11. Data fitting and modeling of regional geomagnetic field

    NASA Astrophysics Data System (ADS)

    Feng, Yan; Sun, Han; Jiang, Yong

    2015-09-01

    The selection of the truncation level (TL) and the control of boundary effect (BE) are critical in regional geomagnetic field models that are based on data fitting. We combine Taylor and Legendre polynomials to model geomagnetic data over mainland China for years 1960, 1970, 1990, and 2000. To tackle the TL and BE problems, we first determine the range of TL by calculating the root-mean-square error (RMSE) of the models. Next, we determine the optimum TL using the Akaike information criterion (AIC) and the normalized rootmean- square error (NRMSE). We use the regional anomaly addition (RAA) and the uniform addition (UA) method to add supplementary point outside the national boundary, and find that the intensities of extreme points gradually decrease and stabilize. The UA method better controls BEs over China, whereas the RAA method does a better job at smaller scales. In summary, we rely on a three-step method to determine the optimum TL and propose criteria to determine the optimum number of supplementary points.

  12. Generation and Suppression of E Region Artificial Field Aligned Irregularities

    NASA Astrophysics Data System (ADS)

    Miceli, R. J.; Hysell, D. L.; Munk, J.; Han, S.

    2012-12-01

    Artificial field-aligned plasma density irregularities (FAIs) were generated in the E region of the ionosphere above the High Frequency Active Auroral Research Program (HAARP) facility during campaigns in May and August of 2012 and were quantified using a 30 MHz coherent scatter radar in Homer, Alaska. The purpose of the experiment was to analyze the X-mode suppression of FAIs generated from O-mode heating and to measure the threshold required to excite thermal parametric instabilities. The irregularities were excited by gradually increasing the power of a zenith pointing O-mode emission transmitted at a frequency of 2.75 MHz. To suppress the irregularities, a second X-mode emission at a higher frequency was added on alternating power cycles. The Homer radar measured the signal-to-noise ratio, Doppler shift, and spectral width of echoes reflected from the irregularities. We will calculate the threshold electric field required to excite the irregularities and compare with similar experiments in order to better understand the thermal parametric instability.

  13. Regional TEC mapping with Random Field Priors and Kriging

    NASA Astrophysics Data System (ADS)

    Sayin, I.; Arikan, F.; Arikan, O.

    2008-10-01

    Total Electron Content (TEC) is an important parameter in monitoring ionospheric variability. In a given region, TEC can be obtained only by interpolation of measurements due to sparsity of the useful data. The lack of a complete ionospheric model hinders the choice of the optimum interpolation algorithm. A plausible solution to this problem can be found by investigating the performance of alternative interpolation algorithms on synthetically generated TEC surfaces for various sampling scenarios. The synthetic TEC data should represent the possible trends and variations of ionosphere. In this study, the performance of Random Field Priors (RFP) and Kriging interpolation algorithms are investigated over the parameter set of spatially correlated synthetic TEC data for various variance, range and trend options. Synthetic TEC data are sampled with regular and random sampling patterns, for number of samples from sparse to dense samplings. Interpolation scenarios are generated to investigate the improvement of the interpolation accuracy of the methods for each parameter. It is observed that for the random sampling patterns, when the trend is not modeled correctly, the errors of the algorithms increase and when the trend is modeled correctly, the reconstruction errors decrease. For the regular sampling patterns, the trend model does not affect the accuracy of the methods, and the reconstruction errors are close to lower bound error values. An example reconstruction is also provided over GPS-derived TEC, and error variances are compared over Kriging and Random Field Prior algorithms.

  14. The effects of magnetic field in plume region on the performance of multi-cusped field thruster

    NASA Astrophysics Data System (ADS)

    Hu, Peng; Liu, Hui; Mao, Wei; Yu, Daren; Gao, Yuanyuan

    2015-10-01

    The performance characteristics of a Multi-cusped Field Thruster depending on the magnetic field in the plume region were investigated. Five magnetic field shielding rings were separately mounted near the exit of discharge channel to decrease the strength of magnetic field in the plume region in different levels, while the magnetic field in the upstream was well maintained. The test results show that the electron current increases with the decrease of magnetic field strength in the plume region, which gives rise to higher propellant utilization and lower current utilization. On the other hand, the stronger magnetic field in the plume region improves the performance at low voltages (high current mode) while lower magnetic field improves the performance at high voltages (low current mode). This work can provide some optimal design ideas of the magnetic strength in the plume region to improve the performance of thruster.

  15. A paddy eco-ditch and wetland system to reduce non-point source pollution from rice-based production system while maintaining water use efficiency.

    PubMed

    Xiong, Yujiang; Peng, Shizhang; Luo, Yufeng; Xu, Junzeng; Yang, Shihong

    2015-03-01

    Non-point source (NPS) pollution from agricultural drainage has aroused widespread concerns throughout the world due to its contribution to eutrophication of water bodies. To remove nitrogen (N) and phosphorus (P) from agricultural drainage in situ, a Paddy Eco-ditch and Wetland System (PEDWS) was designed and built based on the characteristics of the irrigated rice district. A 2-year (2012-2013) field experiment was conducted to evaluate the performance of this system in Gaoyou Irrigation District in Eastern China. The results showed that the reduction in water input in paddy field of the PEDWS enabled the maintenance of high rice yield; it significantly increased irrigation water productivity (WPI), gross water productivity (WPG), and evapotranspiration water productivity (WPET) by 109.2, 67.1, and 17.6%, respectively. The PEDWS dramatically decreased N and P losses from paddy field. Compared with conventional irrigation and drainage system (CIDS), the amount of drainage water from PEDWS was significantly reduced by 56.2%, the total nitrogen (TN) concentration in drainage was reduced by 42.6%, and thus the TN and total phosphorus (TP) losses were reduced by 87.8 and 70.4%. PEDWS is technologically feasible and applicable to treat nutrient losses from paddy fields in situ and can be used in similar areas. PMID:25304242

  16. 77 FR 4862 - Agency Requests for Renewal of a Previously Approved Information Collection: SBTRC Regional Field...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-31

    ... Information Collection: SBTRC Regional Field Offices Intake Form (DOT F 4500) and SBTRC Regional Field Offices Quarterly Report Form (DOT F 4502) AGENCY: Office of Small and Disadvantaged Business Utilization (OSDBU... Offices Quarterly Report Form, respectively. The Regional Field Offices Intake Form (No. DOT F 4500)...

  17. Wide Field Imaging of the Hubble Deep Field-South Region III: Catalog

    NASA Technical Reports Server (NTRS)

    Palunas, Povilas; Collins, Nicholas R.; Gardner, Jonathan P.; Hill, Robert S.; Malumuth, Eliot M.; Rhodes, Jason; Teplitz, Harry I.; Woodgate, Bruce E.

    2002-01-01

    We present 1/2 square degree uBVRI imaging around the Hubble Deep Field - South. These data have been used in earlier papers to examine the QSO population and the evolution of the correlation function in the region around the HDF-S. The images were obtained with the Big Throughput Camera at CTIO in September 1998. The images reach 5 sigma limits of u approx. 24.4, B approx. 25.6, V approx. 25.3, R approx. 24.9 and I approx. 23.9. We present a catalog of approx. 22,000 galaxies. We also present number-magnitude counts and a comparison with other observations of the same field. The data presented here are available over the world wide web.

  18. Soil removal as a decontamination practice and radiocesium accumulation in tadpoles in rice paddies at Fukushima.

    PubMed

    Sakai, Masaru; Gomi, Takashi; Nunokawa, Masanori; Wakahara, Taeko; Onda, Yuichi

    2014-04-01

    We investigated the biological accumulation of radiocesium in tadpoles [Rana (Pelophylax) porosa porosa] in rice paddies with and without decontamination practice at Fukushima. Radiocesium was accumulated in surface part of soils both in the control and decontaminated paddies one year after decontamination. Mean (134)Cs and (137)Cs concentrations in tadpoles in the control and decontaminated paddies were 3000 and 4500, and 600 and 890Bq/kg dry weight, respectively. Radiocesium concentrations in surface soil (0-5cm depth) and tadpoles in the decontaminated paddy were five times smaller than in the control paddy. These results suggest that decontamination practice can reduce radiocesium concentrations in both soil and tadpoles. However, at the decontaminated paddy, radiocesium concentrations in surface soils became 3.8 times greater one year after decontamination, which indicates that monitoring the subsequent movement of radiocesium in rice paddies and surrounding areas is essential for examining contamination propagation. PMID:24463474

  19. Behavior of butachlor and pyrazosulfuron-ethyl in paddy water using micro paddy lysimeters under different temperature conditions in spring and summer.

    PubMed

    Ok, Junghun; Doan, Nguyen Hai; Watanabe, Hirozumi; Thuyet, Dang Quoc; Boulange, Julien

    2012-08-01

    The behavior of butachlor and pyrazosulfuron-ethyl in paddy water was investigated using micro paddy lysimeters with prescribed hydrological conditions under ambient temperature in spring and summer for simulating two rice crop seasons. Although they were not significantly different, the dissipation of both herbicides in paddy water in the summer experiment was faster than in the spring experiment. The half-lives (DT(50)) in paddy water for spring and summer experiments were 3.2 and 2.5 days for butachlor, and 3.1 and 1.6 days for pyrazosulfuron-ethyl, respectively. PMID:22696099

  20. Risk Assessment of Heavy Metals Contamination in Paddy Soil, Plants, and Grains (Oryza sativa L.) at the East Coast of India

    PubMed Central

    Satpathy, Deepmala; Reddy, M. Vikram; Dhal, Soumya Prakash

    2014-01-01

    Heavy metals known to be accumulated in plants adversely affect human health. This study aims to assess the effects of agrochemicals especially chemical fertilizers applied in paddy fields, which release potential toxic heavy metals into soil. Those heavy metals get accumulated in different parts of paddy plant (Oryza sativa L.) including the grains. Concentrations of nonessential toxic heavy metals (Cd, Cr, and Pb) and the micronutrients (Cu, Mn, and Zn) were measured in the paddy field soil and plant parts. Mn and Cd are found to be accumulated more in shoot than in root. The metal transfer factors from soil to rice plant were significant for Pb, Cd, Cu, Cr, Mn, and Zn. The ranking order of bioaccumulation factor (BAF) for heavy metals was Zn > Mn > Cd > Cu > Cr > Pb indicating that the accumulation of micronutrients was more than that of nonessential toxic heavy metals. The concentrations of heavy metals were found to be higher in paddy field soils than that of the nearby control soil but below permissible limits. The higher Health Index (HI) values of rice consuming adults (1.561) and children (1.360) suggest their adverse health effects in the near future. PMID:24995308

  1. Regional Stress Field in the Maghreb Region From an Updated Focal Mechanism Catalog (1954-2014)

    NASA Astrophysics Data System (ADS)

    Lamara, Samir; Friederich, Wolfgang

    2015-04-01

    In order to investigate the regional stress field in the Maghreb region we construct a focal mechanism catalog for earthquakes that occurred from 1954 to 2014. To this intent, all available moment tensor solutions of past earthquakes obtained from different sources were checked, compared and corrected. Furthermore, the focal solutions of all recent earthquakes with magnitude down to 4 and for which data is available were calculated using a new method based on waveform fitting of observed seismograms and synthetics calculated for a range of fault angles and hypocenter depths. Observed seismograms of all stations for a given earthquake were thus collected, processed and subject to a rigorous quality control according to the corresponding signal-to-noise ratio. An average 1-D earth model for the Maghreb-western Mediterranean region was also constructed to calculate synthetics. The misfits between these observed seismograms and a set of synthetics calculated for every value of fault angles (strike, dip and rake) and hypocenter depths were calculated after respectively, a phase fitting obtained by shifting the seismograms to the best cross-correlation between data and synthetics, and amplitudes scaling. The best configuration of fault angles and hypocenter depths was then selected according to the smallest average misfit over all stations. If a systematic time shift was noticeable for all stations or most of them, an additional relocation step was done to obtain the most accurate earthquake's epicenter. Most of the earthquakes included in the catalog define several spatial clusters for which the assumption of homogeneous stress can be fulfilled. Hence, a stress inversion for each cluster was performed and a stress ratio indicating the dominance of compressional or tensional stresses as well as the directions and dips of the tensional, intermediate and compressional axis were obtained.

  2. Oryzobacter terrae gen. nov., sp. nov., isolated from paddy soil.

    PubMed

    Kim, Soo-Jin; Lim, Jun-Muk; Hamada, Moriyuki; Ahn, Jae-Hyung; Weon, Hang-Yeon; Suzuki, Ken-ichiro; Ahn, Tae-Young; Kwon, Soon-Wo

    2015-09-01

    A bacterial strain, PSGM2-16(T), was isolated from a pot of paddy soil grown with rice in Suwon region, Republic of Korea, and was characterized as having aerobic, Gram-stain-positive, short-rod-shaped cells with one polar flagellum. The 16S rRNA gene sequence of strain PSGM2-16(T) revealed the highest sequence similarities with Knoellia locipacati DMZ1T (97.4%), Fodinibacter luteus YIM C003(T) (97.2%) and Lapillicoccus jejuensis R-Ac013(T) (97.0%), and the phylogenetic tree showed that strain PSGM2-16(T) formed a subgroup with Ornithinibacter aureus HB09001(T) and F. luteus YIM C003(T) within the family Intrasporangiaceae. The major fatty acids (>10% of the total fatty acids) of strain PSGM2-16(T) were iso-C16 : 0, C17 : 1?8c and iso-C14 : 0. The predominant menaquinone was MK-8(H4). The polar lipids present were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, three aminophospholipids and two phospholipids. The peptidoglycan was type A4? with meso-diaminopimelic acid as the diagnostic diamino acid. DNA-DNA hybridization values between strain PSGM2-16(T) and closely related taxa were much less than 70%. The genomic DNA G+C content of strain PSGM2-16(T) was 70.0 mol%. On the basis of the evidence presented, it is concluded that strain PSGM2-16(T) represents a novel species of a new genus in the family Intrasporangiaceae, for which the name Oryzobacter terrae gen. nov., sp. nov. is proposed. The type strain of the type species is PSGM2-16(T) (?= KACC 17299(T)= DSM 27137(T)= NBRC 109598(T)). PMID:26297674

  3. On the performance of surface renewal analysis to estimate sensible heat flux over two growing rice fields under the influence of regional advection

    NASA Astrophysics Data System (ADS)

    Castellví, F.; Snyder, R. L.

    2009-09-01

    SummaryHigh-frequency temperature data were recorded at one height and they were used in Surface Renewal (SR) analysis to estimate sensible heat flux during the full growing season of two rice fields located north-northeast of Colusa, CA (in the Sacramento Valley). One of the fields was seeded into a flooded paddy and the other was drill seeded before flooding. To minimize fetch requirements, the measurement height was selected to be close to the maximum expected canopy height. The roughness sub-layer depth was estimated to discriminate if the temperature data came from the inertial or roughness sub-layer. The equation to estimate the roughness sub-layer depth was derived by combining simple mixing-length theory, mixing-layer analogy, equations to account for stable atmospheric surface layer conditions, and semi-empirical canopy-architecture relationships. The potential for SR analysis as a method that operates in the full surface boundary layer was tested using data collected over growing vegetation at a site influenced by regional advection of sensible heat flux. The inputs used to estimate the sensible heat fluxes included air temperature sampled at 10 Hz, the mean and variance of the horizontal wind speed, the canopy height, and the plant area index for a given intermediate height of the canopy. Regardless of the stability conditions and measurement height above the canopy, sensible heat flux estimates using SR analysis gave results that were similar to those measured with the eddy covariance method. Under unstable cases, it was shown that the performance was sensitive to estimation of the roughness sub-layer depth. However, an expression was provided to select the crucial scale required for its estimation.

  4. Imazethapyr and imazapic, bispyribac-sodium and penoxsulam: zooplankton and dissipation in subtropical rice paddy water.

    PubMed

    Reimche, Geovane B; Machado, Srgio L O; Oliveira, Maria Anglica; Zanella, Renato; Dressler, Valderi Luiz; Flores, Erico M M; Gonalves, Fbio F; Donato, Filipe F; Nunes, Matheus A G

    2015-05-01

    Herbicides are very effective at eliminating weed and are largely used in rice paddy around the world, playing a fundamental role in maximizing yield. Therefore, considering the flooded environment of rice paddies, it is necessary to understand the side effects on non-target species. Field experiment studies were carried out during two rice growing seasons in order to address how the commonly-used herbicides imazethapyr and imazapic, bispyribac-sodium and penoxsulam, used at recommended dosage, affect water quality and the non-target zooplankton community using outdoor rice field microcosm set-up. The shortest (4.9 days) and longest (12.2 days) herbicide half-life mean, estimated of the dissipation rate (k) is shown for imazethapyr and bispyribac-sodium, respectively. Some water quality parameters (pH, conductivity, hardness, BOD5, boron, potassium, magnesium, phosphorus and chlorides) achieved slightly higher values at the herbicide treatment. Zooplankton community usually quickly recovered from the tested herbicide impact. Generally, herbicides led to an increase of cladocera, copepods and nauplius population, while rotifer population decreased, with recovery at the end of the experiment (88 days after herbicide treatment). PMID:25659307

  5. Regional Ecorisk Field investigation, upper Clark Fork River Basin

    SciTech Connect

    Pastorok, R.; LaTier, A.; Ginn, T.

    1995-12-31

    The Regional Ecorisk Field Investigation was conducted at the Clark Fork River Superfund Site (Montana) to evaluate the relationships between plant communities and tailings deposits in riparian habitats and to evaluate food-chain transfer of trace elements to selected wildlife species. Stations were selected to represent a range of vegetation biomass (or cover) values and apparent impact of trace elements, with some areas of lush vegetation, some areas of mostly unvegetated soil (e.g., < 30 percent plant cover), and a gradient in between. For the evaluation of risk to wildlife, bioaccumulation of metals was evaluated in native or naturalized plants, terrestrial invertebrates, and the deer mouse (Peromyscus maniculatus). Potential reproductive effects in the deer mouse were evaluated by direct measurements. For other wildlife species, bioaccumulation data were interpreted in the context of food web exposure models. Total biomass and species richness of riparian plant communities are related to tailings content of soil as indicated by pH and metals concentrations. Risk to populations of omnivorous small mammals such as the deer mouse was not significant. Relative abundance and reproductive condition of the deer mouse were normal, even in areas of high metals enrichment. Based on exposure models and site-specific tissue residue data for dietary species, risk to local populations of predators such as red fox and American kestrel that feed on deer mice and terrestrial invertebrates is not significant. Risk to herbivores related to metals bioaccumulation in plant tissues is not significant. Population level effects in deer and other large wildlife are not expected because of the large home ranges of such species and compensatory demographic factors.

  6. Community structure and abundance of ammonia-oxidizing archaea and bacteria after conversion from soybean to rice paddy in albic soils of Northeast China.

    PubMed

    Wang, Jing; Wang, Weidong; Gu, Ji-Dong

    2014-03-01

    Community composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in the albic soil grown with soybean and rice for different years was investigated by construction of clone libraries, denaturing gradient gel electrophoresis (DGGE), and quantitative polymerase chain reaction (q-PCR) by PCR amplification of the ammonia monooxygenase subunit A (amoA) gene. Soil samples were collected at two layers (0-5 and 20-25 cm) from a soybean field and four rice paddy fields with 1, 5, 9, and 17 years of continuous rice cultivation. Both the community structures and abundances of AOA and AOB showed detectable changes after conversion from soybean to rice paddy judged by clone library, DGGE, and q-PCR analyses. In general, the archaeal amoA gene abundance increased after conversion to rice cultivation, while bacterial amoA gene abundance decreased. The abundances of both AOA and AOB were higher in the surface layer than the bottom one in the soybean field, but a reverse trend was observed for AOB in all paddy samples regardless of the duration of paddy cultivation. Phylogenetic analysis identified nine subclusters of AOA and seven subclusters of AOB. Community composition of both AOA and AOB was correlated with available ammonium and increased pH value caused by flooding in multiple variance analysis. Community shift of AOB was also observed in different paddy fields, but the two layers did not show any detectable changes in DGGE analysis. Conversion from soybean to rice cultivation changed the community structure and abundance of AOA and AOB in albic agricultural soil, which requires that necessary cultivation practice be followed to manage the N utilization more effectively. PMID:24092004

  7. A true-field magnetogram in a solar plage region

    NASA Technical Reports Server (NTRS)

    Rabin, Douglas

    1992-01-01

    The Near-Infrared Magnetograph is used to make the first 2D image of true magnetic field strength in the solar photosphere. The magnitude of the magnetic field vector is derived with a typical formal precision of + or - 75 G (2 sigma) from circularly polarized spectra of a highly Zeeman-sensitive iron line at 6388.6/cm. The true-field map demonstrates that the properties of 'kilogauss' flux tubes vary coherently on a variety of spatial scales within the 1-arcmin field of view. The measured fields span the range 1000-1700 G. The amplitude of the polarized signal implies that the spatial filling factor of the flux tubes can approach 0.3 at the seeing-limited resolution of 2 arcsec. Magnetic field strength and magnetic flux are statistically related in the sense that weak-field areas are weak-flux areas, but strong fields are present in both strong-flux and weak-flux areas. This implies a degree of independence in the relationship between the filling factor of flux tubes and their individual properties, such as field strength, pressure, and temperature.

  8. Regional assemblages of Lygus (Heteroptera: Miridae) in Montana canola fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sweep net sampling of canola (Brassica napus L.) was conducted in 2002 and 2003 to determine Lygus (Heteroptera: Miridae) species composition and parasitism levels in four regions of Montana. Regardless of region or seasonal change, Lygus elisus (Van Duzee) was the dominant species in all canola fi...

  9. Risk assessment of Cd polluted paddy soils in the industrial and township areas in Hunan, Southern China.

    PubMed

    Wang, Meie; Chen, Weiping; Peng, Chi

    2016-02-01

    Cadmium (Cd) contamination in rice in Youxian, Hunan, China is a major environmental health concern. In order to reveal the Cd contamination in rice and paddy soils and the health risks to the population consuming the local rice grain, field surveys were conducted in eight towns in Youxian, China. The Cd contents of paddy soils averaged 0.228-1.91 mg kg(-1), 90% exceeding the allowable limit of 0.3 mg kg(-1) stipulated by the China Soil Environmental Quality Standards. Low average pH values (for air dried oxidized soils) ranging from 4.98 to 6.02 in paddy soil were also found. More than seventy percent (39 of 53) of the grain samples exceeded the maximum safe concentration of Cd, 0.2 mg kg(-1) on a dry weight basis. Considering the high consumption of local rice (339 g capita(-1) DW d(-1)) and Cd levels measured, dietary ingestion of 78% of the sampled rice grains would have adverse health risks because the intake exposure of Cd was greater than the JECFA recommended exposures, 0.8 µg Cd BW kg(-1) day(-1) or 25 µg Cd BW kg(-1) month(-1). PMID:26378871

  10. [Effects of biochar application on greenhouse gas emission from paddy soil and its physical and chemical properties].

    PubMed

    Liu, Yu-xue; Wang, Yao-feng; Lü, Hao-hao; Chen, Yi; Tang, Xu; Wu, Chun-yan; Zhong, Zhe-ke; Yang, Sheng-mao

    2013-08-01

    A field experiment was conducted to investigate the effects of rice straw returning and rice straw biochar and life rubbish biochar application on the greenhouse gas (CH4, CO2 and N2O) emission from paddy soil, its physical and chemical properties, and rice grain yield. Compared with rice straw returning, applying rice straw biochar decreased the cumulative CH4 and N2O emissions from paddy soil significantly by 64.2% - 78.5% and 16.3% - 18.4%, respectively. Whether planting rice or not, the cumulative N2O emission from paddy soil under the applications of rice straw biochar and life rubbish biochar was decreased significantly, compared with that without biochar amendment. Under the condition of no rice planting, applying life rubbish biochar reduced the cumulative CO2 emission significantly by 25.3%. Rice straw biochar was superior to life rubbish biochar in improving soil pH and available potassium content. Both rice straw biochar and life rubbish biochar could increase the soil organic carbon content significantly, but had less effects on the soil bulk density, total nitrogen and available phosphorus contents, cation exchange capacity (CEC), and grain yield. It was suggested that compared with rice straw returning, straw biochar was more effective in improving rice grain yield. PMID:24380334

  11. Problems of the acetylene reduction technique applied to water-saturated paddy soils.

    PubMed

    Lee, K K; Watanabe, I

    1977-12-01

    The acetylene reduction assay for the measurement of N(2) fixation in a water-saturated paddy soil is limited by the slow diffusion of acetylene and ethylene. In laboratory incubation tests, vigorous shaking after the assay period is needed to release ethylene into the gas within the assay vials. Shaking prior to the incubation is also effective for dissolving acetylene in the water-saturated soil. However, a water-saturated soil depth of less than 10 mm during incubation is recommended. In field assays, some amounts of ethylene remain in the water-saturated soil phase of the acetylene reduction assay chamber, but stirring the water-saturated soil before sampling reduces the amount of ethylene remaining in soil. Evidence of a downward movement of acetylene and an upward movement of ethylene through rice plants was obtained. Because of the rapid transfer of acetylene to rice plant roots, an in situ acetylene reduction assay covering a rice hill is likely to detect nitrogen fixation in the proximity of roots where acetylene is easily accessible. Acetylene introduction to the water-saturated soil phase prior to assay did not greatly increase the acetylene reduction rate. Carbon dioxide enrichment in the assay chamber did not enhance nitrogen fixation in a paddy including rice and algae during a 1-day cycle. PMID:16345257

  12. Seasonal Transition of Active Bacterial and Archaeal Communities in Relation to Water Management in Paddy Soils

    PubMed Central

    Itoh, Hideomi; Ishii, Satoshi; Shiratori, Yutaka; Oshima, Kenshiro; Otsuka, Shigeto; Hattori, Masahira; Senoo, Keishi

    2013-01-01

    Paddy soils have an environment in which waterlogging and drainage occur during the rice growing season. Fingerprinting analysis based on soil RNA indicated that active microbial populations changed in response to water management conditions, although the fundamental microbial community was stable as assessed by DNA-based fingerprinting analysis. Comparative clone library analysis based on bacterial and archaeal 16S rRNAs (5,277 and 5,436 clones, respectively) revealed stable and variable members under waterlogged or drained conditions. Clones related to the class Deltaproteobacteria and phylum Euryarchaeota were most frequently obtained from the samples collected under both waterlogged and drained conditions. Clones related to syntrophic hydrogen-producing bacteria, hydrogenotrophic methanogenic archaea, rice cluster III, V, and IV, and uncultured crenarchaeotal group 1.2 appeared in greater proportion in the samples collected under waterlogged conditions than in those collected under drained conditions, while clones belonging to rice cluster VI related to ammonia-oxidizing archaea (AOA) appeared at higher frequency in the samples collected under drained conditions than in those collected under waterlogged conditions. These results suggested that hydrogenotrophic methanogenesis may become active under waterlogged conditions, whereas ammonia oxidation may progress by rice cluster VI becoming active under drained conditions in the paddy field. PMID:24005888

  13. A Regional Public Health Field Placement Program: making an IMPACT.

    PubMed

    McCormick, Lisa C; Hites, Lisle; Jenkins, Crystal; Chauvin, Sheila W; Rucks, Andrew C; Ginter, Peter M

    2014-03-01

    Beginning in 2010, the U.S. Department of Health and Human Services, Health Resources and Services Administration, made provisions in its Public Health Training Center cooperative agreements for field placements. This article describes best practices and lessons learned establishing and managing the South Central Public Health Partnership's Interns and Mentors Program for ACTion (IMPACT) Field Placement Program, which was initially funded through the Centers for Disease Control and Prevention's Centers for Public Health Preparedness Cooperative agreement in 2002. The IMPACT program is based on a six-step process that has been developed and refined over its 10-year history: (a) identifying field placement opportunities, (b) marketing field experience opportunities to students, (c) selecting students seeking field experience opportunities, (d) placing students with practice partners, students with practice partners, (e) evaluating student progress toward field experience objectives, and (f) evaluating the program. This article describes the program's structure and processes, delineates the roles of its academic and practice partners, discusses evidence of its effectiveness, and describes lessons learned from its decade-long history. Hopefully, this information will facilitate the establishment, management and evaluation of internship and field placement programs in other Public Health Training Centers and academic public health programs. PMID:24578369

  14. Mapping Magnetic Fields in Star Forming Regions with BLASTPol

    NASA Astrophysics Data System (ADS)

    Fissel, Laura M.; Ade, Peter; Angilè, Francesco E.; Ashton, Peter; Benton, Steven J.; Devlin, Mark J.; Dober, Bradley; Fukui, Yasuo; Galitzki, Nicholas B.; Gandilo, Natalie; Klein, J. R.; Li, Zhi-Yun; Korotkov, Andrei; Martin, Peter G.; Matthews, Tristan; Moncelsi, Lorenzo; nakamura, fumitaka; Barth Netterfield, Calvin; Novak, Giles; Pascale, Enzo; Poidevin, Frédérick; Pereira Santos, Fábio; Savini, Giorgio; Scott, Douglas; Shariff, Jamil; Soler, Juan D.; Thomas, Nicholas; tucker, carole; Tucker, Gregory S.; Ward-Thompson, Derek

    2016-01-01

    A key outstanding question in our understanding of star formation is whether magnetic fields provide support against the gravitational collapse of their parent molecular clouds and cores. Direct measurement of magnetic field strength is observationally challenging, however observations of polarized thermal emission from dust grains aligned with respect to the local cloud magnetic field can be used to map out the magnetic field orientation in molecular clouds. Statistical comparisons between these submillimeter polarization maps and three-dimensional numerical simulations of magnetized star-forming clouds provide a promising method for constraining magnetic field strength. We present early results from a BLASTPol study of the nearby giant molecular cloud (GMC) Vela C, using data collected during a 2012 Antarctic flight. This sensitive balloon-borne polarimeter observed Vela C for 57 hours, yielding the most detailed submillimeter polarization map ever made of a GMC forming high mass stars. We find that most of the structure in p can be modeled by a power-law dependence on two quantities: the hydrogen column density and the local dispersion in magnetic field orientation. Our power-law model for p(N,S) provides new constraints for models of magnetized star-forming clouds and an important first step in the interpretation of the BLASTPol 2012 data set.

  15. An Approach to Assessing Flood Risk in Low-lying Paddy Areas of Japan considering Economic Damage on Rice

    NASA Astrophysics Data System (ADS)

    Minakawa, H.; Masumoto, T.

    2013-12-01

    Hiroki Minakawa, Takao Masumoto National Institute for Rural Engineering (NIRE), NARO, Japan Flooding is one type of nature disaster, and is caused by heavy rainfall events. In the future, the risk of flooding is predicted to increase due to global climate change. Immediate measures such as strengthening drainage capacity are needed to minimize the damage caused by more frequent flooding, so a quantitative evaluation method of flood risks is needed to discuss countermeasure against these problems. At the same time, rice is an important crop for food production in Japan. However, paddy fields are often damaged by flooding because they are principally spread in lower part of the basin. Therefore, it is also important to assess the damages to paddy fields. This study discusses a method for evaluating a relationship between the risk of flood damage and the scale of heavy rainfall. We also developed a method of estimating the economic effect of a reduction in rice yield by flooding. First, we developed a drainage analysis model that incorporates kinematic and diffusive runoff models for calculating water level in channels and paddies. Next, heavy rainfall data for drainage analyses were generated by using a diurnal rainfall pattern generator. The generator can create hourly data of heavy rainfall, and internal pattern of them is different each. These data were input to the drainage model to estimate flood risk. Simultaneously, we tried to clarify economic losses of a rice yields caused by flooding. Here, the reduction scale in rice yield which shows relations between flooding situation (e.g. water level, duration of submersion etc.) and damage of rice is available to calculate reduction of rice yield. In this study, we created new reduction scales through a pseudo-flooding experiment under real inundation conditions. The methodology of the experiment was as follow: We chose the popular Japanese rice cultivar Koshihikari for this experiment. An experimental arena was constructed in a rice paddy plot, which consisted of two zones, one in which the rice was cultivated as usual with normal water levels, and a flood zone, which was used for submerging rice plants. The flood zone, which was designed to reproduce actual flood disaster conditions in paddy fields, can be filled with water to a depth of 0.3, 0.6 or 0.9 m above ground level, and is divided into two plots, a clean water part and a turbid water part. Thus, the experimental conditions can vary according to 1) the development stage of rice, 2) complete or incomplete submersion, 3) clean or turbid water, and 4) duration of submergence. Finally, the reduction scales were formulated by using the resultant data and it was found that rice is most sensitive to damage during the development stage. Flood risk was evaluated by using calculated water level on each paddy. Here, the averaged duration of inundation to a depth of more than 0.3 m was used as the criteria for flood occurrence. The results indicated that the duration increased with larger heavy rainfall amounts. Furthermore, the damage to rice was predicted to increase especially in low-lying paddy fields. Mitigation measures, such as revising drainage planning and/or changing design standards for the capacity of drainage pumps may be necessary in the future.

  16. Correlation between magnetic and electric field perturbations in the field-aligned current regions deduced from DE 2 observations

    NASA Technical Reports Server (NTRS)

    Ishii, M.; Sugiura, M.; Iyemori, T.; Slavin, J. A.

    1992-01-01

    The satellite-observed high correlations between magnetic and electric field perturbations in the high-latitude field-aligned current regions are investigated by examining the dependence of the relationship between Delta-B and E on spatial scale, using the electric and magnetic field data obtained by DE 2 in the polar regions. The results are compared with the Pedersen conductivity inferred from the international reference ionosphere model and the Alfven wave velocity calculated from the in situ ion density and magnetic field measurements.

  17. Eco-Stoichiometric Alterations in Paddy Soil Ecosystem Driven by Phosphorus Application

    PubMed Central

    Li, Xia; Wang, Hang; Gan, ShaoHua; Jiang, DaQian; Tian, GuangMing; Zhang, ZhiJian

    2013-01-01

    Agricultural fertilization may change processes of elemental biogeochemical cycles and alter the ecological function. Ecoenzymatic stoichiometric feature plays a critical role in global soil carbon (C) metabolism, driving element cycles, and mediating atmospheric composition in response to agricultural nutrient management. Despite the importance on crop growth, the role of phosphorous (P) in compliance with eco-stoichiometry on soil C and nitrogen (N) sequestration in the paddy field remains poorly understood in the context of climate change. Here, we collected soil samples from a field experiment after 6 years of chemical P application at a gradient of 0 (P-0), 30 (P-30), 60 (P-60), and 90 (P-90) kg ha?1 in order to evaluate the role of P on stoichiometric properties in terms of soil chemical, microbial biomass, and eco-enzyme activities as well as greenhouse gas (GHG: CO2, N2O and CH4) emissions. Continuous P input increased soil total organic C and N by 1.39.2% and 3%13%, respectively. P input induced C and N limitations as indicated by the decreased ratio of C:P and N:P in the soil and microbial biomass. A synergistic mechanism among the ecoenzymatic stoichiometry, which regulated the ecological function of microbial C and N acquisition and were stoichiometrically related to P input, stimulated soil C and N sequestration in the paddy field. The lower emissions of N2O and CH4 under the higher P application (P-60 and P-90) in July and the insignificant difference in N2O emission in August compared to P-30; however, continuous P input enhanced CO2 fluxes for both samplings. There is a technical conflict for simultaneously regulating three types of GHGs in terms of the eco-stoichiometry mechanism under P fertilization. Thus, it is recommended that the P input in paddy fields not exceed 60 kg ha?1 may maximize soil C sequestration, minimize P export, and guarantee grain yields. PMID:23667435

  18. Eco-stoichiometric alterations in paddy soil ecosystem driven by phosphorus application.

    PubMed

    Li, Xia; Wang, Hang; Gan, Shaohua; Jiang, Daqian; Tian, Guangming; Zhang, Zhijian

    2013-01-01

    Agricultural fertilization may change processes of elemental biogeochemical cycles and alter the ecological function. Ecoenzymatic stoichiometric feature plays a critical role in global soil carbon (C) metabolism, driving element cycles, and mediating atmospheric composition in response to agricultural nutrient management. Despite the importance on crop growth, the role of phosphorous (P) in compliance with eco-stoichiometry on soil C and nitrogen (N) sequestration in the paddy field remains poorly understood in the context of climate change. Here, we collected soil samples from a field experiment after 6 years of chemical P application at a gradient of 0 (P-0), 30 (P-30), 60 (P-60), and 90 (P-90) kg ha(-1) in order to evaluate the role of P on stoichiometric properties in terms of soil chemical, microbial biomass, and eco-enzyme activities as well as greenhouse gas (GHG: CO2, N2O and CH4) emissions. Continuous P input increased soil total organic C and N by 1.3-9.2% and 3%-13%, respectively. P input induced C and N limitations as indicated by the decreased ratio of C:P and N:P in the soil and microbial biomass. A synergistic mechanism among the ecoenzymatic stoichiometry, which regulated the ecological function of microbial C and N acquisition and were stoichiometrically related to P input, stimulated soil C and N sequestration in the paddy field. The lower emissions of N2O and CH4 under the higher P application (P-60 and P-90) in July and the insignificant difference in N2O emission in August compared to P-30; however, continuous P input enhanced CO2 fluxes for both samplings. There is a technical conflict for simultaneously regulating three types of GHGs in terms of the eco-stoichiometry mechanism under P fertilization. Thus, it is recommended that the P input in paddy fields not exceed 60 kg ha(-1) may maximize soil C sequestration, minimize P export, and guarantee grain yields. PMID:23667435

  19. Nitrate leaching in californian rice fields: a field- and regional-scale assessment.

    PubMed

    Liang, X Q; Harter, T; Porta, L; van Kessel, C; Linquist, B A

    2014-05-01

    Irrigated croplands can be a major source of nitrate-N (NO-N) in groundwater due to leaching. In California, where high NO-N levels have been found in some areas of the Central Valley aquifer, the contribution from rice systems has not been determined. Nitrate leaching from rice systems was evaluated from soil cores (0-2 m), from the fate of N fertilizer in replicated microplots, and from about 145 regional groundwater wells. Soil NO-N concentrations were ≤3.3 mg kg (usually <1 mg kg) below the root zone (below 33 cm depth). In pore-water samples, NO-N was observed only below the root zone during the first 2 wk after the onset of flooding in either the growing season or the winter fallow period and was always ≤8.4 mg L. Fertilizer N accounted for 0 to 11.8% of NO-N in pore-water samples below the root zone. One year after application, based on an analysis of soil core samples, on average 2.5% of fertilizer N was recovered as N below the root zone (33-100 cm), possibly due to leaching in permeable soils or via preferential flow through cracks in heavy clay soils. Based on a regional assessment, groundwater samples from wells that are located in proximity to rice fields all had measured median NO-N and NO-N levels below 1 mg L. These results indicate that NO-N leaching from the majority of California rice systems poses little risk to groundwater under current crop management practices. PMID:25602817

  20. Estimation of Korean paddy field soil properties using optical reflectance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An optical sensing approach based on diffuse reflectance has shown potential for rapid and reliable on-site estimation of soil properties. Important sensing ranges and the resulting regression models useful for soil property estimation have been reported. In this study, a similar approach was applie...

  1. ESTIMATION OF KOREAN PADDY FIELD SOIL PROPERTIES USING OPTICAL REFLECTANCE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An optical sensing approach based on diffuse reflectance has shown potential for rapid and reliable on-site estimation of soil properties. Important sensing ranges and the resulting regression models useful for soil property estimation have been reported. In this study, a similar approach was applie...

  2. Cross-flow fluidized bed paddy dryer: Prototype and commercialization

    SciTech Connect

    Soponronnarit, S.; Yapha, M.; Prachayawarakorn, S.

    1995-12-31

    The objective of this paper is to design and test a prototype, 0.82 ton/h capacity, fluidized bed paddy dryer for high moisture paddy. Exhausted air is partially recycled. Experimental results showed that the unit operated efficiently and yielded high product quality in terms of head yield and whiteness. In reducing the moisture content from 45% to 24% dry-basis using air temperature of 100--120 C, fraction of air recycled of 0.66, specific air flow rate of 0.05 kg/s-kg dry matter, superficial air velocity of 3.2 m/s, bed depth of 0.1 m, total primary energy consumption was 2.32 MJ/kg water evaporated of which 0.35 was primary energy from electricity (electrical energy multiplied by 2.6) and 1.79 was primary energy in terms of heat.

  3. Electro-kinetic remediation coupled with phytoremediation to remove lead, arsenic and cesium from contaminated paddy soil.

    PubMed

    Mao, Xinyu; Han, Fengxiang X; Shao, Xiaohou; Guo, Kai; McComb, Jacqueline; Arslan, Zikri; Zhang, Zhanyu

    2016-03-01

    The objectives of this study were to investigate distribution and solubility of Pb, Cs and As in soils under electrokinetic field and examine the processes of coupled electrokinetic phytoremediation of polluted soils. The elevated bioavailability and bioaccumulation of Pb, As and Cs in paddy soil under an electro-kinetic field (EKF) were studied. The results show that the EKF treatment is effective on lowering soil pH to around 1.5 near the anode which is beneficial for the dissolution of metal(loid)s, thus increasing their overall solubility. The acidification in the anode soil efficiently increased the water soluble (SOL) and exchangeable (EXC) Pb, As and Cs, implying enhanced solubility and elevated overall potential bioavailability in the anode region while lower solubility in the cathode areas. Bioaccumulations of Pb, As and Cs were largely determined by the nature of elements, loading levels and EKF treatment. The native Pb in soil usually is not bioavailable. However, EKF treatment tends to transfer Pb to the SOL and EXC fractions improving the phytoextraction efficiency. Similarly, EKF transferred more EXC As and Cs to the SOL fraction significantly increasing their bioaccumulation in plant roots and shoots. Pb and As were accumulated more in plant roots than in shoots while Cs was accumulated more in shoots due to its similarity of chemical properties to potassium. Indian mustard, spinach and cabbage are good accumulators for Cs. Translocation of Pb, As and Cs from plant roots to shoots were enhanced by EKF. However, this study indicated the overall low phytoextraction efficiency of these plants. PMID:26650421

  4. Inhibition experiments on nitrous oxide emission from paddy soils

    NASA Astrophysics Data System (ADS)

    Xu, Xingkai; Boeckx, Pascal; Zhou, Likai; Van Cleemput, Oswald

    2002-08-01

    Rice fields using nitrogen-based fertilizers play an important role in the global N2O budget. However, our knowledge is still limited with regard to the mechanisms affecting the N2O emission and to the measures that can reduce the emission. This paper reports a study of N2O emission from paddy soils. The effects of urea, hydroquinone (HQ, a urease inhibitor), and dicyandiamide (DCD, a nitrification inhibitor) have been studied in pot experiments with and without rice plants and with and without addition of wheat straw. With no wheat straw amendment, all treatments with inhibitors, especially with HQ + DCD, had a much smaller N2O emission during the rice growing period than the urea treatment, whereas a substantially increased N2O emission was observed from a rice-free soil with inhibitors. The N2O emission from the rice-planted soil was exponentially positive correlated with the NO3--N concentration in the rice aboveground biomass. By comparing the total N2O emission from the rice-free soil and from the rice-planted soil, we found that urea application alone might induce an apparent plant-mediated N2O emission, being 0.39 +/- 0.08% of the applied urea N. Wheat straw incorporated into the flooded surface layer soil could increase the plant-mediated N2O emission significantly. However, application of HQ + DCD could reduce this emission (0.27 +/- 0.08% of the applied urea N, compared with 0.89 +/- 0.18% in the urea treatment). It also reduced the N2O emission from the rice-free soil and from the rice-planted soil. Stepwise regression analysis indicates that denitrification in the flooded surface layer soil was the main source of N2O emission from this wetland rice cultivation, particularly when wheat straw was added. A significantly nonlinear negative relation was found between the N2O emission and the CH4 emission when no wheat straw was added, but it was hard to quantify this trade-off relation when wheat straw was incorporated into the flooded surface layer soil.

  5. Determination of the active region magnetic field structure using vector-magnetographic measurements.

    NASA Astrophysics Data System (ADS)

    Grigor'ev, V. M.; Osak, B. F.; Selivanov, V. L.

    Some methodical questions concerning magnetic field vector observations in solar active regions are discussed. The observations of the magnetic field configuration of the single sunspot of 19 May 1983 (E24, S27) and of the leading sunspot in the active region of 24 June 1983 (W08, N17) are reported.

  6. Sensor Measurements and Sediment Incubations Indicate Diurnal Redox Cycling Associate With Arsenic Mobilization at a Bangladeshi Rice Paddy

    NASA Astrophysics Data System (ADS)

    Lin, T.; Lin, C.; Ramanathan, N.; Neumann, R.; Harvey, C.; Jay, J.

    2007-12-01

    The presence of arsenic in the groundwater has led to the largest environmental poisoning in history; tens of millions of people in the Ganges Delta continue to drink groundwater that is dangerously contaminated with arsenic (As). Rice fields receive large loads of arsenic with irrigation water and provide recharge to the underlying aquifer. It is currently not known whether rice fields are a sink or source of arsenic in the hydrologic system. In the dry season, as As(III)-containing minerals are oxidized, As(V) is released and will adhere to Fe hydr(oxide) minerals. When sediments are inundated with water, reducing conditions will then drive reduction of Fe hydr(oxides) and release of As. We have been intensively studying a field site in Munshiganj, Bangladesh with extremely high levels of arsenic in groundwater (up to 1.2 mg/L). To better understand geochemical and microbial processes leading to As mobilization in surface sediment, we deployed sensors to take temporally dense measurements across our experimental rice paddy. Data collected in both 2006 and 2007 showed trends in geochemical parameters indicating that diurnal, possibly plant-induced, processes may be important. Over a two month period, nitrate concentrations decrease consistently each day as ammonium levels increase, presumably through temperature driven reductive processes. Nitrate concentrations in the subsurface then increase while ammonium levels decrease, possibly due to root oxygen leakage or rapid infiltration of oxygen rich surface water. Using sediment from the rice paddy and artificial irrigation water, laboratory microcosms were constructed to simulate the diurnal cycles observed at the field site. In carbon-ammended treatments, Fe and As cycling can occur on the order of days. Oscillations in redox conditions on diurnal as well as seasonal time scales may be important in the mobilization of arsenic into aquifers. By elucidating As mobilization mechanisms at an experimental rice paddy, this work could ultimately lead to solutions that minimize As exposure in critical populations.

  7. Black carbon accrual during 2000years of paddy-rice and non-paddy cropping in the Yangtze River Delta, China.

    PubMed

    Lehndorff, Eva; Roth, Philipp J; Cao, Zhi H; Amelung, W

    2014-06-01

    Rice straw burning has accompanied paddy management for millennia, introducing black carbon (BC) into soil as the residue of incomplete combustion. This study examined the contribution of BC to soil organic matter and the rate at which it accumulates in paddy soils as a result of prolonged paddy management. Soil depth profiles were sampled along a chronosequence of 0-2000 years of rice-wheat rotation systems and adjacent non-paddy systems (50-700 years) in the Bay of Hangzhou (Zhejiang province, China). The soil BC content and its degree of condensation were assessed using benzene-polycarboxylic acids (BPCAs) as geochemical markers. The results showed that despite regular long term BC input, BC only contributed 7-11% of total soil organic carbon (SOC) in the topsoil horizons. Nevertheless, along with SOC, paddy soils accumulated BC with increasing duration of management until 297 years to reach a steady-state of 13 t BC ha(-1). This was 1.8 times more than in non-paddy soils. The fate of BC in paddy soils (0-1 m) could be modeled revealing an average annual input of 44 kg ha(-1) yr(-1), and a mean residence time of 303 years. The subsoils contributed at least 50% to overall BC stocks, which likely derived from periods prior to land embankment and episodic burial of ancient topsoil, as also indicated by BPCA pattern changes. We conclude that there is a significant but limited accumulation of C in charred forms upon prolonged paddy management. The final contribution of BC to total SOC in paddy soils was similar to that in other aerobic ecosystems of the world. PMID:24227744

  8. The stress field of Vrancea region from fault plane solution (FPS)

    NASA Astrophysics Data System (ADS)

    Telesca, L.; Alcaz, V.; Sandu, I.

    2011-10-01

    The fault plane solutions (FPS) of 247 seismic events were used for stress field investigation of the region. The eigenvectors t, p, b, and moment tensor M components for each FPS were defined and computed numerically. The obtained results confirm the hypothesis of subduction-type intermediate depth earthquakes for the Vrancea seismic region and this may be considered the first approximation of the stress field for the whole of the Vrancea (intermediate depth) region.

  9. The Magnetic Field Distribution in Active Regions in the Quiet Time and during Large Solar Flares

    NASA Astrophysics Data System (ADS)

    Podgorny, I. M.; Podgorny, A. I; Meshalkina, N. S.

    2014-03-01

    Many controversial results about magnetic field behavior in active regions during solar flares are published. The magnetic field dynamics of active regions that produce large (X class) flares are investigated in this paper. The magnetic flux is obtained by using the results of calculations of the normal magnetic component in the active region. It is shown that the main condition for appearance of an X clas s flare is the big magnetic flux (' > 1022Mx) of active region. This condition is necessary but not a sufficient. The large flare appears above an active region, if the magnetic field distribution is very complex. A simple active region with the bipolar magnetic field distribution does not produce a flare. There are no singular magnetic lines above a bipolar region, which can be responsible for a current sheet creation before the flare. During a solar flare, when the accumulated energy is fast released, the conservation of the magnetic field distribution in the active region during the majority of flares takes place. This surprising fact follows from the analysis of the array data obtained with the SOHO and SDO space crafts. The presented results support the flare theory based on the slow magnetic energy accumulation in the coronal current sheet before a flare and its explosive realize due to current sheet instability. The scheme of the current sheet creation is discussed, which explains the magnetic field dissipation in the corona without perturbations of magnetic field distribution on the Sun surface during

  10. Investigating Alfvnic wave propagation in coronal open-field regions.

    PubMed

    Morton, R J; Tomczyk, S; Pinto, R

    2015-01-01

    The physical mechanisms behind accelerating solar and stellar winds are a long-standing astrophysical mystery, although recent breakthroughs have come from models invoking the turbulent dissipation of Alfvn waves. The existence of Alfvn waves far from the Sun has been known since the 1970s, and recently the presence of ubiquitous Alfvnic waves throughout the solar atmosphere has been confirmed. However, the presence of atmospheric Alfvnic waves does not, alone, provide sufficient support for wave-based models; the existence of counter-propagating Alfvnic waves is crucial for the development of turbulence. Here, we demonstrate that counter-propagating Alfvnic waves exist in open coronal magnetic fields and reveal key observational insights into the details of their generation, reflection in the upper atmosphere and outward propagation into the solar wind. The results enhance our knowledge of Alfvnic wave propagation in the solar atmosphere, providing support and constraints for some of the recent Alfvn wave turbulence models. PMID:26213234

  11. Polar region Birkeland current, convection, and aurora for northward interplanetary magnetic field

    SciTech Connect

    Zanetti, L.J.; Potemra, T.A.; Erlandson, R.E.; Bythrow, P.F.; Anderson, B.J. ); Murphree, J.S. ); Marklund, G.T. )

    1990-05-01

    Viking magnetic field, electric field, and image data have been used to assess polar region phenomena for steady state northward interplanetary magnetic field (IMF) conditions. Regions of polar Birkeland current and convection and their extent from the vicinity of the magnetic pole are determined. Also discussed are mechanisms that could produce polar aurora in general; two suggestions are (1) converging electric fields from convection patterns alone and (2) the bifurcation of the magnetotail with its associated plasma transport from convection patterns. Macroscopic (> 1{degree} latitude) systems of Birkeland currents and convection in the polar regions have been established for a case on April 9, 1986, from Viking spacecraft data. The current systems were confined to the highest latitudes of the polar regions and occurred during strongly northward IMF with a significantly negative B{sub x}. An arc extends across the polar region within the dawn cell of Birkeland current. The arc is located at a sunward to antisunward convection reversal that corresponds to a converging electric field. A converging electric field ({gradient} {center dot} E < 0) alone is suggested as the cause of this polar arc. The signature of both transverse disturbance vectors indicates that the polar region dawn NBZ Birkeland current does not connect to the dayside auroral region. It is inferred that the dawn polar region convection cell associated with this Birkeland current is also limited in the sunward direction and does not connect to the dayside auroral region convection.

  12. [Quantitative characteristics and source analysis of heavy metals in paddy soils in downstream of the Second Songhua River, Jilin Province].

    PubMed

    Zhu, Li-lu; Yan, Bai-xing; Wang, Li-xia

    2010-11-01

    In autumn 2008, a total of 65 plough layer soil samples were collected from the paddy fields in Qianguo Irrigation Area located at the downstream of the Second Songhua River. These paddy fields were irrigated with water from the River, and had different irrigation histories. The Cu, Pb, Zn, Cd, Ni, As, and Hg concentrations in the soil samples were determined, and the accumulation characteristics, input approaches, and pollution sources of these heavy metals were analyzed. The Cu, Pb, Zn, Cd, Ni, As, and Hg concentrations in the samples were 14.1-28.4 mg x kg(-1), 37.6-57.4 mg x kg(-1), 53.3-84.4 mg x kg(-1), 0.044-0.367 mg x kg(-1), 18.4-37.0 mg x kg(-1), 3.25-12.11 mg x kg(-1), and 0.031-0.155 mg x kg(-1), respectively. The Pb, Hg, and Cd exhibited an obvious accumulation trend, with their concentrations being 100.0%, 38.7%, and 66.1% higher than the baselines, respectively, while Cu, Zn, Ni, and As had less accumulation. With the increase of irrigation history, the Pb concentration showed a decreasing trend, while the Hg concentration was in reverse. There was no significant correlation between the Cd concentration and the irrigation history. According to source analysis, soil Pb mainly originated from the atmospheric Pb deposition via historical use of leaded gasoline, soil Hg was from the polluted irrigation water from the Second Songhua River, and soil Cd was from the use of chemical fertilizers, pesticides, and other agrochemicals. Though the Pb, Hg, and Cd had obviously accumulated in the paddy fields in Qianguo Irrigation Area, their potential ecological risk was still low, and would not pose threat on the local agricultural production and food security. PMID:21361025

  13. Laboratory study of diffusion region with electron energization during high guide field reconnection

    NASA Astrophysics Data System (ADS)

    Yamasaki, K.; Inoue, S.; Kamio, S.; Watanabe, T. G.; Ushiki, T.; Guo, X.; Sugawara, T.; Matsuyama, K.; Kawakami, N.; Yamada, T.; Inomoto, M.; Ono, Y.

    2015-10-01

    Floating potential profile was measured around the X-point during high guide field reconnection in UTST merging experiment where the ratio of guide field ( Bg ) to reconnecting magnetic field ( Brec ) is Bg/Brec>10 . Floating potential measurement revealed that a quadrupole structure of electric potential is formed around the X-point during the fast reconnection phase due to the polarization by inductive electric field. Also, our floating potential measurement revealed the existence of parallel electric field in the vicinity of the X-point. While field-aligned components of inductive electric field ( E∥ind ) and electrostatic electric field ( E∥es ) cancel out with each other away from the X-point, E∥ind exceeds E∥es around the X-point, indicating the deviation from ideal MHD criterion within the region. The diffusion region extends in the outflow region and the scale length of region is an order of ion skin depth, which is quite different from the VTF experiment result. Based on the measured magnetic field and electric field profile, our particle trajectory analysis indicates that fast electrons with energies over 300 eV are produced within 1 μs around the X-point in the non-ideal MHD region. These results indicate that production of fast electrons or electron heating are expected to be observed in the vicinity of the X-point.

  14. The influence of continuous rice cultivation and different waterlogging periods on morphology, clay mineralogy, Eh, pH and K in paddy soils.

    PubMed

    Bahmanyar, M A

    2007-09-01

    The effect of different rice cultivation periods on the properties of selected soils in alluvial plain were studied in Mazandaran province (north of Iran) in 2004. Soils were sampled form 0, 6, 16, 26 and over 40 years rice cultivation fields. In each treatment three soil profiles and six nearby auger holes were studied. The present study results indicated that continuous rice cultivation have changed soil moisture regime from xeric to aquic, soil color from brown to grayish, surface horizons from mollic to ochric epipedon and soil structure changed from granular or blocky to massive. Therefore, the soil order has changed from Mollisols to Inceptisols. No illuviation and eluviation of clay minerals occurred as a consequence of rice cultivation. X-ray diffraction analysis showed that clay minerals in non-rice cultivated field were illite, vermiculite, montmorillonite, kaolinite and chlorite, but in rice field were illite, montmorillonite, kaolinite and chlorite, respectively. In contrast of montmorillonite, the amount of illite and vermiculite have been decreased by increasing periods of rice cultivation. The pH values of the saturated soil surface in six weeks past plantation have shifted toward neutrality. While Eh value of non-paddy soils were about +90 mv, surface horizons of paddy soils at field conditions had Eh value about +40, -12, -84, -122 mv, respectively. The amounts of organic matter and available Fe, Mn, Zn and Cu were increased whereas available K was decreased in paddy soils. PMID:19090186

  15. H II REGION DRIVEN GALACTIC BUBBLES AND THEIR RELATIONSHIP TO THE GALACTIC MAGNETIC FIELD

    SciTech Connect

    Pavel, Michael D.; Clemens, D. P. E-mail: clemens@bu.edu

    2012-12-01

    The relative alignments of mid-infrared traced Galactic bubbles are compared to the orientation of the mean Galactic magnetic field in the disk. The orientations of bubbles in the northern Galactic plane were measured and are consistent with random orientations-no preferential alignment with respect to the Galactic disk was found. A subsample of H II region driven Galactic bubbles was identified, and as a single population they show random orientations. When this subsample was further divided into subthermal and suprathermal H II regions, based on hydrogen radio recombination linewidths, the subthermal H II regions showed a marginal deviation from random orientations, but the suprathermal H II regions showed significant alignment with the Galactic plane. The mean orientation of the Galactic disk magnetic field was characterized using new near-infrared starlight polarimetry and the suprathermal H II regions were found to preferentially align with the disk magnetic field. If suprathermal linewidths are associated with younger H II regions, then the evolution of young H II regions is significantly affected by the Galactic magnetic field. As H II regions age, they cease to be strongly linked to the Galactic magnetic field, as surrounding density variations come to dominate their morphological evolution. From the new observations, the ratios of magnetic-to-ram pressures in the expanding ionization fronts were estimated for younger H II regions.

  16. Kinetic Distribution of 14C-Metsulfuron-methyl Residues in Paddy Soils under Different Moisture Conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice paddy soils undergo several cycles of drying and wetting during a growing season. A laboratory study was conducted to determine the effect of soil moisture conditions on the distribution and kinetics of extractable and bound residues of 14C-metsulfuron-methyl in six Chinese paddy soils during 8...

  17. Capturing field-scale variability in crop performance across a regional-scale climosequence

    NASA Astrophysics Data System (ADS)

    Brooks, E. S.; Poggio, M.; Anderson, T. R.; Gasch, C.; Yourek, M. A.; Ward, N. K.; Magney, T. S.; Brown, D. J.; Huggins, D. R.

    2014-12-01

    With the increasing availability of variable rate technology for applying fertilizers and other agrichemicals in dryland agricultural production systems there is a growing need to better capture and understand the processes driving field scale variability in crop yield and soil water. This need for a better understanding of field scale variability has led to the recent designation of the R. J. Cook Agronomy Farm (CAF) (Pullman, WA, USA) as a United States Department of Agriculture Long-Term Agro-Ecosystem Research (LTAR) site. Field scale variability at the CAF is closely monitored using extensive environmental sensor networks and intensive hand sampling. As investigating land-soil-water dynamics at CAF is essential for improving precision agriculture, transferring this knowledge across the regional-scale climosequence is challenging. In this study we describe the hydropedologic functioning of the CAF in relation to five extensively instrumented field sites located within 50 km in the same climatic region. The formation of restrictive argillic soil horizons in the wetter, cooler eastern edge of the region results in the development of extensive perched water tables, surface saturation, and surface runoff, whereas excess water is not an issue in the warmer, drier, western edge of the region. Similarly, crop and tillage management varies across the region as well. We discuss the implications of these regional differences on field scale management decisions and demonstrate how we are using proximal soil sensing and remote sensing imagery to better understand and capture field scale variability at a particular field site.

  18. Spatial distributions of magnetic field in the RHIC and LHC energy regions

    NASA Astrophysics Data System (ADS)

    Zhong, Yang; Yang, Chun-Bin; Cai, Xu; Feng, Sheng-Qin

    2015-10-01

    Relativistic heavy-ion collisions can produce extremely strong magnetic fields in the collision regions. The spatial variation features of the magnetic fields are analyzed in detail for non-central Pb-Pb collisions at LHC at \\sqrt{s_NN}=900, 2760 and 7000 GeV and Au-Au collisions at RHIC at \\sqrt{s_NN}=62.4, 130 and 200 GeV. The dependencies of magnetic field on proper time, collision energies and impact parameters are investigated in this paper. It is shown that an enormous and highly inhomogeneous spatial distribution magnetic field can indeed be created in off-centre relativistic heavy-ion collisions in RHIC and LHC energy regions. The enormous magnetic field is produced just after the collision, and the magnitude of magnetic field of the LHC energy region is larger than that of the RHIC energy region at small proper time. It is found that the magnetic field in the LHC energy region decreases more quickly with the increase of proper time than that of the RHIC energy region. Supported by National Natural Science Foundation of China (11375069, 11435054, 11075061, 11221504) and Key Laboratory foundation of Quark and Lepton Physics (Hua-Zhong Normal University) (QLPL2014P01)

  19. Scaling up from field to region for wind erosion prediction using a field-scale wind erosion model and GIS

    USGS Publications Warehouse

    Zobeck, T.M.; Parker, N.C.; Haskell, S.; Guoding, K.

    2000-01-01

    Factors that affect wind erosion such as surface vegetative and other cover, soil properties and surface roughness usually change spatially and temporally at the field-scale to produce important field-scale variations in wind erosion. Accurate estimation of wind erosion when scaling up from fields to regions, while maintaining meaningful field-scale process details, remains a challenge. The objectives of this study were to evaluate the feasibility of using a field-scale wind erosion model with a geographic information system (GIS) to scale up to regional levels and to quantify the differences in wind erosion estimates produced by different scales of soil mapping used as a data layer in the model. A GIS was used in combination with the revised wind erosion equation (RWEQ), a field-scale wind erosion model, to estimate wind erosion for two 50 km2 areas. Landsat Thematic Mapper satellite imagery from 1993 with 30 m resolution was used as a base map. The GIS database layers included land use, soils, and other features such as roads. The major land use was agricultural fields. Data on 1993 crop management for selected fields of each crop type were collected from local government agency offices and used to 'train' the computer to classify land areas by crop and type of irrigation (agroecosystem) using commercially available software. The land area of the agricultural land uses was overestimated by 6.5% in one region (Lubbock County, TX, USA) and underestimated by about 21% in an adjacent region (Terry County, TX, USA). The total estimated wind erosion potential for Terry County was about four times that estimated for adjacent Lubbock County. The difference in potential erosion among the counties was attributed to regional differences in surface soil texture. In a comparison of different soil map scales in Terry County, the generalised soil map had over 20% more of the land area and over 15% greater erosion potential in loamy sand soils than did the detailed soil map. As a result, the wind erosion potential determined using the generalised soil map Was about 26% greater than the erosion potential estimated by using the detailed soil map in Terry County. This study demonstrates the feasibility of scaling up from fields to regions to estimate wind erosion potential by coupling a field-scale wind erosion model with GIS and identifies possible sources of error with this approach.

  20. Arsenic speciation in rice paddy soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Arsenic can undergo several chemical and microbial transformations in soil, including oxidation/reduction, methylation/demethylation, and volatilization, which could impact arsenic bioavailability for plant uptake. An experiment was conducted in field plots at Stuttgart, AR to determine whether arse...

  1. HELIOSHEATH MAGNETIC FIELDS BETWEEN 104 AND 113 AU IN A REGION OF DECLINING SPEEDS AND A STAGNATION REGION

    SciTech Connect

    Burlaga, L. F.; Ness, N. F. E-mail: nfnudel@yahoo.com

    2012-04-10

    We examine the relationships between the magnetic field and the radial velocity component V{sub R} observed in the heliosheath by instruments on Voyager 1 (V1). No increase in the magnetic field strength B was observed in a region where V{sub R} decreased linearly from 70 km s{sup -1} to 0 km s{sup -1} as plasma moved outward past V1. An unusually broad transition from positive to negative polarity was observed during a Almost-Equal-To 26 day interval when the heliospheric current sheet (HCS) moved below the latitude of V1 and the speed of V1 was comparable to the radial speed of the heliosheath flow. When V1 moved through a region where V{sub R} Almost-Equal-To 0 (the 'stagnation region'), B increased linearly with time by a factor of two, and the average of B was 0.14 nT. Nothing comparable to this was observed previously. The magnetic polarity was negative throughout the stagnation region for Almost-Equal-To 580 days until 2011 DOY 235, indicating that the HCS was below the latitude of V1. The average passage times of the magnetic holes and proton boundary layers were the same during 2009 and 2011, because the plasma moved past V1 during 2009 at the same speed that V1 moved through the stagnation region during 2011. The microscale fluctuations of B in the stagnation region during 2011 are qualitatively the same as those observed in the heliosheath during 2009. These results suggest that the stagnation region is a part of the heliosheath, rather than a 'transition region' associated with the heliopause.

  2. Influence of non-stationary field of magnetospheric convection on the D-region

    NASA Technical Reports Server (NTRS)

    Eliseyev, A. YU.; Kashpar, Yu. V.; Nikitin, A. A.

    1989-01-01

    Perturbations of F region electron density caused by the extension of magnetospheric convection electric field to middle latitudes are already well known. For the D region of the first observations are believed to be reported by Eliseyev, Kashpar and Nikitin (1988). On several occasions, following the southward turning of the Bz-component of interplanetary magnetic field (IMF) small disturbances of the D region electron density were detected at night by steep-incidence VLF sounding, which may be attributed to the influence of the penetrated convection electric field (CEF). Some evidence is given of a local time dependence of the CEF effect in the D region and a rather good correlation is demonstrated at the initial stage of disturbance between high latitude magnetic field variations and simultaneous perturbation of the midlatitude ionospheric reflection height.

  3. Regional Field Verification -- Operational Results from Four Small Wind Turbines in the Pacific Northwest: Preprint

    SciTech Connect

    Sinclair, K.; Raker, J.

    2006-08-01

    This paper describes four small wind turbines installed in the Pacific Northwest under DOE/NREL's Regional Field Verification Program between 2003 and 2004 and summarizes operational data from each site.

  4. Structure in the DC and AC electric fields associated with the dayside cusp region

    NASA Technical Reports Server (NTRS)

    Maynard, N. C.

    1985-01-01

    The cusp region as seen in the AC and DC electric fields is one of intense variation. The intensity peaks within the soft particle precipitation. The only AC signal that appears to be unique to the cusp is broadband ULF-ELF magnetic noise. Other types of emissions are also found at other local times at high latitudes. The pattern of these signals, especially that of ULF-ELF broadband electrostatic noise (BEN), distinguishes the cusp region from other regions. BEN signatures are indicators of magnetosheath-like soft particle precipitation but not necessarily of open field lines. In addition, large spike-like features in the DC electric field are seen near local magnetic noon which appear to be related to the large convective electric fields that have been observed at the magnetopause. These features are not necessarily tied to convection reversals, but may appear within broader regions of zonal convective flow.

  5. Radar Imaging of E-region Electric Fields at Mid-latitudes during Magnetic Storms

    NASA Astrophysics Data System (ADS)

    Lind, F. D.; Erickson, P. J.; Foster, J. C.

    2001-12-01

    During space weather events ionospheric electric fields can become highly structured at Mid-latitudes due to destabilization of the polarization jet and the equator-ward expansion of auroral precipitation regions. This structure is reflected in the E-region of the ionosphere by the generation of irregularities over scales from centimeters to many kilometers. Using an empirical relationship we can now image E-region electric field structure from coherent scatter observation of these irregularities. We will discuss such observations made by the Millstone Hill radar during several recent geomagnetic storms. In particular we will focus on the distribution of electric field energy at different spatial scales, the detailed dynamics of E-region electric field structures, and the observed differences between storms of different size.

  6. Regional Mapping of the Lunar Crustal Magnetic Field: Correlation of Strong Anomalies with Curvilinear Albedo Markings

    NASA Technical Reports Server (NTRS)

    Hood, L. L.; Yingst, A.; Zakharian, A.; Lin, R. P.; Mitchell, D. L.; Halekas, J.; Acuna, M. H.; Binder, A. B.

    2000-01-01

    Using high-resolution regional Lunar Prospector magnetometer magnetic field maps, we report here a close correlation of the strongest individual crustal anomalies with unusual curvilinear albedo markings of the Reiner Gamma class.

  7. Paddy Rice Identification by Blending Time-series SAR and Optical Data

    NASA Astrophysics Data System (ADS)

    Oyoshi, K.; Sobue, S.

    2014-12-01

    In Asia, rice is a staple cereal crop and Asian countries are responsible for approximately 90% of the world rice production and consumption. Asian space and agriculture related agencies launched an Asia-Rice Crop Estimation & Monitoring (Asia-RiCE) component for the GEOGLAM initiative. However, there are some difficulties to monitor rice crop by satellite imagery, which is different from other crops: 1) rice is mainly cultivated in rainy season and a large amount of cloud cover limits rice crop monitoring by the optical sensors; 2) adequate rainfall and temperature enable to cultivate rice two or three times a year in the tropics; 3) each field size is small compared to croplands in Western countries; and 4) water related agricultural disasters such as flood and drought are frequently occurred. To overcome these issues, C-band backscattering coefficient from RADARSAT-2 and reflectance data from MODIS were blended to estimate rice planted area over the West Java, Indonesia. By blending SAR and optical data, roughness and spectral information can be effectively used to differentiate paddy rice from other landcovers. The methodology using multi-wavelength data including optical (visible to thermal infrared) and SAR (X/C/L) would be a promising way for monitoring paddy rice in terms of the accuracy improvement and also the operational use to meet the requirement of observing the whole country with high-revisit frequency. In particular, the combining C-band SAR with other frequency SAR data such as L-band SAR onboard the ALOS-2 would be a challenge.

  8. Combined impacts of freeze-thaw processes on paddy land and dry land in Northeast China.

    PubMed

    Chen, Siyang; Ouyang, Wei; Hao, Fanghua; Zhao, Xuchen

    2013-07-01

    The quantity of spring snowmelt infiltration and runoff, which affects the hydrology of the freeze zone, depends on the antecedent soil water content (SWC) conditions at the time of the soil's freezing. An understanding of the characteristics of frozen soil is essential for spring sowing in the agricultural freeze zones. The main goal of this study was to evaluate the differences in the freeze-thaw process and the freeze-thaw-induced water redistribution between the paddy and dry lands in a freeze zone. For this purpose, a field study was conducted in the winter of 2011-2012 for two types of farmlands in Northeast China. To illustrate the soil's frost dynamics over time, the measured SWCs at different depths (15, 30, 60, and 90 cm) were transformed into different expressions including the SWC dynamic, the frozen soil's profile, and the freezing and thawing front trace. The freezing characteristics in the paddy land, in contrast to that in the dry land, had a higher freezing point temperature, a larger amount of water movement to the upper layer, and a 2.76 mm larger accumulation of water in the upper layer. However, the increase of SWC (which is equivalent to thawing) was evidently faster than the decrease of SWC (which is equivalent to freezing). The water in the frozen soil's profile was most likely redistributed towards the freezing front before soil temperature (ST) falls below the freezing point. The findings may partially explain the soil's freeze-thaw characteristics for the different stages as well as the combined impact of these characteristics with farmland use types on soil hydrology; the findings may also provide a foundation for forecasting the hydrologic response of the freeze-thaw process and provide guidance for management strategies dealing with seasonally frozen agricultural soils. PMID:23584030

  9. Paddy crop yield estimation in Kashmir Himalayan rice bowl using remote sensing and simulation model.

    PubMed

    Muslim, Mohammad; Romshoo, Shakil Ahmad; Rather, A Q

    2015-06-01

    The Kashmir Himalayan region of India is expected to be highly prone to the change in agricultural land use because of its geo-ecological fragility, strategic location vis-à-vis the Himalayan landscape, its trans-boundary river basins, and inherent socio-economic instabilities. Food security and sustainability of the region are thus greatly challenged by these impacts. The effect of future climate change, increased competition for land and water, labor from non-agricultural sectors, and increasing population adds to this complex problem. In current study, paddy rice yield at regional level was estimated using GIS-based environment policy integrated climate (GEPIC) model. The general approach of current study involved combining regional level crop database, regional soil data base, farm management data, and climatic data outputs with GEPIC model. The simulated yield showed that estimated production to be 4305.55 kg/ha (43.05 q h(-1)). The crop varieties like Jhelum, K-39, Chenab, China 1039, China-1007, and Shalimar rice-1 grown in plains recorded average yield of 4783.3 kg/ha (47.83 q ha(-1)). Meanwhile, high altitude areas with varieties like Kohsaar, K-78 (Barkat), and K-332 recorded yield of 4102.2 kg/ha (41.02 q ha(-1)). The observed and simulated yield showed a good match with R (2) = 0.95, RMSE = 132.24 kg/ha, respectively. PMID:25937498

  10. Understanding the variability of water isotopologues in near-surface atmospheric moisture over a humid subtropical rice paddy in Tsukuba, Japan

    NASA Astrophysics Data System (ADS)

    Wei, Zhongwang; Yoshimura, Kei; Okazaki, Atsushi; Ono, Keisuke; Kim, Wonsik; Yokoi, Masaharu; Lai, Chun-Ta

    2016-02-01

    We observed stable isotopes in precipitation and atmospheric water vapor over a humid subtropical rice paddy field in Tsukuba, Japan, from June 2013 to May 2014. We used observed isotope ratios, in combination with an isotope-enabled general circulation model (GCM; Isotopes-incorporated Global Spectral Model: IsoGSM) to improve our understanding of the impacts of moisture sources and transport on the variability of water vapor isotopes. The isotopic measurements of water vapor and precipitation suggested that vapor isotopes in the study area were controlled by not only air-rain isotopic exchange, but also other kinetic effects associated with land evapotranspiration and large scale atmospheric circulation at the seasonal time scale. The contribution of land evapotranspiration to local water vapor content (FET) was approximately 16.0 ± 12.3% as an annual average, with a summer maximum of 20.5 ± 12.9%. Our results show that large-scale atmospheric circulation is the primary control on the variability of near surface water vapor δD . An IsoGSM tagging simulation experiment demonstrated that the large temporal variation of surface water vapor isotopes can primarily be attributed to advection and mixing of moisture from different oceanic source regions.

  11. Fields and Flares: Understanding the Complex Magnetic Topologies of Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Murray, Sophie A.

    2013-01-01

    Sunspots are regions of decreased brightness on the visible surface of the Sun (photosphere) that are associated with strong magnetic fields. They have been found to be locations associated with solar flares, which occur when energy stored in sunspot magnetic fields is suddenly released. The processes involved in flaring and the link between sunspot magnetic fields and flares is still not fully understood, and this thesis aims to gain a better understanding of these topics. The magnetic field evolution of a number of sunspot regions is examined using high spatial resolution data from the Hinode spacecraft. The research presented in this thesis gives insight into both photospheric and coronal magnetic field evolution of flaring regions. Significant increases in vertical field strength, current density, and field inclination angle towards the vertical are observed in the photosphere just hours before a flare occurs, which is on much shorter timescales than previously studied. First observations of spatial changes in field inclination across a magnetic neutral line (generally believed to be a typical source region of flares) are also discovered. 3D magnetic field extrapolation methods are used to study the coronal magnetic field, using the photospheric magnetic field data as a boundary condition. Magnetic energy and free magnetic energy are observed to increase significantly a few hours before a flare, and decrease afterwards, which is a similar trend to the photospheric field parameter changes observed. Evidence of partial Taylor relaxation is also detected after a flare, as predicted by several previous studies. The results outlined in this thesis show that this particular field of research is vital in furthering our understanding of the magnetic nature of sunspots and its link to flare processes.

  12. 77 FR 16852 - Notice of Reclassification of Five Regional Offices to Investigative Field Offices: Seattle, WA...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-22

    ...: Seattle, WA; New Orleans, LA; Baltimore, MD; Tampa, FL; and Detroit, MI; Closure of Two Investigative..., Washington; New Orleans, Louisiana; Baltimore, Maryland; Tampa, Florida; and Detroit, Michigan regional..., Louisiana; Baltimore, Maryland; Tampa, Florida; and Detroit, Michigan regional offices as field offices...

  13. Relationship between magnetic field properties and an X-class flare in active region NOAA 9077

    NASA Astrophysics Data System (ADS)

    Liu, S.; Liu, D.

    2016-04-01

    The magnetic field plays a key role in producing solar flares, so that the investigation on the relationship between the magnetic field properties and flares is significant. In this paper, based on the magnetic field extrapolated from the photospheric vector magnetograms of the active region NOAA 9077 obtained at Huairou Solar Observing Station, the magnetic field parameters including the height of field lines, force-free factor, free magnetic energy and inclination angle were studied with respect to an X-class flare in this region. We found that the magnetic field lines became lower and the ratio of number of closed field lines to those of open field lines increased after the flare. The force-free factor (α) attained a large value before the flare and then decreased after the flare for the closed field lines, while the open field lines showed the opposite tendency. Free energy reach to maximum before flare, then decrease after flare. The magnetic inclination angles showed opposite change trends after the flare for closed and open field lines. Therefore, we may conclude that non-potential energy released by flare mostly contained in the closed magnetic field lines.

  14. Using Common Region in Node-Link Displays: The Role of Field Dependence/Independence.

    ERIC Educational Resources Information Center

    Chmielewski, Todd L.; Dansereau, Donald F.; Moreland, Jeremy L.

    1998-01-01

    The role common region (CR) plays in acquiring scientific information from node-link displays was studied by testing 88 subjects under conditions of knowledge maps demonstrating or not demonstrating CR. Field-dependent subjects scored better than the field-independent subjects for maps demonstrating CR, whereas the opposite was true for maps not

  15. A region of intense plasma wave turbulence on auroral field lines

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Frank, L. A.

    1976-01-01

    This report presents a detailed study of the plasma wave turbulence observed by HAWKEYE-1 and IMP-6 on high latitude auroral field lines and investigates the relationship of this turbulence to magnetic field and plasma measurements obtained in the same region.

  16. Flexible gas insulated transmission line having regions of reduced electric field

    DOEpatents

    Cookson, Alan H. (Pittsburgh, PA); Fischer, William H. (Wilkins Township, Allegheny County, PA); Yoon, Kue H. (Pittsburgh, PA); Meyer, Jeffry R. (Penn Hills Township, Allegheny County, PA)

    1983-01-01

    A gas insulated transmission line having radially flexible field control means for reducing the electric field along the periphery of the inner conductor at predetermined locations wherein the support insulators are located. The radially flexible field control means of the invention includes several structural variations of the inner conductor, wherein careful controlling of the length to depth of surface depressions produces regions of reduced electric field. Several embodiments of the invention dispose a flexible connector at the predetermined location along the inner conductor where the surface depressions that control the reduced electric field are located.

  17. Paddy rice productivity under climate and land-use change in northern Japan

    NASA Astrophysics Data System (ADS)

    Yoshida, R.; Fukui, S.; Shimada, T.; Hasegawa, T.; Iwasaki, T.

    2013-12-01

    An evaluation of the best rice cultivar under climate change is an important issue because the projected climate change has a potential to bring a negative impact on crop yield. In this study, we estimate an impact of climate change on rice yield and potential best cultivar in northern Japan where the larger paddy field is located than other regions in Japan. Two global climate model data, MIROC5 (RCP 4.5) and MRI-AGCM (SRES A1B), are applied as the future scenario. These data are too coarse to resolve the regional differences in northern Japan; we conduct the downscale experiments by a regional climate model (JMA-NHM) with a 10-km grid spacing. Considering that rice yield is sensitive to warm season climate, we conduct the downscaling from 28th May to 1st September during 1981-2000 and 2081-2099. The biases of downscaled two scenarios are corrected to match their cumulative distribution functions (CDF) of present climate with that of the station-based observation. The derived CDF-based biases are also used to correct the future scenarios. These corrected scenarios are applied to rice growth model (NIAES-Rice). To take account for the impacts of land use change (LUC) on climate and rice yield, we consider the additional temperature changes due to the LUC. As a reference, we add the LUC-induced temperature change in southwest Japan because the data are available from the previous study. We first check the climate change in northern Japan. General tendencies derived from the bias-corrected-downscaled future climates are that 1) surface warming was approximately twice in low elevation area relative to mountainous area and 2) downward shortwave radiation homogeneously increased 7-8 W m-2. Then, we evaluated the simulated yield through comparing with observation. Using observed ambient conditions as input data, the NIAES-Rice model provides the reasonable performance in simulating the rice yield with biases ranging from -19.0 to 29.2 % in prefecture base. Climate changes enhance the rice yield for 'Koshihikari' from 372.4 to 388.1 g/10a. The cultivar is planted in half of prefectures in Japan. For each analysis grid, we chose the cultivar that held the largest yield among the 10 analyzed cultivars and found that the location of cultivar that achieves the largest yields shifted northward in future climate. Also, the grids that cultivar developed in central Japan become the largest yield among 10 cultivars increase more than triple in the future climate. A LUC-induced temperature impact on prefecture-based yield corresponds to about 18 % of the climate-change-induced yield change, ranging from 0.6 to 33.5 % for six prefectures in the