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Sample records for soil carbon content

  1. Variable carbon contents of lunar soil 74220

    NASA Technical Reports Server (NTRS)

    Gibson, E. K., Jr.; Moore, C. B.

    1973-01-01

    Total carbon, sulfur, and inorganic gas release studies have been carried out on an additional split of orange soil 74220. The total carbon content was found to be 4 plus or minus 3 ppm C for this sample as compared to an earlier reported value of 100 plus or minus 10 ppm C. Gas release studies on the two splits of 74220 indicate that the carbon may be present as a surface condensate on the sample showing the higher carbon content. The 'surface condensate' evolves CO2 upon heating to temperatures below 400 C.

  2. Soil total carbon content, aggregation, bulk density, and penetration resistance of croplands and nearby grasslands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Converting native grassland (NGL) to cropland (CL) decreases soil organic matter contents (components of soil total carbon contents, STCCs), which often leads to soil degradation. Reestablishing grass on CL generally increases soil organic matter, which improves soil conditions. This study was condu...

  3. Residue removal and climatic effects on soil carbon content of no-till soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    While no-till management practices usually result in increased soil organic carbon (SOC) contents, the effect of residue removal with no-till is not well understood, especially in warmer climates. A multi-year study was conducted at six locations having a wide range of climatic conditions in centra...

  4. The Impact of Buried Horizons and Deep Soil Pedogenesis on Soil Carbon Content and Vertical Distribution

    NASA Astrophysics Data System (ADS)

    James, J. N.; Dietzen, C.; Harrison, R. B.; Gross, C.; Kirpach, A.

    2015-12-01

    The lower boundary of soil has been a point of contention among soil scientists for decades. Recent evidence suggests that soil is much deeper than is measured by many ecological studies and that arbitrary definitions of maximum soil depth unnecessarily exclude important regions of the soil profile. This paper provides illustrated examples of soil profiles that have important deep soil characteristics or buried horizons. Soil pits were excavated with a backhoe to at least 2.5 m depth at 35 sites throughout the Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) ecoregion of the Pacific Northwest. These soils cover four orders - Andisol, Inceptisol, Alfisol, and Ultisol - and highlight the hidden diversity of subsoil characteristics throughout the region. The roots of trees and understory species often extended deep into the C horizons of soil. Despite experiencing less pedogenic development than surface horizons, C horizons are important as the frontier of soil formation, as an important resource for plant growth, and as a repository of diffuse but significant carbon storage. On average, there was 188.1 Mg C ha-1 total across all 35 sites, of which 76.3 Mg ha-1 (40.5%) was found below 0.5 m and 44.4 Mg ha-1 (23.6%) was found below 1 m. There was substantial variability in the vertical distribution of C with as little as 8.0% and as much as 58.0% of total C below 1 m. In some cases, B horizons are far deeper than the 1 or 2 m depth arbitrarily assumed to represent the whole soil. In other cases, subsoil hides buried profiles that can significantly impact total soil carbon stocks as well as aboveground plant growth. These buried horizons are important repositories of nutrients and carbon that are poorly understood and rarely sampled. Ignoring subsoil precludes incorporating soil burial or deep soil processes into biogeochemical and global carbon cycle models, and limits mechanistic understanding of carbon sequestration and mobilization in soil.

  5. Factors and processes governing the C-14 content of carbonate in desert soils

    NASA Technical Reports Server (NTRS)

    Amundson, Ronald; Wang, Yang; Chadwick, Oliver; Trumbore, Susan; Mcfadden, Leslie; Mcdonald, Eric; Wells, Steven; Deniro, Michael

    1994-01-01

    A model is presented describing the factors and processes which determine the measured C-14 ages of soil calcium carbonate. Pedogenic carbonate forms in isotopic equilium with soil CO2. Carbon dioxide in soils is a mixture of CO2 derived from two biological sources: respiration by living plant roots and respiration of microorganisms decomposing soil humus. The relative proportion of these two CO2 sources can greatly affect the initial C-14 content of pedogenic carbonate: the greater the contribution of humus-derived CO2, the greater the initial C-14 age of the carbonate mineral. For any given mixture of CO2 sources, the steady-state (14)CO2 distribution vs. soil depth can be described by a production/diffusion model. As a soil ages, the C-14 age of soil humus increases, as does the steady-state C-14 age of soil CO2 and the initial C-14 age of any pedogenic carbonate which forms. The mean C-14 age of a complete pedogenic carbonate coating or nodule will underestimate the true age of the soil carbonate. This discrepancy increases the older a soil becomes. Partial removal of outer (and younger) carbonate coatings greatly improves the relationship between measured C-14 age and true age. Although the production/diffusion model qualitatively explains the C-14 age of pedogenic carbonate vs. soil depth in many soils, other factors, such as climate change, may contribute to the observed trends, particularily in soils older than the Holocene.

  6. Soil Water Cycling Links to Carbon Content between Ecosystems in the Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Powell, K. M.; Anderson, D. E.; Stannard, D. I.; Mladinich, C. S.; Thienelt, T. S.; Blanken, P.

    2011-12-01

    Near surface soil-water content is crucial to the sustainability of an ecosystem. Additionally, the feedbacks between soil water and soil carbon improve the ability to predict carbon sequestration rates. Organic-carbon content in surface soils influences soil texture and, subsequently, water holding capacity. Preliminary research for two growing seasons (2010 and 2011) compares soil water, temperature, heat flux, and evapotranspiration (ET) with soil organic carbon content at several sites in the Colorado Front Range. Continuous measurements of precipitation, soil moisture and temperature, and energy fluxes were conducted from eddy covariance flux towers at three sites around metropolitan Denver: one urban site and two adjacent sites, a montane forest (Flying J Ranch Open Space), and a native tallgrass prairie (Rocky Flats National Wildlife Refuge (NWR)). Irrigation data were obtained for the Denver urban site and added to its precipitation to obtain total water inputs. Soil samples (0-5cm) were collected at each tower site and analyzed for bulk density, volumetric water content, and organic carbon content. Soil water inputs and losses (as ET) were analyzed for each site and compared to soil organic carbon content. Rocky Flats NWR soils contained the highest organic carbon content (20-30 percent), while the urban site and Flying J Ranch soils contained between 10-15 percent. Comparing grassland sites, the urban soil received 5 times higher water input (600mm, more than half from irrigation) in 2010 than those of Rocky Flats. Despite less water input, the Rocky Flats site developed more soil organic carbon, possibly due to large amounts of grassland biomass mineralization and moderate soil moisture conditions through the season. The Denver urban site demonstrated less soil moisture variability in response to surface-water inputs from precipitation compared to soils at the native grassland and montane sites, perhaps limiting the conditions under which soil carbon

  7. Estimating the soil organic carbon content for European NUTS2 regions based on LUCAS data collection.

    PubMed

    Panagos, Panos; Ballabio, Cristiano; Yigini, Yusuf; Dunbar, Martha B

    2013-01-01

    Under the European Union Thematic Strategy for Soil Protection, the European Commission Directorate-General for the Environment and the European Environmental Agency (EEA) identified a decline in soil organic carbon and soil losses by erosion as priorities for the collection of policy relevant soil data at European scale. Moreover, the estimation of soil organic carbon content is of crucial importance for soil protection and for climate change mitigation strategies. Soil organic carbon is one of the attributes of the recently developed LUCAS soil database. The request for data on soil organic carbon and other soil attributes arose from an on-going debate about efforts to establish harmonized datasets for all EU countries with data on soil threats in order to support modeling activities and display variations in these soil conditions across Europe. In 2009, the European Commission's Joint Research Centre conducted the LUCAS soil survey, sampling ca. 20,000 points across 23 EU member states. This article describes the results obtained from analyzing the soil organic carbon data in the LUCAS soil database. The collected data were compared with the modeled European topsoil organic carbon content data developed at the JRC. The best fitted comparison was performed at NUTS2 level and showed underestimation of modeled data in southern Europe and overestimation in the new central eastern member states. There is a good correlation in certain regions for countries such as the United Kingdom, Slovenia, Italy, Ireland, and France. Here we assess the feasibility of producing comparable estimates of the soil organic carbon content at NUTS2 regional level for the European Union (EU27) and draw a comparison with existing modeled data. In addition to the data analysis, we suggest how the modeled data can be improved in future updates with better calibration of the model. PMID:23178783

  8. Estimating the soil organic carbon content for European NUTS2 regions based on LUCAS data collection.

    PubMed

    Panagos, Panos; Ballabio, Cristiano; Yigini, Yusuf; Dunbar, Martha B

    2013-01-01

    Under the European Union Thematic Strategy for Soil Protection, the European Commission Directorate-General for the Environment and the European Environmental Agency (EEA) identified a decline in soil organic carbon and soil losses by erosion as priorities for the collection of policy relevant soil data at European scale. Moreover, the estimation of soil organic carbon content is of crucial importance for soil protection and for climate change mitigation strategies. Soil organic carbon is one of the attributes of the recently developed LUCAS soil database. The request for data on soil organic carbon and other soil attributes arose from an on-going debate about efforts to establish harmonized datasets for all EU countries with data on soil threats in order to support modeling activities and display variations in these soil conditions across Europe. In 2009, the European Commission's Joint Research Centre conducted the LUCAS soil survey, sampling ca. 20,000 points across 23 EU member states. This article describes the results obtained from analyzing the soil organic carbon data in the LUCAS soil database. The collected data were compared with the modeled European topsoil organic carbon content data developed at the JRC. The best fitted comparison was performed at NUTS2 level and showed underestimation of modeled data in southern Europe and overestimation in the new central eastern member states. There is a good correlation in certain regions for countries such as the United Kingdom, Slovenia, Italy, Ireland, and France. Here we assess the feasibility of producing comparable estimates of the soil organic carbon content at NUTS2 regional level for the European Union (EU27) and draw a comparison with existing modeled data. In addition to the data analysis, we suggest how the modeled data can be improved in future updates with better calibration of the model.

  9. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    NASA Astrophysics Data System (ADS)

    Yang, X. M.; Drury, C. F.; Reynolds, W. D.; Yang, J. Y.

    2016-06-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2-53 μm) and sand (53-2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg-1 soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg-1, but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation.

  10. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    PubMed

    Yang, X M; Drury, C F; Reynolds, W D; Yang, J Y

    2016-01-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2-53 μm) and sand (53-2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg(-1) soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg(-1), but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation.

  11. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    PubMed Central

    Yang, X. M.; Drury, C. F.; Reynolds, W. D.; Yang, J. Y.

    2016-01-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2–53 μm) and sand (53–2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg−1 soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg−1, but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation. PMID:27251365

  12. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    PubMed

    Yang, X M; Drury, C F; Reynolds, W D; Yang, J Y

    2016-01-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2-53 μm) and sand (53-2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg(-1) soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg(-1), but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation. PMID:27251365

  13. A regional estimate of soil organic carbon content linking the RothC model to spatialised climate and soil database

    NASA Astrophysics Data System (ADS)

    Sirca, Costantino; Salis, Michele; Spano, Donatella

    2014-05-01

    Soil organic carbon (SOC) represents the largest pool of organic carbon in the biosphere, and plays a vital role in ecosystem function determining soil fertility, water holding capacity, and susceptibility to land degradation. The SOC amount is mainly led by soil type, land use, and climate. In this work an assessment of SOC pools in Mediterranean soils is presented. The SOC content was estimated at regional scale in Sardinia, the second largest island of the Mediterranean Basin, linking the RothC model (Rothamsted Carbon model) to a high detailed spatialised climate, land use and soil database. More than 300 soil analysis data, covering different land use typologies, were used for the calibration and validation of the model. A good agreement between soil C estimated from the model and ground data was found. The methodology allowed to obtain the current SOC pools estimation for the different land use categories at regional scale.

  14. The Isiokpo oil-pipeline leakage: total organic carbon/organic matter contents of affected soils.

    PubMed

    Osuji, Leo C; Adesiyan, Samuel O

    2005-08-01

    The environmental impact of the 1997 leakage of the high-pressure crude-oil pipeline at Isiokpo in the Niger Delta in the southeast of Nigeria was evaluated, with particular reference to total-organic-carbon (TOC) and total-organic-matter (TOM) contents of soils within the vicinity of the oil spillage. The soils, taken from depths of 0-15 cm (surface) and 15-30 cm (subsurface), were found to be more acidic (pH 4.2-5.6) than the unpolluted soils, with a high average moisture content of 6.8%. The extractable hydrocarbon content ranged from 2.71-3.48 mg/kg, indicating hydrocarbon contamination. However, contrary to expectation, the TOC and TOM contents of the polluted soils did not show any significant increase in concentration, supposedly due to natural rehabilitation of the affected mat layer of soils. Thus, notwithstanding the possible proliferation of heterotrophic organisms by the presence of the added petroleum hydrocarbons, environmental conditions such as weathering and climatic predispositions, as well as physico-chemical parameters such as pH, moisture content, and temperature must have encumbered the carbon-mineralizing capacity of the heterotrophs, thereby reducing the turnover of carbon and the decomposition of organic matter. The restrictions by high moisture content might not come directly from H(2)O itself, but are probably a consequence of hindered soil ventilation, which reduces O(2) supply and gaseous diffusion, conditions that might have been substantially aggravated by the added petroleum hydrocarbons.

  15. The Effects of Simulated Wildfire on Particle Size and Carbon Content in Piedmont Soils.

    NASA Astrophysics Data System (ADS)

    Wynes, A.; Werts, S. P.

    2014-12-01

    Soils are a known carbon sink, holding twice as much carbon as the atmosphere (Schlesinger, 1995). However, little is known about how much soil organic carbon (SOC) is released from the soil during fire events. Surface fires can heat mineral soils to up to 500°C at depths of several centimeters and maintain that temperature for hours (Werts and Jahren, 2007). This has been known to affect the size of particles in soils, carbon content in the soils, and the clay mineralogy (Hungerford et al, 1993). This study looks at relationships between soil clay content and clay chemistry in relation to carbon emissions during surface fires, to determine temperature effects on several piedmont soil types from South Carolina. Soil samples were taken from three different sites varying in clay content, clay type, parent material, and development. Temperature increases were applied in increments of 50°C, with a range from 100°C to 500°C, to determine fire effects on SOC, particle size, and clay mineralogy of the soils. We found a decrease in SOC (up to 98%) from the original amount in all soil horizons with temperature applications up to 500°C. At a temperature range between 100°C and 300°C, most soil horizons showed an increase in clay of a range between 0.1 and 34%. At temperatures ranging from 300°C to 500°C, there was a decrease in clay ranging from 2.5-42%. While previous research suggests that a positive correlation between the percentage of clay and SOC in soils is common (Feller and Beare, 1997), in this study, a negative correlation was found between the percentage of clay and SOC in all three soil types (R2=0.87, 0.76, and 0.59) at 100°C. There appears to be an increasingly positive relationship between clay and carbon as temperature increases, although a consistent high correlation was not present at all temperatures. This is counter to what was found initially in our soils prior to heating. While research into surface fires is important to the understanding of

  16. [Effects of different tillage methods and straw-returning on soil organic carbon content in a winter wheat field].

    PubMed

    Tian, Shen-Zhong; Ning, Tang-Yuan; Wang, Yu; Li, Hong-Jie; Zhong, Wei-Lei; Li, Zeng-Jia

    2010-02-01

    A two growth seasons experiment was conducted to study the effects of different tillage methods, straw-returning, and their interaction on the dynamic change of organic carbon content in 0-20 cm soil layer during the whole growth period of winter wheat. An obvious change was observed in the soil organic carbon content. Treatments with straw-returning had higher soil organic carbon content than treatments with no straw-returning, and conservation tillage induced higher soil organic carbon content than conventional tillage. In all treatments except conventional tillage, the organic carbon content in 0-10 cm soil layer was higher than that in 10-20 cm soil layer. In treatments with straw-returning, the organic carbon content in 0-10 cm soil layer decreased in order of deep soiling (PS) > rotary tillage (PR) > no tillage (PZ) > normal ploughing (PH) > conventional tillage (PC), while that in 10-20 cm soil layer was PC > PS > PR > PH > PZ, suggesting that conservation tillage could improve the organic carbon content in 0-10 cm soil layer. Multi factor variance analysis showed that tillage method, straw-returning, and their interaction had significant effects on the organic carbon content in 0-20 cm soil layer at various growth stages of winter wheat.

  17. Digital mapping of soil organic carbon contents and stocks in Denmark.

    PubMed

    Adhikari, Kabindra; Hartemink, Alfred E; Minasny, Budiman; Bou Kheir, Rania; Greve, Mette B; Greve, Mogens H

    2014-01-01

    Estimation of carbon contents and stocks are important for carbon sequestration, greenhouse gas emissions and national carbon balance inventories. For Denmark, we modeled the vertical distribution of soil organic carbon (SOC) and bulk density, and mapped its spatial distribution at five standard soil depth intervals (0-5, 5-15, 15-30, 30-60 and 60-100 cm) using 18 environmental variables as predictors. SOC distribution was influenced by precipitation, land use, soil type, wetland, elevation, wetness index, and multi-resolution index of valley bottom flatness. The highest average SOC content of 20 g kg(-1) was reported for 0-5 cm soil, whereas there was on average 2.2 g SOC kg(-1) at 60-100 cm depth. For SOC and bulk density prediction precision decreased with soil depth, and a standard error of 2.8 g kg(-1) was found at 60-100 cm soil depth. Average SOC stock for 0-30 cm was 72 t ha(-1) and in the top 1 m there was 120 t SOC ha(-1). In total, the soils stored approximately 570 Tg C within the top 1 m. The soils under agriculture had the highest amount of carbon (444 Tg) followed by forest and semi-natural vegetation that contributed 11% of the total SOC stock. More than 60% of the total SOC stock was present in Podzols and Luvisols. Compared to previous estimates, our approach is more reliable as we adopted a robust quantification technique and mapped the spatial distribution of SOC stock and prediction uncertainty. The estimation was validated using common statistical indices and the data and high-resolution maps could be used for future soil carbon assessment and inventories.

  18. Digital Mapping of Soil Organic Carbon Contents and Stocks in Denmark

    PubMed Central

    Adhikari, Kabindra; Hartemink, Alfred E.; Minasny, Budiman; Bou Kheir, Rania; Greve, Mette B.; Greve, Mogens H.

    2014-01-01

    Estimation of carbon contents and stocks are important for carbon sequestration, greenhouse gas emissions and national carbon balance inventories. For Denmark, we modeled the vertical distribution of soil organic carbon (SOC) and bulk density, and mapped its spatial distribution at five standard soil depth intervals (0−5, 5−15, 15−30, 30−60 and 60−100 cm) using 18 environmental variables as predictors. SOC distribution was influenced by precipitation, land use, soil type, wetland, elevation, wetness index, and multi-resolution index of valley bottom flatness. The highest average SOC content of 20 g kg−1 was reported for 0−5 cm soil, whereas there was on average 2.2 g SOC kg−1 at 60−100 cm depth. For SOC and bulk density prediction precision decreased with soil depth, and a standard error of 2.8 g kg−1 was found at 60−100 cm soil depth. Average SOC stock for 0−30 cm was 72 t ha−1 and in the top 1 m there was 120 t SOC ha−1. In total, the soils stored approximately 570 Tg C within the top 1 m. The soils under agriculture had the highest amount of carbon (444 Tg) followed by forest and semi-natural vegetation that contributed 11% of the total SOC stock. More than 60% of the total SOC stock was present in Podzols and Luvisols. Compared to previous estimates, our approach is more reliable as we adopted a robust quantification technique and mapped the spatial distribution of SOC stock and prediction uncertainty. The estimation was validated using common statistical indices and the data and high-resolution maps could be used for future soil carbon assessment and inventories. PMID:25137066

  19. Reduction in the earthworm metabolomic response after phenanthrene exposure in soils with high soil organic carbon content.

    PubMed

    McKelvie, Jennifer R; Whitfield Åslund, Melissa; Celejewski, Magda A; Simpson, André J; Simpson, Myrna J

    2013-04-01

    We evaluated the correlation between soil organic carbon (OC) content and metabolic responses of Eisenia fetida earthworms after exposure to phenanthrene (58 ± 3 mg/kg) spiked into seven artificial soils with OC contents ranging from 1 to 27% OC. Principal component analysis of (1)H nuclear magnetic resonance (NMR) spectra of aqueous extracts identified statistically significant differences in the metabolic profiles of control and phenanthrene-exposed E. fetida in the 1% OC soil only. Partial least squares analysis identified a metabolic response in the four soils with OC values ≤11% which was well correlated to estimated phenanthrene porewater concentrations. The results suggest that the higher sorption capability of high OC soils decreased the bioavailability of phenanthrene and the subsequent metabolic response of E. fetida. PMID:23337355

  20. The ratio of clay content to total organic carbon content is a useful parameter to predict adsorption of the herbicide butachlor in soils.

    PubMed

    Liu, Zhongzhen; He, Yan; Xu, Jianming; Huang, Panming; Jilani, Ghulam

    2008-03-01

    Thirteen soils collected from 11 provinces in eastern China were used to investigate the butachlor adsorption. The results indicated that the total organic carbon (TOC) content, clay content, amorphous Fe2O3 content, silt content, CEC, and pH had a combined effect on the butachlor sorption on soil. Combination of the data obtained from the 13 soils in the present study with other 23 soil samples reported by other researchers in the literature showed that Koc would be a poor predictive parameter for butachlor adsorption on soils with TOC content higher than 4.0% and lower than 0.2%. The soils with the ratio of clay content to TOC content (RCO) values less than 60 adsorbed butachlor mainly by the partition into soil organic matter matrix. The soils with RCO values higher than 60 apparently adsorbed butachlor by the combination of the partition into soil organic matter matrix and adsorption on clay surface.

  1. Exploring the multiplicity of soil-human interactions: organic carbon content, agro-forest landscapes and the Italian local communities.

    PubMed

    Salvati, Luca; Barone, Pier Matteo; Ferrara, Carlotta

    2015-05-01

    Topsoil organic carbon (TOC) and soil organic carbon (SOC) are fundamental in the carbon cycle influencing soil functions and attributes. Many factors have effects on soil carbon content such as climate, parent material, land topography and the human action including agriculture, which sometimes caused a severe loss in soil carbon content. This has resulted in a significant differentiation in TOC or SOC at the continental scale due to the different territorial and socioeconomic conditions. The present study proposes an exploratory data analysis assessing the relationship between the spatial distribution of soil organic carbon and selected socioeconomic attributes at the local scale in Italy with the aim to provide differentiated responses for a more sustainable use of land. A strengths, weaknesses, opportunities and threats (SWOT) analysis contributed to understand the effectiveness of local communities responses for an adequate comprehension of the role of soil as carbon sink. PMID:25903408

  2. Exploring the multiplicity of soil-human interactions: organic carbon content, agro-forest landscapes and the Italian local communities.

    PubMed

    Salvati, Luca; Barone, Pier Matteo; Ferrara, Carlotta

    2015-05-01

    Topsoil organic carbon (TOC) and soil organic carbon (SOC) are fundamental in the carbon cycle influencing soil functions and attributes. Many factors have effects on soil carbon content such as climate, parent material, land topography and the human action including agriculture, which sometimes caused a severe loss in soil carbon content. This has resulted in a significant differentiation in TOC or SOC at the continental scale due to the different territorial and socioeconomic conditions. The present study proposes an exploratory data analysis assessing the relationship between the spatial distribution of soil organic carbon and selected socioeconomic attributes at the local scale in Italy with the aim to provide differentiated responses for a more sustainable use of land. A strengths, weaknesses, opportunities and threats (SWOT) analysis contributed to understand the effectiveness of local communities responses for an adequate comprehension of the role of soil as carbon sink.

  3. Soil organic carbon as a factor in passive microwave retrievals of soil water content over agricultural croplands

    NASA Astrophysics Data System (ADS)

    Manns, Hida R.; Berg, Aaron A.; Colliander, Andreas

    2015-09-01

    Remote sensing has the potential to deliver global soil water content (SWC) on vast scales with frequent revisit times for progress in the fields of climate, weather forecasting, agriculture and hydrology. Although surface roughness, vegetation and soil texture have been established as sources of variability in passive microwave interpretation, soil organic carbon (SOC) has not typically been considered as a factor that affects SWC estimation during field sampling campaigns. SOC was observed along with soil texture and bulk density during the Soil Moisture Active Passive Validation Experiment in 2012 (SMAPVEX12), the Soil Moisture Active Passive (SMAP) satellite algorithm development field sampling campaign held June 6 to July 19 in Southern Manitoba, Canada. Aerial measurements from the PALS (Passive Active L-band System) instrument were recorded over agricultural fields and forest areas from aircraft while SWC was measured simultaneously on the ground with resistance probes on 17 sampling dates. Additionally, fields were sampled for surface roughness, vegetation growth and water content, soil and vegetation temperature and soil physical characteristics. A soil core was collected on each field each sampling time to assess bulk density, soil particle size and SOC. SOC accounted for more variability in the anomalies between PALS and ground sampled SWC than sand, clay or bulk density, although all soil variables explained significant variability. With analysis by partial least squares multiple regression over 11 sampling dates and 39 fields where both ground and PALS data were well represented, only SOC contributed significantly to the regression of SWC beyond the variance all soil variables had in common. The significance of SOC in the relative SWC anomalies was highest in very wet and very dry conditions and in loam soil over all sampling dates, while bulk density was more significant in sand soils. This analysis suggests SOC is a simple variable that incorporates

  4. Land abandonment, fire recurrence and soil carbon content in the Macizo del Caroig, Eastern Spain

    NASA Astrophysics Data System (ADS)

    Cerdá, A.; González Peñaloza, F.; Santín, C.; Doerr, S. H.

    2012-04-01

    During the last 50 years two main forces have driven the fate of Mediterranean landscapes: land abandonment and forest fires (MacDonald et al., 2000; Moreira et al., 2001). Due to the economical changes suffered by the of the Mediterranean countries after the Second World War, the population migrated from the rural to the urban areas, and from South to North Europe. The land abandonment allowed the vegetation to recover and, as a consequence, an increase in forest fire took place. The soils of the abandoned land recovered the vegetation and litter layers, and consequently changes in soil properties have being found. One of these changes is the increase of soil carbon content, which is due both to vegetation recovery and to fire occurrence that increases the ash and pyrogenic carbon content in soils. Twenty plots were selected in the Macizo del Caroig in Eastern Spain on soils developed on limestone. The period of abandonment and the forest fires that had affected each plot were determined by interviews with the owners, farmers and shepherds. In addition, six (three + three) plots were selected as forest (no plough) and cultivated control plots. Each plot was sampled (10 random samples) and the organic carbon content determined. The results show that the cultivated plots have organic matter contents of 1.02 %, and the forest (Quercus ilex sp.) plots reach the highest value: 14.98 %. Within those we found values that range from 2.34 %, in the recently abandoned plots (10 year abandonment), to values of 8.23 % in the 50 year old abandoned fields.The results demonstrate that there is a recovery of the organic carbon in abandoned soils and that the forest fires do no affect this trend. The increase of soil organic matter after abandonment is a result of the recovery of vegetation(Debussche et al., 2001), which is the consequence of the end of the disturbance of forest that have affected the Mediterranean for millennia (Barbero et al., 1990). The colonization of the

  5. [Effects of tillage rotation and fertilization on soil aggregates and organic carbon content in corn field in Weibei Highland].

    PubMed

    Wang, Li; Li, Jun; Li, Juan; Bai, Wei-Xia

    2014-03-01

    A field experiment on effects of tillage rotation and fertilization on corn continuous cropping-practiced lands was carried out in Heyang of Shaanxi in 2007-2012. The tillage types included annual rotation of no-tillage and subsoiling (NT-ST), subsoiling and conventional tillage (ST-CT), or conventional tillage and no-tillage (CT-NT), and yearly practice of no tillage (NT-NT), subsoiling (ST-ST) or conventional tillage (CT-CT). The fertilization treatments included balanced fertilization, low-rate fertilization and conventional fertilization, which were separately practiced against the different tillage types. The experiment investigated compositions, mean mass diameters (MWD), geometrical mean diameters (GMD) and fraction dimension numbers (D) of soil aggregates in 0-40 cm soil and contents of organic carbon in 0-60 cm soil. The results indicated that: 1) The increased tillage intensity caused the reduced mechanical stability and content of soil aggregates and increased soil organic carbon loss. No-tillage or tillage rotation increased the MWD, GMD and contents of soil organic carbon and soil aggregates with diameters of more than 0.25 mm, but decreased D. Under the same fertilization treatment, the contents of soil aggregates with diameters of more than 0.25 mm were ranked in the order of NT-NT>NT-ST>NT-CT>ST-ST>CT-ST>CT-CT, and under the same tillage rotations, the soil aggregates were more stable with the balanced or low- rate fertilization than with the conventional fertilization. 2) Mathematical fractal dimension fitting of soil aggregates indicated that the fractal dimension numbers of soil aggregates ranged within 2.247-2.681 by dry sieving and 2.897-2.976 by wet sieving. In 0-30 cm soil, the fractal dimension numbers of soil aggregates were significantly lower under no-tillage or tillage rotation than under conventional tillage, and in 0-40 cm soil, the fractal dimensions of soil aggregates increased with soil depth, and tended to stabilize at the soil

  6. Mapping soil organic carbon content and composition across Australia to assess vulnerability to climate change

    NASA Astrophysics Data System (ADS)

    Viscarra Rossel, R. A.

    2015-12-01

    We can effectively monitor soil condition—and develop sound policies to offset the emissions of greenhouse gases—only with accurate data from which to define baselines. Currently, estimates of soil organic C for countries or continents are either unavailable or largely uncertain because they are derived from sparse data, with large gaps over many areas of the Earth. Here, we derive spatially explicit estimates, and their uncertainty, of the distribution and stock of organic C content and composition in the soil of Australia. The composition of soil organic C may be characterized by chemical separation or physical fractionation based on either particle size or particle density (Skjemstad et al., 2004; Gregorich et al., 2006; Kelleher&Simpson, 2006; Zimmermann et al., 2007). In Australia, for example, Skjemstad et al. (2004) used physical separation of soil samples into 50-2000 and <50-μm particle-size fractions followed by the measurement of char-carbon using solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, giving the three OC pools, particulate organic carbon (POC), humic organic carbon (HOC) and resistant organic carbon (ROC; charcoal or char-carbon). We assembled and harmonized data from several sources to produce the most comprehensive set of data on the current stock of organic C in soil of the continent. Using them, we have produced a fine spatial resolution baseline map of organic C, POC, HOC and ROC at the continental scale. In this presentation I will describe how we made the maps and how we use them to assess the vulnerability of soil organic C to for instance climate change.

  7. Modelling global change impacts on soil carbon contents of agro-silvo-pastoral Mediterranean systems

    NASA Astrophysics Data System (ADS)

    Lozano-García, Beatriz; Muñoz-Rojas, Miriam; Parras-Alcántara, Luis

    2016-04-01

    total of 38 sampling points were selected under two management practices and six different land uses: (1) MEOW-dehesa (D); (2) MEOW-dehesa + some pine trees (D+P); (3) MEOW-dehesa + some cork oaks (D+C); (4) MEOW-dehesa + some gall oaks (D + G); (5) MEOW-dehesa after a clarified process and transformed to olive grove but maintaining isolated oaks (OG) and (6) MEOW-dehesa after a clarified process and transformed to cereal pasture with isolated oaks (C). Preliminary results showed a high heterogeneity of SOC contents along the soil profile for different climate and land use scenarios. The methods used here can be easily implemented in other Mediterranean areas with available information on climate, site, soil and land use. Keywords: CarboSOIL model, land use change, climate change, soil depth, dehesa References: Abd-Elmabod, S.K., Muñoz-Rojas, M., Jordán, A., Anaya-Romero, M., De la Rosa, D., 2014. Modelling soil organic carbon stocks along topographic transects under climate change scenarios using CarboSOIL. Geophys. Res. Abstr. vol. 16 EGU2014-295-1, EGU General Assembly.) Álvaro-Fuentes, J., Easter, M., Paustian, K., 2012. Climate change effects on organic carbon storage in agricultural soils of northeastern Spain. Agric. Ecosyst. Environ. 155, 87-94. Corral-Fernández, R., Parras-Alcántara, L., Lozano-García, B. 2013. Stratification ratio of soil organic C, N and C:N in Mediterranean evergreen oak woodland with conventional and organic tillage. Agric. Ecosyst. Environ. 164, 252-259. Francaviglia, R., Coleman, K., Whitmore, A.P., Doro, L., Urracci, G., Rubino, M., Ledda, L., 2012. Changes in soil organic carbon and climate change - application of the RothC model in agrosilvo-pastoral Mediterranean systems. Agric. Syst. 112, 48- 54. IPCC, 2007. Technical summary. In: Climate Change 2007. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change http://www.ipcc.ch/. Lozano-García, B., Parras-Alcántara, L

  8. Soil Iron Content as a Predictor of Carbon and Nutrient Mobilization in Rewetted Fens

    PubMed Central

    Emsens, Willem-Jan; Aggenbach, Camiel J. S.; Schoutens, Ken; Smolders, Alfons J. P.; Zak, Dominik; van Diggelen, Rudy

    2016-01-01

    Rewetted, previously drained fens often remain sources rather than sinks for carbon and nutrients. To date, it is poorly understood which soil characteristics stimulate carbon and nutrient mobilization upon rewetting. Here, we assess the hypothesis that a large pool of iron in the soil negatively affects fen restoration success, as flooding-induced iron reduction (Fe3+ to Fe2+) causes a disproportionate breakdown of organic matter that is coupled with a release of inorganic compounds. We collected intact soil cores in two iron-poor and two iron-rich drained fens, half of which were subjected to a rewetting treatment while the other half was kept drained. Prolonged drainage led to the mobilization of nitrate (NO3-, > 1 mmol L-1) in all cores, regardless of soil iron content. In the rewetted iron-rich cores, a sharp increase in pore water iron (Fe) concentrations correlated with concentrations of inorganic carbon (TIC, > 13 mmol L-1) and dissolved organic carbon (DOC, > 16 mmol L-1). Additionally, ammonium (NH4+) accumulated up to phytotoxic concentrations of 1 mmol L-1 in the pore water of the rewetted iron-rich cores. Disproportionate mobilization of Fe, TIC, DOC and NH4+ was absent in the rewetted iron-poor cores, indicating a strong interaction between waterlogging and iron-mediated breakdown of organic matter. Concentrations of dissolved phosphorus (P) rose slightly in all cores upon rewetting, but remained low throughout the experiment. Our results suggest that large pools of iron in the top soil of drained fens can hamper the restoration of the fen’s sink-service for ammonium and carbon upon rewetting. We argue that negative effects of iron should be most apparent in fens with fluctuating water levels, as temporary oxygenation allows frequent regeneration of Fe3+. We conclude that rewetting of iron-poor fens may be more feasible for restoration. PMID:27050837

  9. Soil Iron Content as a Predictor of Carbon and Nutrient Mobilization in Rewetted Fens.

    PubMed

    Emsens, Willem-Jan; Aggenbach, Camiel J S; Schoutens, Ken; Smolders, Alfons J P; Zak, Dominik; van Diggelen, Rudy

    2016-01-01

    Rewetted, previously drained fens often remain sources rather than sinks for carbon and nutrients. To date, it is poorly understood which soil characteristics stimulate carbon and nutrient mobilization upon rewetting. Here, we assess the hypothesis that a large pool of iron in the soil negatively affects fen restoration success, as flooding-induced iron reduction (Fe3+ to Fe2+) causes a disproportionate breakdown of organic matter that is coupled with a release of inorganic compounds. We collected intact soil cores in two iron-poor and two iron-rich drained fens, half of which were subjected to a rewetting treatment while the other half was kept drained. Prolonged drainage led to the mobilization of nitrate (NO3-, > 1 mmol L-1) in all cores, regardless of soil iron content. In the rewetted iron-rich cores, a sharp increase in pore water iron (Fe) concentrations correlated with concentrations of inorganic carbon (TIC, > 13 mmol L-1) and dissolved organic carbon (DOC, > 16 mmol L-1). Additionally, ammonium (NH4+) accumulated up to phytotoxic concentrations of 1 mmol L-1 in the pore water of the rewetted iron-rich cores. Disproportionate mobilization of Fe, TIC, DOC and NH4+ was absent in the rewetted iron-poor cores, indicating a strong interaction between waterlogging and iron-mediated breakdown of organic matter. Concentrations of dissolved phosphorus (P) rose slightly in all cores upon rewetting, but remained low throughout the experiment. Our results suggest that large pools of iron in the top soil of drained fens can hamper the restoration of the fen's sink-service for ammonium and carbon upon rewetting. We argue that negative effects of iron should be most apparent in fens with fluctuating water levels, as temporary oxygenation allows frequent regeneration of Fe3+. We conclude that rewetting of iron-poor fens may be more feasible for restoration.

  10. Soil Iron Content as a Predictor of Carbon and Nutrient Mobilization in Rewetted Fens.

    PubMed

    Emsens, Willem-Jan; Aggenbach, Camiel J S; Schoutens, Ken; Smolders, Alfons J P; Zak, Dominik; van Diggelen, Rudy

    2016-01-01

    Rewetted, previously drained fens often remain sources rather than sinks for carbon and nutrients. To date, it is poorly understood which soil characteristics stimulate carbon and nutrient mobilization upon rewetting. Here, we assess the hypothesis that a large pool of iron in the soil negatively affects fen restoration success, as flooding-induced iron reduction (Fe3+ to Fe2+) causes a disproportionate breakdown of organic matter that is coupled with a release of inorganic compounds. We collected intact soil cores in two iron-poor and two iron-rich drained fens, half of which were subjected to a rewetting treatment while the other half was kept drained. Prolonged drainage led to the mobilization of nitrate (NO3-, > 1 mmol L-1) in all cores, regardless of soil iron content. In the rewetted iron-rich cores, a sharp increase in pore water iron (Fe) concentrations correlated with concentrations of inorganic carbon (TIC, > 13 mmol L-1) and dissolved organic carbon (DOC, > 16 mmol L-1). Additionally, ammonium (NH4+) accumulated up to phytotoxic concentrations of 1 mmol L-1 in the pore water of the rewetted iron-rich cores. Disproportionate mobilization of Fe, TIC, DOC and NH4+ was absent in the rewetted iron-poor cores, indicating a strong interaction between waterlogging and iron-mediated breakdown of organic matter. Concentrations of dissolved phosphorus (P) rose slightly in all cores upon rewetting, but remained low throughout the experiment. Our results suggest that large pools of iron in the top soil of drained fens can hamper the restoration of the fen's sink-service for ammonium and carbon upon rewetting. We argue that negative effects of iron should be most apparent in fens with fluctuating water levels, as temporary oxygenation allows frequent regeneration of Fe3+. We conclude that rewetting of iron-poor fens may be more feasible for restoration. PMID:27050837

  11. Advanced in-situ measurement of soil carbon content using inelastic neutron scattering

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Measurement and mapping of natural and anthropogenic variations in soil carbon stores is a critical component of any soil resource evaluation process. Emerging modalities for soil carbon analysis in the field is the registration of gamma rays from soil under neutron irradiation. The inelastic neutro...

  12. [Soil organic carbon content and its distribution pattern in Hangzhou Bay coastal wetlands].

    PubMed

    Shao, Xue-xin; Yang, Wen-ying; Wu, Ming; Jiang, Ke-yi

    2011-03-01

    In this paper, the soil organic carbon (SOC) content and its distribution pattern in the natural intertidal zones and reclaimed wetlands of Hangzhou Bay were studied, aimed to explore the effects of vegetation succession, exotic species invasion, and reclamation on the SOC in costal wetlands of the Bay. In intertidal zones, the surface SOC content ranged from 4.41 to 8.58 g x kg(-1), with an average of 6.45 g x kg(-1), and differed significantly under different vegetations, with a tendency of under Phragmites australis (8.56 +/- 0.04 g x kg(-1)) > Spartina alterniflora (7.31 +/- 0.08 g x kg(-1)) > Scirpus mariqueter (5.48 +/- 0.29 g x kg(-1)) > mudflats (4.47 +/- 0.09 g x kg(-1)); in reclaimed wetlands, the surface SOC content was 7.46 +/- 0.25 g x kg(-1) in the 1960s, 1.96 +/- 0.46 g x kg(-1) in the 1980s, and 5.12 +/- 0.16 g x kg(-1) in 2003, showing a trend of increased after an initial decrease with increasing reclamation year. The SOC in the profiles all showed a decreasing trend from the surface to the bottom. The SOC in intertidal zones and reclaimed wetlands was significantly negatively correlated with soil pH, and positively correlated with soil total nitrogen (TN), suggesting a large reserve of organic nitrogen in TN. The correlation between SOC and soil C/N ratio was not obvious in intertidal zones, but significantly positive in reclaimed wetlands, indicating that reclamation affected soil C/N ratio to a certain extent. This study showed that in the intertidal zones, soil carbon sequestration capacity increased gradually with plant community succession. However, the invasion of exotic species Spartina alternflora might decrease the capacity of carbon sequestration in intertidal zones. It was also found that the changes of soil moisture content, particle composition, vegetation coverage, and reclamation history were the main factors affecting the SOC distribution in reclaimed wetlands.

  13. Regional prediction of soil organic carbon content over croplands using airborne hyperspectral data

    NASA Astrophysics Data System (ADS)

    Vaudour, Emmanuelle; Gilliot, Jean-Marc; Bel, Liliane; Lefebvre, Josias; Chehdi, Kacem

    2015-04-01

    This study was carried out in the framework of the Prostock-Gessol3 and the BASC-SOCSENSIT projects, dedicated to the spatial monitoring of the effects of exogenous organic matter land application on soil organic carbon storage. It aims at identifying the potential of airborne hyperspectral AISA-Eagle data for predicting the topsoil organic carbon (SOC) content of bare cultivated soils over a large peri-urban area (221 km2) with both contrasted soils and SOC contents, located in the western region of Paris, France. Soils comprise hortic or glossic luvisols, calcaric, rendzic cambisols and colluvic cambisols. Airborne AISA-Eagle data (400-1000 nm, 126 bands) with 1 m-resolution were acquired on 17 April 2013 over 13 tracks which were georeferenced. Tracks were atmospherically corrected using a set of 22 synchronous field spectra of both bare soils, black and white targets and impervious surfaces. Atmospherically corrected track tiles were mosaicked at a 2 m-resolution resulting in a 66 Gb image. A SPOT4 satellite image was acquired the same day in the framework of the SPOT4-Take Five program of the French Space Agency (CNES) which provided it with atmospheric correction. The land use identification system layer (RPG) of 2012 was used to mask non-agricultural areas, then NDVI calculation and thresholding enabled to map agricultural fields with bare soil. All 18 sampled sites known to be bare at this very date were correctly included in this map. A total of 85 sites sampled in 2013 or in the 3 previous years were identified as bare by means of this map. Predictions were made from the mosaic spectra which were related to topsoil SOC contents by means of partial least squares regression (PLSR). Regression robustness was evaluated through a series of 1000 bootstrap data sets of calibration-validation samples. The use of the total sample including 27 sites under cloud shadows led to non-significant results. Considering 43 sites outside cloud shadows only, median

  14. Pyrogenic Carbon in soils: a literature-based inventory and a global estimation of its content in soil organic carbon and stocks

    NASA Astrophysics Data System (ADS)

    Reisser, Moritz; Purves, Ross; Schmidt, Michael W. I.; Abiven, Samuel

    2016-08-01

    Pyrogenic carbon (PyC) is considered one of the most stable components in soil and can represent more than 30% of total soil organic carbon (SOC). However, few estimates of global PyC stock or distribution exist and thus PyC is not included in any global carbon cycle models, despite its potential major relevance for the soil pool. To obtain a global picture, we reviewed the literature for published PyC content in SOC data. We generated the first PyC database including more than 560 measurements from 55 studies. Despite limitations due to heterogeneous distribution of the studied locations and gaps in the database, we were able to produce a worldwide PyC inventory. We found that global PyC represent on average 13.7% of the SOC and can be even up to 60%, making it one of the largest groups of identifiable compounds in soil, together with polysaccharides. We observed a consistent range of PyC content in SOC, despite the diverse methods of quantification. We tested the PyC content against different environmental explanatory variables: fire and land use (fire characteristics, land use, net primary productivity), climate (temperature, precipitation, climatic zones, altitude) and pedogenic properties (clay content, pH, SOC content). Surprisingly, soil properties explain PyC content the most. Soils with clay content higher than 50% contain significantly more PyC (> 30% of the SOC) than with clay content lower than 5% (< 6% of the SOC). Alkaline soils contain at least 50% more PyC than acidic soils. Furthermore, climatic conditions, represented by climatic zone or mean temperature or precipitation, correlate significantly with the PyC content. By contrast, fire characteristics could only explain PyC content, if site-specific information was available. Datasets derived from remote sensing did not explain the PyC content. To show the potential of this database, we used it in combination with other global datasets to create a global worldwide PyC content and a stock estimation

  15. Effects of long-term compost application on carbon content and soil physical properties

    NASA Astrophysics Data System (ADS)

    Eden, Marie; Houot, Sabine

    2013-04-01

    Biological treatment through composting of organic wastes fulfils multiple purposes: it not only reduces the amount of waste stored in landfills but can also provide agricultural soils with organic amendments, which affect physicochemical soil properties and reduce the use of mineral fertilizers. However, the impacts of different types of amendments are not yet fully understood, as quantity and quality of the exogenous organic matter (EOM) applied vary greatly and numerous other parameters are affected as well, such as pH, heavy metal content, or nutrient availability. The objective of this project was to investigate the effect of different organic amendments - via simulations - on water holding capacity (WHC) and particularly plant available water (PAW), in regard to irrigation needs. The long-term field experiment "Qualiagro" (INRA - Veolia Environment collaboration) was established in Feucherolles, France in 1998, where five treatments were designed, each with two levels of mineral nitrogen (N) addition: minimal and optimal. Farmyard manure (FYM) and three types of compost - all applied every other year at a rate of 4 t carbon ha-1 - gave rise to varying organic carbon (OC) contents and were compared to a control treatment. The treatments changed the soil's OC content from initially ~10.5 g kg-1 to a range of 9.35 to 15.58 g kg-1. An increased OC content can enhance WHC by increasing total porosity/ reducing bulk density. The PAW - the difference between field capacity (FC) and permanent wilting point (WP); predicted with pedotransfer functions related to OC - increases, if the increase at FC is larger than that at WP. With a higher amount of PAW, the need to irrigate fields - to ensure sufficient water availability for plant growth - decreases. At the same time, soil bulk density (ρd) affects root growth; denser soils can lead to reduced rooting depth. Both of these effects were considered when employing a simple soil water balance model (BUDGET; http

  16. Carbon exchange in biological soil crust communities under differential temperatures and soil water contents: implications for global change

    USGS Publications Warehouse

    Grote, Edmund E.; Belnap, Jayne; Housman, David C.; Sparks, Jed P.

    2010-01-01

    Biological soil crusts (biocrusts) are an integral part of the soil system in arid regions worldwide, stabilizing soil surfaces, aiding vascular plant establishment, and are significant sources of ecosystem nitrogen and carbon. Hydration and temperature primarily control ecosystem CO2 flux in these systems. Using constructed mesocosms for incubations under controlled laboratory conditions, we examined the effect of temperature (5-35 1C) and water content (WC, 20-100%) on CO2 exchange in light cyanobacterially dominated) and dark cyanobacteria/lichen and moss dominated) biocrusts of the cool Colorado Plateau Desert in Utah and the hot Chihuahuan Desert in New Mexico. In light crusts from both Utah and New Mexico, net photosynthesis was highest at temperatures 430 1C. Net photosynthesis in light crusts from Utah was relatively insensitive to changes in soil moisture. In contrast, light crusts from New Mexico tended to exhibit higher rates of net photosynthesis at higher soil moisture. Dark crusts originating from both sites exhibited the greatest net photosynthesis at intermediate soil water content (40-60%). Declines in net photosynthesis were observed in dark crusts with crusts from Utah showing declines at temperatures 425 1C and those originating from New Mexico showing declines at temperatures 435 1C. Maximum net photosynthesis in all crust types from all locations were strongly influenced by offsets in the optimal temperature and water content for gross photosynthesis compared with dark respiration. Gross photosynthesis tended to be maximized at some intermediate value of temperature and water content and dark respiration tended to increase linearly. The results of this study suggest biocrusts are capable of CO2 exchange under a wide range of conditions. However, significant changes in the magnitude of this exchange should be expected for the temperature and precipitation changes suggested by current climate models.

  17. Effect of Charcoal Volatile Matter Content and Feedstock on Soil Microbe-Carbon-Nitrogen Dynamics

    NASA Astrophysics Data System (ADS)

    McClellan, T.; Deenik, J. L.; Hockaday, W. C.; Campbell, S.; Antal, M. J., Jr.

    2010-12-01

    Charcoal has important biogeochemical implications in soil—first as a means to sequester carbon, and second as a soil conditioner to potentially enhance soil quality and fertility. Volatile matter (VM) content is a property of charcoal which describes its degree of thermal alteration, or carbonization. Results from greenhouse experiments have shown that plant growth can be negatively affected by charcoals with high VM content (20-35%), with and without fertilizer supplements, whereas low VM charcoal (6-9%) increased plant growth when combined with fertilizer. We conducted two laboratory studies to characterize the VM content of charcoals derived from two feedstocks (corncob and kiawe) and relate observed differences to key aspects of soil fertility. Using Fourier transform infrared spectroscopy (FTIR), 13C nuclear magnetic resonance (NMR), total phenol content (using a Prussian blue colorimetric assay), and gas chromatography-mass spectrometry (GC-MS), we found that the VM content of charcoal primarily consisted of alkanes, oxygen-substituted alkanes, and phenolic compounds. However, the GC-MS data indicated that charcoals can differ vastly in their extractable fraction, depending upon both VM content and feedstock. In a second set of experiments, we examined the effect of VM content and feedstock on soil microbial activity, available nitrogen (N), and soluble carbon (C). High VM corncob charcoals significantly enhanced microbial activity, coupled with net reduction in available N and soluble C. For a given feedstock, the extent of this effect was dependent upon VM content. However, the overall effect of VM content on microbial dynamics was apparently related to the composition of the acetone-extractable fraction, which was particularly important when comparing two charcoals derived from different feedstocks but with the equivalent VM contents. Removing the acetone-extractable fraction from the 23% VM corncob charcoal significantly reduced the enhancement of

  18. Tillage, cropping sequence, and nitrogen fertilization effects on dryland soil carbon dioxide emission and carbon content.

    PubMed

    Sainju, Upendra M; Jabro, Jalal D; Caesar-Tonthat, Thecan

    2010-01-01

    Management practices are needed to reduce dryland soil CO(2) emissions and to increase C sequestration. We evaluated the effects of tillage and cropping sequence combinations and N fertilization on dryland crop biomass (stems + leaves) and soil surface CO(2) flux and C content (0- to 120-cm depth) in a Williams loam from May to October, 2006 to 2008, in eastern Montana. Treatments were no-tilled continuous malt barley (Hordeum vulgaris L.) (NTCB), no-tilled malt barley-pea (Pisum sativum L.) (NTB-P), no-tilled malt barley-fallow (NTB-F), and conventional-tilled malt barley-fallow (CTB-F), each with 0 and 80 kg N ha(-1). Measurements were made both in Phase I (malt barley in NTCB, pea in NTB-P, and fallow in NTB-F and CTB-F) and Phase II (malt barley in all sequences) of each cropping sequence in every year. Crop biomass varied among years, was greater in the barley than in the pea phase of the NTB-P treatment, and greater in NTCB and NTB-P than in NTB-F and CTB-F in 2 out of 3 yr. Similarly, biomass was greater with 80 than with 0 kg N ha(-1) in 1 out of 3 yr. Soil CO(2) flux increased from 8 mg C m(-2) h(-1) in early May to 239 mg C m(-2) h(-1) in mid-June as temperature increased and then declined to 3 mg C m(-2) h(-1) in September-October. Fluxes peaked immediately following substantial precipitation (>10 mm), especially in NTCB and NTB-P. Cumulative CO(2) flux from May to October was greater in 2006 and 2007 than in 2008, greater in cropping than in fallow phases, and greater in NTCB than in NTB-F. Tillage did not influence crop biomass and CO(2) flux but N fertilization had a variable effect on the flux in 2008. Similarly, soil total C content was not influenced by treatments. Annual cropping increased CO(2) flux compared with crop-fallow probably by increasing crop residue returns to soils and root and rhizosphere respiration. Inclusion of peas in the rotation with malt barley in the no-till system, which have been known to reduce N fertilization rates and

  19. [Effects of nitrogen application on soil greenhouse gas fluxes in Eucalyptus plantations with different soil organic carbon content].

    PubMed

    Li, Rui-Da; Zhang, Kai; Su, Dan; Lu, Fei; Wan, Wu-Xing; Wang, Xiao-Ke; Zheng, Hua

    2014-10-01

    The effects of nitrogen fertilization or nitrogen deposition on soil greenhouse gases fluxes has been well studied, while little has been piloted about the effects of nitrogen application on soil greenhouse gas fluxes and its discrepancy with different soil organic carbon content. In our study, we conducted field control experiment in a young Eucalyptus plantation in Southeast China. We compared the effects of 4 levels of nitrogen fertilization (Control: 0 kg · hm(-2); Low N: 84.2 kg · hm(-2); Medium N: 166.8 kg · hm(-2); High N: 333.7 kg · hm(-2)) on soil GHGs fluxes from 2 sites (LC and HC) with significantly different soil organic carbon (SOC) content (P < 0.05). The results showed: (1) Fertilization had significant priming effect on CO2 and N2O emission fluxes. One month after fertilization, both CO2 and N2O had the flux peak and decreased gradually, and the difference among the treatments disappeared at the end of the growing season. However, fertilization had no significant effect on CH4 oxidation between the 2 sites. (2) Fertilization and SOC were two crucial factors that had significant effects on CO2 and N2O emission. Fertilization had a significant positive effect on CO2 and N2O emission fluxes (P < 0.001). CH4 oxidation rates decreased with the increasing N addition, but there was no statistical difference (P > 0.05). The CO2 and N2O emission fluxes were significantly higher in HC than those in LC (P < 0.01). (3) Fertilization and SOC had great interactive effect on CO2 and N2O emission (P < 0.05). Compared with fluxes in LC, the fluxes in HC were much more sensitive to N input: low N could remarkably stimulate the CO2 and N2O emission. In conclusion, the effects of nitrogen fertilization on soil GHGs fluxes were not only in connection with the intensify of nitrogen, but also closely tied to the SOC content. When we assess the effects of nitrogen on soil GHGs fluxes, the difference induced by SOC should not be ignored.

  20. Modelling global change impacts on soil carbon contents of agro-silvo-pastoral Mediterranean systems

    NASA Astrophysics Data System (ADS)

    Lozano-García, Beatriz; Muñoz-Rojas, Miriam; Parras-Alcántara, Luis

    2016-04-01

    total of 38 sampling points were selected under two management practices and six different land uses: (1) MEOW-dehesa (D); (2) MEOW-dehesa + some pine trees (D+P); (3) MEOW-dehesa + some cork oaks (D+C); (4) MEOW-dehesa + some gall oaks (D + G); (5) MEOW-dehesa after a clarified process and transformed to olive grove but maintaining isolated oaks (OG) and (6) MEOW-dehesa after a clarified process and transformed to cereal pasture with isolated oaks (C). Preliminary results showed a high heterogeneity of SOC contents along the soil profile for different climate and land use scenarios. The methods used here can be easily implemented in other Mediterranean areas with available information on climate, site, soil and land use. Keywords: CarboSOIL model, land use change, climate change, soil depth, dehesa References: Abd-Elmabod, S.K., Muñoz-Rojas, M., Jordán, A., Anaya-Romero, M., De la Rosa, D., 2014. Modelling soil organic carbon stocks along topographic transects under climate change scenarios using CarboSOIL. Geophys. Res. Abstr. vol. 16 EGU2014-295-1, EGU General Assembly.) Álvaro-Fuentes, J., Easter, M., Paustian, K., 2012. Climate change effects on organic carbon storage in agricultural soils of northeastern Spain. Agric. Ecosyst. Environ. 155, 87-94. Corral-Fernández, R., Parras-Alcántara, L., Lozano-García, B. 2013. Stratification ratio of soil organic C, N and C:N in Mediterranean evergreen oak woodland with conventional and organic tillage. Agric. Ecosyst. Environ. 164, 252-259. Francaviglia, R., Coleman, K., Whitmore, A.P., Doro, L., Urracci, G., Rubino, M., Ledda, L., 2012. Changes in soil organic carbon and climate change - application of the RothC model in agrosilvo-pastoral Mediterranean systems. Agric. Syst. 112, 48- 54. IPCC, 2007. Technical summary. In: Climate Change 2007. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change http://www.ipcc.ch/. Lozano-García, B., Parras-Alcántara, L

  1. Can mud (silt and clay) concentration be used to predict soil organic carbon content within seagrass ecosystems?

    NASA Astrophysics Data System (ADS)

    Serrano, Oscar; Lavery, Paul S.; Duarte, Carlos M.; Kendrick, Gary A.; Calafat, Antoni; York, Paul H.; Steven, Andy; Macreadie, Peter I.

    2016-09-01

    The emerging field of blue carbon science is seeking cost-effective ways to estimate the organic carbon content of soils that are bound by coastal vegetated ecosystems. Organic carbon (Corg) content in terrestrial soils and marine sediments has been correlated with mud content (i.e., silt and clay, particle sizes < 63 µm), however, empirical tests of this theory are lacking for coastal vegetated ecosystems. Here, we compiled data (n = 1345) on the relationship between Corg and mud contents in seagrass ecosystems (79 cores) and adjacent bare sediments (21 cores) to address whether mud can be used to predict soil Corg content. We also combined these data with the δ13C signatures of the soil Corg to understand the sources of Corg stores. The results showed that mud is positively correlated with soil Corg content only when the contribution of seagrass-derived Corg to the sedimentary Corg pool is relatively low, such as in small and fast-growing meadows of the genera Zostera, Halodule and Halophila, and in bare sediments adjacent to seagrass ecosystems. In large and long-living seagrass meadows of the genera Posidonia and Amphibolis there was a lack of, or poor relationship between mud and soil Corg content, related to a higher contribution of seagrass-derived Corg to the sedimentary Corg pool in these meadows. The relatively high soil Corg contents with relatively low mud contents (e.g., mud-Corg saturation) in bare sediments and Zostera, Halodule and Halophila meadows was related to significant allochthonous inputs of terrestrial organic matter, while higher contribution of seagrass detritus in Amphibolis and Posidonia meadows disrupted the correlation expected between soil Corg and mud contents. This study shows that mud is not a universal proxy for blue carbon content in seagrass ecosystems, and therefore should not be applied generally across all seagrass habitats. Mud content can only be used as a proxy to estimate soil Corg content for scaling up purposes when

  2. Soil temperature and water content drive microbial carbon fixation in grassland of permafrost area on the Tibetan plateau

    NASA Astrophysics Data System (ADS)

    Kong, W.; Guo, G.; Liu, J.

    2014-12-01

    Soil microbial communities underpin terrestrial biogeochemical cycles and are greatly influenced by global warming and global-warming-induced dryness. However, the response of soil microbial community function to global change remains largely uncertain, particularly in the ecologically vulnerable Tibetan plateau permafrost area with large carbon storage. With the concept of space for time substitution, we investigated the responses of soil CO2-fixing microbial community and its enzyme activity to climate change along an elevation gradient (4400-5100 m) of alpine grassland on the central Tibetan plateau. The elevation gradient in a south-facing hill slope leads to variation in climate and soil physicochemical parameters. The autotrophic microbial communities were characterized by quantitative PCR (qPCR), terminal restriction fragment length polymorphism analysis (T-RFLP) and cloning/sequencing targeting the CO2-fixing gene (RubisCO). The results demonstrated that the autotrophic microbial community abundance, structure and its enzyme activity were mainly driven by soil temperature and water content. Soil temperature increase and water decrease dramatically reduced the abundance of the outnumbered form IC RubisCO-containing microbes, and significantly changed the structure of form IC, IAB and ID RubisCO-containing microbial community. Structural equation model revealed that the RubisCO enzyme was directly derived from RubisCO-containing microbes and its activity was significantly reduced by soil temperature increase and water content decrease. Thus our results provide a novel positive feedback loop of climate warming and warming-induced dryness by that soil microbial carbon fixing potential will reduce by 3.77%-8.86% with the soil temperature increase of 1.94oC and water content decrease of 60%-70%. This positive feedback could be capable of amplifying the climate change given the significant contribution of soil microbial CO2-fixing up to 4.9% of total soil organic

  3. Visible and near infrared reflectance spectroscopy as a tool to monitor in situ soil organic carbon content.

    NASA Astrophysics Data System (ADS)

    Noon, C.; Stevens, A.; van Wesemael, B.

    2012-04-01

    The demand for up-to-date soil information has driven the development of rapid techniques to determine soil properties such as soil organic carbon (SOC) in situ. Proximally sensed diffuse reflectance has produced promising results. However, large scale applications are difficult to develop because the relationship between spectral data and soil properties depend on soil type and therefore is inherently local. This study aims to generate robust and locally-relevant calibration models that are applicable to a large scale database in order to provide accurate measures of SOC content in Belgian agricultural land. We collected more than 400 soil samples in South of Belgium covering 6 out 14 agro-ecological zones of the country. Soil samples were spectrally measured in laboratory with an ASD FieldSpec Pro spectroradiometer. By means of cluster analysis of the spectral library linked with several soil attributes (geographical locations, soil types, etc.) multivariate calibration models were built for each identified cluster. Based on their spectral characteristics and easy-obtainable soil attributes, these local calibration models will allow to determine the SOC content of unknown soil samples at large scales.

  4. [Effects of conservation tillage and weed control on soil water and organic carbon contents in winter wheat field].

    PubMed

    Han, Hui-Fang; Ning, Tang-Yuan; Li, Zeng-Jia; Tian, Shen-Zhong; Wang, Yu; Zhong, Wei-Lei; Tian, Xin-Xin

    2011-05-01

    Taking a long-term (since 2004) straw-returning winter wheat field as the object, an investigation was made in the wheat growth seasons of 2008-2009 and 2009-2010 to study the effects of different tillage methods (rotary tillage, harrow tillage, no-tillage, subsoil tillage, and conventional tillage) and weed management on the soil water and organic carbon contents. No matter retaining or removing weeds, the weed density under subsoil tillage and no-tillage was much higher than that under rotary tillage, harrow tillage, and conventional tillage. From the jointing to the milking stage of winter wheat, retaining definite amounts of weeds, no matter which tillage method was adopted, could significantly increase the 0-20 cm soil water content, suggesting the soil water conservation effect of retaining weeds. Retaining weeds only increased the soil organic carbon content in 0-20 cm layer at jointing stage. At heading and milking stages, the soil organic carbon contents in 0-20, 20-40, and 40-60 cm layers were lower under weed retaining than under weed removal. Under the conditions of weed removal, the grain yield under subsoil tillage increased significantly, compared with that under the other four tillage methods. Under the conditions of weed retaining, the grain yield was the highest under rotary tillage, and the lowest under conventional tillage.

  5. Spatial and temporal changes of soil organic carbon content since time of reclamation of mine soils in a semi-arid environment of Australia

    NASA Astrophysics Data System (ADS)

    Baumgartl, Thomas; Glenn, Vanessa; Erskine, Peter; Chan, Jaclyn

    2016-04-01

    Quantifying carbon fluxes in reclaimed mining environments informs about the success of rehabilitation. Increasing soil organic matter (SOM) improves crucial functional properties of soil; thus, it is highly desirable to promote SOM accumulation in rehabilitated mine soils. The carbon content is often used as a surrogate to describe the status of soil health. Organic carbon in soils contributes to nutrient storage and exchange for plant growth, but also improves water storage capacity and microbial activity. Particularly for poor quality soil substrates with low clay contents, like many spoils from open-cut mining, elevating the carbon concentration is an ideal means to improve the soil quality. The objective of the study was to investigate the change of SOC of re-established soils in mining dependent on the length of time since reclamation under different types of vegetation communities in a semi-arid environment of Central Queensland, Australia. Deviating from standard sampling programs, the SOC of the soil profile was determined in small depth sampling increments from the surface following the assumption, that fresh (green) organic matter will be highest close to the surface and that in semi-arid environments, the dislocation of organic matter to depth by precipitation and microbial activity will be limited. The investigations showed that the most recently rehabilitated sites (>3 years post rehabilitation) show a high organic carbon (OC) gradient decreasing from the surface downwards into the soil. The highest concentration of OC was generally found in the first cm from the surface. Below a depth of 5cm no increase of OC with time since reclamation (max. 25 years) could be determined. An increase of OC with time could be determined, although it appears that even after more than 20 years since reclamation the concentration and depth distribution of OC of an unmined soil could not be rebuilt. Thus, it may be inferred that introducing support practices of

  6. The soil organic carbon content of anthropogenically altered organic soils effects the dissolved organic matter quality, but not the dissolved organic carbon concentrations

    NASA Astrophysics Data System (ADS)

    Frank, Stefan; Tiemeyer, Bärbel; Bechtold, Michel; Lücke, Andreas; Bol, Roland

    2016-04-01

    Dissolved organic carbon (DOC) is an important link between terrestrial and aquatic ecosystems. This is especially true for peatlands which usually show high concentrations of DOC due to the high stocks of soil organic carbon (SOC). Most previous studies found that DOC concentrations in the soil solution depend on the SOC content. Thus, one would expect low DOC concentrations in peatlands which have anthropogenically been altered by mixing with sand. Here, we want to show the effect of SOC and groundwater level on the quantity and quality of the dissolved organic matter (DOM). Three sampling sites were installed in a strongly disturbed bog. Two sites differ in SOC (Site A: 48%, Site B: 9%) but show the same mean annual groundwater level of 15 and 18 cm below ground, respectively. The SOC content of site C (11%) is similar to Site B, but the groundwater level is much lower (-31 cm) than at the other two sites. All sites have a similar depth of the organic horizon (30 cm) and the same land-use (low-intensity sheep grazing). Over two years, the soil solution was sampled bi-weekly in three depths (15, 30 and 60 cm) and three replicates. All samples were analyzed for DOC and selected samples for dissolved organic nitrogen (DON) and delta-13C and delta-15N. Despite differences in SOC and groundwater level, DOC concentrations did not differ significantly (A: 192 ± 62 mg/L, B: 163 ± 55 mg/L and C: 191 ± 97 mg/L). At all sites, DOC concentrations exceed typical values for peatlands by far and emphasize the relevance even of strongly disturbed organic soils for DOC losses. Individual DOC concentrations were controlled by the temperature and the groundwater level over the preceding weeks. Differences in DOM quality were clearer. At site B with a low SOC content, the DOC:DON ratio of the soil solution equals the soil's C:N ratio, but the DOC:DON ratio is much higher than the C:N ratio at site A. In all cases, the DOC:DON ratio strongly correlates with delta-13C. There is no

  7. [Effects of transgenic Bt rice on soil dissolved organic carbon and nitrogen contents and microbiological properties].

    PubMed

    Li, Xiu-Qiang; Chen, Fa-Jun; Liu, Man-Qiang; Hu, Feng

    2012-01-01

    A two-year field experiment (2009 and 2010) was conducted to evaluate the effects of three transgenic Bt rice lines (KMD, HH1, and BtSY63) and their non-Bt lines (XSD, MH63, and SY63) on soil dissolved organic carbon (DOC) and nitrogen (DON) and microbiological properties. All the measured indices changed significantly with sampling time. Comparing with their corresponding non-Bt lines, the test transgenic Bt lines had little effects on the soil DOC, DON, and microbial biomass nitrogen (MBN). The transgenic Bt lines had significant effects on the soil microbial biomass carbon (MBC), basal respiration (BR), and microbial metabolic quotient (qCO2) in certain periods of time in the first year, but no effects in the second year. Among the soils planted with the three non-Bt rice lines, no difference was observed in the DOC, DON, and microbiological properties, whereas in the soil planted with BtSY63, the MBC and BR were significantly higher, but the qCO2 was significantly lower, as compared with those in the soils planted with KMD and HH1. In sum, two years' planting transgenic Bt rice had little effects on the soil DOC, DON, and microbiological properties, but the differences of soil microbiological properties induced by the planting of different transgenic Bt rice lines were larger than those induced by the planting of different non-Bt lines, implying that long term monitoring would help to reveal the effects of transgenic Bt rice on the structure and function of soil ecosystem. PMID:22489485

  8. Statistical evaluation of the relationships between spatial variability in the organic carbon content in gray forest soils, soil density, concentrations of heavy metals, and topography

    NASA Astrophysics Data System (ADS)

    Shary, P. A.; Pinskii, D. L.

    2013-11-01

    The spatial variability in the organic carbon content (Corg) in the gray forest soils was studied in relation to topography, soil density ( D); and concentrations of Al, Fe, K, Ca, Mg, Mn, Cu, and Zn measured at 47 points in the upper (0-10 cm) and lower (10-20 cm) layers by the X-ray fluorescent method. The study area (48 by 104 m) under meadow vegetation included the break of slope of a river valley with strongly eroded gray forest soils and active development of erosional processes. Methods of geomorphometry were used for the quantitative characterization of topographic conditions. Statistical relationships between the studied characteristics were investigated by multiple regression methods with verification of the models according to specially developed criteria. The obtained statistical relationships were used to develop 3D cartographic models of the Corg and D distribution in the two soil layers. It was shown that the content of Corg in the upper layer increased on south-facing slopes, whereas the content of Corg in the lower layer gained its maximum of southwestern slopes, and the reasons for this distribution were determined. The major characteristics of topography affecting the distribution of Corg in the different soil layers were identified. The Corg content in any soil layer was most tightly correlated with the D values; a less tight correlation was observed between the Corg and Mg contents. The Zn and Cu contents correlated with the Corg in the lower (10-20 cm) layer, whereas the Ca and Fe contents correlated with the Corg in the upper (0-10 cm) layer. The interpretation of the observed regularities involved data on the stability of metal complexes with humic acids under different conditions of the soil acidity; the effect of the erosional processes was also taken into account.

  9. Mercury content of Illinois soils

    USGS Publications Warehouse

    Dreher, G.B.; Follmer, L.R.

    2004-01-01

    For a survey of Illinois soils, 101 cores had been collected and analyzed to determine the current and background elemental compositions of Illinois soils. Mercury and other elements were determined in six samples per core, including a surface sample from each core. The mean mercury content in the surface samples was 33 ?? 20 ??g/kg soil, and the background content was 20 ?? 9 ??g/kg. The most probable sources of mercury in these soils were the parent material, and wet and dry deposition of Hg0 and Hg2+ derived from coal-burning power plants, other industrial plants, and medical and municipal waste incinerators. Mercury-bearing sewage sludge or other fertilizers applied to agricultural fields could have been the local sources of mercury. Although the mercury content correlated with organic carbon content or clay content in individual cores, when all the data were considered, there was no strong correlation between mercury and either the organic carbon or the clay-size content.

  10. Mapping within-field variations of soil organic carbon content using UAV multispectral visible near-infrared images

    NASA Astrophysics Data System (ADS)

    Gilliot, Jean-Marc; Vaudour, Emmanuelle; Michelin, Joël

    2016-04-01

    This study was carried out in the framework of the PROSTOCK-Gessol3 project supported by the French Environment and Energy Management Agency (ADEME), the TOSCA-PLEIADES-CO project of the French Space Agency (CNES) and the SOERE PRO network working on environmental impacts of Organic Waste Products recycling on field crops at long time scale. The organic matter is an important soil fertility parameter and previous studies have shown the potential of spectral information measured in the laboratory or directly in the field using field spectro-radiometer or satellite imagery to predict the soil organic carbon (SOC) content. This work proposes a method for a spatial prediction of bare cultivated topsoil SOC content, from Unmanned Aerial Vehicle (UAV) multispectral imagery. An agricultural plot of 13 ha, located in the western region of Paris France, was analysed in April 2013, shortly before sowing while it was still bare soil. Soils comprised haplic luvisols, rendzic cambisols and calcaric or colluvic cambisols. The UAV platform used was a fixed wing provided by Airinov® flying at an altitude of 150m and was equipped with a four channels multispectral visible near-infrared camera MultiSPEC 4C® (550nm, 660nm, 735 nm and 790 nm). Twenty three ground control points (GCP) were sampled within the plot according to soils descriptions. GCP positions were determined with a centimetric DGPS. Different observations and measurements were made synchronously with the drone flight: soil surface description, spectral measurements (with ASD FieldSpec 3® spectroradiometer), roughness measurements by a photogrammetric method. Each of these locations was sampled for both soil standard physico-chemical analysis and soil water content. A Structure From Motion (SFM) processing was done from the UAV imagery to produce a 15 cm resolution multispectral mosaic using the Agisoft Photoscan® software. The SOC content was modelled by partial least squares regression (PLSR) between the

  11. Soil carbon dioxide emission and carbon content as affected by irrigation, tillage, cropping system, and nitrogen fertilization.

    PubMed

    Sainju, Upendra M; Jabro, Jalal D; Stevens, William B

    2008-01-01

    Management practices can influence soil CO(2) emission and C content in cropland, which can effect global warming. We examined the effects of combinations of irrigation, tillage, cropping systems, and N fertilization on soil CO(2) flux, temperature, water, and C content at the 0- to 20-cm depth from May to November 2005 at two sites in the northern Great Plains. Treatments were two irrigation systems (irrigated vs. non-irrigated) and six management practices that contained tilled and no-tilled malt barley (Hordeum vulgaris L.) with 0 to 134 kg N ha(-1), no-tilled pea (Pisum sativum L.), and a conservation reserve program (CRP) planting applied in Lihen sandy loam (sandy, mixed, frigid, Entic Haplustolls) in western North Dakota. In eastern Montana, treatments were no-tilled malt barley with 78 kg N ha(-1), no-tilled rye (Secale cereale L.), no-tilled Austrian winter pea, no-tilled fallow, and tilled fallow applied in dryland Williams loam (fine-loamy, mixed Typic Argiborolls). Irrigation increased CO(2) flux by 13% compared with non-irrigation by increasing soil water content in North Dakota. Tillage increased CO(2) flux by 62 to 118% compared with no-tillage at both places. The flux was 1.5- to 2.5-fold greater with tilled than with non-tilled treatments following heavy rain or irrigation in North Dakota and 1.5- to 2.0-fold greater with crops than with fallow following substantial rain in Montana. Nitrogen fertilization increased CO(2) flux by 14% compared with no N fertilization in North Dakota and cropping increased the flux by 79% compared with fallow in no-till and 0 kg N ha(-1) in Montana. The CO(2) flux in undisturbed CRP was similar to that in no-tilled crops. Although soil C content was not altered, management practices influenced CO(2) flux within a short period due to changes in soil temperature, water, and nutrient contents. Regardless of irrigation, CO(2) flux can be reduced from croplands to a level similar to that in CRP planting using no

  12. Interaction of hydration, aging, and carbon content of soil on the evaporation and skin bioavailability of munition contaminants.

    PubMed

    Reifenrath, William G; Kammen, Harold O; Reddy, Gunda; Major, Michael A; Leach, Glenn J

    2008-01-01

    Water plays a key role in enhancing the permeability of human skin to many substances. To further understand its ability to potentially increase the bioavailability of soil contaminants, artificial sweat was applied to excised pig skin prior to dosing with munition-contaminated soils. Skin was mounted in chambers to allow simultaneous measurement of evaporation and penetration and to control air flow, which changed the dwell time of skin surface water within a l-h period post application of test materials. Additional variables included type of compound, aging of spiked soil samples, and carbon content of soil. To this end, the evaporation and skin penetration of C-14 labeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,6-dinitrotoluene (26DNT), and 2,4,6-trinitrotoluene (TNT) were determined from two soil types, Yolo, having 1.2% carbon, and Tinker, having 9.5% carbon. RDX soil samples aged 27 mo and 62 mo were compared to freshly spiked soils samples. Similarly, 26DNT samples aged 35-36 mo and TNT samples aged 18 mo were compared to freshly spiked samples. Approximately 10 microg/cm(2) of radiolabeled compound was applied in 10 mg/cm(2) of soil. Radiolabel recovered from the dermis and tissue culture media (receptor fluid) was summed to determine percent absorption from the soils. Radiolabel recovered from vapor traps determined evaporation. Mean skin absorption of all compounds was higher for low-carbon soil, regardless of soil age and skin surface water as affected by air flow conditions. For 26DNT, a simultaneous increase in evaporation and penetration with conditions that favored enhanced soil hydration of freshly prepared samples was consistent with a mechanism that involved water displacement of 26DNT from its binding sites. A mean penetration of 17.5 +/- 3.6% was observed for 26DNT in low-carbon soil, which approached the value previously reported for acetone vehicle (24 +/- 6%). 26DNT penetration was reduced to 0.35% under dryer conditions and to 0

  13. Interaction of hydration, aging, and carbon content of soil on the evaporation and skin bioavailability of munition contaminants.

    PubMed

    Reifenrath, William G; Kammen, Harold O; Reddy, Gunda; Major, Michael A; Leach, Glenn J

    2008-01-01

    Water plays a key role in enhancing the permeability of human skin to many substances. To further understand its ability to potentially increase the bioavailability of soil contaminants, artificial sweat was applied to excised pig skin prior to dosing with munition-contaminated soils. Skin was mounted in chambers to allow simultaneous measurement of evaporation and penetration and to control air flow, which changed the dwell time of skin surface water within a l-h period post application of test materials. Additional variables included type of compound, aging of spiked soil samples, and carbon content of soil. To this end, the evaporation and skin penetration of C-14 labeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,6-dinitrotoluene (26DNT), and 2,4,6-trinitrotoluene (TNT) were determined from two soil types, Yolo, having 1.2% carbon, and Tinker, having 9.5% carbon. RDX soil samples aged 27 mo and 62 mo were compared to freshly spiked soils samples. Similarly, 26DNT samples aged 35-36 mo and TNT samples aged 18 mo were compared to freshly spiked samples. Approximately 10 microg/cm(2) of radiolabeled compound was applied in 10 mg/cm(2) of soil. Radiolabel recovered from the dermis and tissue culture media (receptor fluid) was summed to determine percent absorption from the soils. Radiolabel recovered from vapor traps determined evaporation. Mean skin absorption of all compounds was higher for low-carbon soil, regardless of soil age and skin surface water as affected by air flow conditions. For 26DNT, a simultaneous increase in evaporation and penetration with conditions that favored enhanced soil hydration of freshly prepared samples was consistent with a mechanism that involved water displacement of 26DNT from its binding sites. A mean penetration of 17.5 +/- 3.6% was observed for 26DNT in low-carbon soil, which approached the value previously reported for acetone vehicle (24 +/- 6%). 26DNT penetration was reduced to 0.35% under dryer conditions and to 0

  14. The role of fungi for carbon decomposition in soils of different structure and fresh organic matter content

    NASA Astrophysics Data System (ADS)

    Schmidt, Sonja; Chenu, Claire; Falconer, Ruth; Geradin, Cyril; Nunan, Naoise; Otten, Wilfred; Pouteau, Valerie

    2014-05-01

    Sequestration of C in soils has a major influence on climate change. Fungi play an important role in carbon decomposition and sequestration but the effect of soil structure and input of fresh organic matter (particulate organic matter POM) is still unclear. Fungi is predominant involved in cellulose decomposition and the priming effect (PE) where old SOM is decomposed by using fresh carbon as a source of energy. Information on how soil structure affects colonisation and decomposition of POM and SOM by fungi could help to get explain processes involved in carbon sequestration and CO2respiration. The objective of this study was to get a better understanding on the involvement of fungi in CO2 emissions arising from soils and to gain information on what factors in the soil are driving organic matter (OM) decomposition. Experimental data on fungal growth and carbon decomposition as affected by POM abundance and soil structure were obtained. Sterilised maize straw (1-2 mm2) and soil (

  15. Effects of land use and mineral characteristics on the organic carbon content, and the amount and composition of Na-pyrophosphate soluble organic matter in subsurface soils

    NASA Astrophysics Data System (ADS)

    Ellerbrock, R.; Kaiser, M.; Walter, K.; Sommer, M.

    2010-12-01

    Land use and mineral characteristics affect the balance of organic carbon in surface as well as in subsurface soils and related feedbacks on soil functions like their potential to mitigate the greenhouse effect. Actually, there are less information about the effects of land use as well as soil properties on the amount and composition of organic matter (OM) for subsurface soils as compared to surface soils. Here we aimed to analyze the long-term impact of arable and forest land use and soil mineral characteristics on subsurface soil organic carbon (SOC) contents, as well as on amount and composition of OM sequentially separated by Na-pyrophosphate solution (OM(PY)) from subsurface soil samples. Seven soils different in mineral characteristics were selected within Germany. Soil samples were taken from subsurface horizons of forest and adjacent arable sites continuously used >100 years. The OM(PY) fractions were analysed on their OC content (OCPY) and characterized by FTIR spectroscopy. A distinct influence of the long-term land use on the SOC contents could not be detected because only for four out of seven sites the forest subsurface soils showed larger SOC contents than the adjacent agricultural soils. A generally site independent enhanced OC sequestration in subsurface soils due to differences in land use cannot be expected in the long-term. Multiple regression analyses indicated for the arable subsurface soils significant positive relationships between the SOC contents and combined effects of the i) exchangeable Ca (Caex) and oxalate soluble Fe (Feox), and ii) the Caex and Alox contents. For the arable subsurface soils the increase of OCPY* (OCPY multiplied by the relative C=O content of OM(PY)) by increasing contents of Caex indicated that OM(PY) mainly interacts with Ca2+ cations. For the forest subsurface soils (pH <5), the OCPY contents were found to be related to the contents of Na-pyrophosphate soluble Fe and Al. The long-term arable and forest land use

  16. Differential Effects of Legume Species on the Recovery of Soil Microbial Communities, and Carbon and Nitrogen Contents, in Abandoned Fields of the Loess Plateau, China

    NASA Astrophysics Data System (ADS)

    Li, Jin Hua; Jiao, Shu Mei; Gao, Rong Qing; Bardgett, Richard D.

    2012-12-01

    Plant-soil interactions are known to influence a wide range of ecosystem-level functions. Moreover, the recovery of these functions is of importance for the successful restoration of soils that have been degraded through intensive and/or inappropriate land use. Here, we assessed the effect of planting treatments commonly used to accelerate rates of grassland restoration, namely introduction of different legume species Medicago sativa, Astragalus adsurgens, Melilotus suaveolens, on the recovery of soil microbial communities and carbon and nitrogen contents in abandoned fields of the Loess Plateau, China. The results showed effects were species-specific, and either positive, neutral or negative depending on the measure and time-scale. All legumes increased basal respiration and metabolic quotient and had a positive effect on activity and functional diversity of the soil microbial community, measured using Biolog EcoPlate. However, soil under Astragalus adsurgens had the highest activity and functional diversity relative to the other treatments. Soil carbon and nitrogen content and microbial biomass were effectively restored in 3-5 years by introducing Medicago sativa and Astragalus adsurgens into early abandoned fields. Soil carbon and nitrogen content were retarded in 3-5 years and microbial biomass was retarded in the fifth year by introducing Melilotus suaveolens. Overall, the restoration practices of planting legumes can significantly affect soil carbon and nitrogen contents, and the biomass, activity, and functional diversity of soil microbial community. Therefore, we propose certain legume species could be used to accelerate ecological restoration of degraded soils, hence assist in the protection and preservation of the environment.

  17. Differential effects of legume species on the recovery of soil microbial communities, and carbon and nitrogen contents, in abandoned fields of the Loess Plateau, China.

    PubMed

    Li, Jin Hua; Jiao, Shu Mei; Gao, Rong Qing; Bardgett, Richard D

    2012-12-01

    Plant-soil interactions are known to influence a wide range of ecosystem-level functions. Moreover, the recovery of these functions is of importance for the successful restoration of soils that have been degraded through intensive and/or inappropriate land use. Here, we assessed the effect of planting treatments commonly used to accelerate rates of grassland restoration, namely introduction of different legume species Medicago sativa, Astragalus adsurgens, Melilotus suaveolens, on the recovery of soil microbial communities and carbon and nitrogen contents in abandoned fields of the Loess Plateau, China. The results showed effects were species-specific, and either positive, neutral or negative depending on the measure and time-scale. All legumes increased basal respiration and metabolic quotient and had a positive effect on activity and functional diversity of the soil microbial community, measured using Biolog EcoPlate. However, soil under Astragalus adsurgens had the highest activity and functional diversity relative to the other treatments. Soil carbon and nitrogen content and microbial biomass were effectively restored in 3-5 years by introducing Medicago sativa and Astragalus adsurgens into early abandoned fields. Soil carbon and nitrogen content were retarded in 3-5 years and microbial biomass was retarded in the fifth year by introducing Melilotus suaveolens. Overall, the restoration practices of planting legumes can significantly affect soil carbon and nitrogen contents, and the biomass, activity, and functional diversity of soil microbial community. Therefore, we propose certain legume species could be used to accelerate ecological restoration of degraded soils, hence assist in the protection and preservation of the environment.

  18. Influence of humic acid applications on modulus of rupture, aggregate stability, electrical conductivity, carbon and nitrogen content of a crusting problem soil

    NASA Astrophysics Data System (ADS)

    Gümüş, İ.; Şeker, C.

    2015-11-01

    Soil structure is often said to be the key to soil productivity since a fertile soil, with desirable soil structure and adequate moisture supply, constitutes a productive soil. Soil structure influences soil water movement and retention, erosion, crusting, nutrient recycling, root penetration and crop yield. The objective of this work is to study humic acid (HA) application on some physical and chemical properties in weakly structured soils. The approach involved establishing a plot experiment in laboratory conditions. Different rates of HA (control, 0.5, 1, 2 and 4 %) were applied to soil during three incubation periods (21, 42 and 62 days). At the end of the each incubation period, the changes in physicochemical properties were measured. Generally, HA addition increased electrical conductivity values during all incubation periods. HA applications decreased soil modulus of rupture. Application of HA at the rate of 4 % significantly increased soil organic carbon contents. HA applications at the rate of 4 % significantly increased both mean soil total nitrogen content and aggregate stability after three incubation periods (p < 0.05). Therefore, HA has the potential to improve the structure of soil in the short term.

  19. Spatial prediction of Soil Organic Carbon contents in croplands, grasslands and forests using environmental covariates and Generalized Additive Models (Southern Belgium)

    NASA Astrophysics Data System (ADS)

    Chartin, Caroline; Stevens, Antoine; van Wesemael, Bas

    2015-04-01

    Providing spatially continuous Soil Organic Carbon data (SOC) is needed to support decisions regarding soil management, and inform the political debate with quantified estimates of the status and change of the soil resource. Digital Soil Mapping techniques are based on relations existing between a soil parameter (measured at different locations in space at a defined period) and relevant covariates (spatially continuous data) that are factors controlling soil formation and explaining the spatial variability of the target variable. This study aimed at apply DSM techniques to recent SOC content measurements (2005-2013) in three different landuses, i.e. cropland, grassland, and forest, in the Walloon region (Southern Belgium). For this purpose, SOC databases of two regional Soil Monitoring Networks (CARBOSOL for croplands and grasslands, and IPRFW for forests) were first harmonized, totalising about 1,220 observations. Median values of SOC content for croplands, grasslands, and forests, are respectively of 12.8, 29.0, and 43.1 g C kg-1. Then, a set of spatial layers were prepared with a resolution of 40 meters and with the same grid topology, containing environmental covariates such as, landuses, Digital Elevation Model and its derivatives, soil texture, C factor, carbon inputs by manure, and climate. Here, in addition to the three classical texture classes (clays, silt, and sand), we tested the use of clays + fine silt content (particles < 20 µm and related to stable carbon fraction) as soil covariate explaining SOC variations. For each of the three land uses (cropland, grassland and forest), a Generalized Additive Model (GAM) was calibrated on two thirds of respective dataset. The remaining samples were assigned to a test set to assess model performance. A backward stepwise procedure was followed to select the relevant environmental covariates using their approximate p-values (the level of significance was set at p < 0.05). Standard errors were estimated for each of

  20. The effects of land abandonment and long-term afforestation practices on the organic carbon and lignin content of a Mediteranean soil

    NASA Astrophysics Data System (ADS)

    Stijsiger, Romy; Nadal-Romero, Estela; Campo, Julian; Cammeraat, Erik

    2016-04-01

    Afforestation is an important strategy that can decrease atmospheric carbon in sequestering it in biomass and soils (Pérez-Crusado et al., 2014). In Spain an active afforestation program was adopted in the 1950s, when after wide spread land abandonment the soils were severely eroded (FAO, 2015). In this research the organic carbon and lignin content of the soils in the Araguás catchment area in the Spanish Pyrenees were examined. This research is part of a larger research examining the effect of afforestation over time (Med Afforest Project, PIEF-GA-2013-624974). The research area was afforested with both the P. sylvestris (Scotts Pine) and the P.nigra (Black Pine). Both sites were compared to bare soil (representing severely eroded soil), natural secondary succession (re-vegetation) and meadows. The method used to assess the lignin content is Curie-point pyrolysis with tetramethylammonium hydroxide (TMAH). The results showed a reducing trend for the soil organic carbon (SOC) content with depth. The highest SOC and lignin contents in the topsoil were found under P.nigra and secondary succession. This decline in lignin content corresponds with a high degradation rate (Ad/Al) in the top soil and lower degradation rates in depths of >20 cm. Meadows showed an increased SOC content in deeper horizons, which corresponds to high lignin content as well. In which the meadows showed an increase in lignin content for the soil depths of >20 cm that was unusual and could not be explained by the S/G and P/G ratios and the degradation ratio (Ad/Al). According to the results, P. nigra was the best afforestation practice for increasing the SOC and lignin contents in the soil. The P. sylvestris was considered but proved to be less successful than natural secondary succession. Acknowledgements This research was supported by a Marie Curie Intra-European Fellowship in the project "MED-AFFOREST" (PIEF-GA-2013-624974). JC also acknowledges the VALi+d postdoctoral contract (APOSTD/2014

  1. Assessment of near-surface soil carbon content across several U.S. cropland watersheds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The cropland Conservation Effects Assessment Project (CEAP) was initiated to provide a scientific basis for assessing effectiveness of conservation practices on water and soil quality. In 2006, sampling was initiated within a number of USDA-ARS experimental watersheds to measure and assess managemen...

  2. Worldwide organic soil carbon and nitrogen data

    SciTech Connect

    Zinke, P.J.; Stangenberger, A.G.; Post, W.M.; Emanual, W.R.; Olson, J.S.

    1986-09-01

    The objective of the research presented in this package was to identify data that could be used to estimate the size of the soil organic carbon pool under relatively undisturbed soil conditions. A subset of the data can be used to estimate amounts of soil carbon storage at equilibrium with natural soil-forming factors. The magnitude of soil properties so defined is a resulting nonequilibrium values for carbon storage. Variation in these values is due to differences in local and geographic soil-forming factors. Therefore, information is included on location, soil nitrogen content, climate, and vegetation along with carbon density and variation.

  3. Assessment of the Impact of Climate Change and Land Management Change on Soil Organic Carbon Content, Leached Carbon Rates and Dissolved Organic Carbon Concentrations

    NASA Astrophysics Data System (ADS)

    Stergiadi, Maria; de Nijs, Ton; van der Perk, Marcel; Bonten, Luc

    2014-05-01

    Climate change is projected to significantly affect the concentrations and mobility of contaminants, such as metals and pathogens, in soil, groundwater and surface water. Climate- and land management-induced changes in soil organic carbon and dissolved organic carbon levels may promote the transport of toxic substances, such as copper and cadmium, and pathogenic microorganisms, ultimately affecting the exposure of humans and ecosystems to these contaminants. In this study, we adopted the Century model to simulate past (1900 - 2010), present, and future (2010 - 2100) SOC and DOC levels for a sandy and a loamy soil typical for Central and Western European conditions under three land use types (forest, grassland and arable land) and several future scenarios addressing climate change and land management change. The climate scenarios were based on the KNMI'06 G+ and W+ scenarios from the Royal Dutch Meteorological Institute. The simulated current SOC levels were compared to observed SOC values derived from various Dutch soil databases, taking into account the different soil depths the simulated and observed values refer to. The simulated SOC levels were generally in line with the observed values for the different kinds of soil and land use types. Climate change scenarios resulted in a decrease in both SOC and DOC for the grassland systems, whereas in the arable land (on sandy soil) and in the forest systems, SOC was found to increase and DOC to decrease. A sensitivity analysis of the individual effects of changes in temperature and precipitation showed that the effect of temperature predominates over the effect of precipitation. A reduction in the application rates of artificial fertilizers leads to a decrease in the SOC stocks and the leached carbon rates in the arable land systems, but has a negligible effect on SOC and DOC levels of the grassland systems. This study demonstrated the ability of the Century model to simulate climate change and agricultural management

  4. Diurnal hysteresis between soil CO2 and soil temperature is controlled by soil water content

    NASA Astrophysics Data System (ADS)

    Riveros-Iregui, Diego A.; Emanuel, Ryan E.; Muth, Daniel J.; McGlynn, Brian L.; Epstein, Howard E.; Welsch, Daniel L.; Pacific, Vincent J.; Wraith, Jon M.

    2007-09-01

    Recent years have seen a growing interest in measuring and modeling soil CO2 efflux, as this flux represents a large component of ecosystem respiration and is a key determinant of ecosystem carbon balance. Process-based models of soil CO2 production and efflux, commonly based on soil temperature, are limited by nonlinearities such as the observed diurnal hysteresis between soil CO2 concentration ([CO2]) and temperature. Here we quantify the degree to which hysteresis between soil [CO2] and soil temperature is controlled by soil water content in a montane conifer forest, and how this nonlinearity impacts estimates of soil CO2 efflux. A representative model that does not consider hysteresis overestimated soil CO2 efflux for the entire growing season by 19%. At high levels of soil water content, hysteresis imposes organized, daily variability in the relationship between soil [CO2] and soil temperature, and at low levels of soil water content, hysteresis is minimized.

  5. Soil carbon dynamics

    NASA Astrophysics Data System (ADS)

    Trumbore, Susan; Barbosa de Camargo, Plínio

    The amount of organic carbon (C) stored in the upper meter of mineral soils in the Amazon Basin (˜40 Pg C) represents ˜3% of the estimated global store of soil carbon. Adding surface detrital C stocks and soil carbon deeper than 1 m can as much as quadruple this estimate. The potential for Amazon soil carbon to respond to changes in land use, climate, or atmospheric composition depends on the form and dynamics of soil carbon. Much (˜30% in the top ˜10 cm but >85% in soils to 1 m depth) of the carbon in mineral soils of the Oxisols and Ultisols that are the predominant soil types in the Amazon Basin is in forms that are strongly stabilized, with mean ages of centuries to thousands of years. Measurable changes in soil C stocks that accompany land use/land cover change occur in the upper meter of soil, although the presence of deep roots in forests systems drives an active C cycle at depths >1 m. Credible estimates of the potential for changes in Amazon soil C stocks with future land use and climate change are much smaller than predictions of aboveground biomass change. Soil organic matter influences fertility and other key soil properties, and thus is important independent of its role in the global C cycle. Most work on C dynamics is limited to upland soils, and more is needed to investigate C dynamics in poorly drained soils. Work is also needed to relate cycles of C with water, N, P, and other elements.

  6. Relationship between specific surface area and the dry end of the water retention curve for soils with varying clay and organic carbon contents

    NASA Astrophysics Data System (ADS)

    Resurreccion, Augustus C.; Moldrup, Per; Tuller, Markus; Ferré, T. P. A.; Kawamoto, Ken; Komatsu, Toshiko; de Jonge, Lis Wollesen

    2011-06-01

    Accurate description of the soil water retention curve (SWRC) at low water contents is important for simulating water dynamics and biochemical vadose zone processes in arid environments. Soil water retention data corresponding to matric potentials of less than -10 MPa, where adsorptive forces dominate over capillary forces, have also been used to estimate soil specific surface area (SA). In the present study, the dry end of the SWRC was measured with a chilled-mirror dew point psychrometer for 41 Danish soils covering a wide range of clay (CL) and organic carbon (OC) contents. The 41 soils were classified into four groups on the basis of the Dexter number (n = CL/OC), and the Tuller-Or (TO) general scaling model describing water film thickness at a given matric potential (<-10 MPa) was evaluated. The SA estimated from the dry end of the SWRC (SA_SWRC) was in good agreement with the SA measured with ethylene glycol monoethyl ether (SA_EGME) only for organic soils with n > 10. A strong correlation between the ratio of the two surface area estimates and the Dexter number was observed and applied as an additional scaling function in the TO model to rescale the soil water retention curve at low water contents. However, the TO model still overestimated water film thickness at potentials approaching ovendry condition (about -800 MPa). The semi-log linear Campbell-Shiozawa-Rossi-Nimmo (CSRN) model showed better fits for all investigated soils from -10 to -800 MPa and yielded high correlations with CL and SA. It is therefore recommended to apply the empirical CSRN model for predicting the dry part of the water retention curve (-10 to -800 MPa) from measured soil texture or surface area. Further research should aim to modify the more physically based TO model to obtain better descriptions of the SWRC in the very dry range (-300 to -800 MPa).

  7. Pseudomonas aeruginosa RRALC3 Enhances the Biomass, Nutrient and Carbon Contents of Pongamia pinnata Seedlings in Degraded Forest Soil.

    PubMed

    Radhapriya, Parthasarathy; Ramachandran, Andimuthu; Anandham, Rangasamy; Mahalingam, Sundararajan

    2015-01-01

    The study was aimed at assessing the effects of indigenous Plant Growth Promoting Bacterium (PGPB) on the legume Pongamia pinnata in the degraded soil of the Nanmangalam Reserve Forest (NRF) under nursery conditions. In total, 160 diazotrophs were isolated from three different nitrogen-free semi-solid media (LGI, Nfb, and JMV). Amongst these isolates, Pseudomonas aeruginosa RRALC3 exhibited the maximum ammonia production and hence was selected for further studies. RRALC3 was found to possess multiple plant growth promoting traits such as nitrogen accumulation (120.6ppm); it yielded a positive amplicon with nifH specific primers, tested positive for Indole Acetic Acid (IAA; 18.3μg/ml) and siderophore production, tested negative for HCN production and was observed to promote solubilization of phosphate, silicate and zinc in the plate assay. The 16S rDNA sequence of RRALC3 exhibited 99% sequence similarity to Pseudomonas aeruginosa JCM5962. Absence of virulence genes and non-hemolytic activity indicated that RRALC3 is unlikely to be a human pathogen. When the effects of RRALC3 on promotion of plant growth was tested in Pongamia pinnata, it was observed that in Pongamia seedlings treated with a combination of RRALC3 and chemical fertilizer, the dry matter increased by 30.75%. Nitrogen, phosphorus and potassium uptake increased by 34.1%, 27.08%, and 31.84%, respectively, when compared to control. Significant enhancement of total sugar, amino acids and organic acids content, by 23.4%, 29.39%, and 26.53% respectively, was seen in the root exudates of P. pinnata. The carbon content appreciated by 4-fold, when fertilized seedlings were treated with RRALC3. From the logistic equation, the rapid C accumulation time of Pongamia was computed as 43 days longer than the control when a combination of native PGPB and inorganic fertilizer was applied. The rapid accumulation time of N, P and K in Pongamia when treated with the same combination as above was 15, 40 and 33 days longer

  8. Pseudomonas aeruginosa RRALC3 Enhances the Biomass, Nutrient and Carbon Contents of Pongamia pinnata Seedlings in Degraded Forest Soil

    PubMed Central

    Radhapriya, Parthasarathy; Ramachandran, Andimuthu; Anandham, Rangasamy; Mahalingam, Sundararajan

    2015-01-01

    The study was aimed at assessing the effects of indigenous Plant Growth Promoting Bacterium (PGPB) on the legume Pongamia pinnata in the degraded soil of the Nanmangalam Reserve Forest (NRF) under nursery conditions. In total, 160 diazotrophs were isolated from three different nitrogen-free semi-solid media (LGI, Nfb, and JMV). Amongst these isolates, Pseudomonas aeruginosa RRALC3 exhibited the maximum ammonia production and hence was selected for further studies. RRALC3 was found to possess multiple plant growth promoting traits such as nitrogen accumulation (120.6ppm); it yielded a positive amplicon with nifH specific primers, tested positive for Indole Acetic Acid (IAA; 18.3μg/ml) and siderophore production, tested negative for HCN production and was observed to promote solubilization of phosphate, silicate and zinc in the plate assay. The 16S rDNA sequence of RRALC3 exhibited 99% sequence similarity to Pseudomonas aeruginosa JCM5962. Absence of virulence genes and non-hemolytic activity indicated that RRALC3 is unlikely to be a human pathogen. When the effects of RRALC3 on promotion of plant growth was tested in Pongamia pinnata, it was observed that in Pongamia seedlings treated with a combination of RRALC3 and chemical fertilizer, the dry matter increased by 30.75%. Nitrogen, phosphorus and potassium uptake increased by 34.1%, 27.08%, and 31.84%, respectively, when compared to control. Significant enhancement of total sugar, amino acids and organic acids content, by 23.4%, 29.39%, and 26.53% respectively, was seen in the root exudates of P. pinnata. The carbon content appreciated by 4-fold, when fertilized seedlings were treated with RRALC3. From the logistic equation, the rapid C accumulation time of Pongamia was computed as 43 days longer than the control when a combination of native PGPB and inorganic fertilizer was applied. The rapid accumulation time of N, P and K in Pongamia when treated with the same combination as above was 15, 40 and 33 days longer

  9. Pseudomonas aeruginosa RRALC3 Enhances the Biomass, Nutrient and Carbon Contents of Pongamia pinnata Seedlings in Degraded Forest Soil.

    PubMed

    Radhapriya, Parthasarathy; Ramachandran, Andimuthu; Anandham, Rangasamy; Mahalingam, Sundararajan

    2015-01-01

    The study was aimed at assessing the effects of indigenous Plant Growth Promoting Bacterium (PGPB) on the legume Pongamia pinnata in the degraded soil of the Nanmangalam Reserve Forest (NRF) under nursery conditions. In total, 160 diazotrophs were isolated from three different nitrogen-free semi-solid media (LGI, Nfb, and JMV). Amongst these isolates, Pseudomonas aeruginosa RRALC3 exhibited the maximum ammonia production and hence was selected for further studies. RRALC3 was found to possess multiple plant growth promoting traits such as nitrogen accumulation (120.6ppm); it yielded a positive amplicon with nifH specific primers, tested positive for Indole Acetic Acid (IAA; 18.3μg/ml) and siderophore production, tested negative for HCN production and was observed to promote solubilization of phosphate, silicate and zinc in the plate assay. The 16S rDNA sequence of RRALC3 exhibited 99% sequence similarity to Pseudomonas aeruginosa JCM5962. Absence of virulence genes and non-hemolytic activity indicated that RRALC3 is unlikely to be a human pathogen. When the effects of RRALC3 on promotion of plant growth was tested in Pongamia pinnata, it was observed that in Pongamia seedlings treated with a combination of RRALC3 and chemical fertilizer, the dry matter increased by 30.75%. Nitrogen, phosphorus and potassium uptake increased by 34.1%, 27.08%, and 31.84%, respectively, when compared to control. Significant enhancement of total sugar, amino acids and organic acids content, by 23.4%, 29.39%, and 26.53% respectively, was seen in the root exudates of P. pinnata. The carbon content appreciated by 4-fold, when fertilized seedlings were treated with RRALC3. From the logistic equation, the rapid C accumulation time of Pongamia was computed as 43 days longer than the control when a combination of native PGPB and inorganic fertilizer was applied. The rapid accumulation time of N, P and K in Pongamia when treated with the same combination as above was 15, 40 and 33 days longer

  10. [Research methods of carbon sequestration by soil aggregates: a review].

    PubMed

    Chen, Xiao-Xia; Liang, Ai-Zhen; Zhang, Xiao-Ping

    2012-07-01

    To increase soil organic carbon content is critical for maintaining soil fertility and agricultural sustainable development and for mitigating increased greenhouse gases and the effects of global climate change. Soil aggregates are the main components of soil, and have significant effects on soil physical and chemical properties. The physical protection of soil organic carbon by soil aggregates is the important mechanism of soil carbon sequestration. This paper reviewed the organic carbon sequestration by soil aggregates, and introduced the classic and current methods in studying the mechanisms of carbon sequestration by soil aggregates. The main problems and further research trends in this study field were also discussed.

  11. Soil carbon determination by thermogravimetrics.

    PubMed

    Pallasser, Robert; Minasny, Budiman; McBratney, Alex B

    2013-01-01

    Determination of soil constituents and structure has a vital role in agriculture generally. Methods for the determination of soil carbon have in particular gained greater currency in recent times because of the potential that soils offer in providing offsets for greenhouse gas (CO2-equivalent) emissions. Ideally, soil carbon which can also be quite diverse in its makeup and origin, should be measureable by readily accessible, affordable and reliable means. Loss-on-ignition is still a widely used method being suitably simple and available but may have limitations for soil C monitoring. How can these limitations be better defined and understood where such a method is required to detect relatively small changes during soil-C building? Thermogravimetric (TGA) instrumentation to measure carbonaceous components has become more interesting because of its potential to separate carbon and other components using very precise and variable heating programs. TGA related studies were undertaken to assist our understanding in the quantification of soil carbon when using methods such as loss-on-ignition. Combining instrumentation so that mass changes can be monitored by mass spectrometer ion currents has elucidated otherwise hidden features of thermal methods enabling the interpretation and evaluation of mass-loss patterns. Soil thermogravimetric work has indicated that loss-on-ignition methods are best constrained to temperatures from 200 to 430 °C for reliable determination for soil organic carbon especially where clay content is higher. In the absence of C-specific detection where mass only changes are relied upon, exceeding this temperature incurs increasing contributions from inorganic sources adding to mass losses with diminishing contributions related to organic matter. The smaller amounts of probably more recalcitrant organic matter released at the higher temperatures may represent mineral associated material and/or simply more refractory forms.

  12. Revealing spatial distribution of soil organic carbon contents and stocks of a disturbed bog relict by in-situ NIR and apparent EC mapping

    NASA Astrophysics Data System (ADS)

    Bechtold, Michel; Tiemeyer, Bärbel; Don, Axel; Altdorff, Daniel; van der Kruk, Jan; Huisman, Johan A.

    2013-04-01

    Previous studies showed that in-situ visible near-infrared (vis-NIR) spectroscopy can overcome the limitations of conventional soil sampling. Costs can be reduced and spatial resolution enhanced when mapping field-scale variability of soil organic carbon (SOC). Detailed maps can help to improve SOC management and lead to better estimates of field-scale total carbon stocks. Knowledge of SOC field patterns may also help to reveal processes and factors controlling SOC variability. In this study, we apply in situ vis-NIR and apparent electrical conductivity (ECa) mapping to a disturbed bog relict. The major question of this application study was how field-scale in-situ vis-NIR mapping performs for a very heterogeneous area and under difficult grassland conditions and under highly-variable water content conditions. Past intensive peat cutting and deep ploughing in some areas, in combination with a high background heterogeneity of the underlying mineral sediments, have led to a high variability of SOC content (5.6 to 41.3 %), peat layer thickness (25 to 60 cm) and peat degradation states (from nearly fresh to amorphous). Using a field system developed by Veris Technologies (Salina KS, USA), we continuously collected vis-NIR spectra at 10 cm depth (measurement range: 350 nm to 2200 nm) over an area of around 12 ha with a line spacing of about 12 m. The system includes a set of discs for measuring ECa of the first 30 and 90 cm of the soil. The same area was also mapped with a non-invasive electro-magnetic induction (EMI) setup that provided ECa data of the first 25, 50 and 100 cm. For calibration and validation of the spatial data, we took 30 representative soil samples and 15 soil cores of about 90 cm depth, for which peat thickness, water content, pore water EC, bulk density (BD), as well as C and N content were determined for various depths. Preliminary results of the calibration of the NIR spectra to the near-surface SOC contents indicate good data quality despite the

  13. Nitrogen deposition alters nitrogen cycling and reduces soil carbon content in low-productivity semiarid Mediterranean ecosystems

    PubMed Central

    Ochoa-Hueso, Raúl; Maestre, Fernando T.; Ríos, Asunción de los; Valea, Sergio; Theobald, Mark R.; Vivanco, Marta G.; Manrique, Esteban; Bowker, Mathew A.

    2015-01-01

    Nitrogen (N) deposition is a threat to European Mediterranean ecosystems, but the evidence of real ecological impacts is still scarce. We combined data from a real N deposition gradient (4.3-7.3 kg N ha−1 yr−1) from semiarid portions of Spain with data from a field experiment in central Spain to evaluate N deposition effects on soil fertility, function and cyanobacteria community structure. Soil organic N did not increase along the extant deposition gradient, whereas C:N ratios decreased in most locations. Nitrogen fixation decreased along existing and experimental N deposition gradients, a result possibly related to compositional shifts in soil cyanobacteria community. Nitrogen mineralization rates were reduced by N fertilization, suggesting ecosystem N saturation. Soil organic C content and the activity of β-glucosidase decreased along the extant gradient. Our results suggest that semiarid soils in low-productivity sites are unable to store additional N inputs, and that are also unable to mitigate increasing C emissions to the atmosphere when experiencing increased N deposition. PMID:23685631

  14. Positive feedback of crop residue incorporation on dissolved organic carbon contents under anaerobic conditions in temperate rice paddy soils

    NASA Astrophysics Data System (ADS)

    Said-Pullicino, Daniel; Sodano, Marcella; Bertora, Chiara; Lerda, Cristina; Sacco, Dario; Celi, Luisella

    2016-04-01

    Rice paddy soils are generally characterized by large concentrations and fluxes of DOC in comparison to other ecosystems. Our recent studies have shown that the combination of relatively high pore-water DOC concentrations under anoxic soil conditions (>10-20 mg C l‑1) and important percolation fluxes of water during field flooding may contribute significant organic C inputs into the subsoil (18-51 g C m‑2) over the cropping season. Crop residues incorporated into the soil after harvest represent the main input of organic C into paddy soils, returning about 200-300 g C m‑2 y‑1 in single-cropped rice paddies. The anaerobic decomposition of these residues may supply important amounts of DOC to soil pore waters. Moreover, the supply of electron donors with the input of residue-derived labile OM may further increase DOC contents by stimulating the microbially-catalyzed reductive dissolution of Fe and Mn oxyhydroxides under anoxic conditions, and release of DOC previously stabilized on the mineral matrix (i.e. positive feedback). This could have important implications on organic C inputs into the subsoil as well as substrate availability for methane production. We therefore hypothesized that crop residue management practices that influence the amount of labile organic matter present in the soil at the time of field flooding may strongly influence soil solution DOC concentrations as well as the positive feedback on the release of soil-derived DOC. We tested this hypothesis at field-scale by evaluating variations in the contents and quality of DOC above and beneath the plough pan over the cropping season as a function of crop residue management practices involving: tillage and crop residue incorporation in spring (SPR), tillage and crop residue incorporation in spring, dry seeding and 1 month delayed flooding (DRY), tillage and crop residue incorporation in autumn (AUT), and straw removal after harvest and tillage in spring (REM). Moreover, we linked changes in DOC

  15. Positive feedback of crop residue incorporation on dissolved organic carbon contents under anaerobic conditions in temperate rice paddy soils

    NASA Astrophysics Data System (ADS)

    Said-Pullicino, Daniel; Sodano, Marcella; Bertora, Chiara; Lerda, Cristina; Sacco, Dario; Celi, Luisella

    2016-04-01

    Rice paddy soils are generally characterized by large concentrations and fluxes of DOC in comparison to other ecosystems. Our recent studies have shown that the combination of relatively high pore-water DOC concentrations under anoxic soil conditions (>10-20 mg C l-1) and important percolation fluxes of water during field flooding may contribute significant organic C inputs into the subsoil (18-51 g C m-2) over the cropping season. Crop residues incorporated into the soil after harvest represent the main input of organic C into paddy soils, returning about 200-300 g C m-2 y-1 in single-cropped rice paddies. The anaerobic decomposition of these residues may supply important amounts of DOC to soil pore waters. Moreover, the supply of electron donors with the input of residue-derived labile OM may further increase DOC contents by stimulating the microbially-catalyzed reductive dissolution of Fe and Mn oxyhydroxides under anoxic conditions, and release of DOC previously stabilized on the mineral matrix (i.e. positive feedback). This could have important implications on organic C inputs into the subsoil as well as substrate availability for methane production. We therefore hypothesized that crop residue management practices that influence the amount of labile organic matter present in the soil at the time of field flooding may strongly influence soil solution DOC concentrations as well as the positive feedback on the release of soil-derived DOC. We tested this hypothesis at field-scale by evaluating variations in the contents and quality of DOC above and beneath the plough pan over the cropping season as a function of crop residue management practices involving: tillage and crop residue incorporation in spring (SPR), tillage and crop residue incorporation in spring, dry seeding and 1 month delayed flooding (DRY), tillage and crop residue incorporation in autumn (AUT), and straw removal after harvest and tillage in spring (REM). Moreover, we linked changes in DOC

  16. Profiling soil water content sensor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A waveguide-on-access-tube (WOAT) sensor system based on time domain reflectometry (TDR) principles was developed to sense soil water content and bulk electrical conductivity in 20-cm (8 inch) deep layers from the soil surface to depths of 3 m (10 ft) (patent No. 13/404,491 pending). A Cooperative R...

  17. Comparison of PLSR and SVM methods for predicting the organic carbon content using VNIR DRS at five locations with different soil types

    NASA Astrophysics Data System (ADS)

    Klement, Ales; Kodesova, Radka; Vasat, Radim; Fer, Miroslav; Brodsky, Lukas; Jaksik, Ondrej

    2015-04-01

    Visible and near-infrared diffuse reflectance spectroscopy (VNIR DRS) is cost- and time-effective and environmentally friendly techniques method used for prediction of soil properties. There are many studies dealing with this approach for particular conditions (single locality, different area size, etc.). This study was therefore focused on evaluating the suitability of VNIR DRS (400 - 2500 nm) for predicting organic carbon content, using samples collected at 5 agricultural lands from the municipalities of Brumovice (107 samples), Hostoun (58 samples), Sedlcany (78 samples), Vidim (86 samples) and Zelezna (69 samples). In Brumovice original soil type was Haplic Chernozem on loess, which was due to erosion changed into Regosol (steep parts) and Colluvial soil (base slope and the tributary valley). A similar process has been observed at other four locations Hostoun, Sedlcany, Vidim and Zelezna where the original soil types were Calcaric Leptosol, Haplic Cambisol on gneiss, Haplic Luvisol on loess and Haplic Cambisol on shales, respectively. Samples were taken from the topsoil within regular grid covering studied areas. Variable approaches may be applied to relate reflectance spectral data to particular soil property. Here were used Partial Least Square Regression (PLSR) and Support Vector Machine (SVM) with cross-validation to relate organic carbon content data to the reflectance spectral data by applying different preprocessing strategies. According to the criteria of minimal Root Mean Square Error of Prediction of Cross Validation (RMSEPcv) and maximal coefficient of determination (R2cv), the PLSR and SVMR models with raw spectra, the first and second derivative pretreatment provided the most accurate prediction for the organic carbon content from Brumovice (SVM, 1st. derivative, R2cv = 0.87, RMSEPcv = 0.11) and decreased as follows: Hostoun (PLSR, 2nd. derivative, R2cv = 0.69, RMSEPcv = 0.11), Sedlcany (SVM, 2nd. derivative, R2cv = 0.66, RMSEPcv = 0.17), Zelezna

  18. Distribution of polycyclic aromatic hydrocarbons in different size fractions of soil from a coke oven plant and its relationship to organic carbon content.

    PubMed

    Li, Helian; Chen, Jiajun; Wu, Wei; Piao, Xuesong

    2010-04-15

    The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in US EPA priority list were analyzed in the bulk and six particle size fractions of soil samples from a coke oven plant. The relationships of PAHs concentrations with total organic carbon (TOC), black carbon (BC) and other forms of organic carbon (OC) contents have been investigated. Total PAH concentrations ranged from 6.27 to 40.18 mg kg(-1) dry weight. The highest total PAH concentration occurred in the 250-500 microm size fraction. The maximum individual PAH concentration was in the 250-500 microm or 500-2000 microm size fraction. The size fractions of 125-500 microm and <50 microm have higher percentages and contributed 24.62% and 23.33% of the total PAH mass, respectively. The relative abundance of individual PAH compounds and PAH molecular indices present typical characteristic pyrogenic origin. The maximal TOC and BC contents were found in the 125-250 microm size fraction. Strong positive linear relationship between total PAH concentration and TOC or BC has been demonstrated, with a linear regression coefficient value of 0.7277 and 0.9245, respectively. The linear relationship between total PAH concentration versus OC (OC = TOC - BC) is weaker than that versus TOC or BC, with a correlation coefficient of 0.4117. It indicates that partitioned in organic matter, especially in black carbon is the dominant form of PAHs in the soil. PMID:20031305

  19. Multiple-Input Data Acquisition System (MIDAS) for Measuring the Carbon Content in Soil Using Inelastic Neutron Scattering

    SciTech Connect

    Warburton, William K.

    2014-01-24

    This report describes work funder under STTR grants Phase I and II and carried out jointly by XIA LLC and Brookhaven National Laboratory (BNL). The project goal was to develop a mobile nuclear activation analysis instrument that could be towed behind a tractor to document soil carbon levels in agricultural lands for carbon credit certification. XIA developed large NaI(Tl) detectors with integrated digital pulse processors controlled over USB 2.0 and delivered 16 of these units to BNL for integration into the prototype instrument, together with the necessary software to calibrate them and collect data. For reasons that are unknown to XIA, the BNL participants never completed the prototype vehicle, performed system integration, or carried out the proposed qualification and field tests, leaving the project incomplete.

  20. Underestimation of boreal soil carbon stocks by mathematical soil carbon models linked to soil nutrient status

    NASA Astrophysics Data System (ADS)

    Ťupek, Boris; Ortiz, Carina A.; Hashimoto, Shoji; Stendahl, Johan; Dahlgren, Jonas; Karltun, Erik; Lehtonen, Aleksi

    2016-08-01

    Inaccurate estimate of the largest terrestrial carbon pool, soil organic carbon (SOC) stock, is the major source of uncertainty in simulating feedback of climate warming on ecosystem-atmosphere carbon dioxide exchange by process-based ecosystem and soil carbon models. Although the models need to simplify complex environmental processes of soil carbon sequestration, in a large mosaic of environments a missing key driver could lead to a modeling bias in predictions of SOC stock change.We aimed to evaluate SOC stock estimates of process-based models (Yasso07, Q, and CENTURY soil sub-model v4) against a massive Swedish forest soil inventory data set (3230 samples) organized by a recursive partitioning method into distinct soil groups with underlying SOC stock development linked to physicochemical conditions.For two-thirds of measurements all models predicted accurate SOC stock levels regardless of the detail of input data, e.g., whether they ignored or included soil properties. However, in fertile sites with high N deposition, high cation exchange capacity, or moderately increased soil water content, Yasso07 and Q models underestimated SOC stocks. In comparison to Yasso07 and Q, accounting for the site-specific soil characteristics (e. g. clay content and topsoil mineral N) by CENTURY improved SOC stock estimates for sites with high clay content, but not for sites with high N deposition.Our analysis suggested that the soils with poorly predicted SOC stocks, as characterized by the high nutrient status and well-sorted parent material, indeed have had other predominant drivers of SOC stabilization lacking in the models, presumably the mycorrhizal organic uptake and organo-mineral stabilization processes. Our results imply that the role of soil nutrient status as regulator of organic matter mineralization has to be re-evaluated, since correct SOC stocks are decisive for predicting future SOC change and soil CO2 efflux.

  1. [Organic carbon and carbon mineralization characteristics in nature forestry soil].

    PubMed

    Yang, Tian; Dai, Wei; An, Xiao-Juan; Pang, Huan; Zou, Jian-Mei; Zhang, Rui

    2014-03-01

    Through field investigation and indoor analysis, the organic carbon content and organic carbon mineralization characteristics of six kinds of natural forest soil were studied, including the pine forests, evergreen broad-leaved forest, deciduous broad-leaved forest, mixed needle leaf and Korean pine and Chinese pine forest. The results showed that the organic carbon content in the forest soil showed trends of gradual decrease with the increase of soil depth; Double exponential equation fitted well with the organic carbon mineralization process in natural forest soil, accurately reflecting the mineralization reaction characteristics of the natural forest soil. Natural forest soil in each layer had the same mineralization reaction trend, but different intensity. Among them, the reaction intensity in the 0-10 cm soil of the Korean pine forest was the highest, and the intensities of mineralization reaction in its lower layers were also significantly higher than those in the same layers of other natural forest soil; comparison of soil mineralization characteristics of the deciduous broad-leaved forest and coniferous and broad-leaved mixed forest found that the differences of litter species had a relatively strong impact on the active organic carbon content in soil, leading to different characteristics of mineralization reaction.

  2. Acid neutralizing capacity and leachate results for igneous rocks, with associated carbon contents of derived soils, Animas River AML site, Silverton, Colorado

    USGS Publications Warehouse

    Yager, Douglas B.; Stanton, Mark R.; Choate, LaDonna M.; Burchell,

    2009-01-01

    Mine planning efforts have historically overlooked the possible acid neutralizing capacity (ANC) that local igneous rocks can provide to help neutralize acidmine drainage. As a result, limestone has been traditionally hauled to mine sites for use in neutralizing acid drainage. Local igneous rocks, when used as part of mine life-cycle planning and acid mitigation strategy, may reduce the need to transport limestone to mine sites because these rocks can contain acid neutralizing minerals. Igneous hydrothermal events often introduce moderately altered mineral assemblages peripheral to more intensely altered rocks that host metal-bearing veins and ore bodies. These less altered rocks can contain ANC minerals (calcite-chlorite-epidote) and are referred to as a propylitic assemblage. In addition, the carbon contents of soils in areas of new mining or those areas undergoing restoration have been historically unknown. Soil organic carbon is an important constituent to characterize as a soil recovery benchmark that can be referred to during mine cycle planning and restoration.
    This study addresses the mineralogy, ANC, and leachate chemistry of propylitic volcanic rocks that host polymetallic mineralization in the Animas River watershed near the historical Silverton, Colorado, mining area. Acid titration tests on volcanic rocks containing calcite (2 – 20 wt %) and chlorite (6 – 25 wt %), have ANC ranging from 4 – 146 kg/ton CaCO3 equivalence. Results from a 6-month duration, kinetic reaction vessel test containing layered pyritic mine waste and underlying ANC volcanic rock (saturated with deionized water) indicate that acid generating mine waste (pH 2.4) has not overwhelmed the ANC of propylitic volcanic rocks (pH 5.8). Sequential leachate laboratory experiments evaluated the concentration of metals liberated during leaching. Leachate concentrations of Cu-Zn-As-Pb for ANC volcanic rock are one-to-three orders of magnitude lower when compared to leached

  3. Impact of the addition of different plant residues on carbon-nitrogen content and nitrogen mineralization-immobilization turnover in a soil incubated under laboratory conditions

    NASA Astrophysics Data System (ADS)

    Abbasi, M. K.; Tahir, M. M.; Sabir, N.; Khurshid, M.

    2014-10-01

    Application of plant residues as soil amendment may represent a valuable recycling strategy that affects on carbon (C) and nitrogen (N) cycling, soil properties improvement and plant growth promotion. The amount and rate of nutrient release from plant residues depend on their quality characteristics and biochemical composition. A laboratory incubation experiment was conducted for 120 days under controlled conditions (25 °C and 58% water filled pore space (WFPS)) to quantify initial biochemical composition and N mineralization of leguminous and non-leguminous plant residues i.e. the roots, shoots and leaves of Glycine max, Trifolium repens, Zea mays, Poplus euramericana, Rubinia pseudoacacia and Elagnus umbellate incorporated into the soil at the rate of 200 mg residue N kg-1 soil. The diverse plant residues showed wide variation in total N, carbon, lignin, polyphenols and C/N ratio with higher polyphenol content in the leaves and higher lignin content in the roots. The shoot of G. max and the shoot and root of T. repens displayed continuous mineralization by releasing a maximum of 109.8, 74.8 and 72.5 mg N kg-1 and representing a 55, 37 and 36% of added N being released from these resources. The roots of G. max and Z. mays and the shoot of Z. mays showed continuous negative values throughout the incubation showing net immobilization. After an initial immobilization, leaves of P. euramericana, R. pseudoacacia and E. umbellate exhibited net mineralization by releasing a maximum of 31.8, 63.1 and 65.1 mg N kg-1, respectively and representing a 16, 32 and 33% of added N being released. Nitrogen mineralization from all the treatments was positively correlated with the initial residue N contents (r = 0.89; p ≤ 0.01), and negatively correlated with lignin content (r = -0.84; p ≤ 0.01), C/N ratio (r = -0.69; p ≤ 0.05), lignin/N ratio (r = -0.68; p ≤ 0.05), polyphenol/N ratio (r = -0.73; p ≤ 0.05) and ligin + polyphenol/N ratio (r = -0.70; p ≤ 0.05) indicating

  4. Nuclear forensics: Soil content

    SciTech Connect

    Beebe, Merilyn Amy

    2015-08-31

    Nuclear Forensics is a growing field that is concerned with all stages of the process of creating and detonating a nuclear weapon. The main goal is to prevent nuclear attack by locating and securing nuclear material before it can be used in an aggressive manner. This stage of the process is mostly paperwork; laws, regulations, treaties, and declarations made by individual countries or by the UN Security Council. There is some preliminary leg work done in the form of field testing detection equipment and tracking down orphan materials; however, none of these have yielded any spectacular or useful results. In the event of a nuclear attack, the first step is to analyze the post detonation debris to aid in the identification of the responsible party. This aspect of the nuclear forensics process, while reactive in nature, is more scientific. A rock sample taken from the detonation site can be dissolved into liquid form and analyzed to determine its chemical composition. The chemical analysis of spent nuclear material can provide valuable information if properly processed and analyzed. In order to accurately evaluate the results, scientists require information on the natural occurring elements in the detonation zone. From this information, scientists can determine what percentage of the element originated in the bomb itself rather than the environment. To this end, element concentrations in soils from sixty-nine different cities are given, along with activity concentrations for uranium, thorium, potassium, and radium in various building materials. These data are used in the analysis program Python.

  5. Capacity of microorganisms to decompose organic carbon affected by an increasing content of reactive mineral phases in a podzolic soil chronosequence

    NASA Astrophysics Data System (ADS)

    Vermeire, Marie-Liesse; Doetterl, Sebastian; Bode, Samuel; Delmelle, Pierre; Van Oost, Kristof; Cornelis, Jean-Thomas

    2014-05-01

    Soil organic matter stabilization has received considerable interest in the last decades due to the importance of the soil organic carbon (SOC) pool in the global C budget. There is increasing evidence that the formation of organo-mineral associations play a major role in the mechanisms of organic carbon stabilization, indicating that the persistence of organic matter in soils relates primarily to soil physico-chemical and biological conditions than to intrinsic recalcitrance. Al and Fe oxy-hydroxides and short-range ordered aluminosilicates are known for their high capacity to sorb organic carbon. However, the impact of the evolution of these reactive mineral phases over short time scale on the distribution of microorganisms and their ability to decompose SOC is still poorly understood. To further study the short-term evolution of organo-mineral associations, we investigated a 500-year podzolic soil chronosequence which is characterized by an increasing amount of secondary reactive mineral phases with pedogenesis and soil age, and thus by increased organo-mineral associations. In order to determine the impact of these secondary mineral phases on the degradation of SOC by microorganisms, an incubation experiment was carried out using soil horizons up to 1m deep from 6 profiles of different ages along the chronosequence. Furthermore, we used amino sugars and phospholipid fatty acids as tracers of dead and living microbial biomass, respectively, in the incubated samples. Our results show that SOC mineralization was significantly lower in the illuvial Bh/Bhs horizons (which contain more reactive mineral phases) compared to the surface E horizons (depleted in reactive mineral phases), although the content in amino sugars is similar in these horizons. In the deeper Bw and BC horizons, as well as in the young profiles (<300 yrs) that have not yet undergone podzolization and related formation of organo-mineral associations, SOC mineralization rates were the highest. These

  6. Carbon Sequestration in Forest Soils

    NASA Astrophysics Data System (ADS)

    Lal, R.

    2006-05-01

    Carbon (C) sequestration in soils and forests is an important strategy of reducing the net increase in atmospheric CO2 concentration by fossil fuel combustion, deforestation, biomass burning, soil cultivation and accelerated erosion. Further, the so-called "missing or fugitive CO2" is also probably being absorbed in a terrestrial sink. Three of the 15 strategies proposed to stabilize atmospheric CO2 concentrations by 2054, with each one to sequester 1 Pg Cyr-1, include: (i) biofuel plantations for bioethanol production, (ii) reforestation, afforestation and establishment of new plantations, and (iii) conversion of plow tillage to no-till farming. Enhancing soil organic carbon (SOC) pool is an important component in each of these three options, but especially so in conversion of degraded/marginal agricultural soils to short rotation woody perennials, and establishment of plantations for biofuel, fiber and timber production. Depending upon the prior SOC loss because of the historic land used and management-induced soil degradation, the rate of soil C sequestration in forest soils may be 0 to 3 Mg C ha-1 yr-1. Tropical forest ecosystems cover 1.8 billion hectares and have a SOC sequestration potential of 200 to 500 Tg C yr-1 over 59 years. However, increasing production of forest biomass may not always increase the SOC pool. Factors limiting the rate of SOC sequestration include C: N ratio, soil availability of N and other essential nutrients, concentration of recalcitrant macro-molecules (e.g., lignin, suberin), soil properties (e.g., clay content and mineralogy, aggregation), soil drainage, and climate (mean annual precipitation and temperature). The SOC pool can be enhanced by adopting recommended methods of forest harvesting and site preparation to minimize the "Covington effect," improving soil drainage, alleviating soil compaction, growing species with a high NPP, and improving soil fertility including the availability of micro-nutrients. Soil fertility

  7. Stuffing Carbon Away: Mechanisms of Carbon Sequestration in Soils

    SciTech Connect

    Reimer, P J; Masiello, C A; Southon, J R; Trumbore, S E; Harden, J W; White, A F; Chadwick, O A; Torn, M S

    2003-01-24

    Soils offer the potential to sequester large quantities of carbon from the atmosphere for decades to millennia and so may ameliorate the anthropogenic influence of fossil fuel release. However changes in climate can drastically affect the soil's ability to store carbon through changes mineralogy on time scales of human interest. It is essential to understand the major controls on soil carbon dynamics before we attempt to manage sequestration to control atmospheric CO{sub 2} buildup. Models of the terrestrial carbon cycle often use clay content to parameterize soil carbon turnover. Evidence from volcanic soils suggests that soil mineralogy is a major control on a soil's ability to store carbon, because different types of minerals have widely varying abilities to physically and chemically isolate soil organic matter from decomposition, however volcanic soils represent only a small percentage of the earth's soils. The relationship between precipitation and soil carbon storage is also complex and poorly constrained. Significantly, precipitation changes predicted as a result of atmospheric CO{sub 2} doubling include increased rainfall throughout California. We utilized {sup 14}C, {delta}{sup 13}C, and the total organic carbon, iron, and aluminum contents to address the question of the importance of mineralogy and climate on carbon storage in soils formed on a globally representative parent material. The California coastal terraces, formed over the last 500 thousand years as a result of tectonic uplift and sea level change, provide a natural laboratory to examine the effect of mineralogy and climate on carbon storage. We have focused on two terraces sequences, one near Eureka and one near Santa Cruz. Within each set of terraces only soil mineral development varies; all other variables are constant (rainfall, plant systems, and soil parent material, and land management). Annual precipitation at Eureka is twice that at Santa Cruz, allowing us to examine its role in the

  8. Impact of the addition of different plant residues on nitrogen mineralization-immobilization turnover and carbon content of a soil incubated under laboratory conditions

    NASA Astrophysics Data System (ADS)

    Kaleeem Abbasi, M.; Tahir, M. Mahmood; Sabir, N.; Khurshid, M.

    2015-02-01

    Application of plant residues as soil amendment may represent a valuable recycling strategy that affects carbon (C) and nitrogen (N) cycling in soil-plant systems. The amount and rate of nutrient release from plant residues depend on their quality characteristics and biochemical composition. A laboratory incubation experiment was conducted for 120 days under controlled conditions (25 °C and 58% water-filled pore space) to quantify initial biochemical composition and N mineralization of leguminous and non-leguminous plant residues, i.e., the roots, shoots and leaves of Glycine max, Trifolium repens, Zea mays, Populus euramericana, Robinia pseudoacacia and Elaeagnus umbellata, incorporated into the soil at the rate of 200 mg residue N kg-1 soil. The diverse plant residues showed a wide variation in total N, C, lignin, polyphenols and C / N ratio with higher polyphenol content in the leaves and higher lignin content in the roots. The shoot of Glycine max and the shoot and root of Trifolium repens displayed continuous mineralization by releasing a maximum of 109.8, 74.8 and 72.5 mg N kg-1 and representing a 55, 37 and 36% recovery of N that had been released from these added resources. The roots of Glycine max and Zea mays and the shoot of Zea mays showed continuous negative values throughout the incubation. After an initial immobilization, leaves of Populus euramericana, Robinia pseudoacacia and Elaeagnus umbellata exhibited net mineralization by releasing a maximum of 31.8, 63.1 and 65.1 mg N kg-1, respectively, and representing a 16, 32 and 33% N recovery, respectively. Nitrogen mineralization from all the treatments was positively correlated with the initial residue N contents (r = 0.89; p ≤ 0.01) and negatively correlated with lignin content (r = -0.84; p ≤ 0.01), C / N ratio (r = -0.69; p ≤ 0.05), lignin / N ratio (r = -0.68; p ≤ 0.05), polyphenol / N ratio (r = -0.73; p ≤ 0.05) and (lignin + polyphenol) : N ratio (r = -0.70; p ≤ 0.05) indicating a

  9. Soil Carbon Sequestration: Perspectives from Australia

    NASA Astrophysics Data System (ADS)

    Sanderman, J.; Macdonald, L.; Baldock, J.

    2011-12-01

    Australia is currently embarking upon an unparalleled program to mitigate greenhouse gas emissions by engaging farmers and landholders to reduce emissions and store carbon in the soil. Currently, the magnitude of a potential soil carbon sink in Australian agricultural soils is largely unknown. The oft repeated rubric that adoption of recommended management practices (RMP) can raise soil carbon levels to 50-66% of pre-clearing levels has lead many to conclude that soil carbon sequestration can offset a large portion of Australia's current greenhouse gas emissions. Is there evidence in Australia (and abroad) to support these sequestration rates? In this presentation, we will present findings from both a retrospective analysis of existing field trial data and preliminary results from a national scale assessment of current soil carbon stocks under different agricultural management practices. A comprehensive review of field-trial data in Australia suggests that most management shifts within a given agricultural system (i.e. tillage, stubble management, fertilizer application, etc...) result in modest relative gains of 0.1 to 0.3 tC ha-1 yr-1. Importantly, whenever time series data was available, we found that the relative improvement in soil carbon stocks under RMPs was due to a reduction in the rate of loss of soil carbon and not in an actual increase in soil carbon. This finding has important repercussions for both how we think about soil carbon sequestration and how we can account for it in an accounting framework. Current research within the National Soil Carbon Research Program looks to assess the potential for agricultural management to influence soil carbon content and its distribution within various measurable carbon pools (particulate, humus, charcoal-like). For example, 200 randomly selected farms have been sampled in two major agricultural regions in South Australia based on a soil-type by rainfall stratification. In addition to measuring carbon content and

  10. The greenhouse gas balance of a drained fen peatland is mainly controlled by land-use rather than soil organic carbon content

    NASA Astrophysics Data System (ADS)

    Eickenscheidt, T.; Heinichen, J.; Drösler, M.

    2015-04-01

    Drained organic soils are considered as hotspots for greenhouse gas (GHG) emissions. Particularly arable lands and intensively used grasslands have been regarded as the main producers of carbon dioxide (CO2) and nitrous oxide (N2O). However, GHG balances of former peatlands and associated organic soils not considered as peatland according to the definition of the Intergovernmental Panel on Climate Change (IPCC) have not been investigated so far. Therefore, our study addressed the question to what extent the soil organic carbon (SOC) content affects the GHG release of drained organic soils under two different land-use types (arable land and intensively used grassland). Both land-use types were established on a mollic Gleysol (named Cmedium) as well as on a sapric Histosol (named Chigh). The two soil types significantly differed in their SOC contents in the topsoil (Cmedium: 9.4-10.9% SOC; Chigh: 16.1-17.2% SOC). We determined GHG fluxes (CO2, N2O and methane (CH4)) over a period of 2 years. The daily and annual net ecosystem exchange (NEE) of CO2 was determined with the closed dynamic chamber technique and by modeling the ecosystem respiration (RECO) and the gross primary production (GPP). N2O and CH4 were determined by the close chamber technique. Estimated NEE of CO2 significantly differed between the two land-use types with lower NEE values (-6 to 1707 g CO2-C m-2 yr-1) at the arable sites and higher values (1354 to 1823 g CO2-C m-2 yr-1) at the grassland sites. No effect on NEE was found regarding the SOC content. Significantly higher annual N2O exchange rates were observed at the arable sites (0.23-0.86 g N m-2 yr-1) compared to the grassland sites (0.12-0.31 g N m-2 yr-1). Furthermore, N2O fluxes from the Chigh sites significantly exceeded those of the Cmedium sites. CH4 fluxes were found to be close to zero at all plots. Estimated global warming potential, calculated for a time horizon of 100 years (GWP100) revealed a very high release of GHGs from all plots

  11. The greenhouse gas balance of a drained fen peatland is mainly controlled by land-use rather than soil organic carbon content

    NASA Astrophysics Data System (ADS)

    Eickenscheidt, T.; Heinichen, J.; Drösler, M.

    2015-09-01

    Drained organic soils are considered to be hotspots for greenhouse gas (GHG) emissions. Arable lands and intensively used grasslands, in particular, have been regarded as the main producers of carbon dioxide (CO2) and nitrous oxide (N2O). However, GHG balances of former peatlands and associated organic soils not considered to be peatland according to the definition of the Intergovernmental Panel on Climate Change (IPCC) have not been investigated so far. Therefore, our study addressed the question to what extent the soil organic carbon (SOC) content affects the GHG release of drained organic soils under two different land-use types (arable land and intensively used grassland). Both land-use types were established on a Mollic Gleysol (labeled Cmedium) as well as on a Sapric Histosol (labeled Chigh). The two soil types differed significantly in their SOC contents in the topsoil (Cmedium: 9.4-10.9 % SOC; Chigh: 16.1-17.2 % SOC). We determined GHG fluxes over a period of 1 or 2 years in case of N2O or methane (CH4) and CO2, respectively. The daily and annual net ecosystem exchange (NEE) of CO2 was determined by measuring NEE and the ecosystem respiration (RECO) with the closed dynamic chamber technique and by modeling the RECO and the gross primary production (GPP). N2O and CH4 were measured with the static closed chamber technique. Estimated NEE of CO2 differed significantly between the two land-use types, with lower NEE values (-6 to 1707 g CO2-C m-2 yr-1) at the arable sites and higher values (1354 to 1823 g CO2-C m-2 yr-1) at the grassland sites. No effect on NEE was found regarding the SOC content. Significantly higher annual N2O exchange rates were observed at the arable sites (0.23-0.86 g N m-2 yr-1) than at the grassland sites (0.12-0.31 g N m-2 yr-1). Furthermore, N2O fluxes from the Chigh sites significantly exceeded those of the Cmedium sites. CH4 fluxes were found to be close to zero at all plots. Estimated global warming potential, calculated for a time

  12. A Soil Carbon Cycle Without Life?: The Content and Residence Times of Organic and Inorganic Carbon in the Atacama Desert of Chile

    NASA Astrophysics Data System (ADS)

    Amundson, R. G.; Navarro-Gonzalez, R.; Ewing, S. A.

    2003-12-01

    The central Atacama Desert of Chile is nearly rainless and virtually devoid of biota. Precipitation increases steadily as one moves to more southern latitudes, providing a natural experiment to assess the role of water in the soil C cycle. We have established three research sites along this gradient, where the mean annual precipitation varies from nearly 0 to about 15 mm y-1. At the driest site, where plants are completely absent and soil microorganisms quite rare, trace quantities of organic C (OC) are present ( ˜0.009+/-0.0038%), and OC increases slightly with precipitation (and the increasing presence of vegetation) to 0.053%. The apparent radiocarbon age of the organic matter at the driest site is exceedingly old (> 7,000 y), suggesting C cycling rates on the order of 104 y. The source of the incoming C is being investigated, and may include a combination of marine aerosols and exceedingly rare cyanobacteria on the undersides of quartz clasts ("hypoliths"). Radiocarbon-based turnover times appear to increase to decadal scales with increasing rainfall, with annually cycling OC concentrated in coppice dunes (0.32% OC) and hypolith-associated soils (0.39% OC). The radiocarbon age of co-existing soil carbonate was ˜12,000 years at the driest site and thus older than that of the OC, suggesting limited weathering and incorporation of modern atmospheric CO2 with increasing precipitation. The character of the organic matter present in the soil was analyzed by pyrolysis-GC-MS. The main organic molecules released at 750° C in an inert atmosphere are benzene and formic acid. Their concentrations in the driest soil are in the ppb range, and decrease by about an order of magnitude with depth. This suggests that either the environmental conditions in the past were much more severe or else that there are slow downward fluxes of organic materials accompanied by decomposition (either biological or abiotic). In contrast, soil organic matter from the other two southern sites

  13. [Effects of different fertilizer application on soil active organic carbon].

    PubMed

    Zhang, Rui; Zhang, Gui-Long; Ji, Yan-Yan; Li, Gang; Chang, Hong; Yang, Dian-Lin

    2013-01-01

    The variation characteristics of the content and components of soil active organic carbon under different fertilizer application were investigated in samples of calcareous fluvo-aquic soil from a field experiment growing winter wheat and summer maize in rotation in the North China Plain. The results showed that RF (recommended fertilization), CF (conventional fertilization) and NPK (mineral fertilizer alone) significantly increased the content of soil dissolved organic carbon and easily oxidized organic carbon by 24.92-38.63 mg x kg(-1) and 0.94-0.58 mg x kg(-1) respectively compared to CK (unfertilized control). The soil dissolved organic carbon content under OM (organic manure) increased greater than those under NPK and single fertilization, soil easily oxidized organic carbon content under OM and NPK increased greater than that under single chemical fertilization. OM and NPK showed no significant role in promoting the soil microbial biomass carbon, but combined application of OM and NPK significantly increased the soil microbial biomass carbon content by 36.06% and 20.69%, respectively. Soil easily oxidized organic carbon, dissolved organic carbon and microbial biomass carbon accounted for 8.41% - 14.83%, 0.47% - 0.70% and 0.89% - 1.20% of the total organic carbon (TOC), respectively. According to the results, the fertilizer application significantly increased the proportion of soil dissolved organic carbon and easily oxidized organic carbon, but there was no significant difference in the increasing extent of dissolved organic carbon. The RF and CF increased the proportion of soil easily oxidized organic carbon greater than OM or NPK, and significantly increased the proportion of microbial biomass carbon. OM or RF had no significant effect on the proportion of microbial biomass carbon. Therefore, in the field experiment, appropriate application of organic manure and chemical fertilizers played an important role for the increase of soil active organic carbon

  14. [Effects of different fertilizer application on soil active organic carbon].

    PubMed

    Zhang, Rui; Zhang, Gui-Long; Ji, Yan-Yan; Li, Gang; Chang, Hong; Yang, Dian-Lin

    2013-01-01

    The variation characteristics of the content and components of soil active organic carbon under different fertilizer application were investigated in samples of calcareous fluvo-aquic soil from a field experiment growing winter wheat and summer maize in rotation in the North China Plain. The results showed that RF (recommended fertilization), CF (conventional fertilization) and NPK (mineral fertilizer alone) significantly increased the content of soil dissolved organic carbon and easily oxidized organic carbon by 24.92-38.63 mg x kg(-1) and 0.94-0.58 mg x kg(-1) respectively compared to CK (unfertilized control). The soil dissolved organic carbon content under OM (organic manure) increased greater than those under NPK and single fertilization, soil easily oxidized organic carbon content under OM and NPK increased greater than that under single chemical fertilization. OM and NPK showed no significant role in promoting the soil microbial biomass carbon, but combined application of OM and NPK significantly increased the soil microbial biomass carbon content by 36.06% and 20.69%, respectively. Soil easily oxidized organic carbon, dissolved organic carbon and microbial biomass carbon accounted for 8.41% - 14.83%, 0.47% - 0.70% and 0.89% - 1.20% of the total organic carbon (TOC), respectively. According to the results, the fertilizer application significantly increased the proportion of soil dissolved organic carbon and easily oxidized organic carbon, but there was no significant difference in the increasing extent of dissolved organic carbon. The RF and CF increased the proportion of soil easily oxidized organic carbon greater than OM or NPK, and significantly increased the proportion of microbial biomass carbon. OM or RF had no significant effect on the proportion of microbial biomass carbon. Therefore, in the field experiment, appropriate application of organic manure and chemical fertilizers played an important role for the increase of soil active organic carbon

  15. Regional prediction of soil organic carbon content over temperate croplands using visible near-infrared airborne hyperspectral imagery and synchronous field spectra

    NASA Astrophysics Data System (ADS)

    Vaudour, E.; Gilliot, J. M.; Bel, L.; Lefevre, J.; Chehdi, K.

    2016-07-01

    This study aimed at identifying the potential of Vis-NIR airborne hyperspectral AISA-Eagle data for predicting the topsoil organic carbon (SOC) content of bare cultivated soils over a large peri-urban area (221 km2) with both contrasted soils and SOC contents, located in the western region of Paris, France. Soil types comprised haplic luvisols, calcaric cambisols and colluvic cambisols. Airborne AISA-Eagle data (400-1000 nm, 126 bands) with 1 m-resolution were acquired on 17 April 2013 over 13 tracks. Tracks were atmospherically corrected then mosaicked at a 2 m-resolution using a set of 24 synchronous field spectra of bare soils, black and white targets and impervious surfaces. The land use identification system layer (RPG) of 2012 was used to mask non-agricultural areas, then calculation and thresholding of NDVI from an atmospherically corrected SPOT image acquired the same day enabled to map agricultural fields with bare soil. A total of 101 sites sampled either in 2013 or in the 3 previous years and in 2015 were identified as bare by means of this map. Predictions were made from the mosaic AISA spectra which were related to topsoil SOC contents by means of partial least squares regression (PLSR). Regression robustness was evaluated through a series of 1000 bootstrap data sets of calibration-validation samples, considering 74 sites outside cloud shadows only, and different sampling strategies for selecting calibration samples. Validation root-mean-square errors (RMSE) were comprised between 3.73 and 4.49 g Kg-1 and were ∼4 g Kg-1 in median. The most performing models in terms of coefficient of determination (R2) and Residual Prediction Deviation (RPD) values were the calibration models derived either from Kennard-Stone or conditioned Latin Hypercube sampling on smoothed spectra. The most generalizable model leading to lowest RMSE value of 3.73 g Kg-1 at the regional scale and 1.44 g Kg-1 at the within-field scale and low bias was the cross-validated leave

  16. How does soil management affect carbon losses from soils?

    NASA Astrophysics Data System (ADS)

    Klik, A.; Trümper, G.

    2009-04-01

    Agricultural soils are a major source as well as a sink of organic carbon (OC). Amount and distribution of OC within the soil and within the landscape are driven by land management but also by erosion and deposition processes. At the other hand the type of soil management influences mineralization and atmospheric carbon dioxide losses by soil respiration. In a long-term field experiment the impacts of soil tillage systems on soil erosion processes were investigated. Following treatments were compared: 1) conventional tillage (CT), 2) conservation tillage with cover crop during the winter period (CS), and 3) no-till with cover crop during winter period (NT). The studies were carried out at three sites in the Eastern part of Austria with annual precipitation amounts from 650 to 900 mm. The soil texture ranged from silt loam to loam. Since 2007 soil CO2 emissions are measured with a portable soil respiration system in intervals of about one week, but also in relation to management events. Concurrent soil temperature and soil water content are measured and soil samples are taken for chemical and microbiological analyses. An overall 14-yr. average soil loss between 1.0 t.ha-1.yr-1 for NT and 6.1 t.ha-1.yr-1 for CT resulted in on-site OC losses from 18 to 79 kg ha-1.yr-1. The measurements of the carbon dioxide emissions from the different treatments indicate a high spatial variation even within one plot. Referred to CT plots calculated carbon losses amounted to 65-94% for NT plots while for the different RT plots they ranged between 84 and 128%. Nevertheless site specific considerations have to be taken into account. Preliminary results show that the adaptation of reduced or no-till management strategies has enormous potential in reducing organic carbon losses from agricultural used soils.

  17. Salinity and nutrient contents of tidal water affects soil respiration and carbon sequestration of high and low tidal flats of Jiuduansha wetlands in different ways.

    PubMed

    Hu, Yu; Wang, Lei; Fu, Xiaohua; Yan, Jianfang; Wu, Jihua; Tsang, Yiufai; Le, Yiquan; Sun, Ying

    2016-09-15

    Soils were collected from low tidal flats and high tidal flats of Shang shoal located upstream and Xia shoal located downstream with different tidal water qualities, in the Jiuduansha wetland of the Yangtze River estuary. Soil respiration (SR) in situ and soil abiotic and microbial characteristics were studied to clarify the respective differences in the effects of tidal water salinity and nutrient levels on SR and soil carbon sequestration in low and high tidal flats. In low tidal flats, higher total nitrogen (TN) and lower salinity in the tidal water of Shang shoal resulted in higher TN and lower salinity in its soils compared with Xia shoal. These would benefit β-Proteobacteria and Anaerolineae in Shang shoal soil, which might have higher heterotrophic microbial activities and thus soil microbial respiration and SR. In low tidal flats, where soil moisture was high and the major carbon input was active organic carbon from tidal water, increasing TN was a more important factor than salinity and obviously enhanced soil microbial heterotrophic activities, soil microbial respiration and SR. While, in high tidal flats, higher salinity in Xia shoal due to higher salinity in tidal water compared with Shang shoal benefited γ-Proteobacteria which might enhance autotrophic microbial activity, and was detrimental to β-Proteobacteria in Xia shoal soil. These might have led to lower soil microbial respiration and thus SR in Xia shoal compared with Shang shoal. In high tidal flats, where soil moisture was relatively lower and the major carbon input was plant biomass that was difficult to degrade, soil salinity was the major factor restraining microbial activities, soil microbial respiration and SR.

  18. Salinity and nutrient contents of tidal water affects soil respiration and carbon sequestration of high and low tidal flats of Jiuduansha wetlands in different ways.

    PubMed

    Hu, Yu; Wang, Lei; Fu, Xiaohua; Yan, Jianfang; Wu, Jihua; Tsang, Yiufai; Le, Yiquan; Sun, Ying

    2016-09-15

    Soils were collected from low tidal flats and high tidal flats of Shang shoal located upstream and Xia shoal located downstream with different tidal water qualities, in the Jiuduansha wetland of the Yangtze River estuary. Soil respiration (SR) in situ and soil abiotic and microbial characteristics were studied to clarify the respective differences in the effects of tidal water salinity and nutrient levels on SR and soil carbon sequestration in low and high tidal flats. In low tidal flats, higher total nitrogen (TN) and lower salinity in the tidal water of Shang shoal resulted in higher TN and lower salinity in its soils compared with Xia shoal. These would benefit β-Proteobacteria and Anaerolineae in Shang shoal soil, which might have higher heterotrophic microbial activities and thus soil microbial respiration and SR. In low tidal flats, where soil moisture was high and the major carbon input was active organic carbon from tidal water, increasing TN was a more important factor than salinity and obviously enhanced soil microbial heterotrophic activities, soil microbial respiration and SR. While, in high tidal flats, higher salinity in Xia shoal due to higher salinity in tidal water compared with Shang shoal benefited γ-Proteobacteria which might enhance autotrophic microbial activity, and was detrimental to β-Proteobacteria in Xia shoal soil. These might have led to lower soil microbial respiration and thus SR in Xia shoal compared with Shang shoal. In high tidal flats, where soil moisture was relatively lower and the major carbon input was plant biomass that was difficult to degrade, soil salinity was the major factor restraining microbial activities, soil microbial respiration and SR. PMID:27208721

  19. Permafrost soils and carbon cycling

    DOE PAGESBeta

    Ping, C. L.; Jastrow, J. D.; Jorgenson, M. T.; Michaelson, G. J.; Shur, Y. L.

    2015-02-05

    Knowledge of soils in the permafrost region has advanced immensely in recent decades, despite the remoteness and inaccessibility of most of the region and the sampling limitations posed by the severe environment. These efforts significantly increased estimates of the amount of organic carbon stored in permafrost-region soils and improved understanding of how pedogenic processes unique to permafrost environments built enormous organic carbon stocks during the Quaternary. This knowledge has also called attention to the importance of permafrost-affected soils to the global carbon cycle and the potential vulnerability of the region's soil organic carbon (SOC) stocks to changing climatic conditions. Inmore » this review, we briefly introduce the permafrost characteristics, ice structures, and cryopedogenic processes that shape the development of permafrost-affected soils, and discuss their effects on soil structures and on organic matter distributions within the soil profile. We then examine the quantity of organic carbon stored in permafrost-region soils, as well as the characteristics, intrinsic decomposability, and potential vulnerability of this organic carbon to permafrost thaw under a warming climate. Overall, frozen conditions and cryopedogenic processes, such as cryoturbation, have slowed decomposition and enhanced the sequestration of organic carbon in permafrost-affected soils over millennial timescales. Due to the low temperatures, the organic matter in permafrost soils is often less humified than in more temperate soils, making some portion of this stored organic carbon relatively vulnerable to mineralization upon thawing of permafrost.« less

  20. Soil carbon content and CO2 flux along a hydrologic gradient in a High-Arctic tundra lake basin, Northwest Greenland

    NASA Astrophysics Data System (ADS)

    McKnight, J.; Klein, E. S.; Welker, J. M.; Schaeffer, S. M.; Franklin, M.

    2015-12-01

    High Arctic landscapes are composed of watershed basins that vary in size and ecohydrology, but typically have a plant community complex that ranges from dry tundra to moist tundra to wet sedge systems along water body shorelines. The spatial extent of these plant communities reflects mean annual soil moisture and temperature, and is vulnerable to changes in climate conditions. Soil moisture and temperature significantly influence organic matter microbial activity and decomposition, and can affect the fate of soil carbon in tundra soils. Consequently, due to the unique soil carbon differences between tundra plant communities, shifts in their spatial extent may drive future High Arctic biosphere-atmosphere interactions. Understanding this terrestrial-atmosphere trace gas feedback, however, requires quantification of the rates and patterns of CO2 exchange along soil moisture gradients and the associated soil properties. In summer of 2015, soil CO2 flux rate, soil moisture and temperature were measured along a soil moisture gradient spanning three vegetation zones (dry tundra, wet tundra, and wet grassland) in a snow melt-fed lake basin near Thule Greenland. Mean soil temperature during the 2015 growing season was greater in dry tundra than in wet tundra and wet grassland (13.0 ± 1.2, 7.8 ± 0.8, and 5.5 ± 0.9°C, respectively). Mean volumetric soil moisture differed among all three vegetation zones where the soil moisture gradient ranged from 9 % (dry tundra) to 34 % (wet tundra) to 51 % (wet grassland). Mean soil CO2 flux was significantly greater in the wet grassland (1.7 ± 0.1 μmol m-2 s-1) compared to wet tundra (0.9 ± 0.2 μmol m-2 s-1) and dry tundra (1.2 ± 0.2 μmol m-2 s-1). Soil CO2 flux increased and decreased with seasonal warming and cooling of soil temperature. Although soil temperature was an important seasonal driver of soil CO2 flux rates, differences in mean seasonal soil CO2 flux rates among vegetation zones appeared to be a function of the

  1. [Characteristics of soil microbial biomass carbon and soil water soluble organic carbon in the process of natural restoration of Karst forest].

    PubMed

    Huang, Zong-Sheng; Fu, Yu-Hong; Yu, Li-Fei

    2012-10-01

    By the method of taking space instead of time, an incubation test was conducted to study the characteristics of soil microbial biomass carbon and water soluble organic carbon in the process of natural restoration of Karst forest in Maolan Nature Reserve, Guizhou Province of Southwest China. The soil microbial biomass carbon content and soil basal respiration decreased with increasing soil depth but increased with the process of the natural restoration, soil microbial quotient increased with increasing soil depth and with the process of restoration, and soil water soluble organic carbon content decreased with increasing soil depth. In the process of the natural restoration, surface soil water soluble organic carbon content increased, while sublayer soil water soluble organic carbon content decreased after an initial increase. The ratio of soil water soluble organic carbon to total soil organic carbon increased with increasing soil depth but decreased with the process of restoration. Soil quality increased with the process of restoration. Also, the quality and quantity of soil organic carbon increased with the process of restoration, in which, soil microbial biomass carbon content had the greatest change, while soil water soluble organic carbon content had less change. PMID:23359931

  2. [Characteristics of soil microbial biomass carbon and soil water soluble organic carbon in the process of natural restoration of Karst forest].

    PubMed

    Huang, Zong-Sheng; Fu, Yu-Hong; Yu, Li-Fei

    2012-10-01

    By the method of taking space instead of time, an incubation test was conducted to study the characteristics of soil microbial biomass carbon and water soluble organic carbon in the process of natural restoration of Karst forest in Maolan Nature Reserve, Guizhou Province of Southwest China. The soil microbial biomass carbon content and soil basal respiration decreased with increasing soil depth but increased with the process of the natural restoration, soil microbial quotient increased with increasing soil depth and with the process of restoration, and soil water soluble organic carbon content decreased with increasing soil depth. In the process of the natural restoration, surface soil water soluble organic carbon content increased, while sublayer soil water soluble organic carbon content decreased after an initial increase. The ratio of soil water soluble organic carbon to total soil organic carbon increased with increasing soil depth but decreased with the process of restoration. Soil quality increased with the process of restoration. Also, the quality and quantity of soil organic carbon increased with the process of restoration, in which, soil microbial biomass carbon content had the greatest change, while soil water soluble organic carbon content had less change.

  3. [Vertical distribution of soil active carbon and soil organic carbon storage under different forest types in the Qinling Mountains].

    PubMed

    Wang, Di; Geng, Zeng-Chao; She, Diao; He, Wen-Xiang; Hou, Lin

    2014-06-01

    Adopting field investigation and indoor analysis methods, the distribution patterns of soil active carbon and soil carbon storage in the soil profiles of Quercus aliena var. acuteserrata (Matoutan Forest, I), Pinus tabuliformis (II), Pinus armandii (III), pine-oak mixed forest (IV), Picea asperata (V), and Quercus aliena var. acuteserrata (Xinjiashan Forest, VI) of Qinling Mountains were studied in August 2013. The results showed that soil organic carbon (SOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), and easily oxidizable carbon (EOC) decreased with the increase of soil depth along the different forest soil profiles. The SOC and DOC contents of different depths along the soil profiles of P. asperata and pine-oak mixed forest were higher than in the other studied forest soils, and the order of the mean SOC and DOC along the different soil profiles was V > IV > I > II > III > VI. The contents of soil MBC of the different forest soil profiles were 71.25-710.05 mg x kg(-1), with a content sequence of I > V > N > III > II > VI. The content of EOC along the whole soil profile of pine-oak mixed forest had a largest decline, and the order of the mean EOC was IV > V> I > II > III > VI. The sequence of soil organic carbon storage of the 0-60 cm soil layer was V > I >IV > III > VI > II. The MBC, DOC and EOC contents of the different forest soils were significanty correlated to each other. There was significant positive correlation among soil active carbon and TOC, TN. Meanwhile, there was no significant correlation between soil active carbon and other soil basic physicochemical properties.

  4. Does unsaturated flow drive soil carbon residence times?

    NASA Astrophysics Data System (ADS)

    Lawrence, C. R.; Mnich, M.; Druhan, J. L.; Schulz, M. S.; Stonestrom, D. A.; Maher, K.; Harden, J. W.

    2015-12-01

    Soil moisture is widely recognized as a driver of many important biogeochemical processes. For example, ecosystem productivity, microbial lifecycles, soil organic matter decomposition, soil secondary mineralogy, the development and persistence of redox gradients, and the export of dissolved carbon are all sensitive to soil-water content and potential. In turn, each of these processes is recognized as an important control on the turnover of soil organic carbon. These dependencies raise a key question: Is the flux of water through unsaturated soils the dominant driver of soil organic carbon turnover across broad spatial scales? To better characterize the importance of soil moisture fluxes, we synthesize data from a number of soil studies to evaluate how total soil carbon storage, carbon residence time, and depth dependent gradients vary in relation to soil hydrologic fluxes. Specifically, we compare soil carbon storage and stability to measured and/or modeled infiltration ([precipitation + condensation] - [evapotranspiration + runoff]) and long-term soil water flux estimates from chloride mass balance, or other techniques. Additionally, we consider the interaction of soil age and hydrology, as the development of secondary mineral horizons during pedogenesis represents a critical threshold in both soil water flux and soil organic carbon turnover. We focus on data from 3 previously descried soil chronosequences, including the Santa Cruz, Mattole, and Merced terraces, which together span a wide range of age and soil moisture conditions. Across these sites, organic carbon accumulates to greater depths in the soils with highest infiltration but the relationship between turnover and soil moisture is not as straightforward. To help interpret these results, we compare field data against simulations of biogeochemical reactions involving soil carbon and the resulting isotopic gradients using the reactive transport model CrunchTope. Overall, this effort provides for an improved

  5. Contents and composition of organic matter in subsurface soils affected by land use and soil mineralogy

    NASA Astrophysics Data System (ADS)

    Ellerbrock, Ruth H.; Kaiser, Michael

    2010-05-01

    Land use and mineralogy affect the ability of surface as well as subsurface soils to sequester organic carbon and their contribution to mitigate the greenhouse effect. This study aimed to investigate the long-term impact of land use (i.e., arable and forest) and soil mineralogy on contents and composition of soil organic matter (SOM) from subsurface soils. Seven soils different in mineralogy (Albic and Haplic Luvisol, Colluvic and Haplic Regosol, Haplic and Vertic Cambisol, Haplic Stagnosol) were selected within Germany. Soil samples were taken from forest and adjacent arable sites. First, particulate and water soluble organic matter were separated from the subsurface soil samples. From the remaining solid residues the OM(PY) fractions were separated, analyzed for its OC content (OCPY) and characterized by FTIR spectroscopy. For the arable subsurface soils multiple regression analyses indicate significant positive relationships between the soil organic carbon contents and the contents of i) exchangeable Ca and oxalate soluble Fe, and Alox contents. Further for the neutral arable subsurface soils the contents OCPY weighted by its C=O contents were found to be related to the contents of Ca indicating interactions between OM(PY) and Ca cations. For the forest subsurface soils (pH <5) the OCPY contents were positively related with the contents of Na-pyrophosphate soluble Fe and Al. For the acidic forest subsurface soils such findings indicate interactions between OM(PY) and Fe3+ and Al3+ cations. The effects of land use and soil mineralogy on contents and composition of SOM and OM(PY) will be discussed.

  6. Soil aggregates and their associated carbon and nitrogen content in winter annual pastures using different tillage management options

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Traditionally, winter annual pastures are established on grazing areas that are steeply sloping and not regarded as suitable for row-crop production. Using conventional (CT) tillage methods to prepare these fragile lands for winter annual pastures leads to increased erosion and rapid soil degradatio...

  7. Sequestration of Soil Carbon as Secondary Carbonates (Invited)

    NASA Astrophysics Data System (ADS)

    Lal, R.

    2013-12-01

    Rattan Lal Carbon Management and Sequestration Center The Ohio State University Columbus, OH 43210 USA Abstract World soils, the major carbon (C) reservoir among the terrestrial pools, contain soil organic C (SOC) and soil inorganic C (SIC). The SIC pool is predominant in soils of arid and semi-arid regions. These regions cover a land area of about 4.9x109 ha. The SIC pool in soils containing calcic and petrocalcic horizons is estimated at about 695-748 Pg (Pg = 1015 g = 1 gigaton) to 1-m depth. There are two types of carbonates. Lithogenic or primary carbonates are formed from weathering of carbonaceous rocks. Pedogenic or secondary carbonates are formed by dissolution of CO2 in the soil air to form carbonic acid and precipitation as carbonates of Ca+2 or Mg+2. It is the availability of Ca+2 or Mg+2 from outside the ecosystem that is essential to sequester atmospheric CO2. Common among outside sources of Ca+2 or Mg+2 are irrigation water, aerial deposition, sea breeze, fertilizers, manure and other amendments. The decomposition of SOC and root respiration may increase the partial pressure of CO2 in the soil air and lead to the formation of HCO_3^- upon dissolution in H20. Precipitation of secondary carbonates may result from decreased partial pressure of CO2 in the sub-soil, increased concentration of Ca+2, Mg+2 and HCO_3^- in soil solution, and decreased soil moisture content by evapotranspiration. Transport of bicarbonates in irrigated soils and subsequent precipitation above the ground water (calcrete), activity of termites and other soil fauna, and management of urban soils lead to formation of secondary carbonates. On a geologic time scale, weathering of silicate minerals and transport of the by-products into the ocean is a geological process of sequestration of atmospheric CO2. Factors affecting formation of secondary carbonates include land use, and soil and crop management including application of biosolids, irrigation and the quality of irrigation water

  8. Application of Geant4 simulation for analysis of soil carbon inelastic neutron scattering measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Inelastic neutron scattering (INS) was applied to determine soil carbon content. Due to non-uniform soil carbon depth distribution, the correlation between INS signals with some soil carbon content parameter is not obvious; however, a proportionality between INS signals and average carbon weight per...

  9. [Correlation Among Soil Organic Carbon, Soil Inorganic Carbon and the Environmental Factors in a Typical Oasis in the Southern Edge of the Tarim Basin].

    PubMed

    Gong, Lu; Zhu, Mei-ling; Liu, Zeng-yuan; Zhang, Xue-ni; Xie, Li-na

    2016-04-15

    We analyzed the differentiation among the environmental factors and soil organic/inorganic carbon contents of irrigated desert soil, brown desert soil, saline soil and aeolian sandy soil by classical statistics methods, and studied the correlation between soil carbon contents and the environmental factor by redundancy analysis (RDA) in a typical oasis of Yutian in the southern edge of the Tarim Basin. The results showed that the average contents of soil organic carbon and soil inorganic carbon were 2.51 g · kg⁻¹ and 25.63 g · kg⁻¹ respectively. The soil organic carbon content of the irrigated desert soil was significantly higher than those of brown desert soil, saline soil and aeolian sandy soil, while the inorganic carbon content of aeolian sandy soil was significantly higher than those of other soil types. The soil moisture and nutrient content were the highest in the irrigated desert soil and the lowest in the aeolian sandy sail. All soil types had high degree of salinization except the irrigated desert soil. The RDA results showed that the impacts of environmental factors on soil carbon contents ranked in order of importance were total nitrogen > available phosphorus > soil moisture > ground water depth > available potassium > pH > total salt. The soil carbon contents correlated extremely significantly with total nitrogen, available phosphorus, soil moisture and ground water depth (P < 0.01), and it correlated significantly with available potassium and pH (P < 0.05). There was no significant correlation between soil carbon contents and other environmental factors (P > 0.05). PMID:27548977

  10. [Correlation Among Soil Organic Carbon, Soil Inorganic Carbon and the Environmental Factors in a Typical Oasis in the Southern Edge of the Tarim Basin].

    PubMed

    Gong, Lu; Zhu, Mei-ling; Liu, Zeng-yuan; Zhang, Xue-ni; Xie, Li-na

    2016-04-15

    We analyzed the differentiation among the environmental factors and soil organic/inorganic carbon contents of irrigated desert soil, brown desert soil, saline soil and aeolian sandy soil by classical statistics methods, and studied the correlation between soil carbon contents and the environmental factor by redundancy analysis (RDA) in a typical oasis of Yutian in the southern edge of the Tarim Basin. The results showed that the average contents of soil organic carbon and soil inorganic carbon were 2.51 g · kg⁻¹ and 25.63 g · kg⁻¹ respectively. The soil organic carbon content of the irrigated desert soil was significantly higher than those of brown desert soil, saline soil and aeolian sandy soil, while the inorganic carbon content of aeolian sandy soil was significantly higher than those of other soil types. The soil moisture and nutrient content were the highest in the irrigated desert soil and the lowest in the aeolian sandy sail. All soil types had high degree of salinization except the irrigated desert soil. The RDA results showed that the impacts of environmental factors on soil carbon contents ranked in order of importance were total nitrogen > available phosphorus > soil moisture > ground water depth > available potassium > pH > total salt. The soil carbon contents correlated extremely significantly with total nitrogen, available phosphorus, soil moisture and ground water depth (P < 0.01), and it correlated significantly with available potassium and pH (P < 0.05). There was no significant correlation between soil carbon contents and other environmental factors (P > 0.05).

  11. Effect of gypsum content on soil water retention

    NASA Astrophysics Data System (ADS)

    Moret-Fernández, D.; Herrero, J.

    2015-09-01

    Many gypsiferous soils occur in arid lands, where the water retention capacity of the soil is vital to plant life and crop production. This study investigated the effect of gypsum content on the gravimetric soil water retention curve (WRC). We analyzed calcium carbonate equivalent (CCE), equivalent gypsum content (EG), soil organic carbon content (SOC), and electrical conductivity of 43 samples collected from various horizons in soils in the Ebro Valley, NE Spain. The WRC of the fine earth was determined using the pressure-plate method (pressure heads = 0, -33, -100, -200, -500, and -1500 kPa), and the gravimetric water retention curves were fitted to the unimodal van Genuchten function. Soil gypsum content had a significant effect on water retention. Soils that had high gypsum content made WRC with higher water retention at near saturation conditions, and steeper WRC slopes. The EG threshold at which gypsum content had an effect on WRC was about 40%, and EG was positively and negatively correlated with the α and n parameters of the WRC, respectively.

  12. Intercropping enhances soil carbon and nitrogen.

    PubMed

    Cong, Wen-Feng; Hoffland, Ellis; Li, Long; Six, Johan; Sun, Jian-Hao; Bao, Xing-Guo; Zhang, Fu-Suo; Van Der Werf, Wopke

    2015-04-01

    Intercropping, the simultaneous cultivation of multiple crop species in a single field, increases aboveground productivity due to species complementarity. We hypothesized that intercrops may have greater belowground productivity than sole crops, and sequester more soil carbon over time due to greater input of root litter. Here, we demonstrate a divergence in soil organic carbon (C) and nitrogen (N) content over 7 years in a field experiment that compared rotational strip intercrop systems and ordinary crop rotations. Soil organic C content in the top 20 cm was 4% ± 1% greater in intercrops than in sole crops, indicating a difference in C sequestration rate between intercrop and sole crop systems of 184 ± 86 kg C ha(-1) yr(-1). Soil organic N content in the top 20 cm was 11% ± 1% greater in intercrops than in sole crops, indicating a difference in N sequestration rate between intercrop and sole crop systems of 45 ± 10 kg N ha(-1) yr(-1). Total root biomass in intercrops was on average 23% greater than the average root biomass in sole crops, providing a possible mechanism for the observed divergence in soil C sequestration between sole crop and intercrop systems. A lowering of the soil δ(15) N signature suggested that increased biological N fixation and/or reduced gaseous N losses contributed to the increases in soil N in intercrop rotations with faba bean. Increases in soil N in wheat/maize intercrop pointed to contributions from a broader suite of mechanisms for N retention, e.g., complementary N uptake strategies of the intercropped plant species. Our results indicate that soil C sequestration potential of strip intercropping is similar in magnitude to that of currently recommended management practises to conserve organic matter in soil. Intercropping can contribute to multiple agroecosystem services by increased yield, better soil quality and soil C sequestration.

  13. Intercropping enhances soil carbon and nitrogen.

    PubMed

    Cong, Wen-Feng; Hoffland, Ellis; Li, Long; Six, Johan; Sun, Jian-Hao; Bao, Xing-Guo; Zhang, Fu-Suo; Van Der Werf, Wopke

    2015-04-01

    Intercropping, the simultaneous cultivation of multiple crop species in a single field, increases aboveground productivity due to species complementarity. We hypothesized that intercrops may have greater belowground productivity than sole crops, and sequester more soil carbon over time due to greater input of root litter. Here, we demonstrate a divergence in soil organic carbon (C) and nitrogen (N) content over 7 years in a field experiment that compared rotational strip intercrop systems and ordinary crop rotations. Soil organic C content in the top 20 cm was 4% ± 1% greater in intercrops than in sole crops, indicating a difference in C sequestration rate between intercrop and sole crop systems of 184 ± 86 kg C ha(-1) yr(-1). Soil organic N content in the top 20 cm was 11% ± 1% greater in intercrops than in sole crops, indicating a difference in N sequestration rate between intercrop and sole crop systems of 45 ± 10 kg N ha(-1) yr(-1). Total root biomass in intercrops was on average 23% greater than the average root biomass in sole crops, providing a possible mechanism for the observed divergence in soil C sequestration between sole crop and intercrop systems. A lowering of the soil δ(15) N signature suggested that increased biological N fixation and/or reduced gaseous N losses contributed to the increases in soil N in intercrop rotations with faba bean. Increases in soil N in wheat/maize intercrop pointed to contributions from a broader suite of mechanisms for N retention, e.g., complementary N uptake strategies of the intercropped plant species. Our results indicate that soil C sequestration potential of strip intercropping is similar in magnitude to that of currently recommended management practises to conserve organic matter in soil. Intercropping can contribute to multiple agroecosystem services by increased yield, better soil quality and soil C sequestration. PMID:25216023

  14. Clumped isotopes in soil carbonate

    NASA Astrophysics Data System (ADS)

    Quade, J.; Eiler, J. M.; Daeron, M.

    2011-12-01

    We are monitoring soil temperature and measuring clumped isotopes from modern soil carbonate in North and South America, Hawaii, and Tibet. Clumped isotopes from 50-200 cm soil depth show a strong and systematic bias toward formation in the warmest summer months. For example, soil carbonate as these depths exceed local mean annual temperature by 10-15°C in soils from India and Tibet. Clumped isotope temperatures from modern carbonate increase very regularly (r2 = 0.90) with elevation gain from lowland India to Tibet. Here carbonate forms largely in May-June, just prior to the arrival of the soil-cooling monsoon rains. In this regard, clumped isotopes hold great promise as a paleoaltimeter on the plateau. The question is whether these patterns from a monsoonal climate can be generalized (and they probably can't be) to other climate regimes when soil carbonate forms at a different time of year than the pre-monsoon. For example, in winter-dominated rainfall regimes soil carbonate may form as soils dewater in the spring and soil temperature is closer to mean annual temperature. These are open questions. Diurnal temperature information is also archived in the upper 30 cm of soils. Modern carbonate in Tibet appears to form in very late morning through afternoon, when the surface soil is warmest. Shade and aspect also strongly influence measured soil and clumped isotope temperatures. Both variables will have to be controlled for to correctly interpret clumped isotopes from the paleosol record. Clumped isotope values correlate with δ13C values in soil carbonate from shallowly buried (<1 km) paleosols from Nepal and Pakistan. This makes sense since δ13C values in the sub-tropics are determined the fraction of tree (C3) to grass (C4) cover, and soils under tree-covered areas are cooler. Finally, clumped isotopes from carbonates are reset to higher temperatures at burial depths roughly >2-3 km or >50-75°C. This was reproduced from paleosol and lake carbonates from three

  15. NON-DESTRUCTIVE SOIL CARBON ANALYZER.

    SciTech Connect

    Wielopolski, Lucian; Hendrey, G.; Orion, I.; Prior, S.; Rogers, H.; Runion, B.; Torbert, A.

    2004-02-01

    This report describes the feasibility, calibration, and safety considerations of a non-destructive, in situ, quantitative, volumetric soil carbon analytical method based on inelastic neutron scattering (INS). The method can quantify values as low as 0.018 gC/cc, or about 1.2% carbon by weight with high precision under the instrument's configuration and operating conditions reported here. INS is safe and easy to use, residual soil activation declines to background values in under an hour, and no radiological requirements are needed for transporting the instrument. The labor required to obtain soil-carbon data is about 10-fold less than with other methods, and the instrument offers a nearly instantaneous rate of output of carbon-content values. Furthermore, it has the potential to quantify other elements, particularly nitrogen. New instrumentation was developed in response to a research solicitation from the U.S. Department of Energy (DOE LAB 00-09 Carbon Sequestration Research Program) supporting the Terrestrial Carbon Processes (TCP) program of the Office of Science, Biological and Environmental Research (BER). The solicitation called for developing and demonstrating novel techniques for quantitatively measuring changes in soil carbon. The report includes raw data and analyses of a set of proof-of-concept, double-blind studies to evaluate the INS approach in the first phase of developing the instrument. Managing soils so that they sequester massive amounts of carbon was suggested as a means to mitigate the atmospheric buildup of anthropogenic CO{sub 2}. Quantifying changes in the soils' carbon stocks will be essential to evaluating such schemes and documenting their performance. Current methods for quantifying carbon in soil by excavation and core sampling are invasive, slow, labor-intensive and locally destroy the system being observed. Newly emerging technologies, such as Laser Induced Breakdown Spectroscopy and Near-Infrared Spectroscopy, offer soil-carbon

  16. An invisible soil acidification: Critical role of soil carbonate and its impact on heavy metal bioavailability.

    PubMed

    Wang, Cheng; Li, Wei; Yang, Zhongfang; Chen, Yang; Shao, Wenjing; Ji, Junfeng

    2015-01-01

    It is well known that carbonates inhibit heavy metals transferring from soil to plants, yet the mechanism is poorly understood. Based on the Yangtze River delta area, we investigated bioaccumulation of Ni and Cd in winter wheat as affected by the presence of carbonates in soil. This study aimed to determine the mechanism through which soil carbonates restrict transport and plant uptake of heavy metals in the wheat cropping system. The results indicate that soil carbonates critically influenced heavy metal transfer from soil to plants and presented a tipping point. Wheat grains harvested from carbonates-depleted (due to severe leaching) soils showed Ni and Cd concentrations 2-3 times higher than those of the wheat grains from carbonates-containing soils. Correspondingly, the incidence of Ni or Cd contamination in the wheat grain samples increased by about three times. With the carbonate concentration >1% in soil, uptake and bioaccumulation of Ni and Cd by winter wheat was independent with the soil pH and carbonate content. The findings suggest that soil carbonates play a critical role in heavy metal transfer from soil to plants, implying that monitoring soil carbonate may be necessary in addition to soil pH for the evaluating soil quality and food safety. PMID:26227091

  17. An invisible soil acidification: Critical role of soil carbonate and its impact on heavy metal bioavailability

    NASA Astrophysics Data System (ADS)

    Wang, Cheng; Li, Wei; Yang, Zhongfang; Chen, Yang; Shao, Wenjing; Ji, Junfeng

    2015-07-01

    It is well known that carbonates inhibit heavy metals transferring from soil to plants, yet the mechanism is poorly understood. Based on the Yangtze River delta area, we investigated bioaccumulation of Ni and Cd in winter wheat as affected by the presence of carbonates in soil. This study aimed to determine the mechanism through which soil carbonates restrict transport and plant uptake of heavy metals in the wheat cropping system. The results indicate that soil carbonates critically influenced heavy metal transfer from soil to plants and presented a tipping point. Wheat grains harvested from carbonates-depleted (due to severe leaching) soils showed Ni and Cd concentrations 2-3 times higher than those of the wheat grains from carbonates-containing soils. Correspondingly, the incidence of Ni or Cd contamination in the wheat grain samples increased by about three times. With the carbonate concentration >1% in soil, uptake and bioaccumulation of Ni and Cd by winter wheat was independent with the soil pH and carbonate content. The findings suggest that soil carbonates play a critical role in heavy metal transfer from soil to plants, implying that monitoring soil carbonate may be necessary in addition to soil pH for the evaluating soil quality and food safety.

  18. [Organic carbon decomposition rate in different soil types].

    PubMed

    Yin, Yun-Feng; Cai, Zu-Cong

    2007-10-01

    With incubation experiment, this paper studied the decomposition rate of organic carbon in black soil, fluvo-aquic soil, and red soil. It was shown that these three soil types had significantly different decomposition rate constant of organic carbon (P < 0.05 ), with the corresponding value being 2.2 x 10(-4) x d(-1), 6.0 x 10(-4) x d(-1), and 3.4 x 10(-4) x d(-1), respectively. The decomposition rate constant had a significant correlation with soil pH, which was increased greatly when the soil pH was < 5.5 or > 8.0, and a significant negative correlation with the contents of soil clay and silt, indicating that soil clay and silt content was one of the dominant factors affecting the decomposition rate of organic carbon in these soil types.

  19. Microwave remote sensing of soil water content

    NASA Technical Reports Server (NTRS)

    Cihlar, J.; Ulaby, F. T.

    1975-01-01

    Microwave remote sensing of soils to determine water content was considered. A layered water balance model was developed for determining soil water content in the upper zone (top 30 cm), while soil moisture at greater depths and near the surface during the diurnal cycle was studied using experimental measurements. Soil temperature was investigated by means of a simulation model. Based on both models, moisture and temperature profiles of a hypothetical soil were generated and used to compute microwave soil parameters for a clear summer day. The results suggest that, (1) soil moisture in the upper zone can be predicted on a daily basis for 1 cm depth increments, (2) soil temperature presents no problem if surface temperature can be measured with infrared radiometers, and (3) the microwave response of a bare soil is determined primarily by the moisture at and near the surface. An algorithm is proposed for monitoring large areas which combines the water balance and microwave methods.

  20. CRADA Carbon Sequestration in Soils and Commercial Products

    SciTech Connect

    Jacobs, G.K.

    2002-01-31

    ORNL, through The Consortium for Research on Enhancing Carbon Sequestration in Terrestrial Ecosystems (CSiTE), collaborated with The Village Botanica, Inc. (VB) on a project investigating carbon sequestration in soils and commercial products from a new sustainable crop developed from perennial Hibiscus spp. Over 500 pre-treated samples were analyzed for soil carbon content. ORNL helped design a sampling scheme for soils during the planting phase of the project. Samples were collected and prepared by VB and analyzed for carbon content by ORNL. The project did not progress to a Phase II proposal because VB declined to prepare the required proposal.

  1. Critical water contents of hydrophobic soils in New Zealand

    NASA Astrophysics Data System (ADS)

    Landl, Magdalena; Holzinger, Ursula; Singh, Ranvir; Klik, Andreas

    2013-04-01

    Soil water repellency is an important problem for pasture farming in New Zealand which causes low infiltration rates and increased surface runoff. However, the real extent of this issue is not yet evaluated. Water repellency is thought to appear on dry soils, when the water content falls below a critical limit. The main objectives of this study was 1) to investigate the effects of different amounts of infiltration water on hydrophobicity of three selected soils under grassland in the North island of New Zealand, and 2) to determine the critical water content for ten sites with five different soil types. In April 2011 undisturbed and disturbed soil samples from a brown, gley and organic soil have been taken from sites around Mount Taranaki. Soil water repellency was determined using the Water Droplet Penetration Time Test (WDPT) and the Molarity of Ethanol Droplet Test (MED). During the lab experiment four amounts of water were applied to the 270 cm³ samples: 400, 800, 1600 and 2400 mL . One test was performed with cold and one with hot (80 °C) water. Each test was replicated four times. In the leachate the amount of dissolved organic carbon was analyzed. The experiments showed that only for the brown soil water repellency decreased significantly with increasing amount of infiltration water whereas for gley soils no correlation was found. Gley soil had initially a lower degree of hydrophobicity compared to the other soils. Possibly due to the higher bulk density of these soils, the carbon compounds directly surrounding the soil particles wre rearranged rather than leached. No clear pattern could be obtained for organic soils. This may be explained by the high initial carbon content of more than 20%. It may take a much greater amount of infiltration to affect hydrophobicity. The critical contact angle of investigated soils above which water repellency is moderately persistent, was 93.8°. In May 2012 ten more sites were sampled and five soil types were investigated

  2. Switchgrass cultivars differentially affect soil carbon stabilization

    NASA Astrophysics Data System (ADS)

    Adkins, J.; Jastrow, J. D.; Wullschleger, S. D.; De Graaff, M.

    2012-12-01

    Soil organic carbon (SOC) storage depends on the amount and quality of plant-derived carbon (C) inputs to soil, which is largely regulated by plant roots via the processes of root turnover and exudation. While we know that plant roots mediate SOC stabilization, we do not fully understand which root characteristics specifically promote soil C storage. With this study we asked whether roots with coarse root systems versus roots with finely branched root systems differentially affect soil C stabilization. In order to answer this question, we collected soil cores (4.8 cm diameter, to a depth of 30 cm) from directly over the crown of six switchgrass (Panicum virgatum L.) cultivars that differed in root architecture. Specifically, three cultivars had fibrous root systems (i.e. high specific root length) and three had coarse root systems (i.e. low specific root length). The cultivars (C4 species) were grown in a C3 grassland for four years, allowing us to use isotopic fractionation techniques to assess differences in soil C input and stabilization. The cores were divided into depth increments of 10 cm and the soils were sieved (2mm). Soil from each depth increment was dispersed by shaking for 16 hours in a NaHMP solution to isolate coarse particulate organic matter (C-POM), fine particulate organic matter (F-POM), silt, and clay-sized fractions. Samples of soil fractions across all depths were analyzed for C and N contents as well as δ13C signature. We found that the relative abundance of the different soil fractions and associated δ13C signatures differed significantly among cultivars. These results indicate that switchgrass cultivars can differentially impact soil carbon inputs and stabilization. We hypothesize that these differences may be driven by variability in root architectures.

  3. Soil Carbon Transformation in Heterogeneous Landscapes

    NASA Astrophysics Data System (ADS)

    Riveros-Iregui, D.; Liang, L.; Emanuel, R. E.; McGlynn, B. L.; Dore, J. E.; Kaiser, K.; Seybold, E. C.; Covino, T. P.

    2012-12-01

    Understanding critical belowground carbon processes (e.g., soil carbon turnover, root and microbial dynamics, and greenhouse gas generation and flux) requires examination of coupled physical and biological processes. The spatial patterns of first-order controls such as soil water content, soil temperature, substrate, and vegetation cover has been shown to impose spatial and temporal organization of soil CO2 efflux to the atmosphere. We examined the spatial and temporal variability of soil CO2 ([CO2]) and soil CH4 ([CH4]) concentrations and flux, and the stable isotope composition of CO2 (δ13CCO2) across two watersheds of differing topographic complexity and vegetation cover, including both forested and harvested areas. Samples were collected at 5cm, 20cm, and 50cm at multiple sites (6-10) along seven transects in the Tenderfoot Creek Experimental Forest (TCEF), central Montana. Our results show that [CO2] increases with depth while [CH4] decreases with depth in all dry sites, meaning that dry sites simultaneously act as a source for CO2 and a sink for CH4. Wet sites, however, had pronounced differences in their [CO2] and [CH4] profiles, depending on soil water content and water table depth. Isotopically, deep soil layers had systematically more negative δ13CCO2 values, but the difference between shallow and deep δ13CCO2 values varied as a function of landscape position and vegetation cover. Our results suggest that belowground processes and rates of soil carbon transformation vary across the landscape as a function of environmental gradients.

  4. Elevated atmospheric carbon dioxide increases soil carbon

    SciTech Connect

    Norby, Richard J; Jastrow, Julie D; Miller, Michael R; Matamala, Roser; Boutton, Thomas W; Rice, Charles W; Owensby, Clenton E

    2005-01-01

    In a study funded by the U.S. Department of Energy's Office of Science, researchers from Argonne and Oak Ridge National Laboratories and Kansas State and Texas A&M Universities evaluated the collective results of earlier studies by using a statistical procedure called meta-analysis. They found that on average elevated CO2 increased soil carbon by 5.6 percent over a two to nine year period. They also measured comparable increases in soil carbon for Tennessee deciduous forest and Kansas grassland after five to eight years of experimental exposure to elevated CO2.

  5. Effects of changes in land use on soil physical properties and soil organic carbon content in a wheat-corn-sunflower crop sequence, in a loam soil of Argentina.

    NASA Astrophysics Data System (ADS)

    Aparicio, V.; Costa, J. L.

    2012-04-01

    The Argentinean Humid Pampas extend over about 60 million hectares, 90% of which are agricultural lands. The Southeast of the Buenos Aires Province is part of the Humid Pampas, it covers over 1,206,162 hectares, the mean annual temperature is 13.3 °C and the climate is sub-humid. At the present only 6% of the lands are used for pasture. The main activities are agriculture and cattle production. The main crops are wheat, sunflower, corn and soybean. The tillage systems used in the area are: moldboard plow (MP), chisel plow (CP) and no-till (NT). Excessive soil cultivation under MP generates decreases in the levels of soil organic carbon (SOC). The magnitude of such decrease depends on the intensity of the tillage system, the tillage timeliness and the amount and quality of the residues. Adopting NT may reduce the effects of intensive agriculture, through the maintenance and accumulation of SOC. However, there are evidences that, under NT, the bulk density (ρb) in the superficial layers of the soil increases. The soil compaction causes degradation of the soil structure, reduces the soil water availability and reduces the soil hydraulic conductivity. With this scenario and the tendency to increase the surface under NT in the Southeast Humid Pampas, we evaluated the evolution of some soil physical properties and the SOC in a 10-year experiment with a wheat-corn-sunflower rotation. The experiment was carried out in four localities at farmerś fields under three different tillage systems: MP, CP and NT in a randomized complete block design, considering each locality as a block. Each plot had 50 m in width by 100 m length and the treatments were: NT, MP and CP. The results of this experiment have allowed us to verify that: i) the wheat-corn-sunflower crop sequence showed a tendency to reduce the values of bulk density (ρb) but NT increased ρb in the superficial soil layers; ii) the more intensive the tillage system, the higher the change in the mean weight diameter

  6. Experimental Evidence that Fungi are Dominant Microbes in Carbon Content and Growth Response to Added Soluble Organic Carbon in Moss-rich Tundra Soil.

    PubMed

    Anderson, O Roger; Lee, Jee Min; McGuire, Krista

    2016-05-01

    Global warming significantly affects Arctic tundra, including permafrost thaw and soluble C release that may differentially affect tundra microbial growth. Using laboratory experiments, we report some of the first evidence for the effects of soluble glucose-C enrichment on tundra soil prokaryotes (bacteria and archaea) and fungi, with comparisons to microbial eukaryotes. Fungal increase in C-biomass was equivalent to 10% (w/w) of the added glucose-C, and for prokaryote biomass 2% (w/w), the latter comparable to prior published results. The C-gain after 14 d was 1.3 mg/g soil for fungi, and ~200 μg/g for prokaryotes. PMID:26662659

  7. Experimental Evidence that Fungi are Dominant Microbes in Carbon Content and Growth Response to Added Soluble Organic Carbon in Moss-rich Tundra Soil.

    PubMed

    Anderson, O Roger; Lee, Jee Min; McGuire, Krista

    2016-05-01

    Global warming significantly affects Arctic tundra, including permafrost thaw and soluble C release that may differentially affect tundra microbial growth. Using laboratory experiments, we report some of the first evidence for the effects of soluble glucose-C enrichment on tundra soil prokaryotes (bacteria and archaea) and fungi, with comparisons to microbial eukaryotes. Fungal increase in C-biomass was equivalent to 10% (w/w) of the added glucose-C, and for prokaryote biomass 2% (w/w), the latter comparable to prior published results. The C-gain after 14 d was 1.3 mg/g soil for fungi, and ~200 μg/g for prokaryotes.

  8. Isotopic studies of Yucca Mountain soil fluids and carbonate pedogenesis

    SciTech Connect

    McConnaughey, T.A.; Whelan, J.F.; Wickland, K.P.; Moscati, R.J.

    1994-12-31

    Secondary carbonates occurring within the soils, faults, and subsurface fractures of Yucca Mountain contain some of the best available records of paleoclimate and palehydrology for the potential radioactive waste repository site. This article discusses conceptual and analytical advances being made with regard to the interpretation of stable isotope data from pedogenic carbonates, specifically related to the {sup 13}C content of soil CO{sub 2}, CaCO{sub 3}, precipitation mechanisms, and isotopic fractionations between parent fluids and precipitating carbonates. The {sup 13}C content of soil carbon dioxide from Yucca Mountain and vicinity shows most of the usual patterns expected in such contexts: Decreasing {sup 13}C content with depth decreasing {sup 13}C with altitude and reduced {sup 13}C during spring. These patterns exist within the domain of a noisy data set; soil and vegetational heterogeneities, weather, and other factors apparently contribute to isotopic variability in the system. Several soil calcification mechanisms appear to be important, involving characteristic physical and chemical environments and isotopic fractionations. When CO{sub 2} loss from thin soil solutions is an important driving factor, carbonates may contain excess heavy isotopes, compared to equilibrium precipitation with soil fluids. When root calcification serves as a proton generator for plant absorption of soil nutrients, heavy isotope deficiencies are likely. Successive cycles of dissolution and reprecipitation mix and redistribute pedogenic carbonates, and tend to isotopically homogenize and equilibrate pedogenic carbonates with soil fluids.

  9. Linear modeling of the soil-water partition coefficient normalized to organic carbon content by reversed-phase thin-layer chromatography.

    PubMed

    Andrić, Filip; Šegan, Sandra; Dramićanin, Aleksandra; Majstorović, Helena; Milojković-Opsenica, Dušanka

    2016-08-01

    Soil-water partition coefficient normalized to the organic carbon content (KOC) is one of the crucial properties influencing the fate of organic compounds in the environment. Chromatographic methods are well established alternative for direct sorption techniques used for KOC determination. The present work proposes reversed-phase thin-layer chromatography (RP-TLC) as a simpler, yet equally accurate method as officially recommended HPLC technique. Several TLC systems were studied including octadecyl-(RP18) and cyano-(CN) modified silica layers in combination with methanol-water and acetonitrile-water mixtures as mobile phases. In total 50 compounds of different molecular shape, size, and various ability to establish specific interactions were selected (phenols, beznodiazepines, triazine herbicides, and polyaromatic hydrocarbons). Calibration set of 29 compounds with known logKOC values determined by sorption experiments was used to build simple univariate calibrations, Principal Component Regression (PCR) and Partial Least Squares (PLS) models between logKOC and TLC retention parameters. Models exhibit good statistical performance, indicating that CN-layers contribute better to logKOC modeling than RP18-silica. The most promising TLC methods, officially recommended HPLC method, and four in silico estimation approaches have been compared by non-parametric Sum of Ranking Differences approach (SRD). The best estimations of logKOC values were achieved by simple univariate calibration of TLC retention data involving CN-silica layers and moderate content of methanol (40-50%v/v). They were ranked far well compared to the officially recommended HPLC method which was ranked in the middle. The worst estimates have been obtained from in silico computations based on octanol-water partition coefficient. Linear Solvation Energy Relationship study revealed that increased polarity of CN-layers over RP18 in combination with methanol-water mixtures is the key to better modeling of

  10. Electrical methods of determining soil moisture content

    NASA Technical Reports Server (NTRS)

    Silva, L. F.; Schultz, F. V.; Zalusky, J. T.

    1975-01-01

    The electrical permittivity of soils is a useful indicator of soil moisture content. Two methods of determining the permittivity profile in soils are examined. A method due to Becher is found to be inapplicable to this situation. A method of Slichter, however, appears to be feasible. The results of Slichter's method are extended to the proposal of an instrument design that could measure available soil moisture profile (percent available soil moisture as a function of depth) from a surface measurement to an expected resolution of 10 to 20 cm.

  11. Soil carbon stock and soil characteristics at Tasik Chini Forest Reserve, Pahang, Malaysia

    NASA Astrophysics Data System (ADS)

    Nur Aqlili Riana, R.; Sahibin A., R.

    2015-09-01

    This study was carried out to determine soil carbon stock and soil characteristic at Tasik Chini Forest Reserve (TCFR), Pahang. A total of 10 (20 m x 25 m) permanent sampling plot was selected randomly within the area of TCFR. Soil samples were taken from all subplots using dutch auger based on soil depth of 0-20cm, 20-40cm, 40-60cm. Soil parameters determined were size distribution, soil water content, bulk density, organic matter, organic carbon content, pH and electrical conductivity. All parameters were determined following their respective standard methods. Results obtained showed that the soil in TCFR was dominated by clay texture (40%), followed by sandy clay loam (30%), loam (20%). Silty clay, clay loam and sandy loam constitutes about 10% of the soil texture. Range of mean percentage of organic matter and bulk density are from 2.42±0.06% to 11.64±0.39% and 1.01 to 1.04 (gcm-ł), respectively. Soil pH are relatively very acidic and mean of electrical conductivity is low. Soil carbon content ranged from 0.83±0.03 to 1.87±0.41%. All soil parameter showed a decreasing trend with depth except electrical conductivity. ANOVA test of mean percentage of organic matter, soil water content, soil pH and electrical conductivity showed a significant difference between plot (p<0.05). However there are no significant difference of mean bulk density between plots (p>0.05). There are no significant difference in mean percentage of soil water content, organic matter and bulk density between three different depth (p>0.05). There were a significant difference on percentage of soil carbon organic between plots and depth. The mean of soil organic carbon stock in soil to a depth of 60 cm calculated was 35.50 t/ha.

  12. Australian climate-carbon cycle feedback reduced by soil black carbon

    NASA Astrophysics Data System (ADS)

    Lehmann, Johannes; Skjemstad, Jan; Sohi, Saran; Carter, John; Barson, Michele; Falloon, Pete; Coleman, Kevin; Woodbury, Peter; Krull, Evelyn

    2008-12-01

    Annual emissions of carbon dioxide from soil organic carbon are an order of magnitude greater than all anthropogenic carbon dioxide emissions taken together. Global warming is likely to increase the decomposition of soil organic carbon, and thus the release of carbon dioxide from soils, creating a positive feedback. Current models of global climate change that recognize this soil carbon feedback are inaccurate if a larger fraction of soil organic carbon than postulated has a very slow decomposition rate. Here we show that by including realistic stocks of black carbon in prediction models, carbon dioxide emissions are reduced by 18.3 and 24.4% in two Australian savannah regions in response to a warming of 3∘C over 100 years. This reduction in temperature sensitivity, and thus the magnitude of the positive feedback, results from the long mean residence time of black carbon, which we estimate to be approximately 1,300 and 2,600 years, respectively. The inclusion of black carbon in climate models is likely to require spatially explicit information about its distribution, given that the black carbon content of soils ranged from 0 to 82% of soil organic carbon in a continental-scale analysis of Australia. We conclude that accurate information about the distribution of black carbon in soils is important for projections of future climate change.

  13. The distribution in lunar soil of carbon released by pyrolysis

    NASA Technical Reports Server (NTRS)

    Desmarais, D. J.; Hayes, J. M.; Meinschein, W. G.

    1973-01-01

    The carbon contents of various lunar soil particle types and sieve fractions of Apollo 15 and 16 samples have been determined by the pyrolysis method. The mineral, glass, and high-grade breccia fragments in the soils examined contain relatively low amounts of carbon (approximately 8, 25, and 25 microg C/g sample respectively in 149-250 micron grains). Most low-grade breccias and all agglutinates examined have high carbon contents (approximately 52 and 80 microg C/g sample respectively), and agglutinate abundance is indicative of the carbon content and maturity of a soil. The distribution of carbon with respect to particle size in mature soils generally reveals a minimum in carbon content at about 100 micron particle diameter. At smaller particle diameters, carbon content is directly proportional to particle surface area and therefore increases with the ratio (surface area)/(particle mass). A model relating the cycle of comminution and aggregation of soil particles to the redistribution of surface implanted carbon is developed.

  14. Fertilization increases paddy soil organic carbon density*

    PubMed Central

    Wang, Shao-xian; Liang, Xin-qiang; Luo, Qi-xiang; Fan, Fang; Chen, Ying-xu; Li, Zu-zhang; Sun, Huo-xi; Dai, Tian-fang; Wan, Jun-nan; Li, Xiao-jun

    2012-01-01

    Field experiments provide an opportunity to study the effects of fertilization on soil organic carbon (SOC) sequestration. We sampled soils from a long-term (25 years) paddy experiment in subtropical China. The experiment included eight treatments: (1) check, (2) PK, (3) NP, (4) NK, (5) NPK, (6) 7F:3M (N, P, K inorganic fertilizers+30% organic N), (7) 5F:5M (N, P, K inorganic fertilizers+50% organic N), (8) 3F:7M (N, P, K inorganic fertilizers+70% organic N). Fertilization increased SOC content in the plow layers compared to the non-fertilized check treatment. The SOC density in the top 100 cm of soil ranged from 73.12 to 91.36 Mg/ha. The SOC densities of all fertilizer treatments were greater than that of the check. Those treatments that combined inorganic fertilizers and organic amendments had greater SOC densities than those receiving only inorganic fertilizers. The SOC density was closely correlated to the sum of the soil carbon converted from organic amendments and rice residues. Carbon sequestration in paddy soils could be achieved by balanced and combined fertilization. Fertilization combining both inorganic fertilizers and organic amendments is an effective sustainable practice to sequestrate SOC. PMID:22467369

  15. Fertilization increases paddy soil organic carbon density.

    PubMed

    Wang, Shao-xian; Liang, Xin-qiang; Luo, Qi-xiang; Fan, Fang; Chen, Ying-xu; Li, Zu-zhang; Sun, Huo-xi; Dai, Tian-fang; Wan, Jun-nan; Li, Xiao-jun

    2012-04-01

    Field experiments provide an opportunity to study the effects of fertilization on soil organic carbon (SOC) sequestration. We sampled soils from a long-term (25 years) paddy experiment in subtropical China. The experiment included eight treatments: (1) check, (2) PK, (3) NP, (4) NK, (5) NPK, (6) 7F:3M (N, P, K inorganic fertilizers+30% organic N), (7) 5F:5M (N, P, K inorganic fertilizers+50% organic N), (8) 3F:7M (N, P, K inorganic fertilizers+70% organic N). Fertilization increased SOC content in the plow layers compared to the non-fertilized check treatment. The SOC density in the top 100 cm of soil ranged from 73.12 to 91.36 Mg/ha. The SOC densities of all fertilizer treatments were greater than that of the check. Those treatments that combined inorganic fertilizers and organic amendments had greater SOC densities than those receiving only inorganic fertilizers. The SOC density was closely correlated to the sum of the soil carbon converted from organic amendments and rice residues. Carbon sequestration in paddy soils could be achieved by balanced and combined fertilization. Fertilization combining both inorganic fertilizers and organic amendments is an effective sustainable practice to sequestrate SOC.

  16. Radar measurement of soil moisture content

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.

    1974-01-01

    The effect of soil moisture on the radar backscattering coefficient was investigated by measuring the 4- to 8-GHz spectral response from two types of bare-soil fields: slightly rough and very rough, in terms of the wavelength. An FM-CW radar system mounted atop a 75-ft truck-mounted boom was used to measure the return at ten frequency points across the 4- to 8-GHz band, at eight different look angles (0 through 70 deg), and for all polarization combinations. A total of 17 sets of data were collected covering the range from 4 to 36% soil moisture content by weight. The results indicate that the radar response to soil moisture content is highly dependent on the surface roughness, microwave frequency, and look angle. The response seems to be linear, however, over the range from 15 to 30% moisture content for all angles, frequencies, polarizations and surface conditions.

  17. Soil carbon dynamics in cropland and rangeland.

    PubMed

    Lal, R

    2002-01-01

    Most soils in the Midwestern USA have lost 30 to 50% of their original pool, or 25 to 40 Mg C/ha, upon conversion from natural to agricultural ecosystems. About 60 to 70% of the C thus depleted can be resequestered through adoption of recommended soil and crop management practices. These practices include conversion from plow till to no till, frequent use of winter cover crops in the rotation cycle, elimination of summer fallow, integrated nutrient management along with liberal use of biosolids and biological nitrogen fixation, precision farming to minimize losses and enhance fertilizer use efficiency, and use of improved varieties with ability to produce large root biomass with high content of lignin and suberin. The gross rate of soil organic carbon (SOC) sequestration ranges from 500 to 800 kg/ha/year in cold and humid regions and 100 to 300 kg/ha/year in dry and warm regions. The rate of SOC sequestration can be measured with procedures that are cost effective and credible at soil pedon level, landscape level, regional or national scale. In addition to SOC, there is also a large potential to sequester soil inorganic carbon (SIC) in arid and semi-arid regions. Soil C sequestration has numerous ancillary benefits. It is truly a win-win situation: extremely cost-effective, and a bridge to the future until alternative energy options take effect.

  18. Sensitivity and uncertainty analysis of estimated soil hydraulic parameters for simulating soil water content

    NASA Astrophysics Data System (ADS)

    Gupta, Manika; Garg, Naveen Kumar; Srivastava, Prashant K.

    2014-05-01

    The sensitivity and uncertainty analysis has been carried out for the scalar parameters (soil hydraulic parameters (SHPs)), which govern the simulation of soil water content in the unsaturated soil zone. The study involves field experiments, which were conducted in real field conditions for wheat crop in Roorkee, India under irrigated conditions. Soil samples were taken for the soil profile of 60 cm depth at an interval of 15 cm in the experimental field to determine soil water retention curves (SWRCs). These experimentally determined SWRCs were used to estimate the SHPs by least square optimization under constrained conditions. Sensitivity of the SHPs estimated by various pedotransfer functions (PTFs), that relate various easily measurable soil properties like soil texture, bulk density and organic carbon content, is compared with lab derived parameters to simulate respective soil water retention curves. Sensitivity analysis was carried out using the monte carlo simulations and the one factor at a time approach. The different sets of SHPs, along with experimentally determined saturated permeability, are then used as input parameters in physically based, root water uptake model to ascertain the uncertainties in simulating soil water content. The generalised likelihood uncertainty estimation procedure (GLUE) was subsequently used to estimate the uncertainty bounds (UB) on the model predictions. It was found that the experimentally obtained SHPs were able to simulate the soil water contents with efficiencies of 70-80% at all the depths for the three irrigation treatments. The SHPs obtained from the PTFs, performed with varying uncertainties in simulating the soil water contents. Keywords: Sensitivity analysis, Uncertainty estimation, Pedotransfer functions, Soil hydraulic parameters, Hydrological modelling

  19. Soil Organic Carbon dynamics in agricultural soils of Veneto Region

    NASA Astrophysics Data System (ADS)

    Bampa, F. B.; Morari, F. M.; Hiederer, R. H.; Toth, G. T.; Giandon, P. G.; Vinci, I. V.; Montanarella, L. M.; Nocita, M.

    2012-04-01

    One of the eight soil threats expressed in the European Commission's Thematic Strategy for Soil Protection (COM (2006)231 final) it's the decline in Soil Organic Matter (SOM). His preservation is recognized as with the objective to ensure that the soils of Europe remain healthy and capable of supporting human activities and ecosystems. One of the key goals of the strategy is to maintain and improve Soil Organic Carbon (SOC) levels. As climate change is identified as a common element in many of the soil threats, the European Commission (EC) intends to assess the actual contribution of the soil protection to climate change mitigation and the effects of climate change on the possible depletion of SOM. A substantial proportion of European land is occupied by agriculture, and consequently plays a crucial role in maintaining natural resources. Organic carbon preservation and sequestration in the EU's agricultural soils could have some potential to mitigate the effects of climate change, particularly linked to preventing certain land use changes and maintaining SOC stocks. The objective of this study is to assess the SOC dynamics in agricultural soils (cropland and grassland) at regional scale, focusing on changes due to land use. A sub-objective would be the evaluation of the most used land management practices and their effect on SOC content. This assessment aims to determine the geographical distribution of the potential GHG mitigation options, focusing on hot spots in the EU, where mitigation actions would be particularly efficient and is linked with the on-going work in the JRC SOIL Action. The pilot area is Veneto Region. The data available are coming from different sources, timing and involve different variables as: soil texture, climate, soil disturbance, managements and nutrients. The first source of data is the LUCAS project (Land Use/Land Cover Area Frame statistical Survey). Started in 2001, the LUCAS project aims to monitor changes in land cover/use and

  20. Windthrows increase soil carbon stocks in a Central Amazon forest

    NASA Astrophysics Data System (ADS)

    dos Santos, L. T.; Magnabosco Marra, D.; Trumbore, S.; Camargo, P. B.; Chambers, J. Q.; Negrón-Juárez, R. I.; Lima, A. J. N.; Ribeiro, G. H. P. M.; dos Santos, J.; Higuchi, N.

    2015-12-01

    Windthrows change forest structure and species composition in Central Amazon forests. However, the effects of widespread tree mortality associated with wind-disturbances on soil properties have not yet been described. In this study, we investigated short-term effects (seven years after disturbance) of a windthrow event on soil carbon stocks and concentrations in a Central Amazon terra firme forest. The soil carbon stock (averaged over a 0-30 cm depth profile) in disturbed plots (61.4 ± 4.18 Mg ha-1, mean ± standard error) was marginally higher (p = 0.009) than that from undisturbed plots (47.7 ± 6.95 Mg ha-1). The soil organic carbon concentration in disturbed plots (2.0 ± 0.08 %) was significantly higher (p < 0.001) than that from undisturbed plots (1.36 ± 0.12 %). Moreover, soil carbon stocks were positively correlated with soil clay content (r = 0.575 and p = 0.019) and with tree mortality intensity (r = 0.493 and p = 0.045). Our results indicate that large inputs of plant litter associated with large windthrow events cause a short-term increase in soil carbon content, and the degree of increase is related to soil clay content and tree mortality intensity. Higher nutrient availability in soils from large canopy gaps created by wind disturbance may increase vegetation resilience and favor forest recovery.

  1. Effects of Biochar Amendment on Soil Properties and Soil Carbon Sequestration

    NASA Astrophysics Data System (ADS)

    Zhang, R.; Zhu, S.

    2015-12-01

    Biochar addition to soils potentially affects various soil properties and soil carbon sequestration, and these effects are dependent on biochars derived from different feedstock materials and pyrolysis processes. The objective of this study was to investigate the effects of amendment of different biochars on soil physical and biological properties as well as soil carbon sequestration. Biochars were produced with dairy manure and woodchip at temperatures of 300, 500, and 700°C, respectively. Each biochar was mixed at 5% (w/w) with a forest soil and the mixture was incubated for 180 days, during which soil physical and biological properties, and soil respiration rates were measured. Results showed that the biochar addition significantly enhanced the formation of soil macroaggregates at the early incubation time. The biochar application significantly reduced soil bulk density, increased the amount of soil organic matter, and stimulated microbial activity and soil respiration rates at the early incubation stage. Biochar applications improved water retention capacity, with stronger effects by biochars produced at higher pyrolysis temperatures. At the same suction, the soil with woodchip biochars possessed higher water content than with the dairy manure biochars. Biochar addition significantly affected the soil physical and biological properties, which resulted in different soil carbon mineralization rates and the amount of soil carbon storage.

  2. Soil clay content underlies prion infection odds

    USGS Publications Warehouse

    David, Walter W.; Walsh, D.P.; Farnsworth, Matthew L.; Winkelman, D.L.; Miller, M.W.

    2011-01-01

    Environmental factors-especially soil properties-have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with relatively high soil clay content. In this study, we report apparent influences of soil clay content on the odds of prion infection in free-ranging deer. Analysis of data from prion-infected deer herds in northern Colorado, USA, revealed that a 1% increase in the clay-sized particle content in soils within the approximate home range of an individual deer increased its odds of infection by up to 8.9%. Our findings suggest that soil clay content and related environmental properties deserve greater attention in assessing risks of prion disease outbreaks and prospects for their control in both natural and production settings. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  3. Soil clay content underlies prion infection odds

    PubMed Central

    David Walter, W.; Walsh, Daniel P.; Farnsworth, Matthew L.; Winkelman, Dana L.; Miller, Michael W.

    2011-01-01

    Environmental factors—especially soil properties—have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with relatively high soil clay content. In this study, we report apparent influences of soil clay content on the odds of prion infection in free-ranging deer. Analysis of data from prion-infected deer herds in northern Colorado, USA, revealed that a 1% increase in the clay-sized particle content in soils within the approximate home range of an individual deer increased its odds of infection by up to 8.9%. Our findings suggest that soil clay content and related environmental properties deserve greater attention in assessing risks of prion disease outbreaks and prospects for their control in both natural and production settings. PMID:21326232

  4. Permafrost soils and carbon cycling

    DOE PAGESBeta

    Ping, C. L.; Jastrow, J. D.; Jorgenson, M. T.; Michaelson, G. J.; Shur, Y. L.

    2014-10-30

    Knowledge of soils in the permafrost region has advanced immensely in recent decades, despite the remoteness and inaccessibility of most of the region and the sampling limitations posed by the severe environment. These efforts significantly increased estimates of the amount of organic carbon (OC) stored in permafrost-region soils and improved understanding of how pedogenic processes unique to permafrost environments built enormous OC stocks during the Quaternary. This knowledge has also called attention to the importance of permafrost-affected soils to the global C cycle and the potential vulnerability of the region's soil OC stocks to changing climatic conditions. In this review,more » we briefly introduce the permafrost characteristics, ice structures, and cryopedogenic processes that shape the development of permafrost-affected soils and discuss their effects on soil structures and on organic matter distributions within the soil profile. We then examine the quantity of OC stored in permafrost-region soils, as well as the characteristics, intrinsic decomposability, and potential vulnerability of this OC to permafrost thaw under a warming climate.« less

  5. Biogeochemistry: Soil carbon in a beer can

    NASA Astrophysics Data System (ADS)

    Davidson, Eric A.

    2015-10-01

    Decomposition of soil organic matter could be an important positive feedback to climate change. Geochemical properties of soils can help determine what fraction of soil carbon may be protected from climate-induced decomposition.

  6. [Relationships between soil organic carbon and environmental factors in gully watershed of the Loess Plateau].

    PubMed

    Wei, Xiao-Rong; Shao, Ming-An; Gao, Jian-Lun

    2008-10-01

    Understanding the distribution of organic carbon fractions in soils and their relationships with environmental factors are very important for appraising soil organic carbon status and assessing carbon cycling in the Loess Plateau. In this research, through field investigation and laboratory analysis, we studied the relationships between soil organic carbon and environmental factors in a gully watershed of the Loess Plateau. The environmental factors are landforms, land use conditions and soil types. The results showed that total soil organic carbon presented less variance, while high labile organic carbon presented greater variance. The variation coefficients of them are 34% and 43%, respectively, indicating that the variability of organic carbon in soils increased with the increasing of their activities. Total soil organic carbon, labile organic carbon, middle and high labile organic carbon were highly interrelated and presented similar distribution trend with environmental factors. Among different landforms, land uses, and soil types, the highest contents of organic carbon in different fractions were observed in plateau land, forest and farm lands, and black loessial soils, while the lowest contents of them were observed in gully bottom, grass land, and rubified soils, respectively. The relationships between organic carbon and environmental factors indicate that environmental factors not only directly influence the distribution of soil organic carbon, but also indirectly influence them through affecting the relationships among organic carbon fractions. The relationship between total organic carbon and labile organic carbon responses rapidly to environmental factors, while that between middle labile organic carbon and high labile organic carbon responses slowly to environmental factors. PMID:19143389

  7. Carbon sequestration potential of soils in southeast Germany derived from stable soil organic carbon saturation.

    PubMed

    Wiesmeier, Martin; Hübner, Rico; Spörlein, Peter; Geuß, Uwe; Hangen, Edzard; Reischl, Arthur; Schilling, Bernd; von Lützow, Margit; Kögel-Knabner, Ingrid

    2014-02-01

    Sequestration of atmospheric carbon (C) in soils through improved management of forest and agricultural land is considered to have high potential for global CO2 mitigation. However, the potential of soils to sequester soil organic carbon (SOC) in a stable form, which is limited by the stabilization of SOC against microbial mineralization, is largely unknown. In this study, we estimated the C sequestration potential of soils in southeast Germany by calculating the potential SOC saturation of silt and clay particles according to Hassink [Plant and Soil 191 (1997) 77] on the basis of 516 soil profiles. The determination of the current SOC content of silt and clay fractions for major soil units and land uses allowed an estimation of the C saturation deficit corresponding to the long-term C sequestration potential. The results showed that cropland soils have a low level of C saturation of around 50% and could store considerable amounts of additional SOC. A relatively high C sequestration potential was also determined for grassland soils. In contrast, forest soils had a low C sequestration potential as they were almost C saturated. A high proportion of sites with a high degree of apparent oversaturation revealed that in acidic, coarse-textured soils the relation to silt and clay is not suitable to estimate the stable C saturation. A strong correlation of the C saturation deficit with temperature and precipitation allowed a spatial estimation of the C sequestration potential for Bavaria. In total, about 395 Mt CO2 -equivalents could theoretically be stored in A horizons of cultivated soils - four times the annual emission of greenhouse gases in Bavaria. Although achieving the entire estimated C storage capacity is unrealistic, improved management of cultivated land could contribute significantly to CO2 mitigation. Moreover, increasing SOC stocks have additional benefits with respect to enhanced soil fertility and agricultural productivity.

  8. [Effects of gaps on distribution of soil aggregates and organic carbon in Pinus massoniana plantation].

    PubMed

    Song, Xiao-Yan; Zhang, Dan-Ju; Zhang, Jian; Li, Jian-Ping; Deng, Chang-Chun; Deng, Chao

    2014-11-01

    The effects of forest gap size on the distribution of soil aggregates, organic carbon and labile organic carbon were investigated in a 39-year-old Pinus massoniana plantation in Yibin, Sichuan Province. The results showed that the composition of soil aggregates was dominated by particles > 2 mm, which accounted for 51.7%-78.7% of the whole soil samples under different sized forest gaps and beneath P. massoniana plantation. Soil organic carbon content and labile organic carbon content in > 5 mm aggregates were significantly positively correlated with the soil organic carbon and labile organic carbon contents. Furthermore, the amounts of organic carbon and labile organic carbon storage > 5 mm particles were higher than those in other size particles. Therefore, particles > 5 mm of aggregates dominated the soil carbon pool. Compared with those P. massoniana plantations, the contents of organic carbon in aggregates and total topsoil decreased during the formation of forest gaps, whereas the soil organic carbon storage under 1225 m2 gap was higher. In addition, the soil labile organic carbon content under 225 and 400 m2 gaps and the labile organic carbon storage under 225, 400, 900 and 1225 m2 gaps were higher than those the plantations, but were lower than under the other gaps. It was suggested that an appropriate size of forest gap would increase the accumulation of soil organic carbon and labile organic carbon content. The size of forest gap had significant effects on the distribution of soil aggregates, organic carbon and labile organic carbon. The soil sample under 1225 m2 gap had the highest organic carbon content and storage and a better aggregate proportion, and the higher labile organic carbon storage. Therefore, it was suggested that 1225 m2 gap might be an optimal logging gap size.

  9. Mineral Control of Soil Carbon Dynamics in Forest Soils: A Lithosequence Under Ponderosa Pine

    NASA Astrophysics Data System (ADS)

    Heckman, K. A.; Welty-Bernard, A.; Rasmussen, C.; Schwartz, E.; Chorover, J.

    2008-12-01

    The role of soil organic carbon in regulating atmospheric CO2 concentration has spurred interest in both quantifying existing soil C stocks and modeling the behavior of soil C under climate change scenarios. Soil parent material exerts direct control over soil organic carbon content through its influence on soil pH and mineral composition. Soil acidity and mineral composition also influence soil microbial community composition and activity, thereby controlling soil respiration rates and microbial biomass size. We sampled a lithosequence of four parent materials (rhyolite, granite, basalt, limestone) under Pinus ponderosa to examine the effects of soil mineralogy and acidity on soil organic carbon content and soil microbial community. Three soil profiles were examined on each parent material and analyzed by X-ray diffraction, pH, selective dissolution, C and N content, and 13C signature. Soils from each of the four parent materials were incubated for 40 days, and microbial communities were compared on the basis of community composition (as determined through T-RFLP analysis), specific metabolic activity, biomass, δ13C of respired CO2, and cumulative amount of C mineralized over the course of the incubation. Soil C content varied significantly among soils of different parent material, and was strongly and positively associated with the abundance of Al-humus complexes r2 = 0.71; P < 0.0001, Fe-humus complexes r2 = 0.74; P = 0.0003, and crystalline Fe-oxide content r2 = 0.63; P = 0.0023. Microbial community composition varied significantly among soils and showed strong associations with soil pH 1:1 in KCl; r2 = 0.87; P < 0.0001, concentration of exchangeable Al r2 = 0.81; P < 0.0001, amorphous Fe oxide content r2 = 0.59; P < 0.004, and Al-humus content r2 = 0.35; P < 0.04. Mineralization rates, biomass and δ13C of respired CO2 differed among parent materials, and also varied with incubation time as substrate quality and N availability changed. The results demonstrate

  10. Niobium content of soils from West Africa

    USGS Publications Warehouse

    Grimaldi, F.S.; Berger, I.A.

    1961-01-01

    Analysis of twenty lateritic soil samples from West Africa has shown them to contain an average 24 p.p.m. of niobium; four similar samples taken from within a few miles from a niobium deposit contain from 79 to 87 p.p.m. niobium. It has been shown that as the aluminum content of the soils increases, the following depletion sequence is obtained: Si > Nb > Al = Fe The data indicate that, in general, high enrichments of niobium are not to be expected in lateritic soils. ?? 1961.

  11. Linking soil functions to carbon fluxes and stocks

    NASA Astrophysics Data System (ADS)

    Olesen, Jørgen E.

    2014-05-01

    Farming practices causing declining returns and inputs of carbon (C) to soils pose threats to sustainable soil functioning by reducing availability of organic matter for soil microbial activities and by affecting soil structure, and soil C stocks that contribute to regulating greenhouse gas emissions. Declines in soil C also affect availability and storage capacity of a range of essential plant nutrients thus affecting needs for external inputs. Soil degradation is considered a serious problem in Europe and a large part of the degradation is caused by agricultural activity with intensive cultivation in arable and mixed farming system contributing to several soil threats. About 45% of European soils are estimated to have low SOM content, principally in southern Europe, but also in areas of France, UK and Germany. The European SOC stocks follow a clear north to south gradient with cooler temperatures favouring higher stocks. However, SOC stocks strongly depend on soil and land management, and there is thus a potential to both increase and lose SOC, although the potential to increase SOC strongly depends on incentives and structures for implementing improved management. Understanding the role of soil C may be better conceptualised by using a soil C flow and stocks concept to assess the impact of C management on crop productivity, soil organic C stocks and other ecosystem services. This concept distinguishes C flows and stocks, which may be hypothesized to have distinctly different effects on biological, chemical and physical soil functions. By separating the roles of carbon flows from the role of carbon stocks, it may become possible to better identify critical levels not only of soil carbon stocks, but also critical levels of carbon inputs, which directly relate to needs for crop and soil management measures. Such critical soil carbon stocks may be linked to soil mineralogy through complexed organic carbon on clay and silt surfaces. Critical levels of soil carbon

  12. [Changes of soil nutrient contents after prescribed burning of forestland in Heshan City, Guangdong Province].

    PubMed

    Sun, Yu-xin; Wu, Jian-ping; Zhou, Li-xia; Lin, Yong-biao; Fu, Sheng-lei

    2009-03-01

    A comparative study was conducted to analyze the changes of soil nutrient contents in Eucalyptus forestland and in shrubland after three years of prescribed burning. In Eucalyptus forestland, soil organic carbon, total nitrogen, available potassium contents and soil pH decreased significantly; soil available phosphorus and exchangeable magnesium contents, net nitrogen mineralization rate and ammonification rate also decreased but showed no significant difference. In shrubland, soil exchangeable calcium content increased significantly, but the contents of other nutrients had no significant change. The main reason of the lower soil net nitrogen mineralization rate in Eucalyptus forest could be the decrease of available substrates and the uptake of larger amount of soil nutrients by the fast growth of Eucalyptus. The soil nutrients in shrubland had a quick restoration rate after burning. PMID:19637584

  13. [Variation characteristics of soil carbon sequestration under long-term different fertilization in red paddy soil].

    PubMed

    Huang, Jing; Zhang, Yang-zhu; Gao, Ju-sheng; Zhang, Wen-ju; Liu, Shu-jun

    2015-11-01

    The objective of this study was to clarify the changes of soil organic carbon (SOC) content, the saturation capacity of soil carbon sequestration and its cooperation with carbon input (crop source and organic fertilizer source carbon) under long-term (1982-2012) different fertilization in red paddy soil. The results showed that fertilization could increase SOC content. The SOC content of all the fertilization treatments demonstrated a trend of stabilization after applying fertilizer for 30 years. The SOC content in the treatments applying organic manure with mineral fertilizers was between 21.02 and 21.24 g · kg(-1), and the increase rate ranged from 0.41 to 0.59 g · kg(-1) · a(-1). The SOC content in the treatments applying mineral fertilizers only was 15.48 g · kg(-1). The average soil carbon sequestration in the treatments that applied organic manure with mineral fertilizers ranged from 43.61 to 48.43 t C · hm(-2), and the average SOC storage over the years in these treatments was significantly greater than those applying mineral fertilizers only. There was an exponentially positive correlation between C sequestration efficiency and annual average organic C input. It must input exogenous organic carbon at least at 0. 12 t C · hm(-2) · a(-1) to maintain the balance of soil organic carbon under the experimental conditions. PMID:26915193

  14. [Variation characteristics of soil carbon sequestration under long-term different fertilization in red paddy soil].

    PubMed

    Huang, Jing; Zhang, Yang-zhu; Gao, Ju-sheng; Zhang, Wen-ju; Liu, Shu-jun

    2015-11-01

    The objective of this study was to clarify the changes of soil organic carbon (SOC) content, the saturation capacity of soil carbon sequestration and its cooperation with carbon input (crop source and organic fertilizer source carbon) under long-term (1982-2012) different fertilization in red paddy soil. The results showed that fertilization could increase SOC content. The SOC content of all the fertilization treatments demonstrated a trend of stabilization after applying fertilizer for 30 years. The SOC content in the treatments applying organic manure with mineral fertilizers was between 21.02 and 21.24 g · kg(-1), and the increase rate ranged from 0.41 to 0.59 g · kg(-1) · a(-1). The SOC content in the treatments applying mineral fertilizers only was 15.48 g · kg(-1). The average soil carbon sequestration in the treatments that applied organic manure with mineral fertilizers ranged from 43.61 to 48.43 t C · hm(-2), and the average SOC storage over the years in these treatments was significantly greater than those applying mineral fertilizers only. There was an exponentially positive correlation between C sequestration efficiency and annual average organic C input. It must input exogenous organic carbon at least at 0. 12 t C · hm(-2) · a(-1) to maintain the balance of soil organic carbon under the experimental conditions.

  15. Effect of soil organic matter composition on unfrozen water content of frozen soils, and their heterotrophic CO2 production

    NASA Astrophysics Data System (ADS)

    Harrysson Drotz, S.; Schleucher, J.; Sparrman, T.; Nilsson, M.; Oquist, M. G.

    2009-04-01

    Heterotrophic microbial processes and associated production and emission of atmospheric trace gases proceed during the winter months in the frozen soils of high latitude ecosystems. The ability of soil to retain unfrozen water at below-zero temperatures is integral for this activity. The soil organic matter (SOM) is believed to play an important role for the soil liquid water contents in frozen bulk soil, but the specific factors contributing to this control are presently unknown. Here we evaluate the effect of the organic chemical composition on the amount of unfrozen water and the microbial heterotrophic activity at below zero temperatures in boreal forest soils. To achieve this, we have characterized the chemical composition of SOM in boreal pine and spruce forest soils using solid state CP-MAS (cross polarization magic angle spinning) NMR spectroscopy. We then use acquired data on SOM composition to elucidate to what extent it can explain the observed variation in unfrozen water content and biogenic CO2 production rates among the soil samples under frozen conditions (-4°C). We conclude that aromatic carbon, O-aromatic carbon, methoxy/N-alkyl carbon, and alkyl carbon are the major SOM components affecting frozen boreal forest soils' ability to retain unfrozen water and their microbial CO2 production. Surprisingly, our results reveal that solid carbohydrates have a negative impact on CO2 production in frozen boreal forest soils. More recalcitrant SOM compounds, mainly aromatic carbon and alkyl carbon, need to be considered to fully understand winter biogeochemical processes and carbon dynamics in frozen soil. In addition, SOM-associated controls on the unfrozen water content differed between samples originating from Pine forests as compared to Spruce dominated forests. Given the strong link between unfrozen water content and SOM mineralization during winter this may represent a previously unrecognized potential feedback mechanism of global climate change, and

  16. Plant soil interactions alter carbon cycling in an upland grassland soil.

    PubMed

    Thomson, Bruce C; Ostle, Nick J; McNamara, Niall P; Oakley, Simon; Whiteley, Andrew S; Bailey, Mark J; Griffiths, Robert I

    2013-01-01

    Soil carbon (C) storage is dependent upon the complex dynamics of fresh and native organic matter cycling, which are regulated by plant and soil-microbial activities. A fundamental challenge exists to link microbial biodiversity with plant-soil C cycling processes to elucidate the underlying mechanisms regulating soil carbon. To address this, we contrasted vegetated grassland soils with bare soils, which had been plant-free for 3 years, using stable isotope ((13)C) labeled substrate assays and molecular analyses of bacterial communities. Vegetated soils had higher C and N contents, biomass, and substrate-specific respiration rates. Conversely, following substrate addition unlabeled, native soil C cycling was accelerated in bare soil and retarded in vegetated soil; indicative of differential priming effects. Functional differences were reflected in bacterial biodiversity with Alphaproteobacteria and Acidobacteria dominating vegetated and bare soils, respectively. Significant isotopic enrichment of soil RNA was found after substrate addition and rates varied according to substrate type. However, assimilation was independent of plant presence which, in contrast to large differences in (13)CO2 respiration rates, indicated greater substrate C use efficiency in bare, Acidobacteria-dominated soils. Stable isotope probing (SIP) revealed most community members had utilized substrates with little evidence for competitive outgrowth of sub-populations. Our findings support theories on how plant-mediated soil resource availability affects the turnover of different pools of soil carbon, and we further identify a potential role of soil microbial biodiversity. Specifically we conclude that emerging theories on the life histories of dominant soil taxa can be invoked to explain changes in soil carbon cycling linked to resource availability, and that there is a strong case for considering microbial biodiversity in future studies investigating the turnover of different pools of soil

  17. Plant soil interactions alter carbon cycling in an upland grassland soil

    PubMed Central

    Thomson, Bruce C.; Ostle, Nick J.; McNamara, Niall P.; Oakley, Simon; Whiteley, Andrew S.; Bailey, Mark J.; Griffiths, Robert I.

    2013-01-01

    Soil carbon (C) storage is dependent upon the complex dynamics of fresh and native organic matter cycling, which are regulated by plant and soil-microbial activities. A fundamental challenge exists to link microbial biodiversity with plant-soil C cycling processes to elucidate the underlying mechanisms regulating soil carbon. To address this, we contrasted vegetated grassland soils with bare soils, which had been plant-free for 3 years, using stable isotope (13C) labeled substrate assays and molecular analyses of bacterial communities. Vegetated soils had higher C and N contents, biomass, and substrate-specific respiration rates. Conversely, following substrate addition unlabeled, native soil C cycling was accelerated in bare soil and retarded in vegetated soil; indicative of differential priming effects. Functional differences were reflected in bacterial biodiversity with Alphaproteobacteria and Acidobacteria dominating vegetated and bare soils, respectively. Significant isotopic enrichment of soil RNA was found after substrate addition and rates varied according to substrate type. However, assimilation was independent of plant presence which, in contrast to large differences in 13CO2 respiration rates, indicated greater substrate C use efficiency in bare, Acidobacteria-dominated soils. Stable isotope probing (SIP) revealed most community members had utilized substrates with little evidence for competitive outgrowth of sub-populations. Our findings support theories on how plant-mediated soil resource availability affects the turnover of different pools of soil carbon, and we further identify a potential role of soil microbial biodiversity. Specifically we conclude that emerging theories on the life histories of dominant soil taxa can be invoked to explain changes in soil carbon cycling linked to resource availability, and that there is a strong case for considering microbial biodiversity in future studies investigating the turnover of different pools of soil

  18. Radar measurement of soil moisture content

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.

    1973-01-01

    The effect of soil moisture on the radar backscattering coefficient was investigated by measuring the 4-8 GHz spectral response from two types of bare-soil fields: slightly rough and very rough, in terms of the wavelength. An FM-CW radar system was used to measure the return at 10 frequency points across the 4-8 GHz band, at different look angles, and for all polarization combinations. The results indicate that the radar response to soil moisture content is highly dependent on the surface roughness, microwave frequency, and look angle. The response seems to be linear over the range 15%-30% moisture content for all angles, frequencies, polarizations and surface conditions.

  19. Limits to soil carbon stability; Deep, ancient soil carbon decomposition stimulated by new labile organic inputs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil carbon (C) pools store about one-third of the total terrestrial organic carbon. Deep soil C pools (below 1 m) are thought to be stable due to their low biodegradability, but little is known about soil microbial processes and carbon dynamics below the soil surface, or how global change might aff...

  20. [Soil Microbial Respiration Under Different Soil Temperature Conditions and Its Relationship to Soil Dissolved Organic Carbon and Invertase].

    PubMed

    Wu, Jing; Chen, Shu-tao; Hu, Zheng-hua; Zhang, Xu

    2015-04-01

    In order to investigate the soil microbial respiration under different temperature conditions and its relationship to soil dissolved organic carbon ( DOC) and invertase, an indoor incubation experiment was performed. The soil samples used for the experiment were taken from Laoshan, Zijinshan, and Baohuashan. The responses of soil microbial respiration to the increasing temperature were studied. The soil DOC content and invertase activity were also measured at the end of incubation. Results showed that relationships between cumulative microbial respiration of different soils and soil temperature could be explained by exponential functions, which had P values lower than 0.001. The coefficient of temperature sensitivity (Q10 value) varied from 1.762 to 1.895. The Q10 value of cumulative microbial respiration decreased with the increase of soil temperature for all soils. The Q10 value of microbial respiration on 27 days after incubation was close to that of 1 day after incubation, indicating that the temperature sensitivity of recalcitrant organic carbon may be similar to that of labile organic carbon. For all soils, a highly significant ( P = 0.003 ) linear relationship between cumulative soil microbial respiration and soil DOC content could be observed. Soil DOC content could explain 31.6% variances of cumulative soil microbial respiration. For the individual soil and all soils, the relationship between cumulative soil microbial respiration and invertase activity could be explained by a highly significant (P < 0.01) linear regression function, which suggested that invertase was a good indicator of the magnitude of soil microbial respiration.

  1. [Soil Microbial Respiration Under Different Soil Temperature Conditions and Its Relationship to Soil Dissolved Organic Carbon and Invertase].

    PubMed

    Wu, Jing; Chen, Shu-tao; Hu, Zheng-hua; Zhang, Xu

    2015-04-01

    In order to investigate the soil microbial respiration under different temperature conditions and its relationship to soil dissolved organic carbon ( DOC) and invertase, an indoor incubation experiment was performed. The soil samples used for the experiment were taken from Laoshan, Zijinshan, and Baohuashan. The responses of soil microbial respiration to the increasing temperature were studied. The soil DOC content and invertase activity were also measured at the end of incubation. Results showed that relationships between cumulative microbial respiration of different soils and soil temperature could be explained by exponential functions, which had P values lower than 0.001. The coefficient of temperature sensitivity (Q10 value) varied from 1.762 to 1.895. The Q10 value of cumulative microbial respiration decreased with the increase of soil temperature for all soils. The Q10 value of microbial respiration on 27 days after incubation was close to that of 1 day after incubation, indicating that the temperature sensitivity of recalcitrant organic carbon may be similar to that of labile organic carbon. For all soils, a highly significant ( P = 0.003 ) linear relationship between cumulative soil microbial respiration and soil DOC content could be observed. Soil DOC content could explain 31.6% variances of cumulative soil microbial respiration. For the individual soil and all soils, the relationship between cumulative soil microbial respiration and invertase activity could be explained by a highly significant (P < 0.01) linear regression function, which suggested that invertase was a good indicator of the magnitude of soil microbial respiration. PMID:26164932

  2. Carbon sequestration in soil by in situ catalyzed photo-oxidative polymerization of soil organic matter.

    PubMed

    Piccolo, Alessandro; Spaccini, Riccardo; Nebbioso, Antonio; Mazzei, Pierluigi

    2011-08-01

    Here we describe an innovative mechanism for carbon sequestration in soil by in situ photopolymerization of soil organic matter under biomimetic catalysis. Three different Mediterranean soils were added with a synthetic water-soluble iron-porphyrin, irradiated by solar light, and subjected first to 5 days incubation and, then, 15, and 30 wetting and drying (w/d) cycles. The in situ catalyst-assisted photopolymerization of soil organic carbon (SOC) increased water stability of soil aggregates both after 5 days incubation and 15 w/d cycles, but not after 30 w/d cycles. Particle-size distribution of all treated soils confirmed the induced soil physical improvement, by showing a concomitant lower yield of the clay-sized fraction and larger yields of either coarse sand- or fine sand-size fractions, depending on soil texture, though only after 5 days incubation. The gain in soil physical quality was reflected by the shift of OC content from small to large soil aggregates, thereby suggesting that photopolymerization stabilized OC by both chemical and physical processes. A further evidence of the carbon sequestration capacity of the photocatalytic treatment was provided by the significant reduction of CO(2) respired by all soils after both incubation and w/d cycles. Our findings suggest that "green" catalytic technologies may potentially be the bases for future practices to increase soil carbon stabilization and mitigate CO(2) emissions from arable soils.

  3. Ectomycorrhizal fungi slow soil carbon cycling.

    PubMed

    Averill, Colin; Hawkes, Christine V

    2016-08-01

    Respiration of soil organic carbon is one of the largest fluxes of CO2 on earth. Understanding the processes that regulate soil respiration is critical for predicting future climate. Recent work has suggested that soil carbon respiration may be reduced by competition for nitrogen between symbiotic ectomycorrhizal fungi that associate with plant roots and free-living microbial decomposers, which is consistent with increased soil carbon storage in ectomycorrhizal ecosystems globally. However, experimental tests of the mycorrhizal competition hypothesis are lacking. Here we show that ectomycorrhizal roots and hyphae decrease soil carbon respiration rates by up to 67% under field conditions in two separate field exclusion experiments, and this likely occurs via competition for soil nitrogen, an effect larger than 2 °C soil warming. These findings support mycorrhizal competition for nitrogen as an independent driver of soil carbon balance and demonstrate the need to understand microbial community interactions to predict ecosystem feedbacks to global climate. PMID:27335203

  4. Profile storage of organic/inorganic carbon in soil: from forest to desert.

    PubMed

    Wang, Yugang; Li, Yan; Ye, Xuehua; Chu, Yu; Wang, Xinping

    2010-03-15

    Understanding the distribution of organic/inorganic carbon storage in soil profile is crucial for assessing regional, continental and global soil C stores and predicting the consequences of global change. However, little is known about the organic/inorganic carbon storages in deep soil layers at various landscapes. This study was conducted to determine the soil organic/inorganic carbon storage in soil profile of 0-3m at 5 sites of natural landscape from forest to desert. Landscapes are temperate forest, temperate grassland, temperate shrub-grassland, temperate shrub desert, and temperate desert. Root mass density and carbon contents at the profile were determined for each site. The results showed that considerable decrease in root biomass and soil organic carbon content at the soil profile of 0-3m when landscape varied from forest to desert along a precipitation gradient, while soil inorganic carbon content increased significantly along the precipitation gradient. Namely, for density of soil organic carbon: forest>grassland>shrub-grassland>shrub desert>desert; for density of soil inorganic carbon: forest, grasslandsoil carbon storage was found in 1-3m depth. For grassland and shrub-grassland, the contribution from 1-3m was mainly in the form of organic carbon, while for shrub desert and desert the contribution from this depth was mainly in the form of inorganic carbon. The comparison of soil C storage between top 0-1m and 1-3m showed that the using top 1m of soil profile to estimate soil carbon storages would considerably underestimate soil carbon storage. This is especially true for organic soil carbon at grassland region, and for soil inorganic carbon at desert region.

  5. Windthrows increase soil carbon stocks in a central Amazon forest

    NASA Astrophysics Data System (ADS)

    dos Santos, Leandro T.; Magnabosco Marra, Daniel; Trumbore, Susan; de Camargo, Plínio B.; Negrón-Juárez, Robinson I.; Lima, Adriano J. N.; Ribeiro, Gabriel H. P. M.; dos Santos, Joaquim; Higuchi, Niro

    2016-03-01

    Windthrows change forest structure and species composition in central Amazon forests. However, the effects of widespread tree mortality associated with wind disturbances on soil properties have not yet been described in this vast region. We investigated short-term effects (7 years after disturbance) of widespread tree mortality caused by a squall line event from mid-January of 2005 on soil carbon stocks and concentrations in a central Amazon terra firme forest. The soil carbon stock (averaged over a 0-30 cm depth profile) in disturbed plots (61.4 ± 8.2 Mg ha-1, mean ±95 % confidence interval) was marginally higher (p = 0.09) than that from undisturbed plots (47.7 ± 13.6 Mg ha-1). The soil organic carbon concentration in disturbed plots (2.0 ± 0.17 %) was significantly higher (p < 0.001) than that from undisturbed plots (1.36 ± 0.24 %). Moreover, soil carbon stocks were positively correlated with soil clay content (r2 = 0.332, r = 0.575 and p = 0.019) and with tree mortality intensity (r2 = 0.257, r = 0.506 and p = 0.045). Our results indicate that large inputs of plant litter associated with large windthrow events cause a short-term increase in soil carbon content, and the degree of increase is related to soil clay content and tree mortality intensity. The higher carbon content and potentially higher nutrient availability in soils from areas recovering from windthrows may favor forest regrowth and increase vegetation resilience.

  6. [Profile distribution of soil aggregates organic carbon in primary forests in Karst cluster-peak depression region].

    PubMed

    Lu, Ling-Xiao; Song, Tong-Qing; Peng, Wan-Xia; Zeng, Fu-Ping; Wang, Ke-Lin; Xu, Yun-Lei; Yu, Zi; Liu, Yan

    2012-05-01

    Soil profiles were collected from three primary forests (Itoa orientalis, Platycladus orientalis, and Radermachera sinica) in Karst cluster-peak depression region to study the composition of soil aggregates, their organic carbon contents, and the profile distribution of the organic carbon. In the three forests, >2 mm soil aggregates were dominant, occupying about 76% of the total. The content of soil total organic carbon ranged from 12.73 to 68.66 g x kg(-1), with a significant difference among the forests. The organic carbon content in <1 mm soil aggregates was slightly higher than that in >2 mm soil aggregates, but most of soil organic carbon was stored in the soil aggregates with greater particle sizes. About 70% of soil organic carbon came from >2 mm soil aggregates. There was a significant positive relationship between the contents of 2-5 and 5-8 mm soil aggregates and the content of soil organic carbon. To increase the contents of 2-8 mm soil aggregates could effectively improve the soil carbon sequestration in Karst region. In Itoa orientalis forest, 2-8 mm soil aggregates accounted for 46% of the total, and the content of soil total organic carbon reached to 37.62 g x kg(-1), which implied that Itoa orientalis could be the suitable tree species for the ecological restoration in Karst region.

  7. Ecological value of soil carbon management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of soil carbon is critical to the climate change debate, as well as to the long-term productivity and ecosystem resilience of the biosphere. Soil organic carbon is a key ecosystem property that indicates inherent productivity of land, controls soil biological functioning and diversity, r...

  8. Evolution of black carbon properties in soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Black carbon deposited in soil from natural or deliberate wildfires and engineered black carbon products (biochar) intentionally added to soil are known to have significant effects on soil biogeochemical processes and in many cases to influence the yield and quality of crops and to enhance the abili...

  9. Erosion of soil organic carbon: implications for carbon sequestration

    USGS Publications Warehouse

    Van Oost, Kristof; Van Hemelryck, Hendrik; Harden, Jennifer W.; McPherson, B.J.; Sundquist, E.T.

    2009-01-01

    Agricultural activities have substantially increased rates of soil erosion and deposition, and these processes have a significant impact on carbon (C) mineralization and burial. Here, we present a synthesis of erosion effects on carbon dynamics and discuss the implications of soil erosion for carbon sequestration strategies. We demonstrate that for a range of data-based parameters from the literature, soil erosion results in increased C storage onto land, an effect that is heterogeneous on the landscape and is variable on various timescales. We argue that the magnitude of the erosion term and soil carbon residence time, both strongly influenced by soil management, largely control the strength of the erosion-induced sink. In order to evaluate fully the effects of soil management strategies that promote carbon sequestration, a full carbon account must be made that considers the impact of erosion-enhanced disequilibrium between carbon inputs and decomposition, including effects on net primary productivity and decomposition rates.

  10. Ecological controls over global soil carbon storage

    SciTech Connect

    Schimel, D.S.

    1995-09-01

    Globally, soil carbon comprises about 2/3 of terrestrial carbon storage. Soil carbon is thus an important reservoir of carbon, but also influences the responses of ecosystems to change by controlling many aspects of nutrient cycling. While broad-scale patterns of soil carbon accumulation can be explained in terms of climatic and biome distributions, many ecological processes also influence the storage and turnover of carbon in soils. I will present a synthesis of information from field studies, model experiments and global data bases on factors controlling the turnover and storage of soil carbon. First, I will review a series of studies showing links between vegetation change (successional and invasions) and soil carbon. Then I will review model analyses of the sensitivity of soil carbon to climatic and ecological changes. Results show that soil carbon storage is broadly sensitive to climate but greatly influenced by the allocation of detritus between resistant (lignaceous and woody) and more labile forms, and that biotic changes that affect allocation, affect soil carbon substantially at regionally and perhaps global scales.

  11. Effects of composite soil with feldspathic sandstone and sand on soil aggregates and organic carbon

    NASA Astrophysics Data System (ADS)

    Li, J.; Han, J. C.; Zhang, Y.; Lei, G. Y.; Wang, H. Y.; Zhu, D. W.

    2016-08-01

    The case was to study the effects of soils with different proportions of feldspathic sandstone and sand on soil stability and organic carbon at 0-30 cm soil depth with four different ratios(C1, C2, C3 and C4), They were used to prepare the composite soil in Fu Ping, Shaanxi Province of China, then the soil aggregates distribution, WASR, MWD, GMD, D valueand and organic carbon content were measured and analysed.The results showed : the soil stability of C1, C2 and C3 was better than C4, i.e., the composition could improve the soil stability. With the increasing of the planting years, the contents of soil aggregates with the size >0.25 mm and MWD, GMD and SOC increased for each treatment at 0- 30 cm soil depth, which was contrary to D values. WASR of C2 was significantly higher than others (p<0.05) after 3-year planting. The significant logarithmic relationships were found between the D values and the ratios in C1, C2 and C3. Besides C1 and C2 could increase the stability and content of large soil aggregates to improve soil structure; C2 could significantly increase the SOC than others at 0- 30 cm soil depth.

  12. Modelling and mapping the topsoil organic carbon content for Tanzania

    NASA Astrophysics Data System (ADS)

    Kempen, Bas; Kaaya, Abel; Ngonyani Mhaiki, Consolatha; Kiluvia, Shani; Ruiperez-Gonzalez, Maria; Batjes, Niels; Dalsgaard, Soren

    2014-05-01

    Soil organic carbon (SOC), held in soil organic matter, is a key indicator of soil health and plays an important role in the global carbon cycle. The soil can act as a net source or sink of carbon depending on land use and management. Deforestation and forest degradation lead to the release of vast amounts of carbon from the soil in the form of greenhouse gasses, especially in tropical countries. Tanzania has a high deforestation rate: it is estimated that the country loses 1.1% of its total forested area annually. During 2010-2013 Tanzania has been a pilot country under the UN-REDD programme. This programme has supported Tanzania in its initial efforts towards reducing greenhouse gas emission from forest degradation and deforestation and towards preserving soil carbon stocks. Formulation and implementation of the national REDD strategy requires detailed information on the five carbon pools among these the SOC pool. The spatial distribution of SOC contents and stocks was not available for Tanzania. The initial aim of this research, was therefore to develop high-resolution maps of the SOC content for the country. The mapping exercise was carried out in a collaborative effort with four Tanzanian institutes and data from the Africa Soil Information Service initiative (AfSIS). The mapping exercise was provided with over 3200 field observations on SOC from four sources; this is the most comprehensive soil dataset collected in Tanzania so far. The main source of soil samples was the National Forest Monitoring and Assessment (NAFORMA). The carbon maps were generated by means of digital soil mapping using regression-kriging. Maps at 250 m spatial resolution were developed for four depth layers: 0-10 cm, 10-20 cm, 20-30 cm, and 0-30 cm. A total of 37 environmental GIS data layers were prepared for use as covariates in the regression model. These included vegetation indices, terrain parameters, surface temperature, spectral reflectances, a land cover map and a small

  13. Soil Organic Carbon Input from Urban Turfgrasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Turfgrass is a major vegetation type in the urban and suburban environment. Management practices such as species selection, irrigation, and mowing may affect carbon input and storage in these systems. Research was conducted to determine the rate of soil organic carbon (SOC) changes, soil carbon sequ...

  14. Soil Organic Carbon Input from Urban Turfgrasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Turfgrass is a major vegetation type in the urban and suburban environment. Management practices such as species selection, irrigation, and mowing may affect carbon (C) input and storage in these systems. Research was conducted to determine the rate of soil organic carbon (SOC) changes, soil carbon ...

  15. [Seasonal dynamics of soil active carbon pool in a purple paddy soil in southwest China].

    PubMed

    Wu, Yan; Jiang, Chang-sheng; Hao, Qing-ju

    2012-08-01

    The seasonal dynamics of soil organic carbon (SOC), readily oxidized carbon (ROC), dissolved organic carbon (DOC) and microbial biomass carbon (MBC) in a purple paddy soil were studied in a long-term field experimental station in Chongqing, China. The results showed that the seasonal variations of the contents of SOC, ROC and MBC had similar trends in the rape growing season. The contents were much higher in the early and late stages than in the middle stage of the rape growth. SOC, ROC and MBC all achieved the highest values of 16.20 g x kg(-1), 3.58 g x kg(-1) and 309.70 mg x kg(-1) at the end of the growing period, respectively. The seasonal change of DOC content presented as a single peak and reached to the highest value of 37.64 mg x kg(-1) at the middle stage of the rape growth. The temporal dynamics of the allocation ratios of ROC, MBC and DOC were similar to that of their contents. The allocation ratios of ROC, MBC and DOC were 15.49%-23.93%, 1.44%-2.06% and 0.11%-0.32% during the rape growing season, respectively. The influencing factors of SOC and ROC contents were the soil temperature at 5 cm soil depth, soil total nitrogen content and pH. MBC content was jointly impacted by the soil temperature at 5 cm soil depth, root biomass and its C and N contents. DOC content was mainly affected by soil moisture. PMID:23213908

  16. Role of carbonates in soil organic matter stabilization in agricultural Mediterranean soils

    NASA Astrophysics Data System (ADS)

    Apesteguía, Marcos; Virto, Iñigo; Plante, Alain

    2016-04-01

    Carbonated soils are present in many semiarid areas, where lithogenic and secondary carbonates are important constituents of the soil mineral matrix. The presence of CaCO3 in calcareous soils has been described as an organic matter stabilization agent mainly due to chemical stabilization mechanisms. In two recent studies in the north of Spain the importance of CaCO3 on soil physical characteristics was highlighted, as they were observed to be acting as macroaggregates stabilization agents. A third study was carried out on the same experimental site, with the hypothesis that the observed differences in aggregation may favor organic matter stabilization in carbonate-containing soils. With that aim we studied the soil physical characteristics (water retention and porosity) and the bioavailability of soil organic matter (SOM) in the two contrasting soils in that site, one Typic Calcixerept (CALC) and one Calcic Haploxerept (DECALC). Bioavailability was evaluated trough the measurement of mineralization rates in a 30 days soil incubations. Intact and disaggregated samples were incubated to evaluate the effect of physical protection on SOM bioavailability in whole soil and macroaggregates 2-5 mm samples. Therefore, four fractions of each soil were studied: intact whole soil < 5 mm (I-WS), disaggregated whole soil (D-WS), intact macroaggregates 2-5 mm (I-Magg), and disaggregated macroaggregates (D-Magg). Soil organic carbon content was greater in CALC and had smaller mineralization rates during incubation, indicating a smaller organic matter bioavailability for microbial decomposition. However, the greater increment of mineralization observed in DECALC after disaggregation, together with the scarce differences observed in physical characteristics among both soils, indicate that physical protection was not responsible of greater SOM stability in CALC soil. New hypotheses are needed to explain the observed better protection of organic matter in carbonate-rich Mediterranean

  17. Biochar and biological carbon cycling in temperate soils

    NASA Astrophysics Data System (ADS)

    McCormack, S. A.; Vanbergen, A. J.; Bardgett, R. D.; Hopkins, D. W.; Ostle, N.

    2012-04-01

    Production of biochar, the recalcitrant residue formed by pyrolysis of plant matter, is suggested as a means of increasing storage of stable carbon (C) in the soil (1). Biochar has also been shown to act as a soil conditioner, increasing the productivity of certain crops by reducing nutrient leaching and improving soil water-holding capacity. However, the response of soil carbon pools to biochar addition is not yet well understood. Studies have shown that biochar has highly variable effects on microbial C cycling and thus on soil C storage (2,3,4). This discrepancy may be partially explained by the response of soil invertebrates, which occupy higher trophic levels and regulate microbial activity. This research aims to understand the role of soil invertebrates (i.e. Collembola and nematode worms) in biochar-mediated changes to soil C dynamics across a range of plant-soil communities. An open-air, pot-based mesocosm experiment was established in May, 2011 at the Centre for Ecology and Hydrology, Edinburgh. Three treatments were included in a fully-factorial design: biochar (presence [2 % w/w] or absence), soil type (arable sandy, arable sandy loam, grassland sandy loam), and vegetation type (Hordeum vulgare, Lolium perenne, unvegetated). Monitored parameters include: invertebrate and microbial species composition, soil C fluxes (CO2 and trace gas evolution, leachate C content, primary productivity and soil C content), and soil conditions (pH, moisture content and water-holding capacity). Preliminary results indicate that biochar-induced changes to soil invertebrate communities and processes are affected by pre-existing soil characteristics, and that soil texture in particular may be an important determinant of soil response to biochar addition. 1. Lehmann, 2007. A handful of carbon. Nature 447, 143-144. 2. Liang et al., 2010. Black carbon affects the cycling of non-black carbon in soil. Organic Geochemistry 41, 206-213. 3. Van Zwieten et al., 2010. Influence of

  18. Elevated carbon dioxide and ozone alter productivity and ecosystem carbon content in northern temperate forests.

    PubMed

    Talhelm, Alan F; Pregitzer, Kurt S; Kubiske, Mark E; Zak, Donald R; Campany, Courtney E; Burton, Andrew J; Dickson, Richard E; Hendrey, George R; Isebrands, J G; Lewin, Keith F; Nagy, John; Karnosky, David F

    2014-08-01

    Three young northern temperate forest communities in the north-central United States were exposed to factorial combinations of elevated carbon dioxide (CO2 ) and tropospheric ozone (O3 ) for 11 years. Here, we report results from an extensive sampling of plant biomass and soil conducted at the conclusion of the experiment that enabled us to estimate ecosystem carbon (C) content and cumulative net primary productivity (NPP). Elevated CO2 enhanced ecosystem C content by 11%, whereas elevated O3 decreased ecosystem C content by 9%. There was little variation in treatment effects on C content across communities and no meaningful interactions between CO2 and O3 . Treatment effects on ecosystem C content resulted primarily from changes in the near-surface mineral soil and tree C, particularly differences in woody tissues. Excluding the mineral soil, cumulative NPP was a strong predictor of ecosystem C content (r(2) = 0.96). Elevated CO2 enhanced cumulative NPP by 39%, a consequence of a 28% increase in canopy nitrogen (N) content (g N m(-2) ) and a 28% increase in N productivity (NPP/canopy N). In contrast, elevated O3 lowered NPP by 10% because of a 21% decrease in canopy N, but did not impact N productivity. Consequently, as the marginal impact of canopy N on NPP (∆NPP/∆N) decreased through time with further canopy development, the O3 effect on NPP dissipated. Within the mineral soil, there was less C in the top 0.1 m of soil under elevated O3 and less soil C from 0.1 to 0.2 m in depth under elevated CO2 . Overall, these results suggest that elevated CO2 may create a sustained increase in NPP, whereas the long-term effect of elevated O3 on NPP will be smaller than expected. However, changes in soil C are not well-understood and limit our ability to predict changes in ecosystem C content.

  19. Elevated carbon dioxide and ozone alter productivity and ecosystem carbon content in northern temperate forests.

    PubMed

    Talhelm, Alan F; Pregitzer, Kurt S; Kubiske, Mark E; Zak, Donald R; Campany, Courtney E; Burton, Andrew J; Dickson, Richard E; Hendrey, George R; Isebrands, J G; Lewin, Keith F; Nagy, John; Karnosky, David F

    2014-08-01

    Three young northern temperate forest communities in the north-central United States were exposed to factorial combinations of elevated carbon dioxide (CO2 ) and tropospheric ozone (O3 ) for 11 years. Here, we report results from an extensive sampling of plant biomass and soil conducted at the conclusion of the experiment that enabled us to estimate ecosystem carbon (C) content and cumulative net primary productivity (NPP). Elevated CO2 enhanced ecosystem C content by 11%, whereas elevated O3 decreased ecosystem C content by 9%. There was little variation in treatment effects on C content across communities and no meaningful interactions between CO2 and O3 . Treatment effects on ecosystem C content resulted primarily from changes in the near-surface mineral soil and tree C, particularly differences in woody tissues. Excluding the mineral soil, cumulative NPP was a strong predictor of ecosystem C content (r(2) = 0.96). Elevated CO2 enhanced cumulative NPP by 39%, a consequence of a 28% increase in canopy nitrogen (N) content (g N m(-2) ) and a 28% increase in N productivity (NPP/canopy N). In contrast, elevated O3 lowered NPP by 10% because of a 21% decrease in canopy N, but did not impact N productivity. Consequently, as the marginal impact of canopy N on NPP (∆NPP/∆N) decreased through time with further canopy development, the O3 effect on NPP dissipated. Within the mineral soil, there was less C in the top 0.1 m of soil under elevated O3 and less soil C from 0.1 to 0.2 m in depth under elevated CO2 . Overall, these results suggest that elevated CO2 may create a sustained increase in NPP, whereas the long-term effect of elevated O3 on NPP will be smaller than expected. However, changes in soil C are not well-understood and limit our ability to predict changes in ecosystem C content. PMID:24604779

  20. Colluvial soils as a carbon pool in different soil regions

    NASA Astrophysics Data System (ADS)

    Zádorová, Tereza; Penížek, Vít; Žížala, Daniel

    2014-05-01

    Distribution and storage of soil organic matter are controlled by various environmental factors. In areas influenced by soil erosion, the soil organic carbon (SOC) pattern is characterized by both its removal in some parts and its storage in other parts of the landscape. Colluvial soils formed by accumulation of soil sediments represent such a carbon pool. SOC stock in colluvial soils was determined and related to terrain attributes on three agricultural plots (from 7 to 30 hectares) with different soil and geologic (Cambisol, Luvisol and Chernozem) character. The analysis was also focused on differences in SOC distribution in topsoil and subsoil. The study was based on a detailed network of soil borings and deep cores. SOC content was determined in each 25 cm in entire A horizon up to the depth of 5 m. SOC density determined in each point using SOC concentration, bulk density and A horizon thickness was statistically related to various terrain attributes derived from a detailed digital elevation model. Grid of SOC density was obtained by interpolating point measurements using the terrain attributes as accessory variables; the total SOC stock was then calculated by summing the grid cells. In Chernozem and Luvisol regions, SOC stock is strongly related to the terrain character when topographic wetness index and plan curvature were the most significantly related to the distribution of SOC density. In Cambisol region, low relationship between SOC distribution and terrain attributes was observed. Thickness of A horizon is variable in the three plots: its depth reaches up to 5 meters in Chernozem region while in Luvisol and Cambisol the maximum observed thickness was 1 meter. SOC density averages from the three plots are 7.63 kg.m-2 (Cambisol), 12.06 kg.m-2 (Luvisol) and 32.28 kg.m-2 (Chernozem). SOC stock in the topsoil (0-30 cm) represents 54.5 % in Cambisol region, 43.6 % in Luvisol region and only 19.3 % in Chernozem region from the total SOC stock. This finding

  1. Soil organic carbon across scales.

    PubMed

    O'Rourke, Sharon M; Angers, Denis A; Holden, Nicholas M; McBratney, Alex B

    2015-10-01

    Mechanistic understanding of scale effects is important for interpreting the processes that control the global carbon cycle. Greater attention should be given to scale in soil organic carbon (SOC) science so that we can devise better policy to protect/enhance existing SOC stocks and ensure sustainable use of soils. Global issues such as climate change require consideration of SOC stock changes at the global and biosphere scale, but human interaction occurs at the landscape scale, with consequences at the pedon, aggregate and particle scales. This review evaluates our understanding of SOC across all these scales in the context of the processes involved in SOC cycling at each scale and with emphasis on stabilizing SOC. Current synergy between science and policy is explored at each scale to determine how well each is represented in the management of SOC. An outline of how SOC might be integrated into a framework of soil security is examined. We conclude that SOC processes at the biosphere to biome scales are not well understood. Instead, SOC has come to be viewed as a large-scale pool subjects to carbon flux. Better understanding exists for SOC processes operating at the scales of the pedon, aggregate and particle. At the landscape scale, the influence of large- and small-scale processes has the greatest interaction and is exposed to the greatest modification through agricultural management. Policy implemented at regional or national scale tends to focus at the landscape scale without due consideration of the larger scale factors controlling SOC or the impacts of policy for SOC at the smaller SOC scales. What is required is a framework that can be integrated across a continuum of scales to optimize SOC management.

  2. Soil organic carbon across scales.

    PubMed

    O'Rourke, Sharon M; Angers, Denis A; Holden, Nicholas M; McBratney, Alex B

    2015-10-01

    Mechanistic understanding of scale effects is important for interpreting the processes that control the global carbon cycle. Greater attention should be given to scale in soil organic carbon (SOC) science so that we can devise better policy to protect/enhance existing SOC stocks and ensure sustainable use of soils. Global issues such as climate change require consideration of SOC stock changes at the global and biosphere scale, but human interaction occurs at the landscape scale, with consequences at the pedon, aggregate and particle scales. This review evaluates our understanding of SOC across all these scales in the context of the processes involved in SOC cycling at each scale and with emphasis on stabilizing SOC. Current synergy between science and policy is explored at each scale to determine how well each is represented in the management of SOC. An outline of how SOC might be integrated into a framework of soil security is examined. We conclude that SOC processes at the biosphere to biome scales are not well understood. Instead, SOC has come to be viewed as a large-scale pool subjects to carbon flux. Better understanding exists for SOC processes operating at the scales of the pedon, aggregate and particle. At the landscape scale, the influence of large- and small-scale processes has the greatest interaction and is exposed to the greatest modification through agricultural management. Policy implemented at regional or national scale tends to focus at the landscape scale without due consideration of the larger scale factors controlling SOC or the impacts of policy for SOC at the smaller SOC scales. What is required is a framework that can be integrated across a continuum of scales to optimize SOC management. PMID:25918852

  3. Soil warming, carbon-nitrogen interactions, and forest carbon budgets.

    PubMed

    Melillo, Jerry M; Butler, Sarah; Johnson, Jennifer; Mohan, Jacqueline; Steudler, Paul; Lux, Heidi; Burrows, Elizabeth; Bowles, Francis; Smith, Rose; Scott, Lindsay; Vario, Chelsea; Hill, Troy; Burton, Andrew; Zhou, Yu-Mei; Tang, Jim

    2011-06-01

    Soil warming has the potential to alter both soil and plant processes that affect carbon storage in forest ecosystems. We have quantified these effects in a large, long-term (7-y) soil-warming study in a deciduous forest in New England. Soil warming has resulted in carbon losses from the soil and stimulated carbon gains in the woody tissue of trees. The warming-enhanced decay of soil organic matter also released enough additional inorganic nitrogen into the soil solution to support the observed increases in plant carbon storage. Although soil warming has resulted in a cumulative net loss of carbon from a New England forest relative to a control area over the 7-y study, the annual net losses generally decreased over time as plant carbon storage increased. In the seventh year, warming-induced soil carbon losses were almost totally compensated for by plant carbon gains in response to warming. We attribute the plant gains primarily to warming-induced increases in nitrogen availability. This study underscores the importance of incorporating carbon-nitrogen interactions in atmosphere-ocean-land earth system models to accurately simulate land feedbacks to the climate system.

  4. [Effects of land use change on soil labile organic carbon in Central Jiangxi of China].

    PubMed

    Du, Man-Yi; Fan, Shao-Hui; Liu, Guang-Lu; Qi, Liang-Hua; Guo, Bao-Hu; Tang, Xiao-Lu; Xiao, Fu-Ming

    2013-10-01

    Selecting the 15-year abandoned land (AL) and three forest lands [Phyllostachys edulis plantation (PE), Schima superba secondary forest (SS), and Cunninghamia Lanceolata plantation (CL)] in Anfu County of Jiangxi Province as test objects, this paper studied the effects of land use change on the soil organic carbon (SOC) pool and soil labile organic carbon (SLOC) contents. The soil organic carbon (SOC), microbial biomass carbon (MBC), hot- water extractable carbon (HWC), and readily oxidizable carbon (ROC) contents in the test lands were all in the order of PE>CL>SS>AL. As compared with those in AL, the SOC content, soil carbon stock, and soil labile organic carbon (SLOC) contents in the three forest lands all decreased with increasing soil depth, and had an obvious accumulation in surface soil. The proportions of different kinds of SLOC to soil total organic carbon differed markedly, among which, ROC had the highest proportion, while MBC had the smallest one. There existed significant relationships between SOC, MBC, HWC, and ROC. The MBC, HWC, and ROC contained higher content of active carbon, and were more sensitive to the land use change, being able to be used as the indicators for evaluating the soil quality and fertility in central Jiangxi Province. PMID:24483085

  5. [Effects of land use change on soil labile organic carbon in Central Jiangxi of China].

    PubMed

    Du, Man-Yi; Fan, Shao-Hui; Liu, Guang-Lu; Qi, Liang-Hua; Guo, Bao-Hu; Tang, Xiao-Lu; Xiao, Fu-Ming

    2013-10-01

    Selecting the 15-year abandoned land (AL) and three forest lands [Phyllostachys edulis plantation (PE), Schima superba secondary forest (SS), and Cunninghamia Lanceolata plantation (CL)] in Anfu County of Jiangxi Province as test objects, this paper studied the effects of land use change on the soil organic carbon (SOC) pool and soil labile organic carbon (SLOC) contents. The soil organic carbon (SOC), microbial biomass carbon (MBC), hot- water extractable carbon (HWC), and readily oxidizable carbon (ROC) contents in the test lands were all in the order of PE>CL>SS>AL. As compared with those in AL, the SOC content, soil carbon stock, and soil labile organic carbon (SLOC) contents in the three forest lands all decreased with increasing soil depth, and had an obvious accumulation in surface soil. The proportions of different kinds of SLOC to soil total organic carbon differed markedly, among which, ROC had the highest proportion, while MBC had the smallest one. There existed significant relationships between SOC, MBC, HWC, and ROC. The MBC, HWC, and ROC contained higher content of active carbon, and were more sensitive to the land use change, being able to be used as the indicators for evaluating the soil quality and fertility in central Jiangxi Province.

  6. [Humus composition and stable carbon isotope natural abundance in paddy soil under long-term fertilization].

    PubMed

    Ma, Li; Yang, Lin-Zhang; Ci, En; Wang, Yan; Yin, Shi-Xue; Shen, Ming-Xing

    2008-09-01

    Soil samples were collected from an experimental paddy field with long-term (26 years) fertilization in Taihu Lake region of Jiangsu Province to study the effects of different fertilization on the organic carbon distribution and stable carbon isotope natural abundance (delta 13C) in the soil profile, and on the humus composition. The results showed that long-term fertilization increased the organic carbon content in top soil significantly, and there was a significantly negative exponential correlation between soil organic carbon content and soil depth (P < 0.01). The organic carbon content in 10-30 cm soil layer under chemical fertilizations and in 20-40 cm soil layer under organic fertilizations was relatively stable. Soil delta 13C increased gradually with soil depth, its variation range being from -24% per thousand to -28 per thousand, and had a significantly negative linear correlation with soil organic carbon content (P < 0.05). In 0-20 cm soil layer, the delta 13C in treatments organic manure (M), M + NP, M + NPK, M + straw (R) + N, and R + N decreased significantly; while in 30-50 cm soil layer, the delta 13C in all organic fertilization treatments except R + N increased significantly. Tightly combined humus (humin) was the main humus composition in the soil, occupying 50% or more, and the rest were loosely and stably combined humus. Long-term fertilization increased the content of loosely combined humus and the ratio of humic acid (HA) to fulvic acid (FA).

  7. Prediction of soil organic carbon concentration and soil bulk density of mineral soils for soil organic carbon stock estimation

    NASA Astrophysics Data System (ADS)

    Putku, Elsa; Astover, Alar; Ritz, Christian

    2016-04-01

    Soil monitoring networks provide a powerful base for estimating and predicting nation's soil status in many aspects. The datasets of soil monitoring are often hierarchically structured demanding sophisticated data analyzing methods. The National Soil Monitoring of Estonia was based on a hierarchical data sampling scheme as each of the monitoring site was divided into four transects with 10 sampling points on each transect. We hypothesized that the hierarchical structure in Estonian Soil Monitoring network data requires a multi-level mixed model approach to achieve good prediction accuracy of soil properties. We used this database to predict soil bulk density and soil organic carbon concentration of mineral soils in arable land using different statistical methods: median approach, linear regression and mixed model; additionally, random forests for SOC concentration. We compared the prediction results and selected the model with the best prediction accuracy to estimate soil organic carbon stock. The mixed model approach achieved the best prediction accuracy in both soil organic carbon (RMSE 0.22%) and bulk density (RMSE 0.09 g cm-3) prediction. Other considered methods under- or overestimated higher and lower values of soil parameters. Thus, using these predictions we calculated the soil organic carbon stock of mineral arable soils and applied the model to a specific case of Tartu County in Estonia. Average estimated SOC stock of Tartu County is 54.8 t C ha-1 and total topsoil SOC stock 1.8 Tg in humus horizon.

  8. Soil erosion and the global carbon budget.

    PubMed

    Lal, R

    2003-07-01

    Soil erosion is the most widespread form of soil degradation. Land area globally affected by erosion is 1094 million ha (Mha) by water erosion, of which 751 Mha is severely affected, and 549 Mha by wind erosion, of which 296 Mha is severely affected. Whereas the effects of erosion on productivity and non-point source pollution are widely recognized, those on the C dynamics and attendant emission of greenhouse gases (GHGs) are not. Despite its global significance, erosion-induced carbon (C) emission into the atmosphere remains misunderstood and an unquantified component of the global carbon budget. Soil erosion is a four-stage process involving detachment, breakdown, transport/redistribution and deposition of sediments. The soil organic carbon (SOC) pool is influenced during all four stages. Being a selective process, erosion preferentially removes the light organic fraction of a low density of <1.8 Mg/m(3). A combination of mineralization and C export by erosion causes a severe depletion of the SOC pool on eroded compared with uneroded or slightly eroded soils. In addition, the SOC redistributed over the landscape or deposited in depressional sites may be prone to mineralization because of breakdown of aggregates leading to exposure of hitherto encapsulated C to microbial processes among other reasons. Depending on the delivery ratio or the fraction of the sediment delivered to the river system, gross erosion by water may be 75 billion Mg, of which 15-20 billion Mg are transported by the rivers into the aquatic ecosystems and eventually into the ocean. The amount of total C displaced by erosion on the earth, assuming a delivery ratio of 10% and SOC content of 2-3%, may be 4.0-6.0 Pg/year. With 20% emission due to mineralization of the displaced C, erosion-induced emission may be 0.8-1.2 Pg C/year on the earth. Thus, soil erosion has a strong impact on the global C cycle and this component must be considered while assessing the global C budget. Adoption of

  9. Soil Phosphorus Stoichiometry Drives Carbon Turnover Along a Soil C Gradient Spanning Mineral and Organic Soils Under Rice Cultivation

    NASA Astrophysics Data System (ADS)

    Hartman, W.; Ye, R.; Horwath, W. R.; Tringe, S. G.

    2014-12-01

    Soil carbon (C) cycling is linked to the availability of nutrients like nitrogen (N) and phosphorus (P). However, the role of soil P in influencing soil C turnover and accumulation is poorly understood, with most models focusing on C:N ratios based on the assumption that terrestrial ecosystems are N limited. To determine the effects of N and P availability on soil C turnover, we compared soil respiration over the course of a growing season in four adjacent rice fields with 5%, 10%, 20% and 25% soil C. In each of these fields, plots were established to test the effect of N additions on plant growth, using control and N addition treatments (80 kg N/ha urea). Although soil P was not manipulated in parallel, prior work has shown soil P concentrations decline markedly with increasing soil C content. Soil CO2 flux was monitored using static chambers at biweekly intervals during the growing season, along with porewater dissolved organic C and ammonium. Soils were collected at the end of the growing season, and tested for total C, N, and P, extractable N and P, pH, base cations and trace metals. Soil DNA was also extracted for 16S rRNA sequencing to profile microbial communities. Soil N additions significantly increased CO2 flux and soil C turnover (seasonal CO2 flux per unit soil C) in 5% and 10% C fields, but not in 20% or 25% C fields. Soil C content was closely related to soil N:P stoichiometry, with N:P ratios of ca. 12, 16, 24, and 56 respectively in the 5, 10, 20 and 25% C fields. Seasonal CO2 fluxes (per m2) were highest in 10% C soils. However, soil C turnover was inversely related to soil C concentrations, with the greatest C turnover at the lowest values of soil C. Soil C turnover showed stronger relationships with soil chemical parameters than seasonal CO2 fluxes alone, and the best predictors of soil C turnover were soil total and extractable N:P ratios, along with extractable P alone. Our results show that soil P availability and stoichiometry influence the

  10. Deep Soil: Quantifying and Modeling Subsurface Carbon

    NASA Astrophysics Data System (ADS)

    James, J. N.; Devine, W.; Harrison, R. B.

    2014-12-01

    Some soil carbon datasets that are spatially rich, such as the USDA Forest Service Inventory and Analysis National Program dataset, sample soil to only 20 cm (8 inches), despite evidence that substantial stores of soil C can be found deeper in the soil profile. The maximum extent of tree rooting is typically many meters deep and provides: direct exchange with the soil solution; redistribution of water from deep horizons toward the surface during times of drought; resources for active microbial communities in deep soil around root channels; and direct carbon inputs through exudates and root turnover. This study examined soil carbon to a depth of 2.5 meters across 22 soils in Pacific Northwest Douglas-fir forests. Excavations at 20 additional sites took place in summer 2014, greatly expanding the spatial coverage and extent of the data set. Forest floor and mineral soil bulk density samples were collected at depths of 0.1, 0.5, 1.0, 1.5, 2.0 and 2.5 meters. Pool estimates from systematic sampling depths shallower than 1.5 m yielded significantly smaller estimates than the total soil stock to 2.5 meters (P<0.01). On average, only 5% of soil C was found in the litter layer, 35% was found below 0.5 meter, and 21% was found below 1.0 meter. Due to the difficulty of excavating and measuring deep soil carbon, a series of nonlinear mixed effect models were fit to the data to predict deep soil carbon stocks given sampling to 1.0 meter. A model using an inverse polynomial function predicted soil carbon to 2.5 meters with -5.6% mean error. The largest errors occurred in Andisols with non-crystalline minerals, which can adsorb large quantities of carbon on mineral surfaces and preserve it from decomposition. An accurate spatial dataset of soil depth to bedrock would be extremely useful to constrain models of the vertical distribution of soil carbon. Efforts to represent carbon in spatial models would benefit from considering the vertical distribution of carbon in soil. Sampling

  11. [Distribution of soil organic carbon storage and carbon density in Gahai Wetland ecosystem].

    PubMed

    Ma, Wei-Wei; Wang, Hui; Huang, Rong; Li, Jun-Zhen; Li, De-Yu

    2014-03-01

    The profile distribution and accumulation characteristics of organic carbon of four typical marshes (herbaceous peat, marsh wetland, mountain wetland, subalpine meadow) were studied in Gahai Wetlands of Gannan in July 2011. The results showed that the soil bulk densities of the four typical marshes ranged from 0.22 to 1.29 g x cm(-3). The content of soil organic carbon in the herbaceous peat was higher than in other types, with its average content of organic carbon (286. 80 g x kg(-1)) being about 2.91, 4.99, 7.31 times as much as that of the marsh wetland, mountain wetland and subalpine meadow, respectively. The average organic carbon densities were in order of herbaceous peat > subalpine meadow > marsh wetland > mountain wetland, with the highest in the 0-10 cm layer. The change of organic carbon density along the soil profile was basically in accordance with the organic carbon content in the four typical marshes, but fluctuated with soil depth. There were obviously two carbon storage layers (0-10 and 20-40 cm, respectively) in the four typical marshes. The amounts of organic carbon stored in the 0-60 cm layer of the four typical marshes were 369.46, 278.83, 276.16, 292.23 t x hm(-2), respectively. The total amount of organic carbon stored in the 0-60 cm of the four typical marshes was about 9.50 x 10(6) t.

  12. Carbon fiber content measurement in composite

    NASA Astrophysics Data System (ADS)

    Wang, Qiushi

    Carbon fiber reinforced polymers (CFRPs) have been widely used in various structural applications in industries such as aerospace and automotive because of their high specific stiffness and specific strength. Their mechanical properties are strongly influenced by the carbon fiber content in the composites. Measurement of the carbon fiber content in CFRPs is essential for product quality control and process optimization. In this work, a novel carbonization-in-nitrogen method (CIN) is developed to characterize the fiber content in carbon fiber reinforced thermoset and thermoplastic composites. In this method, a carbon fiber composite sample is carbonized in a nitrogen environment at elevated temperatures, alongside a neat resin sample. The carbon fibers are protected from oxidization while the resin (the neat resin and the resin matrix in the composite sample) is carbonized under the nitrogen environment. The residue of the carbonized neat resin sample is used to calibrate the resin carbonization rate and calculate the amount of the resin matrix in the composite sample. The new method has been validated on several thermoset and thermoplastic resin systems and found to yield an accurate measurement of fiber content in carbon fiber polymer composites. In order to further understand the thermal degradation behavior of the high temperature thermoplastic polymer during the carbonization process, the mechanism and the kinetic model of thermal degradation behavior of carbon fiber reinforced poly (phenylene sulfide) (CPPS) are studied using thermogravimetry analysis (TGA). The CPPS is subjected to TGA in an air and nitrogen atmosphere at heating rates from 5 to 40°C min--1. The TGA curves obtained in air are different from those in nitrogen. This demonstrates that weight loss occurs in a single stage in nitrogen but in two stages in air. To elucidate this difference, thermal decomposition kinetics is analyzed by applying the Kissinger, Flynn-Wall-Ozawa, Coat-Redfern and

  13. Effects of organic carbon sequestration strategies on soil enzymatic activities

    NASA Astrophysics Data System (ADS)

    Puglisi, E.; Suciu, N.; Botteri, L.; Ferrari, T.; Coppolecchia, D.; Trevisan, M.; Piccolo, A.

    2009-04-01

    Greenhouse gases emissions can be counterbalanced with proper agronomical strategies aimed at sequestering carbon in soils. These strategies must be tested not only for their ability in reducing carbon dioxide emissions, but also for their impact on soil quality: enzymatic activities are related to main soil ecological quality, and can be used as early and sensitive indicators of alteration events. Three different strategies for soil carbon sequestration were studied: minimum tillage, protection of biodegradable organic fraction by compost amendment and oxidative polimerization of soil organic matter catalyzed by biometic porfirins. All strategies were compared with a traditional agricultural management based on tillage and mineral fertilization. Experiments were carried out in three Italian soils from different pedo-climatic regions located respectively in Piacenza, Turin and Naples and cultivated with maize or wheat. Soil samples were taken for three consecutive years after harvest and analyzed for their content in phosphates, ß-glucosidase, urease and invertase. An alteration index based on these enzymatic activities levels was applied as well. The biomimetic porfirin application didn't cause changes in enzymatic activities compared to the control at any treatment or location. Enzymatic activities were generally higher in the minimum tillage and compost treatment, while differences between location and date of samplings were limited. Application of the soil alteration index based on enzymatic activities showed that soils treated with compost or subjected to minimum tillage generally have a higher biological quality. The work confirms the environmental sustainability of the carbon sequestering agronomical practices studied.

  14. [Soil aggregate stability and soil organic carbon characteristics in Quercus variabilis and Pinus tabulaeformis plantations in Beijing area].

    PubMed

    Liu, Yan; Zha, Tong-Gang; Wang, Yi-Kun; Wang, Gao-min

    2013-03-01

    Based on the field survey and laboratory analysis, this paper studied the soil aggregate stability and soil organic carbon characteristics in Quercus variabilis and Pinus tabulaeformis plantations in Beijing area. In the two plantations, the contents of soil macro-aggregates decreased with soil depth. In P. tabulaeformis plantation, soil macro-aggregates (>0.25 mm) occupied the majority, accounting for 71% -77% of the total; whereas in Q. variabilis plantation, no significant difference was observed in the contents of soil macro-aggregates and micro-aggregates (< or =0.25 mm), which accounted for 51% -58% and 42% -49%, respectively. Both the mean mass diameter and the geometrical mean mass diameter of the soil aggregates in P. tabulaeformis plantation were significantly higher than those in Q. variabilis plantation, and the fractal dimension (D) of the soil water-stable aggregates in P. tabulaeformis plantation was lower than that in Q. variabilis plantation, suggesting that P. tabulaeformis plantation was more favorable for the soil aggregate stability than Q. variabilis plantation. Also in the two plantations, the organic carbon content in soil water-stable aggregates decreased with soil depth. The organic carbon content in soil macro-aggregates was significantly higher in P. tabulaeformis plantation (58% -83%) than in Q. variabilis plantation (49% -66% ). It was suggested that in Beijing area, P. tabulaeformis plantation was more beneficial to the soil organic carbon protection, as compared with Q. variabilis plantation.

  15. Mechanisms of Soil Carbon Sequestration

    NASA Astrophysics Data System (ADS)

    Lal, Rattan

    2015-04-01

    Carbon (C) sequestration in soil is one of the several strategies of reducing the net emission of CO2 into the atmosphere. Of the two components, soil organic C (SOC) and soil inorganic C (SIC), SOC is an important control of edaphic properties and processes. In addition to off-setting part of the anthropogenic emissions, enhancing SOC concentration to above the threshold level (~1.5-2.0%) in the root zone has numerous ancillary benefits including food and nutritional security, biodiversity, water quality, among others. Because of its critical importance in human wellbeing and nature conservancy, scientific processes must be sufficiently understood with regards to: i) the potential attainable, and actual sink capacity of SOC and SIC, ii) permanence of the C sequestered its turnover and mean residence time, iii) the amount of biomass C needed (Mg/ha/yr) to maintain and enhance SOC pool, and to create a positive C budget, iv) factors governing the depth distribution of SOC, v) physical, chemical and biological mechanisms affecting the rate of decomposition by biotic and abiotic processes, vi) role of soil aggregation in sequestration and protection of SOC and SIC pool, vii) the importance of root system and its exudates in transfer of biomass-C into the SOC pools, viii) significance of biogenic processes in formation of secondary carbonates, ix) the role of dissolved organic C (DOC) in sequestration of SOC and SIC, and x) importance of weathering of alumino-silicates (e.g., powered olivine) in SIC sequestration. Lack of understanding of these and other basic processes leads to misunderstanding, inconsistencies in interpretation of empirical data, and futile debates. Identification of site-specific management practices is also facilitated by understanding of the basic processes of sequestration of SOC and SIC. Sustainable intensification of agroecosystems -- producing more from less by enhancing the use efficiency and reducing losses of inputs, necessitates thorough

  16. A method to detect soil carbon degradation during soil erosion

    NASA Astrophysics Data System (ADS)

    Alewell, Christine; Conen, Franz; Schaub, Monika

    2010-05-01

    Soil erosion has been discussed intensively but controversial both as a significant source or a significant sink of atmospheric carbon possibly explaining the gap in the global carbon budget. One of the major points of discussion has been whether or not carbon is degraded and mineralized to CO2 during detachment, transport and deposition of soil material. By combining the caesium-137 (137Cs) approach (quantification of erosion rates) with stable carbon isotope signatures (process indicator of mixing versus degradation of carbon pools) we were able to show that degradation of carbon occurs during soil erosion processes at the investigated mountain grasslands in the central Swiss Alps (Urseren Valley, Canton Uri). Transects from upland (erosion source) to wetland soils (erosion sinks) of sites affected by sheet and land slide erosion were sampled. Analysis of 137Cs yielded an input of 2 and 4.6 tha-1 yr-1 of soil material into the wetlands sites. Assuming no degradation of soil organic carbon during detachment and transport, carbon isotope signature of soil organic carbon in the wetlands could only be explained with an assumed 500-600 and 350-400 years of erosion input into the wetlands Laui and Spissen, respectively. The latter is highly unlikely with alpine peat growth rates indicating that the upper horizons might have an age between 7 and 200 years. While we do not conclude from our data that eroded soil organic carbon is generally degraded during detachment and transport, we propose this method to gain more information on process dynamics during soil erosion from oxic upland to anoxic wetland soils, sediments or water bodies.

  17. A method to detect soil carbon degradation during soil erosion

    NASA Astrophysics Data System (ADS)

    Alewell, C.; Schaub, M.; Conen, F.

    2009-06-01

    Soil erosion has been discussed intensively but controversial both as a significant source or a significant sink of atmospheric carbon possibly explaining the gap in the global carbon budget. One of the major points of discussion has been whether or not carbon is degraded and mineralized to CO2 during detachment, transport and deposition of soil material. By combining the caesium-137 (137Cs) approach (quantification of erosion rates) with stable carbon isotope signatures (process indicator of mixing versus degradation of carbon pools) we were able to show that degradation of carbon occurs during soil erosion processes at the investigated mountain grasslands in the central Swiss Alps (Urseren Valley, Canton Uri). Transects from upland (erosion source) to wetland soils (erosion sinks) of sites affected by sheet and land slide erosion were sampled. Analysis of 137Cs yielded an input of 2 and 2.6 t ha-1 yr-1 of soil material into the wetlands sites. Assuming no degradation of soil organic carbon during detachment and transport, carbon isotope signature of soil organic carbon in the wetlands could only be explained with an assumed 800 and 400 years of erosion input into the wetlands. The latter is highly unlikely with alpine peat growth rates indicating that the upper horizons might have an age between 7 and 200 years. While we do not conclude from our data that eroded soil organic carbon is generally degraded during detachment and transport, we propose this method to gain more information on process dynamics during soil erosion from oxic upland to anoxic wetland soils, sediments or water bodies.

  18. A method to detect soil carbon degradation during soil erosion

    NASA Astrophysics Data System (ADS)

    Alewell, C.; Schaub, M.; Conen, F.

    2009-11-01

    Soil erosion has been discussed intensively but controversial both as a significant source or a significant sink of atmospheric carbon possibly explaining the gap in the global carbon budget. One of the major points of discussion has been whether or not carbon is degraded and mineralized to CO2 during detachment, transport and deposition of soil material. By combining the caesium-137 (137Cs) approach (quantification of erosion rates) with stable carbon isotope signatures (process indicator of mixing versus degradation of carbon pools) we were able to show that degradation of carbon occurs during soil erosion processes at the investigated mountain grasslands in the central Swiss Alps (Urseren Valley, Canton Uri). Transects from upland (erosion source) to wetland soils (erosion sinks) of sites affected by sheet and land slide erosion were sampled. Analysis of 137Cs yielded an input of 2 and 4.6 tha-1 yr-1 of soil material into the wetlands sites. Assuming no degradation of soil organic carbon during detachment and transport, carbon isotope signature of soil organic carbon in the wetlands could only be explained with an assumed 500-600 and 350-400 years of erosion input into the wetlands Laui and Spissen, respectively. The latter is highly unlikely with alpine peat growth rates indicating that the upper horizons might have an age between 7 and 200 years. While we do not conclude from our data that eroded soil organic carbon is generally degraded during detachment and transport, we propose this method to gain more information on process dynamics during soil erosion from oxic upland to anoxic wetland soils, sediments or water bodies.

  19. [Dynamics of unprotected soil organic carbon with the restoration process of Pinus massoniana plantation in red soil erosion area].

    PubMed

    Lü, Mao-Kui; Xie, Jin-Sheng; Zhou, Yan-Xiang; Zeng, Hong-Da; Jiang, Jun; Chen, Xi-Xiang; Xu, Chao; Chen, Tan; Fu, Lin-Chi

    2014-01-01

    By the method of spatiotemporal substitution and taking the bare land and secondary forest as the control, we measured light fraction and particulate organic carbon in the topsoil under the Pinus massoniana woodlands of different ages with similar management histories in a red soil erosion area, to determine their dynamics and evaluate the conversion processes from unprotected to protected organic carbon. The results showed that the content and storage of soil organic carbon increased significantly along with ages in the process of vegetation restoration (P < 0.01). The unprotected soil organic carbon content and distribution proportion to the total soil organic carbon increased significantly (P < 0.05) after 7-11 years' restoration but stabilized after 27 and 30 years of restoration. It suggested that soil organic carbon mostly accumulated in the form of unprotected soil organic carbon during the initial restoration period, and reached a stable level after long-term vegetation restoration. Positive correlations were found between restoration years and the rate constant for C transferring from the unprotected to the protected soil pool (k) in 0-10 cm and 10-20 cm soil layers, which demonstrated that the unprotected soil organic carbon gradually transferred to the protected soil organic carbon in the process of vegetation restoration. PMID:24765840

  20. [Dynamics of unprotected soil organic carbon with the restoration process of Pinus massoniana plantation in red soil erosion area].

    PubMed

    Lü, Mao-Kui; Xie, Jin-Sheng; Zhou, Yan-Xiang; Zeng, Hong-Da; Jiang, Jun; Chen, Xi-Xiang; Xu, Chao; Chen, Tan; Fu, Lin-Chi

    2014-01-01

    By the method of spatiotemporal substitution and taking the bare land and secondary forest as the control, we measured light fraction and particulate organic carbon in the topsoil under the Pinus massoniana woodlands of different ages with similar management histories in a red soil erosion area, to determine their dynamics and evaluate the conversion processes from unprotected to protected organic carbon. The results showed that the content and storage of soil organic carbon increased significantly along with ages in the process of vegetation restoration (P < 0.01). The unprotected soil organic carbon content and distribution proportion to the total soil organic carbon increased significantly (P < 0.05) after 7-11 years' restoration but stabilized after 27 and 30 years of restoration. It suggested that soil organic carbon mostly accumulated in the form of unprotected soil organic carbon during the initial restoration period, and reached a stable level after long-term vegetation restoration. Positive correlations were found between restoration years and the rate constant for C transferring from the unprotected to the protected soil pool (k) in 0-10 cm and 10-20 cm soil layers, which demonstrated that the unprotected soil organic carbon gradually transferred to the protected soil organic carbon in the process of vegetation restoration.

  1. Active microwave measurement of soil water content

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Cihlar, J.; Moore, R. K.

    1974-01-01

    Measurements of radar backscatter from bare soil at 4.7, 5.9, and 7.1 GHz for incident angles of 0-70 deg have been analyzed to determine sensitivity to soil moisture. Because the effective depth of penetration of the radar signal is only about one skin depth, the observed signals were correlated with the moisture in a skin depth as characterized by the attenuation coefficient (reciprocal of skin depth). Since the attenuation coefficient is a monotonically increasing function of moisture density, it may also be used as a measure of moisture content over the distance involved, which varies with frequency and moisture content. The measurements show an approximately linear increase in scattering with attenuation coefficient of the soil at angles within 10 deg of vertical and all frequencies. At 4.7 GHz this increase continues relatively large out to 70 deg incidence, but by 7.1 GHz the sensitivity is much less even at 20 deg and practically gone at 50 deg.

  2. Carbosoil, a land evaluation model for soil carbon accounting

    NASA Astrophysics Data System (ADS)

    Anaya-Romero, M.; Muñoz-Rojas, M.; Pino, R.; Jordan, A.; Zavala, L. M.; De la Rosa, D.

    2012-04-01

    The belowground carbon content is particularly difficult to quantify and most of the time is assumed to be a fixed fraction or ignored for lack of better information. In this respect, this research presents a land evaluation tool, Carbosoil, for predicting soil carbon accounting where this data are scarce or not available, as a new component of MicroLEIS DSS. The pilot study area was a Mediterranean region (Andalusia, Southern Spain) during 1956-2007. Input data were obtained from different data sources and include 1689 soil profiles from Andalusia (S Spain). Previously, detailed studies of changes in LU and vegetation carbon stocks, and soil organic carbon (SOC) dynamic were carried out. Previous results showed the influence of LU, climate (mean temperature and rainfall) and soil variables related with SOC dynamics. For instance, SCS decreased in Cambisols and Regosols by 80% when LU changed from forest to heterogeneous agricultural areas. Taking this into account, the input variables considered were LU, site (elevation, slope, erosion, type-of-drainage, and soil-depth), climate (mean winter/summer temperature and annual precipitation), and soil (pH, nitrates, CEC, sand/clay content, bulk density and field capacity). The available data set was randomly split into two parts: training-set (75%), and validation-set (25%). The model was built by using multiple linear regression. The regression coefficient (R2) obtained in the calibration and validation of Carbosoil was >0.9 for the considered soil sections (0-25, 25-50, and 50-75 cm). The validation showed the high accuracy of the model and its capacity to discriminate carbon distribution regarding different climate, LU and soil management scenarios. Carbosoil model together with the methodologies and information generated in this work will be a useful basis to accurately quantify and understanding the distribution of soil carbon account helpful for decision makers.

  3. Soil and soil organic carbon redistribution on the landscape

    NASA Astrophysics Data System (ADS)

    Ritchie, Jerry C.; McCarty, Gregory W.; Venteris, Erik R.; Kaspar, T. C.

    2007-09-01

    Patterns of soil organic carbon (SOC) vary widely across the landscape leading to large uncertainties in the SOC budget especially for agricultural landscapes where water, tillage and wind erosion redistributes soil and SOC across the landscape. It is often assumed that soil erosion results in a loss of SOC from the agricultural ecosystem but recent studies indicate that soil erosion and its subsequent redistribution within fields can stimulate carbon sequestration in agricultural ecosystems. This study investigates the relationship between SOC and soil redistribution patterns on agricultural landscapes. Soil redistribution (erosion and deposition) patterns were estimated in three tilled agricultural fields using the fallout 137Cesium technique. 137Cs and SOC concentrations of upland soils are significantly correlated in our study areas. Upland areas (eroding) have significantly less SOC than soils in deposition areas. SOC decreased as gradient slope increases and soils on concave slopes had higher SOC than soils on convex slopes. These data suggest that soil redistribution patterns and topographic patterns may be used to help understand SOC dynamics on the landscape. Different productivity and oxidation rates of SOC of eroded versus deposited soils also contribute to SOC spatial patterns. However, the strong significant relationships between soil redistribution and SOC concentrations in the upland soil suggest that they are moving along similar physical pathways in these systems. Our study also indicates that geomorphic position is important for understanding soil movement and redistribution patterns within a field or watershed. Such information can help develop or implement management systems to increase SOC in agricultural ecosystems.

  4. Uncertainties and novel prospects in the study of the soil carbon dynamics.

    PubMed

    Wang, Yang; Hsieh, Yuch-Ping

    2002-12-01

    Establishment of the Kyoto Protocol has resulted in an effort to look towards living biomass and soils for carbon sequestration. In order for carbon credits to be meaningful, sustained carbon sequestration for decades or longer is required. It has been speculated that improved land management could result in sequestration of a substantial amount of carbon in soils within several decades and therefore can be an important option in reducing atmospheric CO2 concentration. However, evaluation of soil carbon sources and sinks is difficult because the dynamics of soil carbon storage and release is complex and still not well understood. There has been rapid development of quantitative techniques over the past two decades for measuring the component fluxes of the global carbon cycle and for studying the soil carbon cycle. Most significant development in the soil carbon cycle study is the application of accelerator mass spectrometry (AMS) in radiocarbon measurements. This has made it possible to unravel rates of carbon cycling in soils, by studying natural levels of radiocarbon in soil organic matter and soil CO2. Despite the advances in the study of the soil carbon cycle in the recent decades, tremendous uncertainties exist in the sizes and turnover times of soil carbon pools. The uncertainties result from lack of standard methods and incomplete understanding of soil organic carbon dynamics, compounded by natural variability in soil carbon and carbon isotopic content even within the same ecosystem. Many fundamental questions concerning the dynamics of the soil carbon cycle have yet to be answered. This paper reviews and synthesizes the isotopic approaches to the study of the soil carbon cycle. We will focus on uncertainties and limitations associated with these approaches and point out areas where more research is needed to improve our understanding of this important component of the global carbon cycle.

  5. Spatial patterns of soil organic carbon stocks in Estonian arable soils

    NASA Astrophysics Data System (ADS)

    Suuster, Elsa; Astover, Alar; Kõlli, Raimo; Roostalu, Hugo; Reintam, Endla; Penu, Priit

    2010-05-01

    Soil organic carbon (SOC) determines ecosystem functions, influencing soil fertility, soil physical, chemical and biological properties and crop productivity. Therefore the spatial pattern of SOC stocks and its appropriate management is important at various scales. Due to climate change and the contribution of carbon store in the soils, the national estimates of soil carbon stocks should be determined. Estonian soils have been well studied and mapped at a scale 1:10,000. Previous studies have estimated SOC stocks based on combinations of large groups of Estonian soils and the mean values of the soil profile database, but were not embedded into the geo-referenced databases. These studies have estimated SOC stocks of Estonian arable soils 122.3 Tg. Despite of available soil maps and databases, this information is still very poorly used for spatial soil modelling. The aim of current study is to assess and model spatial pattern of SOC stocks of arable soils on a pilot area Tartu County (area 3089 sq km). Estonian digital soil map and soil monitoring databases are providing a good opportunity to assess SOC stocks at various scales. The qualitative nature of the initial data from a soil map prohibits any straightforward use in modelling. Thus we have used several databases to construct models and linkages between soil properties that can be integrated into soil map. First step was to reorganize the soil map database (44,046 mapping units) so it can be used as an input to modelling. Arable areas were distinguished by a field layer of Agricultural Registers and Information Board, which provides precise information of current land use as it is the basis of paying CAP subsidies. The estimates of SOC content were found by using the arable land evaluation database of Tartu from the Estonian Land Board (comprising 950 sq km and 31,226 fields), where each soil type was assessed separately and average SOC content grouped by texture was derived. SOC content of epipedon varies in

  6. Organic carbon in soil and the global carbon cycle

    SciTech Connect

    Post, W.M. III

    1991-12-31

    Soil organic matter is, simultaneously, the most inert carbon cycle component of terrestrial ecosystems, and the most dynamic component of terrestrail geologic systems placing it in a pivotal position in the biogeochemistry of carbon. The large size and potentially long residence time of the soil organic matter pool make it an important component of the global carbon cycle. Net terrestrial primary production of about 60 Pg C{center_dot}yr{sup {minus}1} is, over a several-year period of time, balanced by an equivalent flux of litter production and subsequent decomposition of detritus and soil organic matter. However, the input rates and decomposition rates for different terrestrial ecosystems vary over several orders of magnitude resulting in widely different amounts and turnover rates of soil organic matter. The amounts of carbon stored in soils and the rates of exchange of soil carbon with the atmosphere depend on many factors related to the chemistry, biology, and physics of soil and soil organic matter. This report discusses work on organic carbon in soil and aspects of the carbon cycle.

  7. BOREAS TGB-12 Soil Carbon Data over the NSA

    NASA Technical Reports Server (NTRS)

    Trumbore, Susan; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor); Harden, Jennifer; Sundquist, Eric; Winston, Greg

    2000-01-01

    The BOREAS TGB-12 team made measurements of soil carbon inventories, carbon concentration in soil gases, and rates of soil respiration at several sites to estimate the rates of carbon accumulation and turnover in each of the major vegetation types. TGB-12 data sets include soil properties at tower and selected auxiliary sites in the BOREAS NSA and data on the seasonal variations in the radiocarbon content of CO2 in the soil atmosphere at NSA tower sites. The sampling strategies for soils were designed to take advantage of local fire chronosequences, so that the accumulation of C in areas of moss regrowth could be determined. These data are used to calculate the inventory of C and N in moss and mineral soil layers at NSA sites and to determine the rates of input and turnover (using both accumulation since the last stand-killing fire and radiocarbon data). This data set includes physical parameters needed to determine carbon and nitrogen inventory in soils. The data were collected discontinuously from August 1993 to July 1996. The data are stored in tabular ASCII files.

  8. The influence of soil crusting on carbon dioxide emissions from soil

    NASA Astrophysics Data System (ADS)

    Armstrong, Elizabeth; Quinton, John; Kuhn, Nikolaus

    2010-05-01

    Global soils contain an estimated 1500GT of carbon, over twice that present in the atmosphere, however the role of soil in the global carbon cycle is highly debated. The influence of soil erosion and deposition in the global carbon cycle has been primarily investigated through the incubation of small volumes of loose sediment. The physical properties of this sediment are likely to differ to those in the environment where in situ soil forms part of an intact unit which can have a cohesive high density crust at the surface. The primary aim of this investigation was to measure carbon dioxide emissions from intact crusted soil samples. Rainfall simulation was used to create areas of soil crusting under high and low rainfall intensity in areas of erosion and deposition. The carbon dioxide emissions were measured over a 58 day period using an Infra Red Gas Analyser (IRGA). Physical properties of the crusts (total C content, C:N ratio, texture, density, degree of aggregation) were also determined. It was found that CO2 emissions were not related to C content alone, with strong correlation found to density (rs - 0.70) and aggregation (rs - 0.67), and texture also being influential although to a lesser extent. It is the effect that these properties have on OM bioavailability and gas diffusivity which affects the emissions of carbon dioxide. The physical properties of a crust are influenced by rainfall intensity, a conceptual diagram explaining this process has been developed. Given the strong correlation that has been found between carbon dioxide emissions and the physical properties of soils to base estimates of emissions on studies of loose samples maybe flawed. Furthermore given that rainfall intensity is predicted to change with global warming so to may soil crusting and emissions of carbon dioxide.

  9. Fate of Soil Organic Carbon and Polycyclic Aromatic Hydrocarbons in a Vineyard Soil Treated with Biochar.

    PubMed

    Rombolà, Alessandro G; Meredith, Will; Snape, Colin E; Baronti, Silvia; Genesio, Lorenzo; Vaccari, Francesco Primo; Miglietta, Franco; Fabbri, Daniele

    2015-09-15

    The effect of biochar addition on the levels of black carbon (BC) and polcyclic aromatic hydrocarbons (PAHs) in a vineyard soil in central Italy was investigated within a two year period. Hydropyrolysis (HyPy) was used to determine the contents of BC (BCHyPy) in the amended and control soils, while the hydrocarbon composition of the semi-labile (non-BCHyPy) fraction released by HyPy was determined by gas chromatography-mass spectrometry, together with the solvent-extractable PAHs. The concentrations of these three polycyclic aromatic carbon reservoirs changed and impacted differently the soil organic carbon over the period of the trial. The addition of biochar (33 ton dry biochar ha(-1)) gave rise to a sharp increase in soil organic carbon, which could be accounted for by an increase in BCHyPy. Over time, the concentration of BCHyPy decreased significantly from 36 to 23 mg g(-1) and as a carbon percentage from 79% to 61%. No clear time trends were observed for the non-BCHyPy PAHs varying from 39 to 34 μg g(-1) in treated soils, not significantly different from control soils. However, the concentrations of extractable PAHs increased markedly in the amended soils and decreased with time from 153 to 78 ng g(-1) remaining always higher than those in untreated soil. The extent of the BCHyPy loss was more compatible with physical rather than chemical processes.

  10. Drivers of organic carbon stock of agricultural soils in eastern Australia

    NASA Astrophysics Data System (ADS)

    Rabbi, Sheikh M. F.; Tighe, Matthew; Delgado-Baquerizo, Manuel; Cowie, Annette; Robertson, Fiona; Dalal, Ram; Page, Kathryn; Crawford, Doug; Wilson, Brian; Schwenke, Graeme; Mcleod, Malem; Badgery, Warwick; Dang, Yash; Bell, Mike; Baldock, Jeff

    2015-04-01

    Assessing the factors that control carbon storage is the key to formulating conservation policies and sustainable soil management under changing environments. Here, we evaluate the major drivers of soil organic carbon storage in eastern Australia. To do this, we used a regional dataset including 1482 sites and targeting key land uses and soil management practices on major soils of New South Wales (NSW), Queensland (QLD) and Victoria (VIC). Structural equation modeling (SEM) and conditional inference tree (CTREE) analyses were performed to evaluate the relative importance of climate, topography, soil properties, land use and soil management practices on soil organic carbon stocks in 0-30 cm. The results showed that aridity, the most important factor controlling carbon storage, had a strong negative (r = -0.82, p<0.01), whereas clay content had a strong positive (r = 0.42, p<0.01) relationship with soil carbon stock. Only a small portion (<1%) of total variation in carbon stock could be explained by land use. The results of CTREE analysis showed that pastures, and pasture dominant crop-pasture rotations had positive influence on soil carbon stocks. The CTREE results also indicated that aridity regulates the amount of carbon present in the soil under different land uses. Using a novel multivariate technique the current work identified that aridity and clay content of soil are the main drivers of carbon storage at a regional scale over others factors such as land uses and soil management practices.

  11. Soil Organic Carbon Stocks in Depositional Landscapes of Bavaria

    NASA Astrophysics Data System (ADS)

    Kriegs, Stefanie; Schwindt, Daniel; Völkel, Jörg; Kögel-Knabner, Ingrid

    2016-04-01

    Erosion leads to redistribution and accumulation of soil organic matter (SOM) within agricultural landscapes. These fluvic and colluvic deposits are characterized by a highly diverse vertical structure and can contain high amounts of soil organic carbon (SOC) over the whole soil profile. Depositional landscapes are therefore not only productive sites for agricultural use but also influence carbon dynamics which is of great interest with regard on the recent climate change debate. The aim of our study is to elucidate the spatial distribution of organic carbon stocks, as well as its depth function and the role of these landscapes as a reservoir for SOM. Therefore we compare two representative depositional landscapes in Bavaria composed of different parent materials (carbonate vs. granitic). We hypothesize that the soils associated with different depositional processes (fluvial vs. colluvial) differ in SOC contents and stocks, also because of different hydromorphic regimes in fluvic versus colluvic soil profiles. Sampling sites are located in the Alpine Foreland (quaternary moraines with carbonatic parent material) and the foothills of the Bavarian Forest (Granite with Loess) with the main soil types Fluvisols, Gleysols and Luvisols. At both sites we sampled twelve soil profiles up to 150 cm depth, six in the floodplain and six along a vertical slope transect. We took undisturbed soil samples from each horizon and analyzed them for bulk density, total Carbon (OC and IC) and total Nitrogen (N) concentrations. This approach allows to calculate total OC contents and OC stocks and to investigate vertical and horizontal distribution of OC stocks. It will also reveal differences in OC stocks due to the location of the soil profile in fluvic or colluvic deposition scenarios.

  12. Microbial contents of soil from fire pits

    NASA Astrophysics Data System (ADS)

    Moon, K.; Esparza, V.; de Sandre, J.; Cheney, S.; Anderson, A.; White, M. A.

    2006-12-01

    Forest fires generate polycylic aromatic hydrocarbons (PAHs) that can lead to carcinogenic compounds, which are potential health risks. PAHs can be degraded to water and carbon dioxide by certain soil microbes. Thus, during participation in a NASA-funded summer research experience at Utah State University, our high school student team sampled soils from a month-old fire pit in which plant materials had been burnt. We detected in soil samples, from surface, 10 and 20 cm depths, microbes that would grow on a defined minimal medium source. Other microbes were cultured from the roots of plants that had established at the fire pit. A diversity of microbes was present in all samples based on visible differences in cell shape and color. It was surprising that the surface ash, although exposed to sunlight over the month interval, had culturable colonies. Many of these culturable bacteria were pigmented perhaps as a protection against UV radiation from the sun. We searched for genes in the microbes that encoded enzymes called dioxygenases that in other bacteria are involved in degradation of PAHs. This test involved using polymerase chain reactions to detect the genes. PCR products were found in two of the fifteen isolates tested although their sizes differed from the control gene product from a PAH-degrading mycobacterium isolate. These results suggest that the soils did contain microbes with the possible potential to alter the PAH compounds generated from vegetation fires. Our findings serve as a starting point for future studies looking at recovery and remediation of fired acreages.

  13. Ultrasound Algorithm Derivation for Soil Moisture Content Estimation

    NASA Technical Reports Server (NTRS)

    Belisle, W.R.; Metzl, R.; Choi, J.; Aggarwal, M. D.; Coleman, T.

    1997-01-01

    Soil moisture content can be estimated by evaluating the velocity at which sound waves travel through a known volume of solid material. This research involved the development of three soil algorithms relating the moisture content to the velocity at which sound waves moved through dry and moist media. Pressure and shear wave propagation equations were used in conjunction with soil property descriptions to derive algorithms appropriate for describing the effects of moisture content variation on the velocity of sound waves in soils with and without complete soil pore water volumes, An elementary algorithm was used to estimate soil moisture contents ranging from 0.08 g/g to 0.5 g/g from sound wave velocities ranging from 526 m/s to 664 m/s. Secondary algorithms were also used to estimate soil moisture content from sound wave velocities through soils with pores that were filled predominantly with air or water.

  14. [Distribution of soil organic carbon in surface soil along a precipitation gradient in loess hilly area].

    PubMed

    Sun, Long; Zhang, Guang-hui; Luan, Li-li; Li, Zhen-wei; Geng, Ren

    2016-02-01

    Along the 368-591 mm precipitation gradient, 7 survey sites, i.e. a total 63 investigated plots were selected. At each sites, woodland, grassland, and cropland with similar restoration age were selected to investigate soil organic carbon distribution in surface soil (0-30 cm), and the influence of factors, e.g. climate, soil depth, and land uses, on soil organic carbon distribution were analyzed. The result showed that, along the precipitation gradient, the grassland (8.70 g . kg-1) > woodland (7.88 g . kg-1) > farmland (7.73 g . kg-1) in concentration and the grassland (20.28 kg . m-2) > farmland (19.34 kg . m-2) > woodland (17.14 kg . m-2) in density. The differences of soil organic carbon concentration of three land uses were not significant. Further analysis of pooled data of three land uses showed that the surface soil organic carbon concentration differed significantly at different precipitation levels (P<0.00 1). Significant positive relationship was detected between mean annual precipitation and soil organic carbon concentration (r=0.838, P<0.001) in the of pooled data. From south to north (start from northernmost Ordos), i.e. along the 368-591 mm precipitation gradient, the soil organic carbon increased with annual precipitation 0. 04 g . kg-1 . mm-1, density 0.08 kg . m-2 . mm-1. The soil organic carbon distribution was predicted with mean annual precipitation, soil clay content, plant litter in woodland, and root density in farmland.

  15. [Distribution of soil organic carbon in surface soil along a precipitation gradient in loess hilly area].

    PubMed

    Sun, Long; Zhang, Guang-hui; Luan, Li-li; Li, Zhen-wei; Geng, Ren

    2016-02-01

    Along the 368-591 mm precipitation gradient, 7 survey sites, i.e. a total 63 investigated plots were selected. At each sites, woodland, grassland, and cropland with similar restoration age were selected to investigate soil organic carbon distribution in surface soil (0-30 cm), and the influence of factors, e.g. climate, soil depth, and land uses, on soil organic carbon distribution were analyzed. The result showed that, along the precipitation gradient, the grassland (8.70 g . kg-1) > woodland (7.88 g . kg-1) > farmland (7.73 g . kg-1) in concentration and the grassland (20.28 kg . m-2) > farmland (19.34 kg . m-2) > woodland (17.14 kg . m-2) in density. The differences of soil organic carbon concentration of three land uses were not significant. Further analysis of pooled data of three land uses showed that the surface soil organic carbon concentration differed significantly at different precipitation levels (P<0.00 1). Significant positive relationship was detected between mean annual precipitation and soil organic carbon concentration (r=0.838, P<0.001) in the of pooled data. From south to north (start from northernmost Ordos), i.e. along the 368-591 mm precipitation gradient, the soil organic carbon increased with annual precipitation 0. 04 g . kg-1 . mm-1, density 0.08 kg . m-2 . mm-1. The soil organic carbon distribution was predicted with mean annual precipitation, soil clay content, plant litter in woodland, and root density in farmland. PMID:27396128

  16. Modeling carbon dynamics in vegetation and soil under the impact of soil erosion and deposition

    USGS Publications Warehouse

    Liu, S.; Bliss, N.; Sundquist, E.; Huntington, T.G.

    2003-01-01

    Soil erosion and deposition may play important roles in balancing the global atmospheric carbon budget through their impacts on the net exchange of carbon between terrestrial ecosystem and the atmosphere. Few models and studies have been designed to assess these impacts. In this study, we developed a general ecosystem model, Erosion-Deposition-Carbon-Model (EDCM), to dynamically simulate the influences of rainfall-induced soil erosion and deposition on soil organic carbon (SOC) dynamics in soil profiles. EDCM was applied to several landscape positions in the Nelson Farm watershed in Mississippi, including ridge top (without erosion or deposition), eroding hillslopes, and depositional sites that had been converted from native forests to croplands in 1870. Erosion reduced the SOC storage at the eroding sites and deposition increased the SOC storage at the depositional areas compared with the site without erosion or deposition. Results indicated that soils were consistently carbon sources to the atmosphere at all landscape positions from 1870 to 1950, with lowest source strength at the eroding sites (13 to 24 gC m-2 yr-1), intermediate at the ridge top (34 gC m-2 yr-1), and highest at the depositional sites (42 to 49 gC m-2 yr-1). During this period, erosion reduced carbon emissions via dynamically replacing surface soil with subsurface soil that had lower SOC contents (quantity change) and higher passive SOC fractions (quality change). Soils at all landscape positions became carbon sinks from 1950 to 1997 due to changes in management practices (e.g., intensification of fertilization and crop genetic improvement). The sink strengths were highest at the eroding sites (42 to 44 gC m-2 yr-1 , intermediate at the ridge top (35 gC m-2 yr-1), and lowest at the depositional sites (26 to 29 gC m-2 yr-1). During this period, erosion enhanced carbon uptake at the eroding sites by continuously taking away a fraction of SOC that can be replenished with enhanced plant residue

  17. [Modeling Soil Spectral Reflectance with Different Mass Moisture Content].

    PubMed

    Sun, Yue-jun; Zheng, Xiao-po; Qin, Qi-ming; Meng, Qing-ye; Gao, Zhong-ling; Ren, Hua-zhong; Wu, Ling; Wang, Jun; Wang, Jian-hua

    2015-08-01

    The spatio-temporal distribution and variation of soil moisture content have a significant impact on soil temperature, heat balance between land and atmosphere and atmospheric circulation. Hence, it is of great significance to monitor the soil moisture content dynamically at a large scale and to acquire its continuous change during a certain period of time. The object of this paper is to explore the relationship between the mass moisture content of soil and soil spectrum. This was accomplished by building a spectral simulation model of soil with different mass moisture content using hyperspectral remote sensing data. The spectra of soil samples of 8 sampling sites in Beijing were obtained using ASD Field Spectrometer. Their mass moisture contents were measured using oven drying method. Spectra of two soil samples under different mass moisture content were used to construct soil spectral simulation model, and the model was validated using spectra of the other six soil samples. The results show that the accuracy of the model is higher when the mass water content of soil is below field capacity. At last, we used the spectra of three sampling points on campus of Peking University to test the model, and the minimum value of root mean square error between simulated and measured spectral reflectance was 0.0058. Therefore the model is expected to perform well in simulating the spectrum reflectance of different types of soil when mass water content below field capacity. PMID:26672301

  18. Stable carbon isotope depth profiles and soil organic carbon dynamics in the lower Mississippi Basin

    USGS Publications Warehouse

    Wynn, J.G.; Harden, J.W.; Fries, T.L.

    2006-01-01

    Analysis of depth trends of 13C abundance in soil organic matter and of 13C abundance from soil-respired CO2 provides useful indications of the dynamics of the terrestrial carbon cycle and of paleoecological change. We measured depth trends of 13C abundance from cropland and control pairs of soils in the lower Mississippi Basin, as well as the 13C abundance of soil-respired CO2 produced during approximately 1-year soil incubation, to determine the role of several candidate processes on the 13C depth profile of soil organic matter. Depth profiles of 13C from uncultivated control soils show a strong relationship between the natural logarithm of soil organic carbon concentration and its isotopic composition, consistent with a model Rayleigh distillation of 13C in decomposing soil due to kinetic fractionation during decomposition. Laboratory incubations showed that initially respired CO 2 had a relatively constant 13C content, despite large differences in the 13C content of bulk soil organic matter. Initially respired CO2 was consistently 13C-depleted with respect to bulk soil and became increasingly 13C-depleted during 1-year, consistent with the hypothesis of accumulation of 13C in the products of microbial decomposition, but showing increasing decomposition of 13C-depleted stable organic components during decomposition without input of fresh biomass. We use the difference between 13C / 12C ratios (calculated as ??-values) between respired CO 2 and bulk soil organic carbon as an index of the degree of decomposition of soil, showing trends which are consistent with trends of 14C activity, and with results of a two-pooled kinetic decomposition rate model describing CO2 production data recorded during 1 year of incubation. We also observed inconsistencies with the Rayleigh distillation model in paired cropland soils and reasons for these inconsistencies are discussed. ?? 2005 Elsevier B.V. All rights reserved.

  19. Soil carbon changes for bioenergy crops.

    SciTech Connect

    Andress, D.

    2004-04-22

    Bioenergy crops, which displace fossil fuels when used to produce ethanol, biobased products, and/or electricity, have the potential to further reduce atmospheric carbon levels by building up soil carbon levels, especially when planted on lands where these levels have been reduced by intensive tillage. The purpose of this study is to improve the characterization of the soil carbon (C) sequestration for bioenergy crops (switchgrass, poplars, and willows) in the Greenhouse gases, Regulated Emissions, and Energy Use in Transportation (GREET) model (Wang 1999) by using the latest results reported in the literature and by Oak Ridge National Laboratory (ORNL). Because soil carbon sequestration for bioenergy crops can play a significant role in reducing greenhouse gas (GHG) emissions for cellulosic ethanol, it is important to periodically update the estimates of soil carbon sequestration from bioenergy crops as new and better data become available. We used the three-step process described below to conduct our study.

  20. [Characteristics of soil organic carbon and enzyme activities in soil aggregates under different vegetation zones on the Loess Plateau].

    PubMed

    Li, Xin; Ma, Rui-ping; An, Shao-shan; Zeng, Quan-chao; Li, Ya-yun

    2015-08-01

    In order to explore the distribution characteristics of organic carbon of different forms and the active enzymes in soil aggregates with different particle sizes, soil samples were chosen from forest zone, forest-grass zone and grass zone in the Yanhe watershed of Loess Plateau to study the content of organic carbon, easily oxidized carbon, and humus carbon, and the activities of cellulase, β-D-glucosidase, sucrose, urease and peroxidase, as well as the relations between the soil aggregates carbon and its components with the active soil enzymes were also analyzed. It was showed that the content of organic carbon and its components were in order of forest zone > grass zone > forest-grass zone, and the contents of three forms of organic carbon were the highest in the diameter group of 0.25-2 mm. The content of organic carbon and its components, as well as the activities of soil enzymes were higher in the soil layer of 0-10 cm than those in the 10-20 cm soil layer of different vegetation zones. The activities of cellulase, β-D-glucosidase, sucrose and urease were in order of forest zone > grass zone > forest-grass zone. The peroxidase activity was in order of forest zone > forest-grass zone > grass zone. The activities of various soil enzymes increased with the decreasing soil particle diameter in the three vegetation zones. The activities of cellulose, peroxidase, sucrose and urease had significant positive correlations with the contents of various forms of organic carbon in the soil aggregates.

  1. A simple model of carbon in the soil profile for agricultural soils in Northwestern Europe

    NASA Astrophysics Data System (ADS)

    Taghizadeh-Toosi, Arezoo; Hutchings, Nicholas J.; Vejlin, Jonas; Christensen, Bent T.; Olesen, Jørgen E.

    2014-05-01

    World soil carbon (C) stocks are second to those in the ocean, and represent three times as much C as currently present in the atmosphere. The amount of C in soil may play a significant role in carbon exchanges between the atmosphere and the terrestrial environment. The C-TOOL model is a three-pool linked soil organic carbon (SOC) model in well-drained mineral soils under agricultural land management to allow generalized parameterization for estimating effects of management measures at medium to long time scales for the entire soil profile (0-100 cm). C-TOOL has been developed to enable simulations of SOC turnover in soil using temperature dependent first order kinetics for describing decomposition. Compared with many other SOC models, C-TOOL applies a less complicated structure, which facilitates easier calibration, and it requires only few inputs (i.e., average monthly air temperature, soil clay content,soil carbon-to-nitrogen ratio, and C inputs to the soil from plants and other sources). C-TOOL was parameterized using SOC and radiocarbon data from selected long-term field treatments in United Kingdom, Sweden and Denmark. However, less data were available for evaluation of subsoil C (25-100 cm) from the long-term experiments applied. In Denmark a national 7×7 km grid net was established in 1986 for soil C monitoring down to 100 cm depth. The results of SOC showed a significant decline from 1997 to 2009 in the 0-50 cm soil layer. This was mainly attributed to changes in the 25-50 cm layer, where a decline in SOC was found for all soil texture types. Across the period 1986 to 2009 there was clear tendency for increasing SOC on the sandy soils and reductions on the loamy soils. This effect is linked to land use, since grasslands and dairy farms are more abundant in the western parts of Denmark, where most of the sandy soils are located. The results and the data from soil monitoring have been used to validate the C-TOOL modelling approach used for accounting of

  2. Soil salinity decreases global soil organic carbon stocks.

    PubMed

    Setia, Raj; Gottschalk, Pia; Smith, Pete; Marschner, Petra; Baldock, Jeff; Setia, Deepika; Smith, Jo

    2013-11-01

    Saline soils cover 3.1% (397 million hectare) of the total land area of the world. The stock of soil organic carbon (SOC) reflects the balance between carbon (C) inputs from plants, and losses through decomposition, leaching and erosion. Soil salinity decreases plant productivity and hence C inputs to the soil, but also microbial activity and therefore SOC decomposition rates. Using a modified Rothamsted Carbon model (RothC) with a newly introduced salinity decomposition rate modifier and a plant input modifier we estimate that, historically, world soils that are currently saline have lost an average of 3.47 tSOC ha(-1) since they became saline. With the extent of saline soils predicted to increase in the future, our modelling suggests that world soils may lose 6.8 Pg SOC due to salinity by the year 2100. Our findings suggest that current models overestimate future global SOC stocks and underestimate net CO2 emissions from the soil-plant system by not taking salinity effects into account. From the perspective of enhancing soil C stocks, however, given the lower SOC decomposition rate in saline soils, salt tolerant plants could be used to sequester C in salt-affected areas.

  3. Dynamic replacement and loss of soil carbon on eroding cropland

    USGS Publications Warehouse

    Harden, J.W.; Sharpe, J.M.; Parton, W.J.; Ojima, D.S.; Fries, T.L.; Huntington, T.G.; Dabney, S.M.

    1999-01-01

    Links between erosion/sedimentation history and soil carbon cycling were examined in a highly erosive setting in Mississippi loess soils. We sampled soils on (relatively) undisturbed and cropped hillslopes and measured C, N, 14C, and CO2 flux to characterize carbon storage and dynamics and to parameterize Century and spreadsheet 14C models for different erosion and tillage histories. For this site, where 100 years of intensive cotton cropping were followed by fertilization and contour plowing, there was an initial and dramatic decline in soil carbon content from 1870 to 1950, followed by a dramatic increase in soil carbon. Soil erosion amplifies C loss and recovery: About 100% of the original, prehistoric soil carbon was likely lost over 127 years of intensive land use, but about 30% of that carbon was replaced after 1950. The eroded cropland was therefore a local sink for CO2 since the 1950s. However, a net CO2 sink requires a full accounting of eroded carbon, which in turn requires that decomposition rates in lower slopes or wetlands be reduced to about 20% of the upland value. As a result, erosion may induce unaccounted sinks or sources of CO2, depending on the fate of eroded carbon and its protection from decomposition. For erosion rates typical of the United States, the sink terms may be large enough (1 Gt yr-1, back-of-the-envelope) to warrant a careful accounting of site management, cropping, and fertilization histories, as well as burial rates, for a more meaningful global assessment.

  4. Active Layer Soil Carbon and Nutrient Mineralization, Barrow, Alaska, 2012

    DOE Data Explorer

    Stan D. Wullschleger; Holly M. Vander Stel; Colleen Iversen; Victoria L. Sloan; Richard J. Norby; Mallory P. Ladd; Jason K. Keller; Ariane Jong; Joanne Childs; Deanne J. Brice

    2015-10-29

    This data set consists of bulk soil characteristics as well as carbon and nutrient mineralization rates of active layer soils manually collected from the field in August, 2012, frozen, and then thawed and incubated across a range of temperatures in the laboratory for 28 day periods in 2013-2015. The soils were collected from four replicate polygons in each of the four Areas (A, B, C, and D) of Intensive Site 1 at the Next-Generation Ecosystem Experiments (NGEE) Arctic site near Barrow, Alaska. Soil samples were coincident with the established Vegetation Plots that are located in center, edge, and trough microtopography in each polygon. Data included are 1) bulk soil characteristics including carbon, nitrogen, gravimetric water content, bulk density, and pH in 5-cm depth increments and also by soil horizon, 2) carbon, nitrogen, and phosphorus mineralization rates for soil horizons incubated aerobically (and in one case both aerobically and anaerobically) for 28 days at temperatures that included 2, 4, 8, and 12 degrees C. Additional soil and incubation data are forthcoming. They will be available when published as part of another paper that includes additional replicate analyses.

  5. Effects of Tillage Practices on Soil Organic Carbon and Soil Respiration

    NASA Astrophysics Data System (ADS)

    Rusu, Teodor; Ioana Moraru, Paula; Bogdan, Ileana; Ioan Pop, Adrian

    2016-04-01

    replications. In one variant the area of a plot was 300 m2. Soil respiration varies throughout the year for all three crops of rotation, with a maximum in late spring (1383 to 2480 mmoli m-2s-1) and another in fall (2141 to 2350 mmoli m-2s-1). The determinations confirm the effect of soil tillage system on soil respiration; the daily average is lower at no-tillage (315-1914 mmoli m-2s-1), followed by minimum tillage (318-2395 mmoli m-2s-1) and is higher in the conventional tillage (321-2480 mmol m-2s-1). An exceeding amount of CO2 produced in the soil and released into the atmosphere, resulting from aerobic processes of mineralization of organic matter (excessive loosening) is considered to be not only a way of increasing the CO2 in the atmosphere, but also a loss of long-term soil fertility. By determining the humus content after 3 years, it can be observed an increasing tendency when applying the minimum tillage (the increase was up to 0.41%) and no-tillage systems tillage (the increase was up to 0.64%). Carbon sequestration in soil is net advantageous, improving the productivity and sustainability. The more the organic content in soil is higher the better soil aggregation is. The soil without organic content is compact. This reduces its capacity to infiltrate water, nutrients solubility and productivity, and that way it reduces the soil capacity for carbon sequestration. Acknowledgments This paper was performed under the frame of the Partnership in priority domains - PNII, developed with the support of MEN-UEFISCDI, project no. PN-II-PT-PCCA-2013-4-0015: Expert System for Risk Monitoring in Agriculture and Adaptation of Conservative Agricultural Technologies to Climate Change.

  6. Pyrogenic Carbon in forest soils across climate and soil property gradients in Switzerland

    NASA Astrophysics Data System (ADS)

    Reisser, Moritz; González Domínguez, Beatriz R.; Hagedorn, Frank; Abiven, Samuel

    2016-04-01

    Soil organic carbon (SOC) is an important measure for soil quality. Usually a high organic matter content in soils is favourable for most ecosystems. As a very stable component, pyrogenic organic carbon (PyC) can be of major interest to investigate to potential of organic matter, to persist very long in soils. Recent studies have shown, that the mean residence time of organic matter is not only due to its intrinsic chemical nature, but also to a variety of abiotic and biotic variables set by the ecosystem. Especially for PyC it is unclear, whether its content is related to fire regime, soil properties or other climatic conditions. In this study we wanted to investigate, how climatic and soil-related conditions are influencing the persistence of PyC in soils. Therefore we used a sample set from Swiss forest soil (n = 54), which was designed for the purpose of having most differing climatic conditions (aridity and temperature) and a large range of soil properties (pH between 3.4 and 7.6; clay content between 4.7 % and 60 %). The soils were sampled in the first 20 cm of the mineral horizon on a representative plot area of 40 x 40 m. The soils were sieved to 2 mm and dried prior to the analysis. We used the benzene polycarboxylic acids (BPCA) molecular marker method to quantify and characterize PyC in these soil samples. Despite the large span in environmental conditions, we observed rather small differences in the contribution of PyC to SOC between warmer and colder, as well as between wetter and dryer soils. The PyC content in SOC lies well in range with a global average for forest soils estimated in other studies. Stocks of PyC vary more than the content, because of the large range of SOC contents in the samples. The influence of other parameters like soil properties is still under investigation. Qualitative investigation of the BPCAs showed that the degree of condensation, defined by the relative amount of B6CA in the total BPCA, was higher in warmer soils. This

  7. Evaluating Soil Carbon Sequestration in Central Iowa

    NASA Astrophysics Data System (ADS)

    Doraiswamy, P. C.; Hunt, E. R.; McCarty, G. W.; Daughtry, C. S.; Izaurralde, C.

    2005-12-01

    The potential for reducing atmospheric carbon dioxide (CO2) concentration through landuse and management of agricultural systems is of great interest worldwide. Agricultural soils can be a source of CO2 when not properly managed but can also be a sink for sequestering CO2 through proper soil and crop management. The EPIC-CENTURY biogeochemical model was used to simulate the baseline level of soil carbon from soil survey data and project changes in soil organic carbon (SOC) under different tillage and crop management practices for corn and soybean crops. The study was conducted in central Iowa (50 km x 100 km) to simulate changes in soil carbon over the next 50 years. The simulations were conducted in two phases; initially a 25-year period (1971-1995) was simulated using conventional tillage practices since there was a transition in new management after 1995. In the second 25-year period (1996-2020), four different modeling scenarios were applied namely; conventional tillage, mulch tillage, no-tillage and no-tillage with a rye cover crop over the winter. The model simulation results showed potential gains in soil carbon in the top layers of the soil for conservation tillage. The simulations were made at a spatial resolution of 1.6 km x 1.6 km and mapped for the study area. There was a mean reduction in soil organic carbon of 0.095 T/ha per year over the 25-year period starting with 1996 for the conventional tillage practice. However, for management practices of mulch tillage, no tillage and no tillage with cover crop there was an increase in soil organic carbon of 0.12, 0.202 and 0.263 T/ha respectively over the same 25-year period. These results are in general similar to studies conducted in this region.

  8. The carbon balance of forest soils: detectability of changes in soil carbon stocks in temperate and Boreal forests.

    PubMed

    Conen, Frauz; Zerva, Argyro; Arrouays, Dominique; Jolivet, Claude; Jarvis, Paul G; Grace, John; Mencuccini, Maurizio

    2005-01-01

    Estimating soil carbon content as the product of mean carbon concentration and bulk density can result in considerable overestimation. Carbon concentration and soil mass need to be measured on the same sample and carbon contents calculated for each individual sample before averaging. The effect of this bias is likely to be smaller (but still greater than zero) when the primary objective is to determine stock changes over time. Variance and mean carbon content are significantly and positively related to each other, although some sites showed much higher variability than predicted by this relationship, as a likely consequence of their particular site history, forest management, and micro-topography. Because of the proportionality between mean and variance, the number of samples required to detect a fixed change in soil carbon stocks varied directly with the site mean carbon content from less than 10 to several thousands across the range of carbon stocks normally encountered in temperate and Boreal forests. This raises important questions about how to derive an optimal sampling strategy across such a varied range of conditions so as to achieve the aims of the Kyoto Protocol. Overall, on carbon-poor forest sites with little or no disturbance to the soil profile, it is possible to detect changes in total soil organic carbon over time of the order of 0.5 kg (C) m(-2) with manageable sample sizes even using simple random sampling (i.e., about 50 samples per sampling point). More efficient strategies will reveal even smaller differences. On disturbed forest sites (ploughed, windthrow) this is no longer possible (required sample sizes are much larger than 100). Soils developed on coarse aeolian sediments (sand dunes), or where buried logs or harvest residues of the previous rotation are present, can also exhibit large spatial variability in soil carbon. Generally, carbon-rich soils will always require larger numbers of samples. On these sites, simple random sampling is

  9. Biophysical properties as determinants for soil organic carbon and total nitrogen in grassland salinization.

    PubMed

    Pan, Chengchen; Zhao, Halin; Zhao, Xueyong; Han, Huibang; Wang, Yan; Li, Jin

    2013-01-01

    Grassland salinization causes considerable changes to soil and vegetation, which can lead to changes in soil organic carbon (C) and total nitrogen (N). These changes have complex causal relationships. A significant correlation between soil organic C and total N and any soil or vegetation property does not necessarily imply a significant direct effect of the property on soil organic C and total N. In this study, a field survey was conducted to investigate the changes in soil organic C and total N in grassland along a salinity gradient in Hexi corridor, China, and the direct and indirect effects of soil and vegetation properties on both stocks were quantified using a path analysis approach. Significant decrease in soil organic C and total N contents were observed with increasing salinity. Both had significant positive correlations with the Normalized Difference Vegetation Index (NDVI), soil water, and fine particles (silt+clay) content (p<0.01) and significant negative correlations with soil EC, and sand content (p<0.01). NDVI, fine particles content and soil water content had positive direct effects on soil organic C and total N stocks. Soil EC affected soil organic C and total N stocks mainly through its indirect negative effect on NDVI, soil texture, and water content. NDVI, soil texture, and moisture also indirectly affected soil organic C and total N stocks via changes in each other. These indirect effects augmented each other, although in some cases indirect effects worked in opposing directions.

  10. Biophysical Properties as Determinants for Soil Organic Carbon and Total Nitrogen in Grassland Salinization

    PubMed Central

    Pan, Chengchen; Zhao, Halin; Zhao, Xueyong; Han, Huibang; Wang, Yan; Li, Jin

    2013-01-01

    Grassland salinization causes considerable changes to soil and vegetation, which can lead to changes in soil organic carbon (C) and total nitrogen (N). These changes have complex causal relationships. A significant correlation between soil organic C and total N and any soil or vegetation property does not necessarily imply a significant direct effect of the property on soil organic C and total N. In this study, a field survey was conducted to investigate the changes in soil organic C and total N in grassland along a salinity gradient in Hexi corridor, China, and the direct and indirect effects of soil and vegetation properties on both stocks were quantified using a path analysis approach. Significant decrease in soil organic C and total N contents were observed with increasing salinity. Both had significant positive correlations with the Normalized Difference Vegetation Index (NDVI), soil water, and fine particles (silt+clay) content (p<0.01) and significant negative correlations with soil EC, and sand content (p<0.01). NDVI, fine particles content and soil water content had positive direct effects on soil organic C and total N stocks. Soil EC affected soil organic C and total N stocks mainly through its indirect negative effect on NDVI, soil texture, and water content. NDVI, soil texture, and moisture also indirectly affected soil organic C and total N stocks via changes in each other. These indirect effects augmented each other, although in some cases indirect effects worked in opposing directions. PMID:23372776

  11. Uncertainty in soil carbon accounting due to unrecognized soil erosion.

    PubMed

    Sanderman, Jonathan; Chappell, Adrian

    2013-01-01

    The movement of soil organic carbon (SOC) during erosion and deposition events represents a major perturbation to the terrestrial carbon cycle. Despite the recognized impact soil redistribution can have on the carbon cycle, few major carbon accounting models currently allow for soil mass flux. Here, we modified a commonly used SOC model to include a soil redistribution term and then applied it to scenarios which explore the implications of unrecognized erosion and deposition for SOC accounting. We show that models that assume a static landscape may be calibrated incorrectly as erosion of SOC is hidden within the decay constants. This implicit inclusion of erosion then limits the predictive capacity of these models when applied to sites with different soil redistribution histories. Decay constants were found to be 15-50% slower when an erosion rate of 15 t soil ha(-1)  yr(-1) was explicitly included in the SOC model calibration. Static models cannot account for SOC change resulting from agricultural management practices focused on reducing erosion rates. Without accounting for soil redistribution, a soil sampling scheme which uses a fixed depth to support model development can create large errors in actual and relative changes in SOC stocks. When modest levels of erosion were ignored, the combined uncertainty in carbon sequestration rates was 0.3-1.0 t CO2  ha(-1)  yr(-1) . This range is similar to expected sequestration rates for many management options aimed at increasing SOC levels. It is evident from these analyses that explicit recognition of soil redistribution is critical to the success of a carbon monitoring or trading scheme which seeks to credit agricultural activities.

  12. Soil Organic Carbon Mapping by Geostatistics in Europe Scale

    NASA Astrophysics Data System (ADS)

    Aksoy, E.; Panagos, P.; Montanarella, L.

    2013-12-01

    Accuracy in assessing the distribution of soil organic carbon (SOC) is an important issue because SOC is an important soil component that plays key roles in the functions of both natural ecosystems and agricultural systems. The SOC content varies from place to place and it is strongly related with climate variables (temperature and rainfall), terrain features, soil texture, parent material, vegetation, land-use types, and human management (management and degradation) at different spatial scales. Geostatistical techniques allow for the prediction of soil properties using soil information and environmental covariates. In this study, assessment of SOC distribution has been predicted with Regression-Kriging method in Europe scale. In this prediction, combination of the soil samples which were collected from the LUCAS (European Land Use/Cover Area frame statistical Survey) & BioSoil Projects, with local soil data which were collected from six different CZOs in Europe and ten spatial predictors (slope, aspect, elevation, CTI, CORINE land-cover classification, parent material, texture, WRB soil classification, annual average temperature and precipitation) were used. Significant correlation between the covariates and the organic carbon dependent variable was found. Moreover, investigating the contribution of local dataset in watershed scale into regional dataset in European scale was an important challenge.

  13. Soil moisture surpasses elevated CO2 and temperature as a control on soil carbon dynamics in a multi-factor climate change experiment

    SciTech Connect

    Garten Jr, Charles T; Classen, Aimee T; Norby, Richard J

    2009-01-01

    Some single-factor experiments suggest that elevated CO2 concentrations can increase soil carbon, but few experiments have examined the effects of interacting environmental factors on soil carbon dynamics. We undertook studies of soil carbon and nitrogen in a multi-factor (CO2 x temperature x soil moisture) climate change experiment on a constructed old-field ecosystem. After four growing seasons, elevated CO2 had no measurable effect on carbon and nitrogen concentrations in whole soil, particulate organic matter (POM), and mineral-associated organic matter (MOM). Analysis of stable carbon isotopes, under elevated CO2, indicated between 14 and 19% new soil carbon under two different watering treatments with as much as 48% new carbon in POM. Despite significant belowground inputs of new organic matter, soil carbon concentrations and stocks in POM declined over four years under soil moisture conditions that corresponded to prevailing precipitation inputs (1,300 mm yr-1). Changes over time in soil carbon and nitrogen under a drought treatment (approximately 20% lower soil water content) were not statistically significant. Reduced soil moisture lowered soil CO2 efflux and slowed soil carbon cycling in the POM pool. In this experiment, soil moisture (produced by different watering treatments) was more important than elevated CO2 and temperature as a control on soil carbon dynamics.

  14. Age of respired carbon in differently managed grassland and forest soils

    NASA Astrophysics Data System (ADS)

    Schoening, Ingo; Trumbore, Susan; Solly, Emily; Muhr, Jan; Schrumpf, Marion

    2013-04-01

    Grassland management (fertilization, grazing, mowing) and forest management (harvesting, thinning) directly affect biomass production and related leaf and root litter input to the soil. Understanding effects of land management on soil carbon fluxes is therefore critical. We examined the effect of land use and management on soil respiration and the age of respired soil carbon. Soil samples originated from grassland and forest plots in three different German regions. Sieved surface soil samples (0-10 cm) were incubated (20°C, 60% WHC) for 14 days. The respired CO2 was collected and 14C contents in the CO2 of 150 incubated samples were determined with accelerator mass spectrometry (AMS). Large changes recorded in 14C in the atmosphere since atmospheric weapons testing in the 1960s allow precise determination of the mean age of emitted soil carbon. In our study, the rate of respiration was higher in grassland soils (33 ± 10 µg C-CO2 per g dry soil per day) compared to forest soils (14 ± 7 µg C-CO2 per g dry soil per day). Results indicate a strong relation between respiration rates and grassland management with lower soil respiration in more fertilized plots. This relation was not found at sites where degraded peatlands were used as grasslands. At those sites, respiration rates were mainly driven by the soil organic carbon concentration. In forest soils, we did not find any relation between soil respiration and forest management. The 14C contents of the respired CO2 were lower in grassland soils (Percentage Modern carbon content: 104±2%) compared to forest soils (Percentage Modern Carbon content: 108±5%). This indicates that the carbon respired in forests is generally several years to more than a decade older than the carbon respired in grasslands. In grasslands, the 14C is positively related to the respiration rate and negatively related to fertilization. Again, degraded peat soils, where old carbon is released during incubation, were the exception to this

  15. Environmental analyse of soil organic carbon stock changes in Slovakia

    NASA Astrophysics Data System (ADS)

    Koco, Š.; Barančíková, G.; Skalský, R.; Tarasovičová, Z.; Gutteková, M.; Halas, J.; Makovníková, J.; Novákova, M.

    2012-04-01

    The content and quality of soil organic matter is one of the basic soil parameters on which soil production functioning depends as well as it is active in non production soil functions like an ecological one especially. Morphologic segmentation of Slovakia has significant influence of structure in using agricultural soil in specific areas of our territory. Also social changes of early 90´s of 20´th century made their impact on change of using of agricultural soil (transformation from large farms to smaller ones, decreasing the number of livestock). This research is studying changes of development of soil organic carbon stock (SOC) in agricultural soil of Slovakia as results of climatic as well as social and political changes which influenced agricultury since last 40 years. The main goal of this research is an analysis of soil organic carbon stock since 1970 until now at specific agroclimatic regions of Slovakia and statistic analysis of relation between modelled data of SOC stock and soil quality index value. Changes of SOC stock were evaluated on the basis SOC content modeling using RothC-26.3 model. From modeling of SOC stock results the outcome is that in that time the soil organic carbon stock was growing until middle 90´s years of 20´th century with the highest value in 1994. Since that year until new millennium SOC stock is slightly decreasing. After 2000 has slightly increased SOC stock so far. According to soil management SOC stock development on arable land is similar to overall evolution. In case of grasslands after slight growth of SOC stock since 1990 the stock is in decline. This development is result of transformational changes after 1989 which were specific at decreasing amount of organic carbon input from organic manure at grassland areas especially. At warmer agroclimatic regions where mollic fluvisols and chernozems are present and where are soils with good quality and steady soil organic matter (SOM) the amount of SOC in monitored time is

  16. Agglutinates and carbon accumulation in Apollo 17 lunar soils

    NASA Technical Reports Server (NTRS)

    Basu, A.; Meinschein, W. G.

    1976-01-01

    A critical review of maturity with respect to the abundance of implanted solar wind elements (SWE) in lunar soils indicates: (1) that the Rosiwal Principle has limited applicability in determining implantation of SWE in lunar soils, and (2) that despite a depletion of SWE in agglutinitic glass, agglutinates are enriched in SWE due to the presence of buried surfaces of numerous clasts within agglutinates. A statistical analysis of published data of several Apollo 17 soils indicates that the abundance of carbon and, by analogy, the abundance of other SWE are correlatable with the agglutinate content and the mean grain size of lunar soils. Microscopic examination of more than 5000 grains of agglutinates in polished thin sections reveals a wide range of variability in the mineralogy, grain size distribution, degree of recycling, etc., of the clast population in agglutinates. This indicates that the volume-correlated SWE content of agglutinates may vary and need not be constant.

  17. Pore-Scale Investigation of Organic Carbon Degradation in Soils and Sediments and its Implication to Field Applications

    NASA Astrophysics Data System (ADS)

    Yan, Z.; Liu, C.; Smith, A. P.; Todd-Brown, K. E.; Bailey, V. L.

    2015-12-01

    Soil is the largest pool of terrestrial organic carbon in the biosphere. The patterns and controls of soil organic carbon storage are critical for understanding the coupled interactions between biosphere behavior and climate change. Although soil carbon stocks are positively correlated with mean annual precipitation at global scale, moisture is considered to promote carbon decomposition in most macroscale soil carbon models, which include a scaling factor that increases with water content. Therefore, more mechanistic understanding of soil moisture effects on carbon accumulation and cycle are needed. The microbial activity, substrate availability, and gas transfer in soil react differently with water content, and their interactions result in an optimal water content for carbon decomposition. We develop a physical based microscale model to study the effects of soil texture and heterogeneity on the optimal moisture as well as the carbon destabilization. X-ray computed tomography of soil samples with different clay content and pore distribution are used to study the impact of soil texture and heterogeneity on the optimal water content and carbon release. After thorough modeling studies, we introduce a scaling factor, which reflects the optimal effect of water moisture, to the macroscale carbon model. This scaling factor exhibits a strong physical mechanism and can improve the accuracy of predicting carbon storage and cycle in soil.

  18. Characterization of soil water content variability and soil texture using GPR groundwave techniques

    SciTech Connect

    Grote, K.; Anger, C.; Kelly, B.; Hubbard, S.; Rubin, Y.

    2010-08-15

    Accurate characterization of near-surface soil water content is vital for guiding agricultural management decisions and for reducing the potential negative environmental impacts of agriculture. Characterizing the near-surface soil water content can be difficult, as this parameter is often both spatially and temporally variable, and obtaining sufficient measurements to describe the heterogeneity can be prohibitively expensive. Understanding the spatial correlation of near-surface soil water content can help optimize data acquisition and improve understanding of the processes controlling soil water content at the field scale. In this study, ground penetrating radar (GPR) methods were used to characterize the spatial correlation of water content in a three acre field as a function of sampling depth, season, vegetation, and soil texture. GPR data were acquired with 450 MHz and 900 MHz antennas, and measurements of the GPR groundwave were used to estimate soil water content at four different times. Additional water content estimates were obtained using time domain reflectometry measurements, and soil texture measurements were also acquired. Variograms were calculated for each set of measurements, and comparison of these variograms showed that the horizontal spatial correlation was greater for deeper water content measurements than for shallower measurements. Precipitation and irrigation were both shown to increase the spatial variability of water content, while shallowly-rooted vegetation decreased the variability. Comparison of the variograms of water content and soil texture showed that soil texture generally had greater small-scale spatial correlation than water content, and that the variability of water content in deeper soil layers was more closely correlated to soil texture than were shallower water content measurements. Lastly, cross-variograms of soil texture and water content were calculated, and co-kriging of water content estimates and soil texture

  19. Soil carbon sequestration: Quantifying this ecosystem service

    EPA Science Inventory

    Soils have a crucial role in supplying many goods and services that society depends upon on a daily basis. These include food and fiber production, water cleansing and supply, nutrient cycling, waste isolation and degradation. Soils also provide a significant amount of carbon s...

  20. Interactive effects of litter quality and soil mineralogy on temperate forest soil carbon response to temperature

    NASA Astrophysics Data System (ADS)

    Rasmussen, C.; Horwath, W.; Southard, R.

    2007-12-01

    Temperate forest soil organic carbon (C) represents a significant pool of terrestrial C that may be released to the atmosphere as CO2 with predicted climate change. To address feedbacks between climate change and terrestrial C turnover, we quantified forest soil C response to litter quality and temperature change as a function of soil parent material. We collected soils from three conifer forest-types dominated by ponderosa pine (PP), white fir (WF), and red fir (RF) from each of three parent materials, granite (GR), basalt (BS), and andesite (AN) in the Sierra Nevada of California. AN soils were dominated by short-range-order (SRO) minerals, GR soils by crystalline minerals, and BS soils by a mix of crystalline and SRO minerals. Field soils were incubated in the laboratory at their mean annual soil temperature (MAST), with addition of native 13C-labeled litter. Further, we incubated WF and RF soils at PP MAST with 13C-labeled PP litter; and RF soils at WF MAST with 13C-labeled WF litter to simulate a migration of MAST and vegetation type up-elevation in response to predicted climate warming. Results indicated that total CO2 and percent of CO2 derived from soil C varied significantly across forest-types, following the pattern of GR>BS>AN. Regression analyses indicated significant control of C mineralization and soil C priming by litter quality and SRO minerals. Addition of litter derived water-soluble compounds enabled priming of recalcitrant soil C in soils with high SRO mineral content, whereas water-soluble litter components did little to promote priming of extant soil C in soils of low SRO mineral content. Results further indicated a 10-300% increase in WF and RF forest-type soil C mineralization under climate change conditions that varied substantially between parent materials. Soils derived from andesite exhibited minimal change; whereas granite and basalt derived soils lost large amounts of soil C under climate change conditions. This study corroborates the

  1. Soil organic carbon fractionation for improving agricultural soil quality diagnosis in different management practices.

    NASA Astrophysics Data System (ADS)

    Trigalet, Sylvain; Chartin, Caroline; Kruger, Inken; Carnol, Monique; Van Oost, Kristof; van Wesemael, Bas

    2016-04-01

    Preserving ecosystem functions of soil organic matter (SOM) in soils is a key challenge. The need for an efficient diagnosis of SOM state in agricultural soils is a priority in order to facilitate the detection of changes in soil quality as a result of changes in management practices. The nature of SOM is complex and cannot readily be monitored due to the heterogeneity of its components. Assessment of the SOM level dynamics, typically characterized as the bulk soil organic carbon (SOC), can be refined by taking into account carbon pools with different turnover rates and stability. Fractionating bulk SOC in meaningful soil organic fractions helps to better diagnose SOC status. By separating carbon associated with clay and fine silt particles (stable carbon with slow turnover rate) and carbon non-associated with this fraction (labile and intermediate carbon with higher turnover rates), effects of management can be detected more efficiently at different spatial and temporal scales. Until now, most work on SOC fractionation has focused on small spatial scales along management or time gradients. The present case study focuses on SOC fractionation applied in order to refine the interpretation of organic matter turnover and SOC sequestration for regional units in Wallonia with comparable climate, management and, to a certain extent, soil conditions. In each unit, random samples from specific land uses are analyzed in order to assess the Normal Operative Ranges (NOR) of SOC fraction contents for each unit and land use combination. Thus, SOC levels of the different fractions of a specific field in a given unit can be compared to its corresponding NOR. It will help to better diagnose agricultural soil quality in terms of organic carbon compared to a bulk SOC diagnosis.

  2. Environmental Controls of Soil Organic Carbon in Soils Across Amazonia

    NASA Astrophysics Data System (ADS)

    Quesada, Carlos Alberto; Paz, Claudia; Phillips, Oliver; Nonato Araujo Filho, Raimundo; Lloyd, Jon

    2015-04-01

    Amazonian forests store and cycle a significant amount of carbon on its soils and vegetation. Yet, Amazonian forests are now subject to strong environmental pressure from both land use and climate change. Some of the more dramatic model projections for the future of the Amazon predict a major change in precipitation followed by savanization of most currently forested areas, resulting in major carbon losses to the atmosphere. However, how soil carbon stocks will respond to climatic and land use changes depend largely on how soil carbon is stabilized. Amazonian soils are highly diverse, being very variable in their weathering levels and chemical and physical properties, and thus it is important to consider how the different soils of the Basin stabilize and store soil organic carbon (SOC). The wide variation in soil weathering levels present in Amazonia, suggests that soil groups with contrasting pedogenetic development should differ in their predominant mechanism of SOC stabilization. In this study we investigated the edaphic, mineralogical and climatic controls of SOC concentration in 147 pristine forest soils across nine different countries in Amazonia, encompassing 14 different WRB soil groups. Soil samples were collected in 1 ha permanent plots used for forest dynamics studies as part of the RAINFOR project. Only 0-30 cm deep averages are reported here. Soil samples were analyzed for carbon and nitrogen and for their chemical (exchangeable bases, phosphorus, pH) and physical properties, (particle size, bulk density) and mineralogy through standard selective dissolution techniques (Fe and Al oxides) and by semi-quantitative X-Ray diffraction. In Addition, selected soils from each soil group had SOC fractionated by physical and chemical techniques. Our results indicate that different stabilization mechanisms are responsible for SOC stabilization in Amazonian soils with contrasting pedogenetic level. Ferralsols and Acrisols were found to have uniform mineralogy

  3. Mercury content in soils on the territory of Mezhdurechensk

    NASA Astrophysics Data System (ADS)

    Nicolaenko, A. N.; Osipova, N. A.; Yazikov, E. G.; Matveenko, I. A.

    2016-09-01

    The geochemical features of mercury content and distribution in the zone of coal producers have been studied (Mezhdurechensk town). Mercury content in soil (30 samples) was determined by atomic absorption method using mercury analyzer PA-915+ with pyrolytic device. Mercury content in soil samples changed from 0.12 to 0.17 mg/kg, the average value being 0.057 mg/kg. Within the town territory five zones with mercury elevated concentrations in soil were distinguished. 25-year observation period showed a 2.8 time decrease in average mercury content in soil. The major contribution to soil pollution in the urban territory was made by the two factors: local and regional. The mercury content in soil is affected by the emissions from boilers operating on coal as well as coal dust from the open pits near the town.

  4. Soil Inorganic Carbon Formation: Can Parent Material Overcome Climate?

    NASA Astrophysics Data System (ADS)

    Stanbery, C.; Will, R. M.; Seyfried, M. S.; Benner, S. G.; Flores, A. N.; Guilinger, J.; Lohse, K. A.; Good, A.; Black, C.; Pierce, J. L.

    2014-12-01

    Soil carbon is the third largest carbon reservoir and is composed of both organic and inorganic constituents. However, the storage and flux of soil carbon within the global carbon cycle are not fully understood. While organic carbon is often the focus of research, the factors controlling the formation and dissolution of soil inorganic carbon (SIC) are complex. Climate is largely accepted as the primary control on SIC, but the effects of soil parent material are less clear. We hypothesize that effects of parent material are significant and that SIC accumulation will be greater in soils formed from basalts than granites due to the finer textured soils and more abundant calcium and magnesium cations. This research is being conducted in the Reynolds Creek Experimental Watershed (RCEW) in southwestern Idaho. The watershed is an ideal location because it has a range of gradients in precipitation (250 mm to 1200 mm), ecology (sagebrush steppe to juniper), and parent materials (a wide array of igneous and sedimentary rock types) over a relatively small area. Approximately 20 soil profiles will be excavated throughout the watershed and will capture the effects of differing precipitation amounts and parent material on soil characteristics. Several samples at each site will be collected for analysis of SIC content and grain size distribution using a pressure calcimeter and hydrometers, respectively. Initial field data suggests that soils formed over basalts have a higher concentration of SIC than those on granitic material. If precipitation is the only control on SIC, we would expect to see comparable amounts in soils formed on both rock types within the same precipitation zone. However, field observations suggest that for all but the driest sites, soils formed over granite had no SIC detected while basalt soils with comparable precipitation had measurable amounts of SIC. Grain size distribution appears to be a large control on SIC as the sandier, granitic soils promote

  5. Soil Organic Matter Content: A Non-linear Control on Microbial Respiration in Soils

    NASA Astrophysics Data System (ADS)

    Schnecker, J.; Grandy, S.

    2015-12-01

    Decomposition of soil organic matter (SOM) and the amount of CO2 respired from soil largely depends on the amount of substrate available to microbes. Soils with high SOM concentrations will have higher respiration rates than soils with low SOM concentrations given similar environmental conditions. It is widely assumed that microbial activity and respiration rates respond linearly to substrate concentrations. This assumption remains however largely untested. In a lab incubation experiment, we amended a mixture of agricultural soil and sand with increasing amounts of one of three plant residues differing in their C/N ratio (clover 14; rye 23 and wheat straw 110). We used 9 levels of organic carbon (OC) content ranging from 0.25% to 5.7%. The mixtures were then incubated at constant temperature and water contents for 63 days. Our results show that across substrates CO2 production increased with increasing OC content following a quadratic function instead of the expected linear one up to 2.2% OC. Above that point CO2 production leveled off and increased linearly. We hypothesize that the probability that a microbe meets a substrate also increases with increasing amounts of plant residues. At all substrate concentrations, samples amended with clover had the highest carbon losses, followed by rye and straw. Differences between the three kinds of plant residue might have been caused by their C/N ratios and thus the amount of available N. High amounts of N might have led to an increase in microbial biomass, which could occupy more space and is thus more likely to meet new substrate. Additional analysis of microbial biomass, enzyme activities and N pools will help to understand the mechanism leading to the observed CO2 patterns. A non-linear relation of CO2 production and OC content indicates that spatial separation as an inherent property of SOM content is an important control on decomposition at low OC contents. Knowledge of this controlling effect could be used to enhance

  6. Climatic, edaphic, and biotic controls over storage and turnover of carbon in soils

    SciTech Connect

    Schimel, D.S.; Holland, E.A.; McKeown, R.

    1994-09-01

    Soil carbon, a major component of the global carbon inventory, has significant potential for change with changing climate and human land use. We applied the Century ecosystem model to a series of forest and grassland sites distributed globally to examine large-scale controls over soil carbon. Key site-specific parameters influencing soil carbon dynamics are soil texture and foliar lignin content; accordingly, we perturbed these variables at each site to establish a range of carbon concentrations and turnover times. We examined the simulated soil carbon stores, turnover times, and C:N ratios for correlations with patterns of independent variables. Results showed that soil carbon is related linearly to soil texture, increasing as clay content increases, that soil carbon stores and turnover time are related to mean annual temperature by negative exponential functions, and that heterotrophic respiration originates from recent detritus ({approximately}50%), microbial turnover ({approximately}30%), and soil organic matter ({approximately}20%) with modest variations between forest and grassland ecosystems. The effect of changing temperature on soil organic carbon (SOC) estimated by Century is dSOC/dT = 183e-0.0034T. Global extrapolation of this relationship leads to an estimated sensitivity of soil C storage to a temperature of -11.1 Pg{degrees}C{sup -1}, excluding extreme arid and organic soils. In Century, net primary production (NPP) and soil carbon are closely coupled through the N cycle, so that as temperatures increase, accelerated N release first results in fertilization responses, increasing C inputs. The Century-predicted effect of temperature on carbon storage is modified by as much as 100% by the N cycle feedback. Century-estimated soil C sensitivity -11.1 Pg{degrees}C{sup -1} is similar to losses predicted with a simple data-based calculation -14.1 Pg{degrees}C{sup -1}. 66 refs., 6 figs., 4 tabs.

  7. Determining organic carbon distributions in soil particle size fractions as a precondition of lateral carbon transport modeling at large scales

    NASA Astrophysics Data System (ADS)

    Schindewolf, Marcus; Seher, Wiebke; Pfeffer, Eduard; Schultze, Nico; Amorim, Ricardo S. S.; Schmidt, Jürgen

    2016-04-01

    The erosional transport of organic carbon has an effect on the global carbon budget, however, it is uncertain, whether erosion is a sink or a source for carbon in the atmosphere. Continuous erosion leads to a massive loss of top soils including the loss of organic carbon historically accumulated in the soil humus fraction. The colluvial organic carbon could be protected from further degradation depending on the depth of the colluvial cover and local decomposing conditions. Another part of eroded soils and organic carbon will enter surface water bodies and might be transported over long distances. The selective nature of soil erosion results in a preferential transport of fine particles while less carbonic larger particles remain on site. Consequently organic carbon is enriched in the eroded sediment compared to the origin soil. As a precondition of process based lateral carbon flux modeling, carbon distribution on soil particle size fractions has to be known. In this regard the present study refers to the determination of organic carbon contents on soil particle size separates by a combined sieve-sedimentation method for different tropical and temperate soils Our results suggest high influences of parent material and climatic conditions on carbon distribution on soil particle separates. By applying these results in erosion modeling a test slope was simulated with the EROSION 2D simulation software covering certain land use and soil management scenarios referring to different rainfall events. These simulations allow first insights on carbon loss and depletion on sediment delivery areas as well as carbon gains and enrichments on deposition areas on the landscape scale and could be used as a step forward in landscape scaled carbon redistribution modeling.

  8. Black Carbon Contribution to Organic Carbon Stocks in Urban Soil.

    PubMed

    Edmondson, Jill L; Stott, Iain; Potter, Jonathan; Lopez-Capel, Elisa; Manning, David A C; Gaston, Kevin J; Leake, Jonathan R

    2015-07-21

    Soil holds 75% of the total organic carbon (TOC) stock in terrestrial ecosystems. This comprises ecosystem-derived organic carbon (OC) and black carbon (BC), a recalcitrant product of the incomplete combustion of fossil fuels and biomass. Urban topsoils are often enriched in BC from historical emissions of soot and have high TOC concentrations, but the contribution of BC to TOC throughout the urban soil profile, at a regional scale is unknown. We sampled 55 urban soil profiles across the North East of England, a region with a history of coal burning and heavy industry. Through combined elemental and thermogravimetic analyses, we found very large total soil OC stocks (31-65 kg m(-2) to 1 m), exceeding typical values reported for UK woodland soils. BC contributed 28-39% of the TOC stocks, up to 23 kg C m(-2) to 1 m, and was affected by soil texture. The proportional contribution of the BC-rich fraction to TOC increased with soil depth, and was enriched in topsoil under trees when compared to grassland. Our findings establish the importance of urban ecosystems in storing large amounts of OC in soils and that these soils also capture a large proportion of BC particulates emitted within urban areas.

  9. The Unified North American Soil Map and Its Implication on the Soil Organic Carbon Stock in North America

    SciTech Connect

    Liu, Shishi; Wei, Yaxing; Post, Wilfred M; Cook, Robert B; Schaefer, Kevin; Thornton, Michele M

    2013-01-01

    The Unified North American Soil Map (UNASM) was developed to provide more accurate regional soil information for terrestrial biosphere modeling. The UNASM combines information from state-of-the-art U.S. STATSGO2 and Soil Landscape of Canada (SLCs) databases. The area not covered by these datasets is filled with the Harmonized World Soil Database version 1.1 (HWSD1.1). The UNASM contains maximum soil depth derived from the data source as well as seven soil attributes (including sand, silt, and clay content, gravel content, organic carbon content, pH, and bulk density) for the top soil layer (0-30 cm) and the sub soil layer (30-100 cm) respectively, of the spatial resolution of 0.25 degrees in latitude and longitude. There are pronounced differences in the spatial distributions of soil properties and soil organic carbon between UNASM and HWSD, but the UNASM overall provides more detailed and higher-quality information particularly in Alaska and central Canada. To provide more accurate and up-to-date estimate of soil organic carbon stock in North America, we incorporated Northern Circumpolar Soil Carbon Database (NCSCD) into the UNASM. The estimate of total soil organic carbon mass in the upper 100 cm soil profile based on the improved UNASM is 347.70 Pg, of which 24.7% is under trees, 14.2% is under shrubs, and 1.3% is under grasses and 3.8% under crops. This UNASM data will provide a resource for use in land surface and terrestrial biogeochemistry modeling both for input of soil characteristics and for benchmarking model output.

  10. The Unified North American Soil Map and its implication on the soil organic carbon stock in North America

    NASA Astrophysics Data System (ADS)

    Liu, S.; Wei, Y.; Post, W. M.; Cook, R. B.; Schaefer, K.; Thornton, M. M.

    2012-10-01

    The Unified North American Soil Map (UNASM) was developed to provide more accurate regional soil information for terrestrial biosphere modeling. The UNASM combines information from state-of-the-art US STATSGO2 and Soil Landscape of Canada (SLCs) databases. The area not covered by these datasets is filled with the Harmonized World Soil Database version 1.1 (HWSD1.1). The UNASM contains maximum soil depth derived from the data source as well as seven soil attributes (including sand, silt, and clay content, gravel content, organic carbon content, pH, and bulk density) for the top soil layer (0-30 cm) and the sub soil layer (30-100 cm) respectively, of the spatial resolution of 0.25° in latitude and longitude. There are pronounced differences in the spatial distributions of soil properties and soil organic carbon between UNASM and HWSD, but the UNASM overall provides more detailed and higher-quality information particularly in Alaska and Central Canada. To provide more accurate and up-to-date estimate of soil organic carbon stock in North America, we incorporated Northern Circumpolar Soil Carbon Database (NCSCD) into the UNASM. The estimate of total soil organic carbon mass in the upper 100 cm soil profile based on the improved UNASM is 347.70 Pg, of which 24.7% is under trees, 14.2% is under shrubs, and 1.3% is under grasses and 3.8% under crops. This UNASM data will provide a resource for use in land surface and terrestrial biogeochemistry modeling both for input of soil characteristics and for benchmarking model output.

  11. CQESTR Simulations of soil organic carbon dynamics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A processed-based carbon (C) model, CQESTR (sequester), was used to predict soil organic carbon (SOC) dynamics and examine the effect of agricultural management practices on SOC accretion in three diverse regions of the USA. The three regions chosen had long-term experiments (LTEs) ranging from 23 t...

  12. Soil carbon stabilization and turnover at alley-cropping systems, Eastern Germany

    NASA Astrophysics Data System (ADS)

    Medinski, T.; Freese, D.

    2012-04-01

    Alley-cropping system is seen as a viable land-use practice for mitigation of greenhouse gas CO2, energy-wood production and soil carbon sequestration. The extent to which carbon is stored in soil varies between ecosystems, and depends on tree species, soil types and on the extent of physical protection of carbon within soil aggregates. This study investigates soil carbon sequestration at alley-cropping systems presented by alleys of fast growing tree species (black locust and poplar) and maize, in Brandenburg, Eastern Germany. Carbon accumulation and turnover are assessed by measuring carbon fractions differing in decomposition rates. For this purpose soil samples were fractionated into labile and recalcitrant soil-size fractions by wet-sieving: macro (>250 µm), micro (53-250 µm) and clay + silt (<53 µm), followed by determination of organic carbon and nitrogen by gas-chromatography. Soil samples were also analysed for the total C&N content, cold-water extractable OC, and microbial C. Litter decomposition was evaluated by litter bags experiment. Soil CO2 flux was measured by LiCor automated device LI-8100A. No differences for the total and stable (clay+silt, <53 µm) carbon fraction were observed between treatment. While cold water-extractable carbon was significantly higher at maize alley compared to black locust alley. This may indicate faster turnover of organic matter at maize alley due to tillage, which influenced greater incorporation of plant residues into the soil, greater soil respiration and microbial activity.

  13. [Effects of land use change on soil active organic carbon in deep soils in Hilly Loess Plateau region of Northwest China].

    PubMed

    Zhang, Shuai; Xu, Ming-Xiang; Zhang, Ya-Feng; Wang, Chao-Hua; Chen, Gai

    2015-02-01

    Response of soil active organic carbon to land-use change has become a hot topic in current soil carbon and nutrient cycling study. Soil active organic carbon distribution characteristics in soil profile under four land-use types were investigated in Ziwuling forest zone of the Hilly Loess Plateau region. The four types of land-use changes included natural woodland converted into artificial woodland, natural woodland converted into cropland, natural shrubland converted into cropland and natural shrubland converted into revegetated grassland. Effects of land-use changes on soil active organic carbon in deep soil layers (60-200 cm) were explored by comparison with the shallow soil layers (0-60 cm). The results showed that: (1) The labile organic carbon ( LOC) and microbial carbon (MBC) content were mainly concentrated in the shallow 0-60 cm soil, which accounted for 49%-66% and 71%-84% of soil active organic carbon in the profile (0-200 cm) under different land-use types. Soil active organic carbon content in shallow soil was significantly varied for the land-use changes types, while no obvious difference was observed in soil active organic carbon in deep soil layer. (2) Land-use changes exerted significant influence on soil active organic carbon, the active organic carbon in shallow soil was more sensitive than that in deep soil. The four types of land-use changes, including natural woodland to planted woodland, natural woodland to cropland, natural shrubland to revegetated grassland and natural shrubland to cropland, LOC in shallow soil was reduced by 10%, 60%, 29%, 40% and LOC in the deep layer was decreased by 9%, 21%, 12%, 1%, respectively. MBC in the shallow soil was reduced by 24% 73%, 23%, 56%, and that in the deep layer was decreased by 25%, 18%, 8% and 11%, respectively. (Land-use changes altered the distribution ratio of active organic carbon in soil profile. The ratio between LOC and SOC in shallow soil increased when natural woodland and shrubland were

  14. Shrub Expansion Effects on Soil Carbon Dynamics in the Arctic

    NASA Astrophysics Data System (ADS)

    Holden, S. R.; Mortero, G.; Welker, J. M.; Czimczik, C. I.

    2015-12-01

    Shrubs are increasing in abundance in the Arctic in response to climate warming, but the consequences of shrub expansion for the vast soil carbon (C) stocks in the Arctic are poorly understood. Increases in productivity and associated increases in soil C inputs may augment soil C stocks. Alternatively, labile C exudates from shrub roots may stimulate decomposition of existing soil C and decrease C stocks. We used two complementary approaches to characterize the potential impacts of shrub expansion on soil C dynamics in the Arctic. First, in graminoid and shrub tundra near Toolik Lake, AK we surveyed thaw depth, measured depth profiles of %C, %N, δ13C, and Δ14C, and inventoried soil C stocks to 1 m. We found that the thaw depth was 42% shallower under shrubs compared to graminoid tundra. In addition, mineral soils from shrub tundra had a significantly higher C content than graminoid tundra. Similarly, mineral soils from shrub tundra had lower (depleted) δ13C values compared to graminoid tundra, indicating that this soil has undergone less microbial processing. We also found that C under shrub tundra was on average older, and shrub tundra had significantly higher C stocks to 1 m than graminoid tundra. Second, we conducted a priming experiment with graminoid soil from Toolik Lake, AK. We incubated organic soil, the top 10 cm of mineral soil, and the lower 10 cm of active layer mineral soil with supplemental sucrose at 7°C and 22°C. We found that the addition of labile C did not increase microbial decomposition of existing C in mineral soils. Taken together, our findings suggest that shrub expansion may augment soil C storage in the Arctic because a greater proportion of soil C is frozen in permafrost, soil C under shrubs turns over more slowly, and existing C in mineral soil does not appear to be vulnerable to loss via priming. The observed impacts of shrub expansion on soil C stocks should be incorporated into earth system models that predict the carbon

  15. [Variability of soil water soluble organic carbon content and its response to temperature change in green spaces along urban-to-rural gradient of Nanchang, China].

    PubMed

    Li, Pei-qing; Fang, Xiang-min; Chen, Fu-sheng; Wang, Fang-chao; Yu, Jin-rong; Wan, Song-ze; Li, Zu-yao

    2015-11-01

    Topsoil of green space including typical forest, shrub and grassland were collected to measure their water soluble organic carbon ( WSOC) before and after incubation of 30 days at 5, 15, 25, 35 and, 45 °C. The results showed the average values of WSOC were higher in urban than in rural green spaces, but the percentage of WSOC to total organic carbon (TOC) showed an opposite trend. No significant changes were found among the three green space types in WSOC and WSOC/TOC. Response of WSOC in green space to incubation temperature was generally highest in urban sites, followed by suburban sites, and lowest in rural sites at the incubation temperature of 5 °C, but showed an opposite trend at the temperature of 45 °C. Response coefficient of WSOC to temperature change was lower in forest and shrub than in grassland, but increased along the urban-rural gradient. Further analysis showed that WSOC positively correlated with TOC, total nitrogen and available phosphorus, and the response coefficient of WSOC to temperature change negatively correlated with available phosphorus. In summary, exogenous substances input might lead to the accumulation of WSOC in urban green space, however, urban environment was helpful to maintain the stability of WSOC, which might be due to the enrichment of available phosphorus in urban sites.

  16. [Variability of soil water soluble organic carbon content and its response to temperature change in green spaces along urban-to-rural gradient of Nanchang, China].

    PubMed

    Li, Pei-qing; Fang, Xiang-min; Chen, Fu-sheng; Wang, Fang-chao; Yu, Jin-rong; Wan, Song-ze; Li, Zu-yao

    2015-11-01

    Topsoil of green space including typical forest, shrub and grassland were collected to measure their water soluble organic carbon ( WSOC) before and after incubation of 30 days at 5, 15, 25, 35 and, 45 °C. The results showed the average values of WSOC were higher in urban than in rural green spaces, but the percentage of WSOC to total organic carbon (TOC) showed an opposite trend. No significant changes were found among the three green space types in WSOC and WSOC/TOC. Response of WSOC in green space to incubation temperature was generally highest in urban sites, followed by suburban sites, and lowest in rural sites at the incubation temperature of 5 °C, but showed an opposite trend at the temperature of 45 °C. Response coefficient of WSOC to temperature change was lower in forest and shrub than in grassland, but increased along the urban-rural gradient. Further analysis showed that WSOC positively correlated with TOC, total nitrogen and available phosphorus, and the response coefficient of WSOC to temperature change negatively correlated with available phosphorus. In summary, exogenous substances input might lead to the accumulation of WSOC in urban green space, however, urban environment was helpful to maintain the stability of WSOC, which might be due to the enrichment of available phosphorus in urban sites. PMID:26915196

  17. [Distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta].

    PubMed

    Dong, Hong-Fang; Yu, Jun-Bao; Guan, Bo

    2013-01-01

    Applying the method of physical fractionation, distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta were studied. The results showed that the heavy fraction organic carbon was the dominant component of soil organic carbon in the studied region. There was a significantly positive relationship between the content of heavy fraction organic carbon, particulate organic carbon and total soil organic carbon. The ranges of soil light fraction organic carbon ratio and content were 0.008% - 0.15% and 0.10-0.40 g x kg(-1), respectively, and the range of particulate organic carbon ratio was 8.83% - 30.58%, indicating that the non-protection component of soil organic carbon was low and the carbon pool was relatively stable in Suaeda salsa wetland of the Yellow River delta.

  18. Correlation of soil organic carbon and nutrients (NPK) to soil mineralogy, texture, aggregation, and land use pattern.

    PubMed

    Adhikari, Gopi; Bhattacharyya, Krishna G

    2015-11-01

    This work investigates the correlations existing among soil organic carbon (C), nitrogen (N), phosphorous (P), potassium (K), and physicochemical properties like clay mineralogy, textural components, soil aggregation, and land use pattern. Seven different locations were chosen in the tropical rainforest climate region of Assam, India, for the work. The soil texture classifications were clay, sandy clay loam, and sandy loam with mixed clay mineralogy consisting of tectosilicates and phylosilicates. Two distinct compositions of total Fe/Al oxides≥11.5 and <10.8% were observed along with two distinct groups of water stable soil aggregates of mean weight diameter≈6.42 and ≤3.26 mm. The soil clay and sand had positive and negative contributions respectively to the soil organic carbon (SOC) protection, which was observed to be dependent on lesser sand content, higher silt+clay content, and the presence of higher percentages of total Fe/Al oxides. Soil clay mineralogy suggested that the mineral, chlorite, favored retention of higher SOC content in a particular site. Under similar climatic and mineralogical conditions, both natural and anthropogenic soil disturbances destabilized SOC protection through SOM mineralization and soil aggregate destabilization as indicated by SOC protective capacity studies. Urbanization resulting in soil compaction contributed to enhanced SOC level through increased contact between the occluded organic carbon and the soil mineralogical constituents.

  19. Comparative study on carbon accumulation in soils under managed and unmanaged forests in Central Balkan Mountains

    NASA Astrophysics Data System (ADS)

    Naydenova, Lora; Zhiyanski, Miglena; Leifeld, Jens

    2014-05-01

    Each soil has a carbon storage capacity, which depends on many factors including type of soil, vegetation, precipitation and temperature. The aim of this work is to compare the carbon accumulation in forest floor layers and mineral soil horizons under managed and unmanaged spruce and beech forest ecosystems developed on Cambisols in Central Balkan Mountains, Bulgaria. We have investigated two managed and two unmanaged forests - pure stands of European beech (Fagus sylvatica L.) and Norway spruce (Picea abies Karst.). In each experimental site one representative soil profile was prepared with additional 4 sampling profiles for more precise determination of spatial variability of soil characteristic at site level. The forest floor was sampled in 3 repetitions per site, by a plastic frame (25:25 cm). The textural composition of soil, bulk density, coarse fraction content, pH, carbon and nitrogen content were analysed for forest floor layers and soil at different soil depths (0-10 cm, 10-20 cm, 20-30 cm and 30-50 cm). Both European beech and Norway spruce stands had higher accumulation of organic matter in the forest floor and the Ah horizon under unmanaged conditions. When managed, carbon contents tended to be higher in deeper horizons of the mineral soil, probably due to differences in microclimate after cutting. However, the variability in carbon storage was higher in managed sites which may reflect a higher degree of disturbance. Further work will analyse the soil carbon dynamics using radiocarbon as a tracer.

  20. Remote sensing of soil water content at large scales

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil water content at the near surface is a critical parameter for understanding land surface atmosphere interactions, influencing surface energy balances. Using microwave radiometry, an accurate global map of surface soil water content can be generated on a near daily basis. The accuracy of the p...

  1. Advances in spectroscopic methods for quantifying soil carbon

    USGS Publications Warehouse

    Reeves, James B.; McCarty, Gregory W.; Calderon, Francisco; Hively, W. Dean

    2012-01-01

    The current gold standard for soil carbon (C) determination is elemental C analysis using dry combustion. However, this method requires expensive consumables, is limited by the number of samples that can be processed (~100/d), and is restricted to the determination of total carbon. With increased interest in soil C sequestration, faster methods of analysis are needed, and there is growing interest in methods based on diffuse reflectance spectroscopy in the visible, near-infrared or mid-infrared spectral ranges. These spectral methods can decrease analytical requirements and speed sample processing, be applied to large landscape areas using remote sensing imagery, and be used to predict multiple analytes simultaneously. However, the methods require localized calibrations to establish the relationship between spectral data and reference analytical data, and also have additional, specific problems. For example, remote sensing is capable of scanning entire watersheds for soil carbon content but is limited to the surface layer of tilled soils and may require difficult and extensive field sampling to obtain proper localized calibration reference values. The objective of this chapter is to discuss the present state of spectroscopic methods for determination of soil carbon.

  2. Long term yields and soil carbon sequestration from Miscanthus

    NASA Astrophysics Data System (ADS)

    Jones, Michael; Zimmerman, Jesko

    2016-04-01

    Perennial rhizomatous grasses such as Miscanthus have been assumed to give sustainable biomass yields over many years but there have been few productivity trials that have tested this assumption. In addition it has been suggested that soil carbon sequestration increases linearly over time. We review field trials of Miscanthus, established on former grassland and tilled land, that have been harvested annually for up to twenty years and in which changes in soil organic matter content have been measured. Yields of Miscanthus follow an establishment phase, a ceiling phase and then a phase of decline. The lengths of these phases are strongly influenced by climate, soils and management but it is likely that Miscanthus plantations can produce commercially acceptable yield beyond 20 years. Net soil carbon sequestration depends on previous land use and is strongly influenced by the soil carbon stocks at the time of planting. Under Miscanthus a large fraction of the accumulated carbon is labile and would be rapidly lost if Miscanthus plantations were reconverted to cropland. Currently it is not possible to derive a reliable default sequestration rate for land use change from cropland to Miscanthus energy crop.

  3. ESTABLISHING A SOIL CARBON BASELINE FOR CARBON ACCOUNTING THE FORESTED SOILS OF THE UNITED STATES

    EPA Science Inventory

    Soils are an important global reservoir of organic carbon (C). It has been estimated that at 1500 Pg world soils hold approximately three times the amount of C held in vegetation and two times that in the atmosphere. Soils provide a relatively stable reservoir for C. With the int...

  4. Laser-induced breakdown spectroscopy (LIBS) to measure quantitatively soil carbon with emphasis on soil organic carbon. A review.

    PubMed

    Senesi, Giorgio S; Senesi, Nicola

    2016-09-28

    Soil organic carbon (OC) measurement is a crucial factor for quantifying soil C pools and inventories and monitoring the inherent temporal and spatial heterogeneity and changes of soil OC content. These are relevant issues in addressing sustainable management of terrestrial OC aiming to enhance C sequestration in soil, thus mitigating the impact of increasing CO2 concentration in the atmosphere and related effects on global climate change. Nowadays, dry combustion by an elemental analyzer or wet combustion by dichromate oxidation of the soil sample are the most recommended and commonly used methods for quantitative soil OC determination. However, the unanimously recognized uncertainties and limitations of these classical laboursome methods have prompted research efforts focusing on the development and application of more advanced and appealing techniques and methods for the measurement of soil OC in the laboratory and possibly in situ in the field. Among these laser-induced breakdown spectroscopy (LIBS) has raised the highest interest for its unique advantages. After an introduction and a highlight of the LIBS basic principles, instrumentation, methodologies and supporting chemometric methods, the main body of this review provides an historical and critical overview of the developments and results obtained up-to-now by the application of LIBS to the quantitative measurement of soil C and especially OC content. A brief critical summary of LIBS advantages and limitations/drawbacks including some final remarks and future perspectives concludes this review. PMID:27619082

  5. Laser-induced breakdown spectroscopy (LIBS) to measure quantitatively soil carbon with emphasis on soil organic carbon. A review.

    PubMed

    Senesi, Giorgio S; Senesi, Nicola

    2016-09-28

    Soil organic carbon (OC) measurement is a crucial factor for quantifying soil C pools and inventories and monitoring the inherent temporal and spatial heterogeneity and changes of soil OC content. These are relevant issues in addressing sustainable management of terrestrial OC aiming to enhance C sequestration in soil, thus mitigating the impact of increasing CO2 concentration in the atmosphere and related effects on global climate change. Nowadays, dry combustion by an elemental analyzer or wet combustion by dichromate oxidation of the soil sample are the most recommended and commonly used methods for quantitative soil OC determination. However, the unanimously recognized uncertainties and limitations of these classical laboursome methods have prompted research efforts focusing on the development and application of more advanced and appealing techniques and methods for the measurement of soil OC in the laboratory and possibly in situ in the field. Among these laser-induced breakdown spectroscopy (LIBS) has raised the highest interest for its unique advantages. After an introduction and a highlight of the LIBS basic principles, instrumentation, methodologies and supporting chemometric methods, the main body of this review provides an historical and critical overview of the developments and results obtained up-to-now by the application of LIBS to the quantitative measurement of soil C and especially OC content. A brief critical summary of LIBS advantages and limitations/drawbacks including some final remarks and future perspectives concludes this review.

  6. Mycorrhiza-mediated competition between plants and decomposers drives soil carbon storage.

    PubMed

    Averill, Colin; Turner, Benjamin L; Finzi, Adrien C

    2014-01-23

    Soil contains more carbon than the atmosphere and vegetation combined. Understanding the mechanisms controlling the accumulation and stability of soil carbon is critical to predicting the Earth's future climate. Recent studies suggest that decomposition of soil organic matter is often limited by nitrogen availability to microbes and that plants, via their fungal symbionts, compete directly with free-living decomposers for nitrogen. Ectomycorrhizal and ericoid mycorrhizal (EEM) fungi produce nitrogen-degrading enzymes, allowing them greater access to organic nitrogen sources than arbuscular mycorrhizal (AM) fungi. This leads to the theoretical prediction that soil carbon storage is greater in ecosystems dominated by EEM fungi than in those dominated by AM fungi. Using global data sets, we show that soil in ecosystems dominated by EEM-associated plants contains 70% more carbon per unit nitrogen than soil in ecosystems dominated by AM-associated plants. The effect of mycorrhizal type on soil carbon is independent of, and of far larger consequence than, the effects of net primary production, temperature, precipitation and soil clay content. Hence the effect of mycorrhizal type on soil carbon content holds at the global scale. This finding links the functional traits of mycorrhizal fungi to carbon storage at ecosystem-to-global scales, suggesting that plant-decomposer competition for nutrients exerts a fundamental control over the terrestrial carbon cycle.

  7. Thermokarst dynamics and soil organic matter characteristics controlling initial carbon release from permafrost soils in the Siberian Yedoma region

    NASA Astrophysics Data System (ADS)

    Weiss, Niels; Blok, Daan; Elberling, Bo; Hugelius, Gustaf; Jørgensen, Christian Juncher; Siewert, Matthias Benjamin; Kuhry, Peter

    2016-07-01

    This study relates soil organic matter (SOM) characteristics to initial soil incubation carbon release from upper permafrost samples in Yedoma region soils of northeastern Siberia, Russia. Carbon (C) and nitrogen (N) content, carbon to nitrogen ratios (C:N), δ13C and δ15N values show clear trends that correspond with SOM age and degree of decomposition. Incubation results indicate that older and more decomposed soil material shows higher C respiration rates per unit incubated C than younger and less decomposed samples with higher C content. This is important as undecomposed material is often assumed to be more reactive upon thawing. Large stocks of SOM and their potential decomposability, in combination with complex landscape dynamics that include one or more events of Holocene thaw in most of the landscape, are of consequence for potential greenhouse gas release from permafrost soils in the Yedoma region.

  8. [Effects of nitrogen application and winter green manure on soil active organic carbon and the soil carbon pool management index].

    PubMed

    Yang, Bin-Juan; Huang, Guo-Qin; Lan, Yan; Chen, Hong-Jun; Wang, Shu-Bin

    2014-10-01

    Based on a cropping system of "winter green manure-double rice", the 4 x 4 two-factor test was used to study the effects of different nitrogen (N) application levels and winter green manure application on soil active organic carbon (AOC) and the C pool management index. The aim was to explore the ecological effects of winter green manure on soil improvement and determine the appropriate application levels of N fertilizer and winter green manure for improved rice yield. Results were as follows: 1) Compared with the control, the SOC and AOC contents increased by 22.2% and 26.7%, respectively, under the green manure only treatment, but the SOC contents decreased by 0.6%-3.4% under the single N fertilizer treatment. Compared with the control, the soil C pool management index increased by 24.55 and 15.17 under the green manure only and green manure plus N fertilizer treatments, respectively, and reduced by 2.59 under the single N fertilizer treatment. Compared with no fertilization, the average microbial biomass carbon (MBC) increased by 54.0%, 95.2% and 14.3% under the green manure, green manure plus N fertilizer and single N fertilizer treatments, respectively. 2) The soil AOC content was significantly positively correlated with the C pool management index (P < 0.01), and had a significant correlation with dis- solved organic C and MBC (P < 0.05). Rice yield was significantly positively correlated with AOC contents and the C pool management index, and the correlation coefficient was significantly greater than that with the total organic C. These results suggested that application of winter green manure at proper rates with inorganic fertilizer could increase SOC contents and the soil C pool management index, improve soil quality and fertility.

  9. Deep soil carbon dynamics are driven more by soil type than by climate: a worldwide meta-analysis of radiocarbon profiles.

    PubMed

    Mathieu, Jordane A; Hatté, Christine; Balesdent, Jérôme; Parent, Éric

    2015-11-01

    The response of soil carbon dynamics to climate and land-use change will affect both the future climate and the quality of ecosystems. Deep soil carbon (>20 cm) is the primary component of the soil carbon pool, but the dynamics of deep soil carbon remain poorly understood. Therefore, radiocarbon activity (Δ14C), which is a function of the age of carbon, may help to understand the rates of soil carbon biodegradation and stabilization. We analyzed the published 14C contents in 122 profiles of mineral soil that were well distributed in most of the large world biomes, except for the boreal zone. With a multivariate extension of a linear mixed-effects model whose inference was based on the parallel combination of two algorithms, the expectation-maximization (EM) and the Metropolis-Hasting algorithms, we expressed soil Δ14C profiles as a four-parameter function of depth. The four-parameter model produced insightful predictions of soil Δ14C as dependent on depth, soil type, climate, vegetation, land-use and date of sampling (R2=0.68). Further analysis with the model showed that the age of topsoil carbon was primarily affected by climate and cultivation. By contrast, the age of deep soil carbon was affected more by soil taxa than by climate and thus illustrated the strong dependence of soil carbon dynamics on other pedologic traits such as clay content and mineralogy.

  10. Assessment of methods for organic and inorganic carbon quantification in carbonate-containing Mediterranean soils

    NASA Astrophysics Data System (ADS)

    Apesteguia, Marcos; Virto, Iñigo; Plante, Alain

    2014-05-01

    Quantification of soil organic matter (SOM) stocks and fluxes continues to be an important endeavor in assessments of soil quality, and more broadly in assessments of ecosystem functioning. The quantification of SOM in alkaline, carbonate-containing soils, such as those found in Mediterranean areas, is complicated by the need to differentiate between organic carbon (OC) and inorganic carbon (IC), which continues to present methodological challenges. Acidification is frequently used to eliminate carbonates prior to soil OC quantification, but when performed in the liquid phase, can promote the dissolution and loss of a portion of the OC. Acid fumigation (AF) is increasingly preferred for carbonate removal, but its effectiveness is difficult to assess using conventional elemental and isotopic analyses. In addition, the potential effects of AF on SOM are not well characterized. The objective of the current study was to apply a multi-method approach to determine the efficacy of carbonate removal by AF and its effects on the residual SOM. We selected a set of 24 surface agricultural soils representing a large range of textures, SOM contents and presumed carbonate contents. For each soil, OC was determined using wet combustion (Walkley-Black) and IC was determined using the calcimeter method. Samples were then subjected to elemental (total C) and isotopic (δ13C) analyses by dry combustion using a Costech autoanalyzer coupled to a Thermo Finnigan Delta Plus isotope ratio mass spectrometer (IRMS) before and after AF. IC was equated to total C determined after fumigation, and OC was estimated as the different in total C before and after AF. Samples were also subjected to ramped oxidation using a Netzsch STA109 PC Luxx thermal analyzer coupled to a LICOR 820A infrared gas analyzer (IRGA). Quantification of OC was performed using evolved gas analysis of CO2 (CO2-EGA) in the exothermic region 200-500° C associated with organic matter combustion. IC was quantified by CO2-EGA

  11. Dynamics of maize carbon contribution to soil organic carbon in association with soil type and fertility level.

    PubMed

    Pei, Jiubo; Li, Hui; Li, Shuangyi; An, Tingting; Farmer, John; Fu, Shifeng; Wang, Jingkuan

    2015-01-01

    Soil type and fertility level influence straw carbon dynamics in the agroecosystems. However, there is a limited understanding of the dynamic processes of straw-derived and soil-derived carbon and the influence of the addition of straw carbon on soil-derived organic carbon in different soils associated with different fertility levels. In this study, we applied the in-situ carborundum tube method and 13C-labeled maize straw (with and without maize straw) at two cropland (Phaeozem and Luvisol soils) experimental sites in northeast China to quantify the dynamics of maize-derived and soil-derived carbon in soils associated with high and low fertility, and to examine how the addition of maize carbon influences soil-derived organic carbon and the interactions of soil type and fertility level with maize-derived and soil-derived carbon. We found that, on average, the contributions of maize-derived carbon to total organic carbon in maize-soil systems during the experimental period were differentiated among low fertility Luvisol (from 62.82% to 42.90), high fertility Luvisol (from 53.15% to 30.00%), low fertility Phaeozem (from 58.69% to 36.29%) and high fertility Phaeozem (from 41.06% to 16.60%). Furthermore, the addition of maize carbon significantly decreased the remaining soil-derived organic carbon in low and high fertility Luvisols and low fertility Phaeozem before two months. However, the increasing differences in soil-derived organic carbon between both soils with and without maize straw after two months suggested that maize-derived carbon was incorporated into soil-derived organic carbon, thereby potentially offsetting the loss of soil-derived organic carbon. These results suggested that Phaeozem and high fertility level soils would fix more maize carbon over time and thus were more beneficial for protecting soil-derived organic carbon from maize carbon decomposition.

  12. Dynamics of Maize Carbon Contribution to Soil Organic Carbon in Association with Soil Type and Fertility Level

    PubMed Central

    Pei, Jiubo; Li, Hui; Li, Shuangyi; An, Tingting; Farmer, John; Fu, Shifeng; Wang, Jingkuan

    2015-01-01

    Soil type and fertility level influence straw carbon dynamics in the agroecosystems. However, there is a limited understanding of the dynamic processes of straw-derived and soil-derived carbon and the influence of the addition of straw carbon on soil-derived organic carbon in different soils associated with different fertility levels. In this study, we applied the in-situ carborundum tube method and 13C-labeled maize straw (with and without maize straw) at two cropland (Phaeozem and Luvisol soils) experimental sites in northeast China to quantify the dynamics of maize-derived and soil-derived carbon in soils associated with high and low fertility, and to examine how the addition of maize carbon influences soil-derived organic carbon and the interactions of soil type and fertility level with maize-derived and soil-derived carbon. We found that, on average, the contributions of maize-derived carbon to total organic carbon in maize-soil systems during the experimental period were differentiated among low fertility Luvisol (from 62.82% to 42.90), high fertility Luvisol (from 53.15% to 30.00%), low fertility Phaeozem (from 58.69% to 36.29%) and high fertility Phaeozem (from 41.06% to 16.60%). Furthermore, the addition of maize carbon significantly decreased the remaining soil-derived organic carbon in low and high fertility Luvisols and low fertility Phaeozem before two months. However, the increasing differences in soil-derived organic carbon between both soils with and without maize straw after two months suggested that maize-derived carbon was incorporated into soil-derived organic carbon, thereby potentially offsetting the loss of soil-derived organic carbon. These results suggested that Phaeozem and high fertility level soils would fix more maize carbon over time and thus were more beneficial for protecting soil-derived organic carbon from maize carbon decomposition. PMID:25774529

  13. Distinguishing "new" from "old" carbon in post mining soils

    NASA Astrophysics Data System (ADS)

    Vindušková, Olga; Frouz, Jan

    2014-05-01

    study area is highly aliphatic. 13C CPMAS NMR spectroscopy is an analytical technique used for structural characterization of soil organic matter (Preston 1996). Particular regions of NMR spectra can be assigned to alkyl C, O-alkyl C, aromatic C, and carboxylic C (Kögel-Knabner 2000). We hypothesize that recently derived and fossil organic matter will have different relative proportions of signals in these regions and this difference could be used to estimate recently derived SOC in unknown samples. Rock-Eval pyrolysis is a method used in oil exploration to evaluate the quantity, quality and thermal maturity of organic matter in sediments. Lately, is has been applied also to soils and can bring useful information about soil organic matter (Sebag et al. 2006; Disnar et al. 2003). Particularly, it allows to determine the total organic carbon content (TOC wt.%) and also provides Hydrogen and Oxygen Index values (HI and OI) which are known to correlate wit H/C and O/C ratios. Also, pyrolysis and oxidation products (hydrocarbons, CO and CO2) can be plotted against temperature and give us an idea of thermal stability of their source compounds. We hypothesize that recently derived and fossil organic matter will differ in thermal stability and also in the quantity and quality of pyrolysis products. These differences could allow to quantify both fractions in post-mining soils. XRD (X-ray diffraction) is an analytical technique used to identify minerals in rocks and soils and give a semi-quantitative estimate of their content. Carbonates (as an inorganic form of carbon, IC) can be source of bias in some organic carbon analyses. Carbonates can be removed from samples by acid treatment but the specific procedure that is required depends on the type (and solubility) of carbonates present in sample (Brodie et al. 2011). Up to now, other methods did not show a significant content of IC in Sokolov soils; however, previous XRD analyses of parent claystones in the area showed that

  14. Recent AMS measurements of {sup 14}C in soil organic matter: Understanding controls of carbon storage and turnover in soils

    SciTech Connect

    Trumbore, S.E.; Torn, M.S.; Chadwick, O.A.

    1996-10-01

    Radiocarbon measurements are one of the best tools available for determining the rates of carbon and turnover of in soil organic matter. AMS measurements of radiocarbon are essential they allow measurement of {sup 14}C in archived soils with very low carbon content, in physically or chemically fractionated soil organic matter, in dissolved organic carbon leached from soils, as well as in CO{sub 2} and CH{sub 4} produced during decomposition. We report recent results demonstrating the importance of applying AMS soil radiocarbon measurements to questions of soil C dynamics. We used the increase in {open_quote}bomb{close_quote} {sup 14}C between archived an modem soil profiles sampled along an elevation transect in the Sierra Nevada mountains, California, to determine the role of temperature in determining the rate of turnover of fast-cycling soil organic matter. To study the role of soil mineralogy in determining how carbon is stabilized in {open_quote}passive{close_quote} soil organic matter pools, we compare soil mineralogy and C and {sup 14}C storage in soils along a chronosequence in the Hawaiian islands. Implications for the global C cycle will be discussed.

  15. Soil organic carbon pools in olive groves of different age

    NASA Astrophysics Data System (ADS)

    Massaccesi, Luisa; De Feudis, Mauro; Nasini, Luigi; Regni, Luca; D'Ascoli, Rosaria; Castaldi, Simona; Proietti, Primo; Agnelli, Alberto

    2016-04-01

    In the last years, the practices which favor the increase of soil organic carbon in the agroecosystem have been widely studied because of their influence on the reduction of atmospheric CO2 (Lal, 1993; Schlesinger, 2000). The accumulation of the organic carbon into the soil depends to a great extent upon climate and pedological properties (Burke et al., 1989; Miller et al., 1994), although in the agricultural soils the cultivation system also plays a key role. The olive grove might potentially represent a relevant land use to improve C sequestration in soil, but there are few data available to support this hypothesis. In a study site located in central Italy (Deruta, PG), we analyzed the soil organic carbon (SOC) pools in two olive groves of different age (7 and 30 years) and, as control, in a site adjacent to the groves cropped with cereals for at least 30 years. With the aim to isolate and quantify the active, intermediate and passive functional SOC pools in the olive groves and in the control, we used a combined physical and chemical fractionation method (Zimmermann et al., 2007). The main results shown that the total organic carbon content in the Ap horizons was the highest in the 30-years-old olive grove, followed by the 7-years-old olive grove, and then by the control soil. The content of active C, in form of particulate organic matter (POM) and water soluble organic matter (WEOM), was greater in the olive grove compared to the control soil and increase with the age of the grove. About the amount of C in the intermediate and passive pools, no significant differences were found among the olive groves and the control. These preliminary results indicated that the greater total organic C content occurred in the 30-year-old olive grove with respect to the 7-years-old grove and the control, has to be ascribed to the greater content of active organic matter (POM and WEOM), and not to the accumulation in soil of organic C in a more stabilised form.

  16. Role of organic soils in the world carbon cycle: problem analysis and research needs

    SciTech Connect

    Armentano, T.V.

    1980-02-01

    In May 1979, The Institute of Ecology held a workshop to determine the role of organic soils in the global carbon cycle and to ascertain their past, present and future significance in world carbon flux. Wetlands ecologists and soil scientists who participated in the workshop examined such topics as Soils as Sources of Atmospheric CO/sub 2/, Organic Soils, Primary Production and Growth of Wetlands Ecosystems, and Management of Peatlands. The major finding of the workshop is that the organic soils are important in the overall carbon budget. Histosols and Gleysols, the major organic soil deposits of the world, normally sequester organic carbon fixed by plants. They may now be releasing enough carbon to account for nearly 10% of the annual rise in atmospheric content of CO/sub 2/.

  17. Cadmium content of plants as affected by soil cadmium concentration

    SciTech Connect

    Lehoczky, E.; Szabados, I.; Marth, P.

    1996-12-31

    Pot experiments were conducted in greenhouse conditions to study the effects of increasing cadmium (Cd) levels on biomass production and Cd contents in corn, (Zea mays L.), garlic (Allium sativum L.), and spinach (Spinacia oleracea L.). Plants were grown in two soil types: Eutric cambisol soil and A gleyic luvisol soil. Spinach proved to be the most sensitive to Cd treatments as its biomass considerably decreased with the increasing Cd levels. Cadmium contents of the three crops increased with increasing levels of Cd applications. Statistical differences were observed in the Cd contents of crops depending on soil type. With the same Cd rates, Cd tissue concentration of test plants grown in the strongly acidic Gleyic luvisol soil were many times higher than that of plants grown in a neutral Eutric cambisol soil. 14 refs., 4 tabs.

  18. Comparing the methods for determination of carbon in soil

    NASA Astrophysics Data System (ADS)

    Bidló, A.; Szżcs, P.; Horváth, A.; Kámán, O.; Németh, E.; Juhász, P.

    2012-04-01

    The global climate change raised the question of carbon sequestration of forests. Forests are important natural carbon sequesters in the temperate zone. It can be ascertained, that a significant part of carbon (often more than half of it), can be found in the soil. The greater amount of carbon can be found in the organic substance of soil (humus). There are several methods for determination of carbon in soil. The most popular method is determination by dry-burning, which means that the samples are exposed to high temperature and the amount of carbon content of CO2 becomes observable with the help of thermal conductivity detector or infrared spectroscopy. The advantage of this system is that burning and carbon content determination happens in a reproducible way if the conditions are satisfactory. However, this method is limited, because e. g. in Hungary the soil contains too much lime (often above 50%) and during the burning CO2 evolves from decomposition of minerals. The previous hydrochloric destruction of carbonate is not usable for lime content during examination. In the case of soils with high lime content the application of wet oxidation by potassium dichromate for organic matter determination is correct. During our investigation we made a comparison between the results of dry and three different wet burning, in the same way we did with organic matter determination in parallel with the determination of 320 soil samples. Between the results of wet burning we detected a decided difference. The Tyurin-type humus (Benediktas 2006, Tóth and Szabó 2003) determination (which is widely applied in Eastern Europe and it is a gas burning destruction method) showed high dispersion. The other destruction method showed favourable results, this method is applied on water bath, and is corresponding to the Hungarian standard. The correlation coefficient was between 0,87 és 0,98 amongst three analytical methods. We made a comparison between results of wet and dry burning

  19. Assessing the Mercury Content in Mediterranean Calcareous Soils

    NASA Astrophysics Data System (ADS)

    Gil, C.; Ramos-Miras, J.; Roca-Pérez, L.; Boluda, R.; Bech, J.

    2010-05-01

    Soil constitutes the greatest reservoir of mercury in terrestrial ecosystems and is the main pollution route for aquatic systems and the food chain. We determined the mercury total content in Mediterranean calcareous soils by thermal decomposition, amalgamation and atomic absorption spectrophotometry, and on the base of the background level and geochemical baseline concentration concepts the contamination degree in some agricultural soils were assessed. Fifty-three samples from five soil use groups (natural, dry land, greenhouse, irrigated and rice farming soils) were analysed. The results showed that the levels of mercury in these soils were 9.4 to 1585 μg kg-1. Soil organic matter has been related to mercury content in soils. The background level, geochemical baseline concentrations and the reference value were established from natural soils being the followings: 25.1, 9.8-64.3, and 64.3 μg kg-1. These results indicated that rice farming soils (gleyic-calcaric Fluvisols, Fluvaquents), irrigated soils (calcaric Fluvisols, Xerofluvents) and some greenhouse soils (cumulic Anthrosols) presented much higher levels, indicating contamination. Hg accumulation in these soils was associated with local anthropogenic sources.

  20. Climate, soil texture, and soil types affect the contributions of fine-fraction-stabilized carbon to total soil organic carbon in different land uses across China.

    PubMed

    Cai, Andong; Feng, Wenting; Zhang, Wenju; Xu, Minggang

    2016-05-01

    Mineral-associated organic carbon (MOC), that is stabilized by fine soil particles (i.e., silt plus clay, <53 μm), is important for soil organic carbon (SOC) persistence and sequestration, due to its large contribution to total SOC (TSOC) and long turnover time. Our objectives were to investigate how climate, soil type, soil texture, and agricultural managements affect MOC contributions to TSOC in China. We created a dataset from 103 published papers, including 1106 data points pairing MOC and TSOC across three major land use types: cropland, grassland, and forest. Overall, the MOC/TSOC ratio ranged from 0.27 to 0.80 and varied significantly among soil groups in cropland, grassland, and forest. Croplands and forest exhibited significantly higher median MOC/TSOC ratios than in grassland. Moreover, forest and grassland soils in temperate regions had higher MOC/TSOC ratios than in subtropical regions. Furthermore, the MOC/TSOC ratio was much higher in ultisol, compared with the other soil types. Both the MOC content and MOC/TSOC ratio were positively correlated with the amount of fine fraction (silt plus clay) in soil, highlighting the importance of soil texture in stabilizing organic carbon across various climate zones. In cropland, different fertilization practices and land uses (e.g., upland, paddy, and upland-paddy rotation) significantly altered MOC/TSOC ratios, but not in cropping systems (e.g., mono- and double-cropping) characterized by climatic differences. This study demonstrates that the MOC/TSOC ratio is mainly driven by soil texture, soil types, and related climate and land uses, and thus the variations in MOC/TSOC ratios should be taken into account when quantitatively estimating soil C sequestration potential of silt plus clay particles on a large scale. PMID:26905446

  1. Climate, soil texture, and soil types affect the contributions of fine-fraction-stabilized carbon to total soil organic carbon in different land uses across China.

    PubMed

    Cai, Andong; Feng, Wenting; Zhang, Wenju; Xu, Minggang

    2016-05-01

    Mineral-associated organic carbon (MOC), that is stabilized by fine soil particles (i.e., silt plus clay, <53 μm), is important for soil organic carbon (SOC) persistence and sequestration, due to its large contribution to total SOC (TSOC) and long turnover time. Our objectives were to investigate how climate, soil type, soil texture, and agricultural managements affect MOC contributions to TSOC in China. We created a dataset from 103 published papers, including 1106 data points pairing MOC and TSOC across three major land use types: cropland, grassland, and forest. Overall, the MOC/TSOC ratio ranged from 0.27 to 0.80 and varied significantly among soil groups in cropland, grassland, and forest. Croplands and forest exhibited significantly higher median MOC/TSOC ratios than in grassland. Moreover, forest and grassland soils in temperate regions had higher MOC/TSOC ratios than in subtropical regions. Furthermore, the MOC/TSOC ratio was much higher in ultisol, compared with the other soil types. Both the MOC content and MOC/TSOC ratio were positively correlated with the amount of fine fraction (silt plus clay) in soil, highlighting the importance of soil texture in stabilizing organic carbon across various climate zones. In cropland, different fertilization practices and land uses (e.g., upland, paddy, and upland-paddy rotation) significantly altered MOC/TSOC ratios, but not in cropping systems (e.g., mono- and double-cropping) characterized by climatic differences. This study demonstrates that the MOC/TSOC ratio is mainly driven by soil texture, soil types, and related climate and land uses, and thus the variations in MOC/TSOC ratios should be taken into account when quantitatively estimating soil C sequestration potential of silt plus clay particles on a large scale.

  2. Impacts of crop rotations on soil organic carbon sequestration

    NASA Astrophysics Data System (ADS)

    Gobin, Anne; Vos, Johan; Joris, Ingeborg; Van De Vreken, Philippe

    2013-04-01

    Agricultural land use and crop rotations can greatly affect the amount of carbon sequestered in the soil. We developed a framework for modelling the impacts of crop rotations on soil carbon sequestration at the field scale with test case Flanders. A crop rotation geo-database was constructed covering 10 years of crop rotation in Flanders using the IACS parcel registration (Integrated Administration and Control System) to elicit the most common crop rotation on major soil types in Flanders. In order to simulate the impact of crop cover on carbon sequestration, the Roth-C model was adapted to Flanders' environment and coupled to common crop rotations extracted from the IACS geodatabases and statistical databases on crop yield. Crop allometric models were used to calculate crop residues from common crops in Flanders and subsequently derive stable organic matter fluxes to the soil (REGSOM). The REGSOM model was coupled to Roth-C model was run for 30 years and for all combinations of seven main arable crops, two common catch crops and two common dosages of organic manure. The common crops are winter wheat, winter barley, sugar beet, potato, grain maize, silage maize and winter rapeseed; the catch crops are yellow mustard and Italian ryegrass; the manure dosages are 35 ton/ha cattle slurry and 22 ton/ha pig slurry. Four common soils were simulated: sand, loam, sandy loam and clay. In total more than 2.4 million simulations were made with monthly output of carbon content for 30 years. Results demonstrate that crop cover dynamics influence carbon sequestration for a very large percentage. For the same rotations carbon sequestration is highest on clay soils and lowest on sandy soils. Crop residues of grain maize and winter wheat followed by catch crops contribute largely to the total carbon sequestered. This implies that agricultural policies that impact on agricultural land management influence soil carbon sequestration for a large percentage. The framework is therefore

  3. Microbes residing in young organic rich Alaskan soils contain older carbon than those residing in old mineral high Arctic soils

    NASA Astrophysics Data System (ADS)

    Ziolkowski, L. A.; Slater, G. F.; Onstott, T. C.; Whyte, L.; Townsend-Small, A.

    2013-12-01

    Arctic soils range from very organic rich to low carbon and mineral-dominated soils. At present, we do not yet fully understand if all carbon in the Arctic is equally vulnerable to mineralization in a warmer climate. Many studies have demonstrated that ancient carbon is respired when permafrost has thawed, yet our understanding of the active layer and permafrost carbon dynamics is still emerging. In an effort to remedy this disconnect between our knowledge of surface fluxes and below ground processes, we used radiocarbon to examine the microbial carbon dynamics in soil cores from organic rich soils near Barrow, Alaska and mineral soils from the Canadian high Arctic. Specifically, we compared the microbial community using lipid biomarkers, the inputs of carbon using n-alkanes and measured the 14C of both the bulk organic carbon and of the microbial lipids. In theory, the microbial lipids (phospholipid fatty acids, PLFA) represent the viable microbial community, as these lipids are hydrolyzed quickly after cell death. Variations in the PLFA distributions suggested that different microbial communities inhabit organic rich Alaskan soils and those of the Canadian high Arctic. When the PLFA concentrations were converted to cellular concentration, they were within the same order of magnitude (1 to 5 x 108 cells/g dry soil) with slightly higher cell concentrations in the organic rich Alaskan soils. When these cellular concentrations were normalized to the organic carbon content, the Canadian high Arctic soils contained a greater proportion of microbes. Although bulk organic carbon 14C of Alaskan soils indicated more recent carbon inputs into the soil than the Canadian high Arctic soils, the 14C of the PLFA revealed the opposite. For corresponding depth horizons, microbes in Alaskan soils were consuming carbon 1000 to 1500 years older than those in the Canadian high Arctic. Differences between the 14C content of bulk organic carbon and the microbial lipids were much smaller

  4. [Dynamics of active organic carbon in a paddy soil under different rice farming modes].

    PubMed

    Zhan, Ming; Cao, Cou-Gui; Jiang, Yang; Wang, Jin-Ping; Yue, Li-Xin; Cai, Ming-Li

    2010-08-01

    A field experiment was conducted to study the dynamics of dissolved organic carbon (DOC), readily oxidizable organic carbon (ROC), and microbial biomass carbon (MBC) in a paddy soil under integrated rice-duck farming (RD), intermittent irrigation (RW), and conventional flooded irrigation (CK), the three rice farming modes typical in southern China. Under these three farming modes, the soil DOC and MBC contents reached the highest during the period from rice booting to heading, while the soil ROC content had less change during the whole rice growth period. Two-factor variance analysis showed that soil MBC was greatly affected by rice growth stage, soil DOC was greatly affected by rice growth stage and farming mode, and soil ROC was mainly affected by farming mode. Comparing with CK, RD significantly increased the soil DOC and ROC contents and their availability, while RW significantly decreased the soil DOC content and its availability but increased the soil ROC content and its availability. No significant differences were observed in the soil MBC and microbial quotient among RD, RW, and CK.

  5. Urban Tree Effects on Soil Organic Carbon

    PubMed Central

    Edmondson, Jill L.; O'Sullivan, Odhran S.; Inger, Richard; Potter, Jonathan; McHugh, Nicola; Gaston, Kevin J.; Leake, Jonathan R.

    2014-01-01

    Urban trees sequester carbon into biomass and provide many ecosystem service benefits aboveground leading to worldwide tree planting schemes. Since soils hold ∼75% of ecosystem organic carbon, understanding the effect of urban trees on soil organic carbon (SOC) and soil properties that underpin belowground ecosystem services is vital. We use an observational study to investigate effects of three important tree genera and mixed-species woodlands on soil properties (to 1 m depth) compared to adjacent urban grasslands. Aboveground biomass and belowground ecosystem service provision by urban trees are found not to be directly coupled. Indeed, SOC enhancement relative to urban grasslands is genus-specific being highest under Fraxinus excelsior and Acer spp., but similar to grasslands under Quercus robur and mixed woodland. Tree cover type does not influence soil bulk density or C∶N ratio, properties which indicate the ability of soils to provide regulating ecosystem services such as nutrient cycling and flood mitigation. The trends observed in this study suggest that genus selection is important to maximise long-term SOC storage under urban trees, but emerging threats from genus-specific pathogens must also be considered. PMID:25003872

  6. Urban tree effects on soil organic carbon.

    PubMed

    Edmondson, Jill L; O'Sullivan, Odhran S; Inger, Richard; Potter, Jonathan; McHugh, Nicola; Gaston, Kevin J; Leake, Jonathan R

    2014-01-01

    Urban trees sequester carbon into biomass and provide many ecosystem service benefits aboveground leading to worldwide tree planting schemes. Since soils hold ∼75% of ecosystem organic carbon, understanding the effect of urban trees on soil organic carbon (SOC) and soil properties that underpin belowground ecosystem services is vital. We use an observational study to investigate effects of three important tree genera and mixed-species woodlands on soil properties (to 1 m depth) compared to adjacent urban grasslands. Aboveground biomass and belowground ecosystem service provision by urban trees are found not to be directly coupled. Indeed, SOC enhancement relative to urban grasslands is genus-specific being highest under Fraxinus excelsior and Acer spp., but similar to grasslands under Quercus robur and mixed woodland. Tree cover type does not influence soil bulk density or C∶N ratio, properties which indicate the ability of soils to provide regulating ecosystem services such as nutrient cycling and flood mitigation. The trends observed in this study suggest that genus selection is important to maximise long-term SOC storage under urban trees, but emerging threats from genus-specific pathogens must also be considered.

  7. Urban tree effects on soil organic carbon.

    PubMed

    Edmondson, Jill L; O'Sullivan, Odhran S; Inger, Richard; Potter, Jonathan; McHugh, Nicola; Gaston, Kevin J; Leake, Jonathan R

    2014-01-01

    Urban trees sequester carbon into biomass and provide many ecosystem service benefits aboveground leading to worldwide tree planting schemes. Since soils hold ∼75% of ecosystem organic carbon, understanding the effect of urban trees on soil organic carbon (SOC) and soil properties that underpin belowground ecosystem services is vital. We use an observational study to investigate effects of three important tree genera and mixed-species woodlands on soil properties (to 1 m depth) compared to adjacent urban grasslands. Aboveground biomass and belowground ecosystem service provision by urban trees are found not to be directly coupled. Indeed, SOC enhancement relative to urban grasslands is genus-specific being highest under Fraxinus excelsior and Acer spp., but similar to grasslands under Quercus robur and mixed woodland. Tree cover type does not influence soil bulk density or C∶N ratio, properties which indicate the ability of soils to provide regulating ecosystem services such as nutrient cycling and flood mitigation. The trends observed in this study suggest that genus selection is important to maximise long-term SOC storage under urban trees, but emerging threats from genus-specific pathogens must also be considered. PMID:25003872

  8. Effects of grazing intensity on soil labile organic carbon fractions in a desert steppe area in Inner Mongolia.

    PubMed

    Cao, Jixin; Wang, Xiaoping; Sun, Xiangyang; Zhang, Lin; Tian, Yun

    2013-01-01

    Grazing can cause changes in soil carbon (C) level. This study aimed to elucidate the response of soil labile organic carbon (SLOC) under four different grazing intensities: non grazing (NG), 0 sheep·ha(-1); light grazing (LG), 0.91 sheep·ha(-1); moderate grazing (MG), 1.82 sheep·ha(-1), and heavy grazing (HG), 2.73 sheep·ha(-1). Results showed that there was no significant difference in total soil organic carbon (TOC) and soil inorganic carbon (SIC) content from three soil depths (0-15 cm, 15-30 cm, and 30-45 cm) under different grazing intensities. However, the SLOC including particulate organic carbon (POC), light fraction organic carbon (LFOC), and readily oxidizable carbon (ROC) content at a depth of 0-15 cm decreased with the increasing grazing intensity among LG, MG and HG. The SLOC content at depths of 15-30 cm under the NG and LG were significantly higher than that under the MG and the HG. The TOC and SLOC content decreased with increasing depths of soil horizons, but SIC content increased. The variation trend of the density of different soil carbon fractions and the ratio of individual SLOC fractions to TOC were similar to that of the soil carbon content of corresponding fractions. These results indicated that MG and HG treatments caused C loss at 0-30 cm; and SLOC was more sensitive than TOC in response to different grazing intensities.

  9. Storage/Turnover rate of inorganic carbon and its dissolvable part in the profile of saline/alkaline soils.

    PubMed

    Wang, Yugang; Wang, Zhongyuan; Li, Yan

    2013-01-01

    Soil inorganic carbon is the most common form of carbon in arid and semiarid regions, and has a very long turnover time. However, little is known about dissolved inorganic carbon storage and its turnover time in these soils. With 81 soil samples taken from 6 profiles in the southern Gurbantongute Desert, China, we investigated the soil inorganic carbon (SIC) and the soil dissolved inorganic carbon (SDIC) in whole profiles of saline and alkaline soils by analyzing their contents and ages with radiocarbon dating. The results showed that there is considerable SDIC content in SIC, and the variations of SDIC and SIC contents in the saline soil profile were much larger than that in the alkaline profile. SDIC storage accounted for more than 20% of SIC storage, indicating that more than 1/5 of the inorganic carbon in both saline and alkaline soil is not in non-leachable forms. Deep layer soil contains considerable inorganic carbon, with more than 80% of the soil carbon stored below 1 m, whether for SDIC or SIC. More importantly, SDIC ages were much younger than SIC in both saline soil and alkaline soil. The input rate of SDIC and SIC ranged from 7.58 to 29.54 g C m(-2) yr(-1) and 1.34 to 5.33 g C m(-2) yr(-1) respectively for saline soil, and from 1.43 to 4.9 g C m(-2) yr(-1) and 0.79 to 1.27 g C m(-2) yr(-1)respectively for alkaline soil. The comparison of SDIC and SIC residence time showed that using soil inorganic carbon to estimate soil carbon turnover would obscure an important fraction that contributes to the modern carbon cycle: namely the shorter residence and higher input rate of SDIC. This is especially true for SDIC in deep layers of the soil profile.

  10. Storage/Turnover Rate of Inorganic Carbon and Its Dissolvable Part in the Profile of Saline/Alkaline Soils

    PubMed Central

    Wang, Yugang; Wang, Zhongyuan; Li, Yan

    2013-01-01

    Soil inorganic carbon is the most common form of carbon in arid and semiarid regions, and has a very long turnover time. However, little is known about dissolved inorganic carbon storage and its turnover time in these soils. With 81 soil samples taken from 6 profiles in the southern Gurbantongute Desert, China, we investigated the soil inorganic carbon (SIC) and the soil dissolved inorganic carbon (SDIC) in whole profiles of saline and alkaline soils by analyzing their contents and ages with radiocarbon dating. The results showed that there is considerable SDIC content in SIC, and the variations of SDIC and SIC contents in the saline soil profile were much larger than that in the alkaline profile. SDIC storage accounted for more than 20% of SIC storage, indicating that more than 1/5 of the inorganic carbon in both saline and alkaline soil is not in non-leachable forms. Deep layer soil contains considerable inorganic carbon, with more than 80% of the soil carbon stored below 1 m, whether for SDIC or SIC. More importantly, SDIC ages were much younger than SIC in both saline soil and alkaline soil. The input rate of SDIC and SIC ranged from 7.58 to 29.54 g C m-2 yr-1 and 1.34 to 5.33 g C m-2 yr-1 respectively for saline soil, and from 1.43 to 4.9 g C m-2 yr-1 and 0.79 to 1.27 g C m-2 yr-1respectively for alkaline soil. The comparison of SDIC and SIC residence time showed that using soil inorganic carbon to estimate soil carbon turnover would obscure an important fraction that contributes to the modern carbon cycle: namely the shorter residence and higher input rate of SDIC. This is especially true for SDIC in deep layers of the soil profile. PMID:24312399

  11. [Relationship between soil enzyme activities and trace element contents in Eucalyptus plantation soil].

    PubMed

    Li, Yuelin; Peng, Shaolin; Li, Zhihui; Ren, Hai; Li, Zhi'an

    2003-03-01

    Canonical correlation analysis on soil enzyme activities and trace element contents in Eucalyptus plantation soil showed that among the test elements, only Zn and Mn affected enzyme activity. Both Zn and Mn increased soil proteinase activity. Zn decreased the activities of soil urease and peroxidase, while Mn promoted them. "Integral soil enzyme factor" could be used as an index of soil fertility. Together with other growth factors, this index should be considered when evaluating soil fertility of Eucalyptus forest sites. It also had a definite significance on the division of Eucalyptus soil families. PMID:12836538

  12. [Relationships of soil organic carbon with its active and non-active components under different land use types in the middle reaches of Heihe River, China].

    PubMed

    Zhang, Jun-Hua; Li, Guo-Dong; Wang, Yan-Song; Nan, Zhong-Ren; Zhao, Li-Ping

    2012-12-01

    Taking the seven typical land use types (paddy field, dry land, medium coverage grassland, saline-alkali field, bare land, desert, and sandlot) in the middle reaches of Heihe River as test objects, this paper studied the relationships of soil organic carbon content with its components. In the 0-100 cm soil profile, the contents of soil total organic carbon (TOC) , active organic carbon (AOC), and non-active organic carbon (NOC) decreased with increasing depth. The soil TOC, AOC, and NOC contents differed with land use type. Land use change induced the increase or decrease of soil organic carbon content. The tillage in paddy field was an available way to increase the contents of soil TOC, AOC, and NOC. After land use change, soil NOC rather than AOC contributed more to soil TOC content. For the same land use types, soil AOC and NOC contents increased together with increasing soil TOC content, and the NOC content increased faster than the AOC content. The soil TOC content corresponding to the crossing point of the variation trend lines of soil AOC and NOC contents could be considered as the boundary point of TOC accumulation or loss, and the saturation capacities of soil AOC and NOC could be obtained by the variation trend lines of the AOC and NOC.

  13. Riparian reforestation: are there changes in soil carbon and soil microbial communities?

    PubMed

    Mackay, J E; Cunningham, S C; Cavagnaro, T R

    2016-10-01

    Reforestation of pastures in riparian zones has the potential to decrease nutrient runoff into waterways, provide both terrestrial and aquatic habitat, and help mitigate climate change by sequestering carbon (C). Soil microbes can play an important role in the soil C cycle, but are rarely investigated in studies on C sequestration. We surveyed a chronosequence (0-23years) of mixed-species plantings in riparian zones to investigate belowground (chemical and biological) responses to reforestation. For each planting, an adjacent pasture was surveyed to account for differences in soil type and land-use history among plantings. Two remnant woodlands were included in the survey as indicators of future potential of plantings. Both remnant woodlands had significantly higher soil organic C (SOC) content compared with their adjacent pastures. However, there was no clear trend in SOC content among plantings with time since reforestation. The substantial variability in SOC sequestration among plantings was possibly driven by differences in soil moisture among plantings and the inherent variability of SOC content among reference pastures adjacent to plantings. Soil microbial phospholipid fatty acids (PLFA, an indicator of microbial biomass) and activities of decomposition enzymes (β-glucosidase and polyphenol oxidase) did not show a clear trend with increasing planting age. Despite this, there were positive correlations between total SOC concentration and microbial indicators (total PLFA, fungal PLFA, bacterial PLFA and activities of decomposition enzymes) across all sites. The soil microbial community compositions (explored using PLFA markers) of older plantings were similar to those of remnant woodlands. There was a positive correlation between the soil carbon:nitrogen (C:N) and fungal:bacterial (F:B) ratios. These data indicate that in order to maximise SOC sequestration, we need to take into account not only C inputs, but the microbial processes that regulate SOC cycling

  14. Soil carbon distribution and site characteristics in hyper-arid soils of the Atacama Desert: A site with Mars-like soils

    NASA Astrophysics Data System (ADS)

    Valdivia-Silva, Julio E.; Navarro-González, Rafael; Fletcher, Lauren; Perez-Montaño, Saúl; Condori-Apaza, Reneé; Mckay, Christopher P.

    2012-07-01

    The soil carbon content and its relation to site characteristics are important in evaluating current local, regional, and global soil C storage and projecting future variations in response to climate change. In this study we analyzed the concentration of organic and inorganic carbon and their relationship with in situ climatic and geological characteristics in 485 samples of surface soil and 17 pits from the hyper-arid area and 51 samples with 2 pits from the arid-semiarid region from the Atacama Desert located in Peru and Chile. The soil organic carbon (SOC) in hyperarid soils ranged from 1.8 to 50.9 μg C per g of soil for the 0-0.1 m profile and from 1.8 to 125.2 μg C per g of soil for the 0-1 m profile. The analysis of climatic (temperature and precipitation), elevation, and some geologic characteristics (landforms) associated with hyper-arid soils explained partially the SOC variability. On the other hand, soil inorganic carbon (SIC) contents, in the form of carbonates, ranged from 200 to 1500 μg C per g of soil for the 0-0.1 m profile and from 200 to 3000 μg C per g of soil for the 0-1.0 m profile in the driest area. The largest accumulations of organic and inorganic carbon were found near to arid-semiarid areas. In addition, the elemental carbon concentrations show that the presence of other forms of inorganic carbon (e.g. graphite, etc.) was negligible in these hyperarid soils. Overall, the top 1 m soil layer of hyperarid lands contains ˜11.6 Tg of organic carbon and 344.6 Tg of carbonate carbon. The total stored carbon was 30.8-fold the organic carbon alone. To our knowledge, this is the first study evaluating the total budget carbon on the surface and shallow subsurface on ˜160,000 km2 of hyperarid soils.

  15. Determination and assessment of mercury content in calcareous soils.

    PubMed

    Gil, C; Ramos-Miras, J; Roca-Pérez, L; Boluda, R

    2010-01-01

    This paper provides the first available information on the determination of the total mercury content in different Mediterranean calcareous soils by thermal decomposition, amalgamation and atomic absorption spectrophotometry. Fifty-three samples from five soil use groups (natural, dry land, greenhouse, irrigated and rice farming soils) were analysed. The results show that the levels of mercury in these soils were 9.4-1585mugkg(-1). Soil organic matter and the zinc equivalent index have been related to Hg content in soils, suggesting that Cu, Ni, Zn and Hg are of a similar origin. The background level (BL), geochemical baseline concentrations (GBC) and the reference value (RV) were established from natural soils. Calculations are according to the log-normal distribution criterion. The BL, GBC and RV values obtained were 25.1, 9.8-64.3, and 64.3mugkg(-1), respectively. The BL was similar to the baseline concentration in soils obtained at Admiralty Bay (Antarctica) (24.6mugkg(-1)) and a Spanish peat bog (Galicia) (22mugkg(-1)). These data show that rice farming soils (gleyic-calcaric Fluvisols, Fluvaquents), irrigated soils (calcaric Fluvisols, Xerofluvents) and some greenhouse soils (cumulic Antrosols) presented much higher levels, indicating contamination. Hg accumulation in these soils was associated with local anthropogenic sources. PMID:20004461

  16. Soil organic matter content: a non-liner control on microbial respiration in soils

    NASA Astrophysics Data System (ADS)

    Schnecker, Jörg; Grandy, Stuart

    2016-04-01

    It is widely assumed that microbial activity and respiration rates respond linearly to substrate concentrations, irrespective of substrate chemical characteristics, but this assumption remains largely untested. We know that microbial decomposition of soil organic matter (SOM) and the amount of CO2 respired from soil depends on substrate availability. While soils with high SOM concentrations will have higher respiration rates than soils with low SOM concentrations, the specific relationship between substrate quantity and CO2 respired and its underlying mechanisms has robust theoretical, modeling, and management implications. In a lab incubation experiment, we amended a mixture of agricultural soil and sand with increasing amounts of one of three plant residues differing in their C/N ratio (clover C/N 14; rye C/N 23 and wheat straw C/N 110). Keeping the soil/sand mixture at a constant ratio, we obtained 9 levels of organic carbon (OC) content ranging from 0.25% to 5.7%. The sand-soil-residue mixtures were then incubated at constant temperature and water contents for a total of 63 days. Our results show that across substrates CO2 production increased with increasing OC content following a sigmoidal curve function instead of the expected linear one. A breakpoint analysis for the respiration curve of rye revealed two significant break points at 1.3 and 3.8 % OC. The three individual linear relations might be shaped by spatial separation of substrate and microbes and the interaction of the microbes themselves. In the first "survival" phase up to 1.3 % OC, more substrate leads to the survival of more microbes. However, microbial growth does not result in the discovery of new resources. In the "expansion" phase (1.3 % OC to 3.8 % OC), microbial growth is successful and microbes can exploit new resources. Finally, in the "competition" phase microbes start to compete for space and resources, which leads to a decrease in decomposition and respiration. While the results for

  17. Critical carbon input to maintain current soil organic carbon stocks in global wheat systems

    PubMed Central

    Wang, Guocheng; Luo, Zhongkui; Han, Pengfei; Chen, Huansheng; Xu, Jingjing

    2016-01-01

    Soil organic carbon (SOC) dynamics in croplands is a crucial component of global carbon (C) cycle. Depending on local environmental conditions and management practices, typical C input is generally required to reduce or reverse C loss in agricultural soils. No studies have quantified the critical C input for maintaining SOC at global scale with high resolution. Such information will provide a baseline map for assessing soil C dynamics under potential changes in management practices and climate, and thus enable development of management strategies to reduce C footprint from farm to regional scales. We used the soil C model RothC to simulate the critical C input rates needed to maintain existing soil C level at 0.1° × 0.1° resolution in global wheat systems. On average, the critical C input was estimated to be 2.0 Mg C ha−1 yr−1, with large spatial variability depending on local soil and climatic conditions. Higher C inputs are required in wheat system of central United States and western Europe, mainly due to the higher current soil C stocks present in these regions. The critical C input could be effectively estimated using a summary model driven by current SOC level, mean annual temperature, precipitation, and soil clay content. PMID:26759192

  18. Critical carbon input to maintain current soil organic carbon stocks in global wheat systems.

    PubMed

    Wang, Guocheng; Luo, Zhongkui; Han, Pengfei; Chen, Huansheng; Xu, Jingjing

    2016-01-01

    Soil organic carbon (SOC) dynamics in croplands is a crucial component of global carbon (C) cycle. Depending on local environmental conditions and management practices, typical C input is generally required to reduce or reverse C loss in agricultural soils. No studies have quantified the critical C input for maintaining SOC at global scale with high resolution. Such information will provide a baseline map for assessing soil C dynamics under potential changes in management practices and climate, and thus enable development of management strategies to reduce C footprint from farm to regional scales. We used the soil C model RothC to simulate the critical C input rates needed to maintain existing soil C level at 0.1° × 0.1° resolution in global wheat systems. On average, the critical C input was estimated to be 2.0 Mg C ha(-1) yr(-1), with large spatial variability depending on local soil and climatic conditions. Higher C inputs are required in wheat system of central United States and western Europe, mainly due to the higher current soil C stocks present in these regions. The critical C input could be effectively estimated using a summary model driven by current SOC level, mean annual temperature, precipitation, and soil clay content. PMID:26759192

  19. Critical carbon input to maintain current soil organic carbon stocks in global wheat systems

    NASA Astrophysics Data System (ADS)

    Wang, Guocheng; Luo, Zhongkui; Han, Pengfei; Chen, Huansheng; Xu, Jingjing

    2016-01-01

    Soil organic carbon (SOC) dynamics in croplands is a crucial component of global carbon (C) cycle. Depending on local environmental conditions and management practices, typical C input is generally required to reduce or reverse C loss in agricultural soils. No studies have quantified the critical C input for maintaining SOC at global scale with high resolution. Such information will provide a baseline map for assessing soil C dynamics under potential changes in management practices and climate, and thus enable development of management strategies to reduce C footprint from farm to regional scales. We used the soil C model RothC to simulate the critical C input rates needed to maintain existing soil C level at 0.1° × 0.1° resolution in global wheat systems. On average, the critical C input was estimated to be 2.0 Mg C ha‑1 yr‑1, with large spatial variability depending on local soil and climatic conditions. Higher C inputs are required in wheat system of central United States and western Europe, mainly due to the higher current soil C stocks present in these regions. The critical C input could be effectively estimated using a summary model driven by current SOC level, mean annual temperature, precipitation, and soil clay content.

  20. Critical carbon input to maintain current soil organic carbon stocks in global wheat systems

    NASA Astrophysics Data System (ADS)

    Wang, Guocheng; Luo, Zhongkui; Han, Pengfei; Chen, Huansheng; Xu, Jingjing

    2016-01-01

    Soil organic carbon (SOC) dynamics in croplands is a crucial component of global carbon (C) cycle. Depending on local environmental conditions and management practices, typical C input is generally required to reduce or reverse C loss in agricultural soils. No studies have quantified the critical C input for maintaining SOC at global scale with high resolution. Such information will provide a baseline map for assessing soil C dynamics under potential changes in management practices and climate, and thus enable development of management strategies to reduce C footprint from farm to regional scales. We used the soil C model RothC to simulate the critical C input rates needed to maintain existing soil C level at 0.1° × 0.1° resolution in global wheat systems. On average, the critical C input was estimated to be 2.0 Mg C ha-1 yr-1, with large spatial variability depending on local soil and climatic conditions. Higher C inputs are required in wheat system of central United States and western Europe, mainly due to the higher current soil C stocks present in these regions. The critical C input could be effectively estimated using a summary model driven by current SOC level, mean annual temperature, precipitation, and soil clay content.

  1. Soil pyrogenic carbon lacks long-term persistence

    NASA Astrophysics Data System (ADS)

    Lutfalla, Suzanne; Abiven, Samuel; Barré, Pierre; Wiedemeier, Daniel; Christensen, Bent; Houot, Sabine; Kätterer, Thomas; Macdonald, Andy; van Oort, Fok; Chenu, Claire

    2015-04-01

    In the context of climate change, one mitigation technique currently investigated is the use of pyrogenic organic carbon (PyOC) -which is biomass turned into charcoal- to sequester carbon in soils with the hypothesis that PyOC is persistent and will not be biodegraded (or mineralized). In this study, we use the unique opportunity offered by five long term bare fallow (LTBF) experiments across Europe (Askov in Denmark, Grignon and Versailles in France, Ultuna in Sweden and Rothamsted in the United Kingdom) to compare the dynamics of PyOC and soil organic carbon (SOC) in the same plots at the decadal time scale (from 25 to 80 years of bare fallow depending on the site). Bare fallow plots were regularly sampled throughout the bare fallow duration and these samples were carefully archived. In bare fallow plots, with negligible external carbon input and with continuing biodegradation, SOC is depleting. Using the Benzene Polycarboxylic Acid (BPCA) technique to estimate the PyOC quantity and quality in the soils at different sampling dates, we investigated if PyOC content was also decreasing and compared the rates of depletion of PyOC and SOC. We found that PyOC contents decreased rapidly in soils at all sites. The loss of PyOC between the first and the last soil sampling ranged from 19.8 to 57.3% of the initial PyOC content. Furthermore, PyOC quality exhibited a similar evolution at all sites, becoming more enriched in condensed material with time. We applied a one pool model with mono-exponential decay to our data and found an average mean residence time of native PyOC of 116 years across the different sites, with a standard deviation of 15 years, just 1.6 times longer than that of SOC. Our results show that, though having a longer residence time than total SOC, PyOC content can decrease rapidly in soils suggesting that the potential for long-term C storage in soil by PyOC amendments is less than currently anticipated. Our results therefore question the concept of

  2. Stable and radioactive carbon in forest soils of Chhattisgarh, Central India: Implications for tropical soil carbon dynamics and stable carbon isotope evolution

    NASA Astrophysics Data System (ADS)

    Laskar, A. H.; Yadava, M. G.; Ramesh, R.

    2016-06-01

    Soils from two sites viz. Kotumsar and Tirathgarh, located ∼5 km apart in a tropical reserve forest (18°52‧N, 81°56‧E) in central India, have been explored for soil organic carbon (SOC) content, its mean residence time (MRT) and the evolution of stable carbon isotopic composition (δ13C). SOC stocks in the upper 30 cm of soil layers are ∼5.3 kg/m2 and ∼3.0 kg/m2; in the upper 110 m are ∼10.7 kg/m2 and ∼7.8 kg/m2 at Kotumsar and Tirathgarh, respectively. SOC decreases with increasing depth. Bomb carbon signature is observed in the upper ∼10 cm. Organic matters in the top soil layers (0-10 cm) have MRTs of the order of a century which increases gradually with depths, reaching 3500-5000 yrs at ∼100 cm. δ13C values of SOC increase with depth, the carbon isotopic fractionation is obtained to be -1.2‰ and -3‰ for soils at Kotumsar and Tirathgarh, respectively, confirmed using Rayleigh isotopic fractionation model. The evolution of δ13C in soils was also studied using a modified Rayleigh fractionation model incorporating a continuous input into the reservoir: the depth profiles of δ13C for SOC show that the input organic matter from surface into the deeper soil layers is either insignificant or highly labile and decomposes quite fast in the top layers, thus making little contribution to the residual biomasses of the deeper layers. This is an attempt to understand the distillation processes that take place in SOC, assess the extent of decomposition by microbes and effect of percolation of fresh organic matter into dipper soil layers which are important for stable isotope based paleoclimate and paleovegetation reconstruction and understanding the dynamics of organic carbon in soils.

  3. Soil carbon storage in a small arid catchment in the Negev desert (Israel)

    NASA Astrophysics Data System (ADS)

    Hoffmann, Ulrike; Kuhn, Nikolaus

    2010-05-01

    densities (in kg/m²) were estimated for the mineral soil layer. The results indicate a large spatial variability of the carbon contents, the soil volume and depths across the landscape. In general, topography exerts a strong control on the carbon contents and the soil depths in the study site. Lowest carbon contents are apparent at the hillslope tops with increasing contents downslope. Because of the significantly larger carbon content at the northern exposed slope, we suggest that solar radiation driven differences of soil moisture content major controls SOC. Regarding the soil depths, the differences are not that clear. Soil depths seem to be higher at the southern exposed slope, but differences with respect to the slope position are not significant. Concerning the total amount of carbon storage in the study area, the results show that soil carbon may not be neglected in arid areas. Our results should provide an indication that carbon contents in dynamic environments are more affected and controlled by surface properties (soil volume) than by climate. Concluding that hint, climate is less important than surface processes in dryland ecosystems.

  4. Comparison of soil microbial respiration and carbon turnover under perennial and annual biofuel crops in two agricultural soils

    NASA Astrophysics Data System (ADS)

    Szymanski, L. M.; Marin-Spiotta, E.; Sanford, G. R.; Jackson, R. D.; Heckman, K. A.

    2015-12-01

    Bioenergy crops have the potential to provide a low carbon-intensive alternative to fossil fuels. More than a century of agricultural research has shown that conventional cropping systems can reduce soil organic matter (SOM) reservoirs, which cause long-term soil nutrient loss and C release to the atmosphere. In the face of climate change and other human disruptions to biogeochemical cycles, identifying biofuel crops that can maintain or enhance soil resources is desirable for the sustainable production of bioenergy. The objective of our study was to compare the effects of four biofuel crop treatments on SOM dynamics in two agricultural soils: Mollisols at Arlington Agricultural Research Station in Wisconsin and Alfisols at Kellogg Biological Station in Michigan, USA. We used fresh soils collected in 2013 and archived soils from 2008 to measure the effects of five years of crop management. Using a one-year long laboratory soil incubation coupled with a regression model and radiocarbon measurements, we separated soils into three SOM pools and their corresponding C turnover times. We found that the active pool, or biologically available C, was more sensitive to management and is an earlier indicator of changes to soil C dynamics than bulk soil C measurements. There was no effect of treatment on the active pool size at either site; however, the percent C in the active pool decreased, regardless of crop type, in surface soils with high clay content. At depth, the response of the slow pool differed between annual and perennial cropping systems. The distribution of C among SOM fractions varied between the two soil types, with greater C content associated with the active fraction in the coarser textured-soil and greater C content associated with the slow-cycling fraction in the soils with high clay content. These results suggest that the effects of bioenergy crops on soil resources will vary geographically, with implications for the carbon-cost of biocrop production.

  5. Methane and carbon dioxide dynamics in wetland mesocosms: effects of hydrology and soils.

    PubMed

    Altor, Anne E; Mitsch, William J

    2008-07-01

    Methane and carbon dioxide fluxes in created and restored wetlands, and the influence of hydrology and soils on these fluxes, have not been extensively documented. Minimizing methane fluxes while maximizing productivity is a relevant goal for wetland restoration and creation projects. In this study we used replicated wetland mesocosms to investigate relationships between contrasting hydrologic and soil conditions, and methane and carbon dioxide fluxes in emergent marsh systems. Hydrologic treatments consisted of an intermittent flooding regime vs. continuously inundated conditions, and soil treatments utilized hydric vs. non-hydric soils. Diurnal patterns of methane flux were examined to shed light on the relationship between emergent macrophytes and methane emissions for comparison with vegetation-methane relationships reported from natural wetlands. Microbially available organic carbon content was significantly greater in hydric soils than nonhydric soils, despite similar organic matter contents in the contrasting soil types. Mesocosms with hydric soils exhibited the greatest rates of methane flux regardless of hydrology, but intermittent inundation of hydric soils produced significantly lower methane fluxes than continuous inundatation of hydric soils. Methane fluxes were not affected significantly by hydrologic regime in mesocosms containing non-hydric soils. There were no diurnal differences in methane flux, and carbon dioxide and methane fluxes were not significantly correlated. The highest rates of CO2 uptake occurred in the continuously inundated treatment with non-hydric soils, and there were no significant differences in nighttime respiration rates between the treatments. Implications for hydrologic design of created and restored wetlands are discussed.

  6. Prediction of Soil Organic Carbon at the European Scale by Visible and Near InfraRed Reflectance Spectroscopy

    PubMed Central

    Stevens, Antoine; Nocita, Marco; Tóth, Gergely; Montanarella, Luca; van Wesemael, Bas

    2013-01-01

    Soil organic carbon is a key soil property related to soil fertility, aggregate stability and the exchange of CO2 with the atmosphere. Existing soil maps and inventories can rarely be used to monitor the state and evolution in soil organic carbon content due to their poor spatial resolution, lack of consistency and high updating costs. Visible and Near Infrared diffuse reflectance spectroscopy is an alternative method to provide cheap and high-density soil data. However, there are still some uncertainties on its capacity to produce reliable predictions for areas characterized by large soil diversity. Using a large-scale EU soil survey of about 20,000 samples and covering 23 countries, we assessed the performance of reflectance spectroscopy for the prediction of soil organic carbon content. The best calibrations achieved a root mean square error ranging from 4 to 15 g C kg−1 for mineral soils and a root mean square error of 50 g C kg−1 for organic soil materials. Model errors are shown to be related to the levels of soil organic carbon and variations in other soil properties such as sand and clay content. Although errors are ∼5 times larger than the reproducibility error of the laboratory method, reflectance spectroscopy provides unbiased predictions of the soil organic carbon content. Such estimates could be used for assessing the mean soil organic carbon content of large geographical entities or countries. This study is a first step towards providing uniform continental-scale spectroscopic estimations of soil organic carbon, meeting an increasing demand for information on the state of the soil that can be used in biogeochemical models and the monitoring of soil degradation. PMID:23840459

  7. Combining Soil Databases for Topsoil Organic Carbon Mapping in Europe.

    PubMed

    Aksoy, Ece; Yigini, Yusuf; Montanarella, Luca

    2016-01-01

    Accuracy in assessing the distribution of soil organic carbon (SOC) is an important issue because of playing key roles in the functions of both natural ecosystems and agricultural systems. There are several studies in the literature with the aim of finding the best method to assess and map the distribution of SOC content for Europe. Therefore this study aims searching for another aspect of this issue by looking to the performances of using aggregated soil samples coming from different studies and land-uses. The total number of the soil samples in this study was 23,835 and they're collected from the "Land Use/Cover Area frame Statistical Survey" (LUCAS) Project (samples from agricultural soil), BioSoil Project (samples from forest soil), and "Soil Transformations in European Catchments" (SoilTrEC) Project (samples from local soil data coming from six different critical zone observatories (CZOs) in Europe). Moreover, 15 spatial indicators (slope, aspect, elevation, compound topographic index (CTI), CORINE land-cover classification, parent material, texture, world reference base (WRB) soil classification, geological formations, annual average temperature, min-max temperature, total precipitation and average precipitation (for years 1960-1990 and 2000-2010)) were used as auxiliary variables in this prediction. One of the most popular geostatistical techniques, Regression-Kriging (RK), was applied to build the model and assess the distribution of SOC. This study showed that, even though RK method was appropriate for successful SOC mapping, using combined databases was not helpful to increase the statistical significance of the method results for assessing the SOC distribution. According to our results; SOC variation was mainly affected by elevation, slope, CTI, average temperature, average and total precipitation, texture, WRB and CORINE variables for Europe scale in our model. Moreover, the highest average SOC contents were found in the wetland areas; agricultural

  8. Combining Soil Databases for Topsoil Organic Carbon Mapping in Europe.

    PubMed

    Aksoy, Ece; Yigini, Yusuf; Montanarella, Luca

    2016-01-01

    Accuracy in assessing the distribution of soil organic carbon (SOC) is an important issue because of playing key roles in the functions of both natural ecosystems and agricultural systems. There are several studies in the literature with the aim of finding the best method to assess and map the distribution of SOC content for Europe. Therefore this study aims searching for another aspect of this issue by looking to the performances of using aggregated soil samples coming from different studies and land-uses. The total number of the soil samples in this study was 23,835 and they're collected from the "Land Use/Cover Area frame Statistical Survey" (LUCAS) Project (samples from agricultural soil), BioSoil Project (samples from forest soil), and "Soil Transformations in European Catchments" (SoilTrEC) Project (samples from local soil data coming from six different critical zone observatories (CZOs) in Europe). Moreover, 15 spatial indicators (slope, aspect, elevation, compound topographic index (CTI), CORINE land-cover classification, parent material, texture, world reference base (WRB) soil classification, geological formations, annual average temperature, min-max temperature, total precipitation and average precipitation (for years 1960-1990 and 2000-2010)) were used as auxiliary variables in this prediction. One of the most popular geostatistical techniques, Regression-Kriging (RK), was applied to build the model and assess the distribution of SOC. This study showed that, even though RK method was appropriate for successful SOC mapping, using combined databases was not helpful to increase the statistical significance of the method results for assessing the SOC distribution. According to our results; SOC variation was mainly affected by elevation, slope, CTI, average temperature, average and total precipitation, texture, WRB and CORINE variables for Europe scale in our model. Moreover, the highest average SOC contents were found in the wetland areas; agricultural

  9. Combining Soil Databases for Topsoil Organic Carbon Mapping in Europe

    PubMed Central

    Aksoy, Ece

    2016-01-01

    Accuracy in assessing the distribution of soil organic carbon (SOC) is an important issue because of playing key roles in the functions of both natural ecosystems and agricultural systems. There are several studies in the literature with the aim of finding the best method to assess and map the distribution of SOC content for Europe. Therefore this study aims searching for another aspect of this issue by looking to the performances of using aggregated soil samples coming from different studies and land-uses. The total number of the soil samples in this study was 23,835 and they’re collected from the “Land Use/Cover Area frame Statistical Survey” (LUCAS) Project (samples from agricultural soil), BioSoil Project (samples from forest soil), and “Soil Transformations in European Catchments” (SoilTrEC) Project (samples from local soil data coming from six different critical zone observatories (CZOs) in Europe). Moreover, 15 spatial indicators (slope, aspect, elevation, compound topographic index (CTI), CORINE land-cover classification, parent material, texture, world reference base (WRB) soil classification, geological formations, annual average temperature, min-max temperature, total precipitation and average precipitation (for years 1960–1990 and 2000–2010)) were used as auxiliary variables in this prediction. One of the most popular geostatistical techniques, Regression-Kriging (RK), was applied to build the model and assess the distribution of SOC. This study showed that, even though RK method was appropriate for successful SOC mapping, using combined databases was not helpful to increase the statistical significance of the method results for assessing the SOC distribution. According to our results; SOC variation was mainly affected by elevation, slope, CTI, average temperature, average and total precipitation, texture, WRB and CORINE variables for Europe scale in our model. Moreover, the highest average SOC contents were found in the wetland areas

  10. Impact of land use change on soil carbon loss of the Sikkim Himalayan piedmont

    NASA Astrophysics Data System (ADS)

    Prokop, Pawel; Ploskonka, Dominik

    2014-05-01

    Natural and human causes of change in land use on soil carbon were studied at the outlet of the Tista River from the Sikkim Himalayas over the last 150 years. Analysis of topographic maps and satellite images indicates that the land reforms related to location of tea gardens in the piedmont caused rapid deforestation of terraces in the late 19th century. Continuous population growth after 1930 initiated the replacement of floodplain forest by rice cultivation. Both processes changed soil carbon content and intensified fluvial activity expressed through terrace erosion. The replacement of natural forest by tea cultivation reduced the soil carbon content within terraces from 1.95 kg to 1.77 kg (in 1 m of topsoil) respectively. The replacement of natural forest by rice reduced the soil carbon content within floodplains from 0.42 kg to 0.23 kg (in 1 m topsoil) respectively. Much more dangerous, was terrace erosion leading to permanent removal of sediment including soil. The total loss of soil carbon in a 1 m thick soil layer due to conversion of 5 km2 forest to tea cultivation was about 900 t between 1930 and 2010. While the total soil carbon removed due to 1.8 km2 terrace erosion reached 3510 t in the same period. Result is the outcome of research project 2012/05/B/ST10/00309 of the National Science Centre (Poland).

  11. Tracing the source of Beijing soil organic carbon: a carbon isotope approach.

    PubMed

    Guo, Qingjun; Strauss, Harald; Chen, Tong-Bin; Zhu, Guangxu; Yang, Jun; Yang, Junxing; Lei, Mei; Zhou, Xiaoyong; Peters, Marc; Xie, Yunfeng; Zhang, Hanzhi; Wei, Rongfei; Wang, Chunyu

    2013-05-01

    Bulk soil organic carbon concentration and isotopic composition characterize its sources and fate, identify the anthropogenic input of organic carbon into the soil, and trace soil carbon turnover. Coal and/or coal combustion products represent the prime anthropogenic input of organic carbon into three soil profiles located in the vicinity of a steel company. Three profiles positioned away from any direct industrial contribution display vertical pattern in soil organic carbon concentration and isotopic composition that resemble more commonly observed downward gradients in soil carbon chemistry and indicate microbial soil carbon turnover. Two additional profiles located outside of the immediate industrial area display vertical carbon isotope profiles between typical of those from industrial and non-industrial areas. Eight soil profiles and their vertical distribution of bulk organic carbon isotopic composition and concentration collected in the Beijing area reveal and distinguish both anthropogenic and natural contributions of carbon to these soils.

  12. [Effects of biological regulated measures on active organic carbon and erosion-resistance in the Three Gorges Reservoir region soil].

    PubMed

    Huang, Ru; Huang, Lin; He, Bing-Hui; Zhou, Li-Jiang; Yu, Chuan; Wang, Feng

    2013-07-01

    To gain a better knowledge of characteristics of soils and provide a scientific basis for soil erosion control in the Three Gorges Reservoir Area, contents of aggregates and total soil organic carbon (SOC), as well as soil active organic carbon fractions including particulate organic carbon (POC), readily oxidized organic carbon (ROC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) in the 0-30 cm soil layer under seven different biological regulated measures were studied by the field investigation combined with the laboratory analysis. Results showed that the content of the SOC and active organic carbon fractions decreased with the increasing soil depth; the content of the SOC and active organic carbon fractions in 0-10 cm was significantly higher than that in 20-30 cm. The stability of soil aggregates were also significantly influenced by biological regulated measures, the content of > 0.25 mm water-stable aggregates in seven types of biological regulated measures was in the order of Koelreuteria bipinnata + Cassia suffruticasa > hedgerows > closed forest > natural restoration > economic forest > traditional planting > control plot, moreover, the content of 0.25 mm water-stable aggregates correlated positively with the content of SOC. Soils under different biological regulated measures all demonstrated fractal features, and soil under the measure of Koelreuteria bipinnata + Cassia suffruticasa was found to have the lowest value of fractal dimension and soil erodiable K, indicating a relatively strong structure stability and erosion-resistant capacity. Negative correlation was observed when compared the content of active organic carbon fractions with the soil erodiable K. It can be concluded that properties of soil can be managed through biological regulated measures; thence had an influence on the soil erosion-resistant capacity. PMID:24028016

  13. [Effects of biological regulated measures on active organic carbon and erosion-resistance in the Three Gorges Reservoir region soil].

    PubMed

    Huang, Ru; Huang, Lin; He, Bing-Hui; Zhou, Li-Jiang; Yu, Chuan; Wang, Feng

    2013-07-01

    To gain a better knowledge of characteristics of soils and provide a scientific basis for soil erosion control in the Three Gorges Reservoir Area, contents of aggregates and total soil organic carbon (SOC), as well as soil active organic carbon fractions including particulate organic carbon (POC), readily oxidized organic carbon (ROC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) in the 0-30 cm soil layer under seven different biological regulated measures were studied by the field investigation combined with the laboratory analysis. Results showed that the content of the SOC and active organic carbon fractions decreased with the increasing soil depth; the content of the SOC and active organic carbon fractions in 0-10 cm was significantly higher than that in 20-30 cm. The stability of soil aggregates were also significantly influenced by biological regulated measures, the content of > 0.25 mm water-stable aggregates in seven types of biological regulated measures was in the order of Koelreuteria bipinnata + Cassia suffruticasa > hedgerows > closed forest > natural restoration > economic forest > traditional planting > control plot, moreover, the content of 0.25 mm water-stable aggregates correlated positively with the content of SOC. Soils under different biological regulated measures all demonstrated fractal features, and soil under the measure of Koelreuteria bipinnata + Cassia suffruticasa was found to have the lowest value of fractal dimension and soil erodiable K, indicating a relatively strong structure stability and erosion-resistant capacity. Negative correlation was observed when compared the content of active organic carbon fractions with the soil erodiable K. It can be concluded that properties of soil can be managed through biological regulated measures; thence had an influence on the soil erosion-resistant capacity.

  14. Soil Carbon Cycling - More than Changes in Soil Organic Carbon Stocks

    NASA Astrophysics Data System (ADS)

    Lorenz, K.

    2015-12-01

    Discussions about soil carbon (C) sequestration generally focus on changes in soil organic carbon (SOC) stocks. Global SOC mass in the top 1 m was estimated at about 1325 Pg C, and at about 3000 Pg C when deeper soil layers were included. However, both inorganically and organically bound carbon forms are found in soil but estimates on global soil inorganic carbon (SIC) mass are even more uncertain than those for SOC. Globally, about 947 Pg SIC may be stored in the top 1 m, and especially in arid and semi-arid regions SIC stocks can be many times great than SOC stocks. Both SIC and SOC stocks are vulnerable to management practices, and stocks may be enhanced, for example, by optimizing net primary production (NPP) by fertilization and irrigation (especially optimizing belowground NPP for enhancing SOC stocks), adding organic matter (including black C for enhancing SOC stocks), and reducing soil disturbance. Thus, studies on soil C stocks, fluxes, and vulnerability must look at both SIC and SOC stocks in soil profiles to address large scale soil C cycling.

  15. Comparison of Forest Soil Carbon Dynamics at Five Sites Along a Latitudinal Gradient

    SciTech Connect

    Garten Jr, Charles T

    2011-01-01

    Carbon stocks, and C:N ratios, were measured in the forest floor, mineral soil, and two mineral soil fractions (particulate and mineral-associated organic matter, POM and MOM, respectively) at five forest sites, ranging from 60 to 100 years old, along a latitudinal gradient in the eastern United States. Sampling at four sites was replicated over two consecutive years. For many measurements (like forest floor carbon stocks, cumulative soil organic carbon stocks to 20 cm, and the fraction of whole soil carbon in POM), there was no significant difference between years at each site despite the use of somewhat different sampling methods. With one exception, forest floor and mineral soil carbon stocks increased from warm, southern, sites (with fine-textured soils) to northern, cool, sites (with more coarse-textured soils). The exception was a northern site, with less than 10% silt-clay content, that had a soil organic carbon stock similar to those measured at southern sites. Soil carbon at each site was partitioned into two pools (labile and stable) on the basis of carbon measured in the forest floor and POM and MOM fractions from the mineral soil. A two-compartment steady-state model, with randomly varying parameter values, was used in probabilistic calculations to estimate the turnover time of labile soil organic carbon (MRTU) and the annual transfer of labile carbon to stable carbon (k2) at each site in two different years. Based on empirical data, the turnover time of stable soil carbon (MRTS) was determined by mean annual temperature and increased from 30 to 100 years from south to north. Moving from south to north, MRTU increased from approximately 5 to 14 years. Consistent with prior studies, 13C enrichment factors ( ) from the Rayleigh equation, that describe the rate of change in 13C through the soil profile, were an indicator of soil carbon turnover times along the latitudinal gradient. Consistent with its role in stabilization of soil organic carbon, silt

  16. CARBON SEQUESTRATION IN RECLAIMED MINED SOILS OF OHIO

    SciTech Connect

    M.K. Shukla; R. Lal

    2004-10-01

    This research project is aimed at assessing the soil organic carbon (SOC) sequestration potential of reclaimed minesoils (RMS). The experimental sites, owned and maintained by the American Electrical Power, are located in Guernsey, Morgan, Noble, and Muskingum Counties of Ohio. These sites, characterized by age chronosequences, were reclaimed with and without topsoil application and are under continuous grass or forest cover. During this quarter, water infiltration tests were performed on the soil surface in the experimental sites. Soil samples were analyzed for the soil carbon and nitrogen contents, texture, water stable aggregation, and mean weight and geometric mean diameter of aggregates. This report presents the results from two sites reclaimed during 1978 and managed under grass (Wilds) and forest (Cumberland) cover, respectively. The trees were planted in 1982 in the Cumberland site. The analyses of data on soil bulk density ({rho}{sub b}), SOC and total nitrogen (TN) concentrations and stocks were presented in the third quarter report. This report presents the data on infiltration rates, volume of transport and storage pores, available water capacity (AWC) of soil, particle size distribution, and soil inorganic carbon (SIC) and coal carbon contents. The SIC content ranged from 0.04 to 1.68% in Cumberland tree site and 0.01 to 0.65% in the Wilds. The coal content assumed to be the carbon content after oven drying the sample at 350 C varied between 0.04 and 3.18% for Cumberland and 0.06 and 3.49% for Wilds. The sand, silt and clay contents showed moderate to low variability (CV < 0.16) for 0-15 and 15-30 cm depths. The volume of transmission (VTP) and storage pores (VSP) also showed moderate to high variability (CV ranged from 0.22 to 0.39 for Wilds and 0.17 to 0.36 for Cumberland). The CV for SIC was high (0.7) in Cumberland whereas that for coal content was high (0.4) in the Wilds. The steady state infiltration rates (i{sub c}) also showed high variability

  17. Dielectric properties of soils as a function of moisture content

    NASA Technical Reports Server (NTRS)

    Cihlar, J.; Ulaby, F. T.

    1974-01-01

    Soil dielectric constant measurements are reviewed and the dependence of the dielectric constant on various soil parameters is determined. Moisture content is given special attention because of its practical significance in remote sensing and because it represents the single most influential parameter as far as soil dielectric properties are concerned. Relative complex dielectric constant curves are derived as a function of volumetric soil water content at three frequencies (1.3 GHz, 4.0 GHz, and 10.0 GHz) for each of three soil textures (sand, loam, and clay). These curves, presented in both tabular and graphical form, were chosen as representative of the reported experimental data. Calculations based on these curves showed that the power reflection coefficient and emissivity, unlike skin depth, vary only slightly as a function of frequency and soil texture.

  18. Content and persistence of extracellular DNA in native soils

    NASA Astrophysics Data System (ADS)

    Blagodatskaya, Evgenia; Blagodatsky, Sergey; Anderson, Traute-Heidi; Kuzyakov, Yakov

    2014-05-01

    The long-term persistence of soil extracellular DNA is questionable because of high potential activity of nucleases produced by soil microorganisms. By the other hand, the relative persistence of DNA-like biopolymers could be due to their adsorption on clay minerals and humus substances in soil. High-specific and ultra sensitive reagent PicoGreenTM (Molecular Probes) permits the quantitative assessment of microbial dsDNA in diluted soil extracts giving a good tool for tracing the DNA fate in soil. Our goal was to determine intracellular and extracellular DNA content in cambisol (loamy sand) and in chernozem (silty loam) soils and to investigate the possible adsorption and degradation of extracellular DNA in soil. Optimized procedure of mechanical and enzymatic destruction of cell walls was used for direct extraction of microbial DNA with Tris-EDTA buffer (Blagodatskaya et al., 2003). Extracellular dsDNA was determined in distilled water and in Tris-EDTA extracts without enzymatic or mechanical treatments. DNA content was determined after addition of PicoGreen to diluted soil extracts. Degradation of extracellular DNA was traced during 24 h incubation of 2 µg lambda-phage DNA in soil. Possible DNA adsorption to soil matrix was determined by recovery of lambda -phage DNA added to autoclaved soil. Extracellular dsDNA was absent in water extracts of both soils. The content of extracellular dsDNA extracted by Tris-EDTA buffer was 0.46 µg/g in chernozem and 1.59 µg/g in cambisol amounting 0.43 and 2.8% of total dsDNA content in these soils, respectively. 100% and 64.8% of added extracellular lambda -phage dsDNA was found in cambisol and chernozem soils, respectively, in 5 h after application. 39% and 73.5% of added DNA disappeared in cambisol and in chernozem, respectively, during 24 h incubation. Degradation rate of extracellular DNA depended on microbial biomass content, which was 2.5 times higher in chernozem as compared to cambisol. Maximum adsorption of DNA by

  19. Input related microbial carbon dynamic of soil organic matter in particle size fractions

    NASA Astrophysics Data System (ADS)

    Gude, A.; Kandeler, E.; Gleixner, G.

    2012-04-01

    This paper investigated the flow of carbon into different groups of soil microorganisms isolated from different particle size fractions. Two agricultural sites of contrasting organic matter input were compared. Both soils had been submitted to vegetation change from C3 (Rye/Wheat) to C4 (Maize) plants, 25 and 45 years ago. Soil carbon was separated into one fast-degrading particulate organic matter fraction (POM) and one slow-degrading organo-mineral fraction (OMF). The structure of the soil microbial community were investigated using phospholipid fatty acids (PLFA), and turnover of single PLFAs was calculated from the changes in their 13C content. Soil enzyme activities involved in the degradation of carbohydrates was determined using fluorogenic MUF (methyl-umbelliferryl phosphate) substrates. We found that fresh organic matter input drives soil organic matter dynamic. Higher annual input of fresh organic matter resulted in a higher amount of fungal biomass in the POM-fraction and shorter mean residence times. Fungal activity therefore seems essential for the decomposition and incorporation of organic matter input into the soil. As a consequence, limited litter input changed especially the fungal community favouring arbuscular mycorrhizal fungi. Altogether, supply and availability of fresh plant carbon changed the distribution of microbial biomass, the microbial community structure and enzyme activities and resulted in different priming of soil organic matter. Most interestingly we found that only at low input the OMF fraction had significantly higher calculated MRT for Gram-positive and Gram-negative bacteria suggesting high recycling of soil carbon or the use of other carbon sources. But on average all microbial groups had nearly similar carbon uptake rates in all fractions and both soils, which contrasted the turnover times of bulk carbon. Hereby the microbial carbon turnover was always faster than the soil organic carbon turnover and higher carbon input

  20. Relation between L-band soil emittance and soil water content

    NASA Technical Reports Server (NTRS)

    Stroosnijder, L.; Lascano, R. J.; Van Bavel, C. H. M.; Newton, R. W.

    1986-01-01

    An experimental relation between soil emittance (E) at L-band and soil surface moisture content (M) is compared with a theoretical one. The latter depends on the soil dielectric constant, which is a function of both soil moisture content and of soil texture. It appears that a difference of 10 percent in the surface clay content causes a change in the estimate of M on the order of 0.02 cu m/cu m. This is based on calculations with a model that simulates the flow of water and energy, in combination with a radiative transfer model. It is concluded that an experimental determination of the E-M relation for each soil type is not required, and that a rough estimate of the soil texture will lead to a sufficiently accurate estimate of soil moisture from a general, theoretical relationship obtained by numerical simulation.

  1. Spatiotemporal changes of soil organic matter content in cropland of Northeast China during 1985 and 2005

    NASA Astrophysics Data System (ADS)

    Ye, Liming; Yao, Yanmin; Tang, Huajun; Wang, Deying; Van Ranst, Eric

    2015-04-01

    Soil is a vital non-renewable natural resource which plays many essential roles in terrestrial ecosystems. The productive capacity of soils in particular, underlies the foundation of the well-being of humanity on Earth. Soil organic matter (SOM) content is one of the most important indicators of soil quality and hence the productive capacity of soils. In this study, we assessed the spatiotemporal changes of cropland SOM content in Northeast China (NEC) using direct measurements of 2005 and survey data of 1985. We also analysed the driving forces behind the SOM content change. The spatial distribution map of SOM content in 1985 was rasterized from the polygon map of SOM classes using the centre-point conversion method, while the SOM content map in 2005 was first derived from 750 samples through kriging interpolation and then grouped into the same SOM classes as in 1985. Our results showed that SOM content decreased in 39% of all the cropland in NEC, while increase in SOM content was only detected in 16% of the cropland. SOM remained unchanged in nearly half (i.e. 45%) of the cropland. These results suggest that cropland SOM content tended to decline over a period of 20 years in NEC. Our results also revealed that cropping intensity and fertilizer application were the two most important factors driving SOM change between 1985 and 2005. Overall, results from this research provided novel details of the spatiotemporal patterns of cropland SOM content change in NEC which was not revealed in earlier assessments. The datasets presented here can be used not only as baselines for the calibration of process-based carbon budget models, but also to identify regional soil quality hotspots and to guide spatial-explicit soil management practices.

  2. Effects of residue removal on glomalin related soil protein content of soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil organic matter (SOM) mediates many physical soil properties, and may serve as a carbon sink. Identifying agricultural management practices that increase SOM are vital for improving or maintaining soil quality. Glomalin is a glycoprotein produced by arbuscular mycorrhizal fungi (AMF) and is a fr...

  3. Soil Surface Carbon Dioxide Fluxes and Carbon Dioxide Concentrations in Soil Air

    NASA Astrophysics Data System (ADS)

    Arkebauer, T. J.; Billesbach, D.

    2006-12-01

    We have been monitoring soil surface CO2 fluxes at three AmeriFlux sites in eastern Nebraska for several years. Recently, we have installed soil CO2 sensors at the rainfed soybean site in order to obtain profiles of CO2 concentrations in soil air (to 0.8 m depth). Supporting data include profiles of soil water content and soil temperature, aboveground biomass, leaf area index and precipitation. Soil surface fluxes had been rather small for much of the 2006 growing season (e.g., midday values of about 5 umol/m2/s) due, in large part, to the very dry conditions in eastern Nebraska and the consequent low soil water contents. However, copious rainfall in August raised soil water contents to field capacity throughout the profile. Soil air CO2 concentrations during this period also increased and reached peaks near 10% (at 0.4 and 0.8 m depth). Through analyses of relationships between surface CO2 flux and profiles of soil parameters we seek to identify biophysical factors responsible for controlling surface fluxes as well as to begin to quantify sources and sinks of CO2 within the soil profile (e.g., plant-related production of CO2 due to root exudation and respiration). The influence of precipitation events on CO2 profiles and fluxes is of particular interest.

  4. Quantification of soil organic carbon sequestration potential in cropland: a model approach.

    PubMed

    Qin, ZhangCai; Huang, Yao

    2010-07-01

    Agroecosystems have a critical role in the terrestrial carbon cycling process. Soil organic carbon (SOC) in cropland is of great importance for mitigating atmospheric carbon dioxide increases and for global food security. With an understanding of soil carbon saturation, we analyzed the datasets from 95 global long-term agricultural experiments distributed across a vast area spanning wide ranges of temperate, subtropical and tropical climates. We then developed a statistical model for estimating SOC sequestration potential in cropland. The model is driven by air temperature, precipitation, soil clay content and pH, and explains 58% of the variation in the observed soil carbon saturation (n=76). Model validation using independent data observed in China yielded a correlation coefficient R (2) of 0.74 (n=19, P<0.001). Model sensitivity analysis suggested that soils with high clay content and low pH in the cold, humid regions possess a larger carbon sequestration potential than other soils. As a case study, we estimated the SOC sequestration potential by applying the model in Henan Province. Model estimations suggested that carbon (C) density at the saturation state would reach an average of 32 t C ha(-1) in the top 0-20 cm soil depth. Using SOC density in the 1990s as a reference, cropland soils in Henan Province are expected to sequester an additional 100 Tg C in the future.

  5. Green Carbon, Black Carbon, White Carbon: Simultaneous Differentiation Between Soil Organic Matter, Pyrogenic Carbon and Carbonates Using Thermal Analysis Techniques

    NASA Astrophysics Data System (ADS)

    Plante, A. F.; Peltre, C.; Chan, J.; Baumgartl, T.; Erskine, P.; Apesteguía, M.; Virto, I.

    2014-12-01

    Quantification of soil carbon stocks and fluxes continues to be an important endeavor in assessments of soil quality, and more broadly in assessments of ecosystem functioning. The quantification of soil carbon in alkaline, carbonate-containing soils, such as those found in Mediterranean areas, is complicated by the need to differentiate between organic carbon (OC) and inorganic carbon (IC), which continues to present methodological challenges. Acidification is frequently used to eliminate carbonates prior to soil OC quantification, but when performed in the liquid phase, can promote the dissolution and loss of a portion of the OC. Acid fumigation (AF) is increasingly preferred for carbonate removal, but its effectiveness is difficult to assess using conventional elemental and isotopic analyses. The two-step approach is time, labor and cost intensive, and generates additional uncertainties from the calculations. Quantification of the actively cycling pool of soil organic C (SOC) in many soils is further complicated by the potential presence of more recalcitrant/stable forms such as pyrogenic or black carbon (BC) derived from incomplete combustion of vegetation, or even geogenic carbon such as coal. The wide spectrum of materials currently considered BC makes its quantification challenging. The chemical method using benzene polycarboxylic acids (BPCAs) as markers of condensed aromatic structures indicative of pyrogenic C is highly time, labor and cost intensive, and can generate artifacts. Several research groups are now developing method for the simultaneous identification and quantification of these various forms of soil carbon using thermal analysis techniques such as thermogravimetry, differential scanning calorimetry and evolved gas analysis. The objective of this presentation is to provide a general overview and specific examples of the current progress and technical challenges in this evolving methodology.

  6. Introducing a decomposition rate modifier in the Rothamsted Carbon Model to predict soil organic carbon stocks in saline soils.

    PubMed

    Setia, Raj; Smith, Pete; Marschner, Petra; Baldock, Jeff; Chittleborough, David; Smith, Jo

    2011-08-01

    Soil organic carbon (SOC) models such as the Rothamsted Carbon Model (RothC) have been used to estimate SOC dynamics in soils over different time scales but, until recently, their ability to accurately predict SOC stocks/carbon dioxide (CO(2)) emissions from salt-affected soils has not been assessed. Given the large extent of salt-affected soils (19% of the 20.8 billion ha of arable land on Earth), this may lead to miss-estimation of CO(2) release. Using soils from two salt-affected regions (one in Punjab, India and one in South Australia), an incubation study was carried out measuring CO(2) release over 120 days. The soils varied both in salinity (measured as electrical conductivity (EC) and calculated as osmotic potential using EC and water content) and sodicity (measured as sodium adsorption ratio, SAR). For soils from both regions, the osmotic potential had a significant positive relationship with CO(2)-C release, but no significant relationship was found between SAR and CO(2)-C release. The monthly cumulative CO(2)-C was simulated using RothC. RothC was modified to take into account reductions in plant inputs due to salinity. A subset of non-salt-affected soils was used to derive an equation for a "lab-effect" modifier to account for changes in decomposition under lab conditions and this modifier was significantly related with pH. Using a subset of salt-affected soils, a decomposition rate modifier (as a function of osmotic potential) was developed to match measured and modelled CO(2)-C release after correcting for the lab effect. Using this decomposition rate modifier, we found an agreement (R(2) = 0.92) between modelled and independently measured data for a set of soils from the incubation experiment. RothC, modified by including reduced plant inputs due to salinity and the salinity decomposition rate modifier, was used to predict SOC stocks of soils in a field in South Australia. The predictions clearly showed that SOC stocks are reduced in saline soils

  7. Introducing a decomposition rate modifier in the Rothamsted Carbon Model to predict soil organic carbon stocks in saline soils.

    PubMed

    Setia, Raj; Smith, Pete; Marschner, Petra; Baldock, Jeff; Chittleborough, David; Smith, Jo

    2011-08-01

    Soil organic carbon (SOC) models such as the Rothamsted Carbon Model (RothC) have been used to estimate SOC dynamics in soils over different time scales but, until recently, their ability to accurately predict SOC stocks/carbon dioxide (CO(2)) emissions from salt-affected soils has not been assessed. Given the large extent of salt-affected soils (19% of the 20.8 billion ha of arable land on Earth), this may lead to miss-estimation of CO(2) release. Using soils from two salt-affected regions (one in Punjab, India and one in South Australia), an incubation study was carried out measuring CO(2) release over 120 days. The soils varied both in salinity (measured as electrical conductivity (EC) and calculated as osmotic potential using EC and water content) and sodicity (measured as sodium adsorption ratio, SAR). For soils from both regions, the osmotic potential had a significant positive relationship with CO(2)-C release, but no significant relationship was found between SAR and CO(2)-C release. The monthly cumulative CO(2)-C was simulated using RothC. RothC was modified to take into account reductions in plant inputs due to salinity. A subset of non-salt-affected soils was used to derive an equation for a "lab-effect" modifier to account for changes in decomposition under lab conditions and this modifier was significantly related with pH. Using a subset of salt-affected soils, a decomposition rate modifier (as a function of osmotic potential) was developed to match measured and modelled CO(2)-C release after correcting for the lab effect. Using this decomposition rate modifier, we found an agreement (R(2) = 0.92) between modelled and independently measured data for a set of soils from the incubation experiment. RothC, modified by including reduced plant inputs due to salinity and the salinity decomposition rate modifier, was used to predict SOC stocks of soils in a field in South Australia. The predictions clearly showed that SOC stocks are reduced in saline soils

  8. Measurement of soil water content with dielectric dispersion frequency

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Frequency domain reflectometry (FDR) is an inexpensive and attractive methodology for repeated measurements of soil water content (SWC). Although there are some known measurement limitations for dry soil and sand, a fixed-frequency method is commonly employed using commercially available FDR probes....

  9. Soil organic carbon mining versus priming - controls of soil organic carbon stocks along a management gradient

    NASA Astrophysics Data System (ADS)

    Blanes, M. Carmen; Reinsch, Sabine; Glanville, Helen C.; Jones, Davey L.; Carreira, José A.; Pastrana, David N.; Emmett, Bridget A.

    2015-04-01

    Soil carbon (C), nitrogen (N) and phosphorous (P) are assumed to be connected stoichiometrically and C:N(:P) ratios are frequently used to interpret the soils nutrient status. However, plants are capable of initiating the supply of nutrients by releasing rhizodeposits into the soil, thereby stimulating soil organic matter decomposition mediated by the rhizosphere microbial community. To test the relative importance of the two mechanisms across a fertility gradient in the UK we carried out a laboratory experiment. Intact soil cores from two depths (0-15 cm and 85-100 cm) were incubated and C, N and P were added in all possible combinations resulting in a total of 216 soil cores. Soil respiration was measured (1 h incubation, 10 oC) nine times over a 2 week period. Preliminary results indicate that all soils were C limited at the surface as measured as increased soil CO2 efflux. N additions increased soil respiration only marginally, whereas C+N stimulated microbial activity on the surface, and was even more pronounced in the deeper soil layer. Belowground responses to C+P were small and even smaller for N+P but similar for both soil depths. Our results indicate nutrient controls on soil organic matter turnover differ not only across a management/fertility gradient but also vertically down the soil profile.

  10. In-situ soil carbon analysis using inelastic neutron scattering

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In situ soil carbon analysis using inelastic neutron scattering (INS) is based on the emission of 4.43 MeV gamma rays from carbon nuclei excited by fast neutrons. This in-situ method has excellent potential for easily measuring soil carbon since it does not require soil core sampling and processing ...

  11. Changes in soil carbon, nitrogen, and phosphorus due to land-use changes in Brazil

    NASA Astrophysics Data System (ADS)

    Groppo, J. D.; Lins, S. R. M.; Camargo, P. B.; Assad, E. D.; Pinto, H. S.; Martins, S. C.; Salgado, P. R.; Evangelista, B.; Vasconcellos, E.; Sano, E. E.; Pavão, E.; Luna, R.; Martinelli, L. A.

    2015-08-01

    In this paper, soil carbon, nitrogen and phosphorus concentrations and stocks were investigated in agricultural and natural areas in 17 plot-level paired sites and in a regional survey encompassing more than 100 pasture soils In the paired sites, elemental soil concentrations and stocks were determined in native vegetation (forests and savannas), pastures and crop-livestock systems (CPSs). Nutrient stocks were calculated for the soil depth intervals 0-10, 0-30, and 0-60 cm for the paired sites and 0-10, and 0-30 cm for the pasture regional survey by sum stocks obtained in each sampling intervals (0-5, 5-10, 10-20, 20-30, 30-40, 40-60 cm). Overall, there were significant differences in soil element concentrations and ratios between different land uses, especially in the surface soil layers. Carbon and nitrogen contents were lower, while phosphorus contents were higher in the pasture and CPS soils than in native vegetation soils. Additionally, soil stoichiometry has changed with changes in land use. The soil C : N ratio was lower in the native vegetation than in the pasture and CPS soils, and the carbon and nitrogen to available phosphorus ratio (PME) decreased from the native vegetation to the pasture to the CPS soils. In the plot-level paired sites, the soil nitrogen stocks were lower in all depth intervals in pasture and in the CPS soils when compared with the native vegetation soils. On the other hand, the soil phosphorus stocks were higher in all depth intervals in agricultural soils when compared with the native vegetation soils. For the regional pasture survey, soil nitrogen and phosphorus stocks were lower in all soil intervals in pasture soils than in native vegetation soils. The nitrogen loss with cultivation observed here is in line with other studies and it seems to be a combination of decreasing organic matter inputs, in cases where crops replaced native forests, with an increase in soil organic matter decomposition that leads to a decrease in the long

  12. Soil Organic Carbon Pools and Stocks in Permafrost-Affected Soils on the Tibetan Plateau

    PubMed Central

    Dörfer, Corina; Kühn, Peter; Baumann, Frank; He, Jin-Sheng; Scholten, Thomas

    2013-01-01

    The Tibetan Plateau reacts particularly sensitively to possible effects of climate change. Approximately two thirds of the total area is affected by permafrost. To get a better understanding of the role of permafrost on soil organic carbon pools and stocks, investigations were carried out including both discontinuous (site Huashixia, HUA) and continuous permafrost (site Wudaoliang, WUD). Three organic carbon fractions were isolated using density separation combined with ultrasonic dispersion: the light fractions (<1.6 g cm−3) of free particulate organic matter (FPOM) and occluded particulate organic matter (OPOM), plus a heavy fraction (>1.6 g cm−3) of mineral associated organic matter (MOM). The fractions were analyzed for C, N, and their portion of organic C. FPOM contained an average SOC content of 252 g kg−1. Higher SOC contents (320 g kg−1) were found in OPOM while MOM had the lowest SOC contents (29 g kg−1). Due to their lower density the easily decomposable fractions FPOM and OPOM contribute 27% (HUA) and 22% (WUD) to the total SOC stocks. In HUA mean SOC stocks (0–30 cm depth) account for 10.4 kg m−2, compared to 3.4 kg m−2 in WUD. 53% of the SOC is stored in the upper 10 cm in WUD, in HUA only 39%. Highest POM values of 36% occurred in profiles with high soil moisture content. SOC stocks, soil moisture and active layer thickness correlated strongly in discontinuous permafrost while no correlation between SOC stocks and active layer thickness and only a weak relation between soil moisture and SOC stocks could be found in continuous permafrost. Consequently, permafrost-affected soils in discontinuous permafrost environments are susceptible to soil moisture changes due to alterations in quantity and seasonal distribution of precipitation, increasing temperature and therefore evaporation. PMID:23468904

  13. Texture-dependent anaerobic microsites constrain soil carbon oxidation rates

    NASA Astrophysics Data System (ADS)

    Keiluweit, Marco; Fendorf, Scott

    2016-04-01

    Soil texture, which is a product of parent material, climate and other soil forming factors, is a predictor for long-term storage of soil organic carbon (SOC) storage in many soil ecosystems. Positive correlation between texture (particularly clay content) and SOC storage have long been attributed to protective associations between clay minerals and organic compounds that prevent microbial and enzymatic access - a mechanism commonly referred to as 'mineral protection'. Texture therefore acts as the primary proxy for mineral protection in terrestrial ecosystem models used to assess SOC storage and its sensitivity to global change impacts. Here we show that this protective effect of texture is not only due to mineral protection, but also to the formation of anaerobic microsites. Combining micro-scale laboratory experiments with field-scale observations, we find that oxygen diffusion limitations within clay-rich domains create anaerobic microsites within seemingly well-aerated soils, shifting microbial metabolism to less efficient anaerobic SOC oxidation pathways. Kinetic and thermodynamic constraints reduce SOC oxidation rates within these anaerobic microsites by an order of magnitude relative to aerobic rates, and caused the preservation of bioavailable, polymeric and reduced organic compounds. Lifting these metabolic constraints through increased soil aeration (e.g., through changes in precipitation patterns or land use) may stimulate microbial oxidation of this inherently bioavailable SOC pool. Models that attribute the effects of texture merely to 'mineral protection' may therefore underestimate the vulnerability of soil C to global change impacts.

  14. Climatic, edaphic, and biotic controls over storage and turnover of carbon in soils

    NASA Astrophysics Data System (ADS)

    Schimel, David S.; Braswell, B. H.; Holland, Elisabeth A.; McKeown, Rebecca; Ojima, D. S.; Painter, Thomas H.; Parton, William J.; Townsend, Alan R.

    1994-09-01

    Soil carbon, a major component of the global carbon inventory, has significant potential for change with changing climate and human land use. We applied the Century ecosystem model to a series of forest and grassland sites distributed globally to examine large-scale controls over soil carbon. Key site-specific parameters influencing soil carbon dynamics are soil texture and foliar lignin content; accordingly, we perturbed these variables at each site to establish a range of carbon concentrations and turnover times. We examined the simulated soil carbon stores, turnover times, and C:N ratios for correlations with patterns of independent variables. Results showed that soil carbon is related linearly to soil texture, increasing as clay content increases, that soil carbon stores and turnover time are related to mean annual temperature by negative exponential functions, and that heterotrophic respiration originates from recent detritus (˜50%), microbial turnover (˜30%), and soil organic matter (˜20%) with modest variations between forest and grassland ecosystems. The effect of changing temperature on soil organic carbon (SOC) estimated by Century is dSOC/dT= 183e-0.034T. Global extrapolation of this relationship leads to an estimated sensitivity of soil C storage to a temperature of -11.1 Pg° C-1, excluding extreme arid and organic soils. In Century, net primary production (NPP) and soil carbon are closely coupled through the N cycle, so that as temperatures increase, accelerated N release first results in fertilization responses, increasing C inputs. The Century-predicted effect of temperature on carbon storage is modified by as much as 100% by the N cycle feedback. Century-estimated soil C sensitivity (-11.1 Pg° C-1) is similar to losses predicted with a simple data-based calculation (-14.1 Pg° C-1). Inclusion of the N cycle is important for even first-order predictions of terrestrial carbon balance. If the NPP-SOC feedback is disrupted by land use or other

  15. The Effect of Afforestation on Soil Moisture Content in Northeastern China

    PubMed Central

    Yao, Yitong; Wang, Xuhui; Zeng, Zhenzhong; Liu, Yongwen; Peng, Shushi; Zhu, Zaichun; Piao, Shilong

    2016-01-01

    Widespread afforestation programs sequester carbon from the atmosphere and mitigate the rising of atmospheric carbon dioxide (CO2). Meanwhile, afforestation carbon sequestration may cost soil water. However, changes in soil moisture content (SMC) after large-scale afforestation or reforestation have rarely been quantified. In this study, we measured changes in SMC following afforestation using a paired plots method with data from 757 plots in Northeastern China. We found a marginally significant decline in soil moisture content of the top 1-m soil (SMC0-1m) after afforestation (P = 0.08) at the regional scale. The SMC responses to afforestation also vary across species. For example, significant SMC decrease are found for Populus spp. plantations (P < 0.05) and plantations of Pinus sylvestris var. mongolica (P < 0.05). Splitting the first meter of the soil profile into different depth intervals revealed that SMC declined significantly in shallow layers (0–30 cm) for Populus spp. and Pinus sylvestris var. mongolica. We also found that when SMC in the control exceeded a specific threshold, SMC for all five tree species considered tended to decrease, suggesting that the effects of afforestation on soil hydrology vary across different regions. PMID:27513001

  16. The Effect of Afforestation on Soil Moisture Content in Northeastern China.

    PubMed

    Yao, Yitong; Wang, Xuhui; Zeng, Zhenzhong; Liu, Yongwen; Peng, Shushi; Zhu, Zaichun; Piao, Shilong

    2016-01-01

    Widespread afforestation programs sequester carbon from the atmosphere and mitigate the rising of atmospheric carbon dioxide (CO2). Meanwhile, afforestation carbon sequestration may cost soil water. However, changes in soil moisture content (SMC) after large-scale afforestation or reforestation have rarely been quantified. In this study, we measured changes in SMC following afforestation using a paired plots method with data from 757 plots in Northeastern China. We found a marginally significant decline in soil moisture content of the top 1-m soil (SMC0-1m) after afforestation (P = 0.08) at the regional scale. The SMC responses to afforestation also vary across species. For example, significant SMC decrease are found for Populus spp. plantations (P < 0.05) and plantations of Pinus sylvestris var. mongolica (P < 0.05). Splitting the first meter of the soil profile into different depth intervals revealed that SMC declined significantly in shallow layers (0-30 cm) for Populus spp. and Pinus sylvestris var. mongolica. We also found that when SMC in the control exceeded a specific threshold, SMC for all five tree species considered tended to decrease, suggesting that the effects of afforestation on soil hydrology vary across different regions. PMID:27513001

  17. [Effects of land use type on the distribution of organic carbon in different sized soil particles effects of land use type on the distribution of organic carbon in different sized soil particles and its relationships to herb biomass in hilly red soil region of South China].

    PubMed

    Li, Zhong-Wu; Guo, Wang; Wang, Xiao-Yan; Shen, Wei-Ping; Zhang, Xue; Chen, Xiao-Lin; Zhang, Yue-Nan

    2012-04-01

    The changes in organic carbon content in different sized soil particles under different land use patterns partly reflect the variation of soil carbon, being of significance in revealing the process of soil organic carbon cycle. Based on the long-term monitoring of soil erosion, and by the methods of soil particle size fractionation, this paper studied the effects of different land use types (wasteland, pinewood land, and grassland) on the distribution of organic carbon content in different sized soil particles and its relationships to the herb biomass. Land use type and slope position had obvious effects on the organic carbon content in different sized soil particles, and the organic carbon content was in the order of grassland > pinewood land > wasteland. The proportion of the organic carbon in different sized soil particles was mainly depended on the land use type, and had little relationships with slope position. According to the analysis of the ratio of particle-associated organic carbon to mineral-associated organic carbon (POC/MOC), the soil organic carbon in grassland was easily to be mineralized, whereas that in wasteland and pinewood land was relatively stable. On the slopes mainly in hilly red soil region, the soil organic carbon in sand fraction had great effects on herb biomass. PMID:22803447

  18. [Effects of land use type on the distribution of organic carbon in different sized soil particles effects of land use type on the distribution of organic carbon in different sized soil particles and its relationships to herb biomass in hilly red soil region of South China].

    PubMed

    Li, Zhong-Wu; Guo, Wang; Wang, Xiao-Yan; Shen, Wei-Ping; Zhang, Xue; Chen, Xiao-Lin; Zhang, Yue-Nan

    2012-04-01

    The changes in organic carbon content in different sized soil particles under different land use patterns partly reflect the variation of soil carbon, being of significance in revealing the process of soil organic carbon cycle. Based on the long-term monitoring of soil erosion, and by the methods of soil particle size fractionation, this paper studied the effects of different land use types (wasteland, pinewood land, and grassland) on the distribution of organic carbon content in different sized soil particles and its relationships to the herb biomass. Land use type and slope position had obvious effects on the organic carbon content in different sized soil particles, and the organic carbon content was in the order of grassland > pinewood land > wasteland. The proportion of the organic carbon in different sized soil particles was mainly depended on the land use type, and had little relationships with slope position. According to the analysis of the ratio of particle-associated organic carbon to mineral-associated organic carbon (POC/MOC), the soil organic carbon in grassland was easily to be mineralized, whereas that in wasteland and pinewood land was relatively stable. On the slopes mainly in hilly red soil region, the soil organic carbon in sand fraction had great effects on herb biomass.

  19. Soil management and carbon calculation methods influence changes in soil carbon estimation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Throughout the years, many studies have evaluated changes in soil organic carbon (SOC) mass on a fixed-depth (FD) basis without considering changes in soil mass caused by changing in bulk density. In two study sites, we investigated the effect of different management practices on SOC changes calcul...

  20. Evaluation of Different Soil Carbon Determination Methods

    SciTech Connect

    Chatterjee, Dr Amitava; Lal, Dr R; Wielopolski, Dr L; Martin, Madhavi Z; Ebinger, Dr Michael H

    2009-01-01

    Determining soil carbon (C) with high precision is an essential requisite for the success of the terrestrial C sequestration program. The informed choice of management practices for different terrestrial ecosystems rests upon accurately measuring the potential for C sequestration. Numerous methods are available for assessing soil C. Chemical analysis of field-collected samples using a dry combustion method is regarded as the standard method. However, conventional sampling of soil and their subsequent chemical analysis is expensive and time consuming. Furthermore, these methods are not sufficiently sensitive to identify small changes over time in response to alterations inmanagement practices or changes in land use. Presently, several different in situ analytic methods are being developed purportedly offering increased accuracy, precision and cost-effectiveness over traditional ex situ methods. We consider that, at this stage, a comparative discussion of different soil C determination methods will improve the understanding needed to develop a standard protocol.

  1. Austrian Carbon Calculator (ACC) - modelling soil carbon dynamics in Austrian soils

    NASA Astrophysics Data System (ADS)

    Sedy, Katrin; Freudenschuss, Alexandra; Zethner, Gehard; Spiegel, Heide; Franko, Uwe; Gründling, Ralf; Xaver Hölzl, Franz; Preinstorfer, Claudia; Haslmayr, Hans Peter; Formayer, Herbert

    2014-05-01

    Austrian Carbon Calculator (ACC) - modelling soil carbon dynamics in Austrian soils. The project funded by the Klima- und Energiefonds, Austrian Climate Research Programme, 4th call Authors: Katrin Sedy, Alexandra Freudenschuss, Gerhard Zethner (Environment Agency Austria), Heide Spiegel (Austrian Agency for Health and Food Safety), Uwe Franko, Ralf Gründling (Helmholtz Centre for Environmental Research) Climate change will affect plant productivity due to weather extremes. However, adverse effects could be diminished and satisfying production levels may be maintained with proper soil conditions. To sustain and optimize the potential of agricultural land for plant productivity it will be necessary to focus on preserving and increasing soil organic carbon (SOC). Carbon sequestration in agricultural soils is strongly influenced by management practice. The present management is affected by management practices that tend to speed up carbon loss. Crop rotation, soil cultivation and the management of crop residues are very important measures to influence carbon dynamics and soil fertility. For the future it will be crucial to focus on practical measures to optimize SOC and to improve soil structure. To predict SOC turnover the existing humus balance model the application of the "Carbon Candy Balance" was verified by results from Austrian long term field experiments and field data of selected farms. Thus the main aim of the project is to generate a carbon balancing tool box that can be applied in different agricultural production regions to assess humus dynamics due to agricultural management practices. The toolbox will allow the selection of specific regional input parameters for calculating the C-balance at field level. However farmers or other interested user can also apply their own field data to receive the result of C-dynamics under certain management practises within the next 100 years. At regional level the impact of predefined changes in agricultural management

  2. The impact of changing land use, nitrate deposition and CO sub 2 fertilization on soil carbon storage

    SciTech Connect

    Harrison, K.; Broecker, W.

    1992-05-21

    This research strives to assess the impact of changing land use, nitrate deposition and CO{sub 2} fertilization on soil carbon storage. Our motivation is that this reservoir is the most likely candidate for the so-called missing carbon sink. We are working on several aspects of this problem by measuring carbon content, nitrogen content and radiocarbon ratios in paired soil samples from neighboring sites, to determine the impact of land use on soil carbon inventories and turnover times. We are also gathering information on how the C/N ratios in soils vary with climate and changing land use, in an effort to estimate how much carbon has been sequestered as a result of atmospheric fallout of NH{sub 4}OH and HNO{sub 3}. Finally, we are developing a soil greening model that uses CO{sub 2} growth-enhancement results and bomb radiocarbon-based estimates of soil carbon inventory response times.

  3. Distribution of calcium carbonate in desert soils: A model

    SciTech Connect

    Mayer, L.; McFadden, L.D.; Harden, J.W.

    1988-04-01

    A model that describes the distribution of calcium carbonate in desert soils as a function of dust flux, time, climate, and other soil-forming factors shows which factors most strongly influence the accumulation of carbonate and can be used to evaluate carbonate-based soil age estimates or paleoclimatic reconstructions. Models for late Holocene soils have produced carbonate distributions that are very similar to those of well-dated soils in New Mexico and southern California. These results suggest that (1) present climate is a fair representation of late Holocene climate, (2) carbonate dust flux can be approximated by its Holocene rate, and (3) changes in climate and/or dust flux at the end of the Pleistocene effected profound and complex changes in soil carbonate distributions. Both higher carbonate dust flux and greater effective precipitation are required during the latest Pleistocene-early Holocene to explain carbonate distributions in latest Pleistocene soils. 21 refs., 4 figs., 1 tab.

  4. Relationship between soil copper content and copper content of selected crop plants in central Chile.

    PubMed

    Badilla-Ohlbaum, R; Ginocchio, R; Rodríguez, P H; Céspedes, A; González, S; Allen, H E; Lagos, G E

    2001-12-01

    A survey of copper levels in agricultural soils of central Chile revealed two soil clusters-one with a mean copper level of 162 mg/kg and one with a mean copper level of 751 mg/kg of soil. Samples of soils from both soil clusters were characterized on the basis of physicochemical characteristics, and copper extractability was compared by saturation and CaCl2 extraction as well as an acid-leaching procedure (TCLP). We also measured the copper content of various tissues of tomato (Lycopersicon esculentum) and onion (Allium cepa) crops growing on these soils. Other than copper levels, soils from the two clusters were quite similar, with slightly greater levels of molybdenum and cadmium in the high-copper soils. Within each cluster, extracted copper levels and total soil copper levels were not correlated. However, the three extraction procedures solubilized significantly more copper from the high-Cu soils. Mineralogical characterization of the soil particles and depth profiles of soil metal levels in a subsample of sites suggested that highly insoluble copper ore and mining wastes might account for the high copper levels. Neither total nor extractable copper levels allowed statistical prediction of the levels of copper in plant tissue. The edible tissues of both crops had the same mean copper content, regardless of the copper soil level. However, copper contents of stems and leaves were significantly higher for plants growing on the high-Cu soils. These results show that in these soils, high copper levels are associated with very insoluble copper species and thus low bioavailability of copper to crop plants. PMID:11764158

  5. The impact of climate change on carbon storage of urban soils

    NASA Astrophysics Data System (ADS)

    Bidló, András; Gálos, Borbála; Horváth, Adrienn

    2014-05-01

    The soil carbon stock has a very significant role in the global carbon cycle. In many ecosystems the carbon content of soils is higher, than what is stored in plants and this is typical for urban soils too. In order to investigate the carbon content of the soils we have collected samples from the upper layer of sampling sites in the following Hungarian towns: Sopron, Szombathely, Székesfehérvár. In these towns there are significant differences in land use, as besides the old downtown there are also younger suburbs and suburban forests, vineyards, pastures, gardens and agricultural areas. Cause the location of towns will be another determining factor the effect of climate change in future. Samples were collected from soil spots from 0-10 and 10-20 cm depth as well as from soil profiles, where samples were taken from each of the profile layers. First we selected the appropriate method for the measurement of the soil carbon content, as there are several possible methods for this. Carbon content cannot be determined in calcareous soils using the C/N/S apparatus, thus we used wet-burning methods with potassium-permanganate. The results of the field and laboratory measurements were represented in a GIS system (Digiterra Map). The highest average carbon content has been determined in the upper layer of forest lands of Sopron (4.6 % C). The lowest values have been measured in both layers on the agricultural areas of Székesfehérvár (1.72 % C). Differences between carbon results can be explained by the effects of the vegetation and land use. Land use is also significantly determined by ecological conditions and now the whole ecological system depends on effect of climate change. Research was supported financially by the TÁMOP-4.2.2.A-11/1/KONV-2012-0013 project.

  6. Non-invasive Field Measurements of Soil Water Content Using a Pulsed 14 MeV Neutron Generator

    SciTech Connect

    Mitra S.; Wielopolski L.; Omonode, R.; Novak, J.; Frederick, J.; Chan, A.

    2012-01-26

    Current techniques of soil water content measurement are invasive and labor-intensive. Here, we demonstrate that an in situ soil carbon (C) analyzer with a multi-elemental analysis capability, developed for studies of terrestrial C sequestration, can be used concurrently to non-invasively measure the water content of large-volume ({approx}0.3 m{sup 3}) soil samples. Our objectives were to investigate the correlations of the hydrogen (H) and oxygen (O) signals with water to the changes in the soil water content in laboratory experiments, and in an agricultural field. Implementing prompt gamma neutron activation analyses we showed that in the field, the signal from the H nucleus better indicates the soil water content than does that from the O nucleus. Using a field calibration, we were able to use the H signal to estimate a minimum detectable change of {approx}2% volumetric water in a 0-30 cm depth of soil.

  7. [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

  8. [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).

  9. Predicting sub-grid variability of soil water content from basic soil information

    NASA Astrophysics Data System (ADS)

    Qu, Wei; Bogena, Heye; Huisman, Johan Alexander; Vanderborght, Jan; Schuh, Max; Priesack, Eckart; Vereecken, Harry

    2015-04-01

    Knowledge of unresolved soil water content variability within model grid cells (i.e. sub-grid variability) is important for accurate predictions of land-surface energy and hydrologic fluxes. Here, we derived a closed-form expression to describe how soil water content variability depends on mean soil water content using stochastic analysis of 1D unsaturated gravitational flow based on the van Genuchten-Mualem (VGM) model. A sensitivity analysis of this closed-form expression showed that the n parameter strongly influenced both the shape and magnitude of the maximum of this relationship. In a next step, the closed-form expression was used to predict soil water content variability for eight datasets with varying soil texture using VGM parameters obtained from pedotransfer functions that rely on readily available soil information. Generally, there was good agreement between observed and predicted soil water content variability despite the obvious simplifications that were used to derive the closed-form expression (e.g. gravity flow in dry soils). A simplified closed-form expression that neglected the effect of pressure head fluctuations showed that the good performance in the dry soil range is related to the dominant role of the variability in MVG parameters determining water retention as compared to the effect of water flow. Furthermore, the novel closed-form expression was successfully used to inversely estimate the variability of hydraulic properties from observed data on soil water content variability from several test sites in Germany, China and Australia.

  10. Black Carbon Concentrations in Urban and Rural Arid-Land Soils

    NASA Astrophysics Data System (ADS)

    Hamilton, A.; Hartnett, H. E.

    2008-12-01

    central Arizona soils can be defined as black carbon. Mapping these BC contents across the Phoenix metropolitan area reveals a general pattern with higher BC contents in soils from urban locations and lower BC contents in soils from the urban fringe and rural areas. The highest BC contents are associated with major freeways and the pattern suggests that within the urban core, fossil fuel burning contributes a significant source of BC.

  11. Limited transport of functionalized multi-walled carbon nanotubes in two natural soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Column experiments were conducted in undisturbed and in repacked soil columns at water contents close to saturation (85–96%) to investigate the transport and retention of functionalized 14C-labeled multi-walled carbon nanotubes (MWCNT) in two natural soils. Additionally, a field lysimeter experiment...

  12. Recent advances in modeling depth distribution of soil carbon storage

    NASA Astrophysics Data System (ADS)

    Mishra, U.; Shu, S.

    2015-12-01

    Depth distribution of soil carbon storage determines the sensitivity of soil carbon to environmental change. We present different approaches that have been used to represent the vertical heterogeneity of soil carbon both in mapping and modeling studies. In digital soil mapping, many studies applied exponential decay functions in soils where carbon concentration has been observed to decline with depth. Recent studies used various forms of spline functions to better represent the vertical distribution of soil carbon along with soil horizons. These studies fitted mathematical functions that described the observations and then interpolated the model coefficients using soil-forming factors and used maps of model coefficients with depth to predict the SOC storage at desired depth intervals. In general, the prediction accuracy decreased with depth and the challenge remains to find appropriate soil-forming factors that determine/explain subsurface soil variation. Models such as Century, RothC, and Terrestrial Ecosystem Model use the exponential depth distribution functions of soil carbon in their model structures. In CLM 4.5 the soil profile is partitioned into 10 layers down to 3.8 m depth and the carbon input from plant roots is assumed to decrease following an exponential function. Not accounting for soil horizons in representing biogeochemistry and the assumption of globally uniform soil depth remain major sources of uncertainty in these models. In this presentation, we will discuss the merits and demerits of using various profile depth distribution functions to represent the vertical heterogeneity of soil carbon storage.

  13. [Profile distribution and storage of soil organic carbon in a black soil as affected by land use types].

    PubMed

    Hao, Xiang-xiang; Han, Xiao-zeng; Li, Lu-jun; Zou, Wen-xiu; Lu, Xin-chun; Qiao, Yun-fa

    2015-04-01

    Taking soils in a long-term experimental field over 29 years with different land uses types, including arable land, bare land, grassland and larch forest land as test materials, the distribution and storage of soil organic carbon (SOC) in the profile (0-200 cm) in typical black soil (Mollisol) region of China were investigated. The results showed that the most significant differences in SOC content occurred in the 0-10 cm surface soil layer among all soils with the order of grassland > arable land > larch forest land > bare land. SOC contents at 10-120 cm depth were lower in arable land as compared with the other land use types. Compared with arable land, grassland could improve SOC content obviously. SOC content down to a depth of 60 cm in grassland was significantly higher than that in arable land. The content of SOC at 0-10 cm in bare land was significantly lower than that in arable land. Although there were no significant differences in SOC content at 0-20 cm depth between larch forestland and arable land, the SOC contents at 20-140 cm depth were generally higher in larch forestland than that in arable land. In general, SOC content showed a significantly negative relationship with soil pH, bulk density, silt and clay content and an even stronger significantly positive relationship with soil total N content and sand content. The SOC storage in arable land at 0-200 cm depth was significantly lower than that in the other three land use types, which was 13.6%, 11.4% and 10.9% lower than in grassland, bare land and larch forest land, respectively. Therefore, the arable land of black soil has a great potential for sequestering C in soil and improving environmental quality.

  14. [Diversity of carbon source metabolism of microbial community in farmland soils in an arsenic mining area].

    PubMed

    Hua, Jian-Feng; Lin, Xiang-Gui; Jiang, Qian; Zhang, Hua-Yong; Chen, Qian; Yin, Yun-Long

    2013-02-01

    By using Biolog technique, this paper studied the diversity of carbon source metabolism of microbial community in three farmland soils with different levels of arsenic (As) in an As mining area, and the relationships between the diversity of the carbon source metabolism and the main soil chemical properties. The total N (TN), total P (TP), total K (TK), organic matter (OM), total Cu, and total Zn contents in the three soils were in the order of medium level As > high level As > low level As. The average well color development (AWCD), Shannon index (H'), Simpson index (D), and McIntosh index (U) of soil microbes were significantly higher in the soils with medium and high levels As than in the soil with low level As. The principal component analysis and the fingerprints of the physiological carbon metabolism of the microbial community in the three soils demonstrated that the microbes in the soils with medium and high levels As had a significantly higher (P<0. 05) utilization rate in carbohydrates and amino acids than the microbes in the soil with low level As. The correlation analysis showed that the AWCD, H', D, and U were significantly positively correlated with the contents of soil TN, TP, OM, total As, total Cu, total Pb, and total Zn (P<0.05), and the canonical correspondence analysis revealed that soil TP, OM, total Pb, total Zn, TN, and pH rather than soil total As were the main soil chemical properties affecting the carbon source metabolism of soil microbial community. It was considered that soil nutrients could be the main factors affecting the community structure and functions of soil microbes in long-term contaminated soils.

  15. Importance of Iron and Soil Physicochemical Properties to Stabilize Organic Carbon in Soils

    NASA Astrophysics Data System (ADS)

    Zhao, Q.; Yang, Y.; Obrist, D.; Poulson, S.

    2015-12-01

    Global warming can potentially accelerate the decomposition of forest soil organic matter (SOM), as a source of greenhouse gas emissions. Understanding the fate of forest SOM is important for evaluating and managing the global carbon cycle during climate change. Iron minerals play an important role in stabilizing organic carbon (OC) and regulating the biogeochemical cycle in the soil environment, but there is only limited information available concerning how iron-mediated OC stabilization is affected by physicochemical properties of soil. This study investigated the behavior of iron-bound OC in soils collected from 14 forests across the United States, and the impact of soil physicochemical properties on the stabilization of OC by iron minerals. The bicarbonate-citrate-dithionite (BCD) method was used to reduce iron in soil samples, and OC content was characterized prior and after reduction to quantify iron-bound OC. We found that iron-bound OC contributed 1.2 - 57.7 weight % of total OC in forest soils. Atomic ratios of iron-bound OC:Fe ranged from 0.006 to 0.178, indicating the importance of sorptive interactions. The fraction of iron-bound OC was more closely correlated to the molar ratio of iron-bound OC:Fe than the absolute concentration of reactive iron, which is ranged from 0.08 to 19.31 mg/g. Iron-bound OC was enriched in 13C compared to the non-iron-bound SOM. There were significant correlations between the total N concentration and total or non-iron bound OC, but not with iron-bound OC. Overall, iron minerals mainly stabilize 13C-enriched non-nitrogenous OC, which was almost regulated by the sorptive association between iron and OC. Our results illustrate the importance of understanding the stabilization of OC in soil, and the coupled biogeochemical processes of carbon and iron.

  16. Performance evaluation of TDT soil water content and watermark soil water potential sensors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated the performance of digitized Time Domain Transmissometry (TDT) soil water content sensors (Acclima, Inc., Meridian, ID) and resistance-based soil water potential sensors (Watermark 200, Irrometer Company, Inc., Riverside, CA) in two soils. The evaluation was performed by compar...

  17. [Effects of understory removal on soil labile organic carbon pool in a Cinnamomum camphora plantation].

    PubMed

    Wu, Ya-Cong; Li, Zheng-Cai; Cheng, Cai-Fang; Liu, Rong-Jie; Wang, Bin; Geri, Le-Tu

    2013-12-01

    Taking a 48-year-old Cinnamomum camphora plantation in the eastern area of our subtropics as test object, this paper studied the labile organic carbon contents and their ratios to the total organic carbon (TOC) in 0-60 cm soil layer under effects of understory removal (UR). As compared with no understory removal (CK), the soil TOC and easily-oxidized carbon (EOC) contents under UR decreased, with a decrement of 4.8% - 34.1% and 27.1% - 36.2%, respectively, and the TOC and EOC contents had a significant difference in 0-10 cm and 0-20 cm layers, respectively. The water-soluble organic carbon (WSOC) (except in 0-10 cm and 10-20 cm layers) and light fraction organic matter (LFOM) under UR increaesd, but the difference was not significant. The ratio of soil WSOC to soil TOC in UR stand was higher than that in CK stand, while the ratio of soil EOC to soil TOC showed an opposite trend. In the two stands, soil WSOC, EOC, and LFOM had significant or extremely significant correlations with soil TOC, and the correlation coefficients of soil EOC and LFOM with soil TOC were higher in UR stand than in CK, but the correlation coefficient between soil WSOC and TOC was in opposite. The soil EOC, LFOM, and TOC in the two stands were significantly or extremely significantly correlated with soil nutrients, but the soil WSOC in UR stand had no significant correlations with soil hydrolyzable N, available P, exchangeable Ca, and exchangeable Mg.

  18. Stability of Biomass-derived Black Carbon in Soils

    SciTech Connect

    Liang, Biqing; Lehmann, Johannes C.; Solomon, Dawit; Sohi, Saran; Thies, Janice E.; Skjemstad, Jan O.; Luizao, Flavio J.; Engelhard, Mark H.; Neves, Eduaro G.; Wirick, Sue

    2008-12-15

    Black carbon (BC) may play an important role in the global C budget, due to its potential to act as a significant removal (sink) of atmospheric CO2. In order to fully evaluate the influence of BC on the global C cycle, a sound understanding of the stability of BC is required. The biochemical stability of BC was assessed in a chronosequence of high-BC containing Anthrosols from the central Amazon, Brazil, using a range of spectroscopic and biological methods. Results revealed that the Anthrosols had 61-80% lower (P<0.05) CO2 evolution over 532 days compared to that in the corresponding adjacent soils with low BC contents. No significant (P>0.05) differences of CO2 respiration were observed between Anthrosols with contrasting ages of BC and soil textures. Molecular forms of core regions of micrometer-sized BC particles quantified by synchrotron-based near-edge x-ray fine structure (NEXAFS) spectroscopy coupled to scanning x-ray transmission microscopy (STXM) remained similar regardless of their ages (600 to 8,700 years) and closely resembled the spectral characteristics of fresh BC. Deconvolution of NEXAFS spectra revealed greater oxidation on the surfaces of BC particles with little penetration into the core of the particles. The similar C mineralization between different BC-rich soils regardless of soil texture underpins the importance of chemical recalcitrance for the stability of BC, in contrast to adjacent soils which showed the highest mineralization in the sandiest soil. However, C distribution between free, intra-aggregate and organo-mineral pools was significantly different between soils with high and low BC contents, suggesting some degree of physical stabilization, and BC-rich Anthrosols had higher proportions (72-90%) of C in the organo-mineral fraction than BC-poor adjacent soils (2-70%).

  19. Soil permeability as a function of vegetation type and soil water content.

    PubMed

    Morris, R C; Fraley, L

    1994-06-01

    Soil permeability is important for estimating the rate of mass transport of 222Rn through soils and into basements (Nazaroff 1992). We measured permeability and soil water content on a set of nine plots consisting of three plots vegetated with common barley (Hordeum vulgare), three plots vegetated with Russian thistle (Salsola kali), and three bare plots. Soil moisture was consistently highest on the bare plots and lowest on the Russian thistle plots. Plots with vegetation had lower soil water content during the growing season. Permeability was consistently higher on Russian thistle plots. ANOVA showed that both soil water content and presence of Russian thistle had a significant impact on permeability but that presence of barley did not. The effect of vegetation and moisture on permeability may have significant effects on 222Rn transport in soils.

  20. Soil permeability as a function of vegetation type and soil water content

    SciTech Connect

    Morris, R.C.; Fraley, L. Jr.

    1994-06-01

    Soil permeability is important for estimating the rate of mass transport of {sup 222}Rn through soils and into basements. We measured permeability and soil water content on a set of nine plots consisting of three plots vegetated with common barley (Hordeum vulgare), three plots vegetated with Russian thistle (Salsola kali), and three bare plots. Soil moisture was consistently highest on the bare plots and lowest on the Russian thistle plots. Plots with vegetation had lower soil water content during the growing season. Permeability was consistently higher on Russian thistle plots. ANOVA showed that both soil water content and presence of Russian thistle had a significant impact on permeability but that presence of barley did not. The effect of vegetation and moisture on permeability may have significant effects on {sup 222}Rn transport in soils. 18 refs., 8 figs., 1 tab.

  1. Remediation of Contaminated Soils By Supercritical Carbon Dioxide Extraction

    NASA Astrophysics Data System (ADS)

    Ferri, A.; Zanetti, M. C.; Banchero, M.; Fiore, S.; Manna, L.

    superficial velocity of the supercritical carbon dioxide; therefore, the mass transfer resistance can be reduced increasing such velocity. In this work, higher values of superficial velocity were investigated. The experimental apparatus includes a pump, an extraction vessel, an adjustable restrictor and a trap to collect the extracted substance. Liquid carbon dioxide coming from a cylinder with a dip-tube is cooled by a cryostatic bath and then it is compressed by a pneumatic drive pump (the max- imum available pressure is 69 MPa). Subsequently, the pressurised current flows into 1 a heating coil and then into the extraction vessel, which is contained in a stove; the outlet flow is depressurised in an adjustable restrictor and the extracted substance is collected in a trap by dissolution into a solvent. The extracted naphthalene quantity was obtained by weighting the solvent and measuring the naphthalene concentration with a gas chromatograph. The soil sample is a sandy soil geologically representative of the North of Italy that was sampled and physically and chemically characterized: particle-size distribution analysis, diffractometric analysis, Cation Exchange Capac- ity, Total Organic Carbon, iron content and manganese content in order to evaluate the potential sorption degree. The soil was artificially polluted by means of a naphta- lene and methylene chloride solution. The experimental work consists in a number of naphthalene extractions from the spiked soil, that were carried out at different operat- ing conditions, temperature, pressure and flow rate by means of supercritical carbon dioxide evaluating the corresponding recovery efficiencies. The results obtained were analysed and compared in order to determine which parameters influence the system. [1] G. A. Montero, T.D. Giorgio, and K. B. Schnelle, Jr..Removal of Hazardous ,1994, Contaminants form Soils by Supercritical Fluid Extraction. Innovations in Supercriti- cal Fluids. ACS Symposium Series, 608, 280-197. 2

  2. Aggregate formation and soil carbon sequestration by earthworms at the ORNL FACE experiment

    NASA Astrophysics Data System (ADS)

    Sanchez-de Leon, Y.; Gonzalez-Meler, M. A.; Lugo-Perez, J.; Wise, D. H.; Jastrow, J. D.

    2012-12-01

    Earthworms have an important role in soil carbon sequestration, but their contribution to carbon sequestration in soils exposed to elevated atmospheric CO2 concentrations has been largely overlooked. Previous studies at the Oak Ridge National Laboratory Free Air CO2 Experiment (ORNL FACE) site showed that the formation of soil aggregates is a key mechanism for soil carbon sequestration. We did a microcosm experiment to quantify earthworm-mediated aggregate formation and compare between two earthworm species with different feeding habits (endogeic vs. epi-edogeic). In addition, we wanted to identify the carbon source (soil, leaf litter or root litter) within aggregates formed by earthworms. We used 13C-depleted soil and 15N-enriched sweetgum (Liquidambar styraciflua) leaf and root litter collected from the ORNL FACE site to assess soil aggregate formation of the native, endogeic earthworm Diplocardia sp. and European, epi-endogeic earthworm Lumbricus rubellus. Both earthworm species are present at the ORNL FACE site. We crushed, sieved (< 250 μm) soil and prepared four treatments: (I) soil only; (II) soil and plant material; (III) soil, plant material and Diplocardia sp.; (IV) soil, plant material and L. rubellus. All treatments were at 30% water content and temperature was maintained at 20°C. The incubation period lasted 26 days. We measured aggregate size distribution, total aggregate carbon content and 13C and 15N to elucidate aggregate carbon source. Newly formed soil macroaggregates (> 250 μm) were higher in treatments with earthworms (III and IV) than in treatments without earthworms (I and II) (p = 0.02). Within macroaggregates, most of the carbon was soil-derived. Leaf and root-derived carbon was found in treatment IV only. Our results suggest that earthworms at the ORNL FACE site directly contribute to the formation of soil aggregates, thus contributing to soil carbon sequestration. Carbon source within macroaggregates correspond with earthworm feeding

  3. Total organic carbon in aggregates as a soil recovery indicator

    NASA Astrophysics Data System (ADS)

    Luciene Maltoni, Katia; Rodrigues Cassiolato, Ana Maria; Amorim Faria, Glaucia; Dubbin, William

    2015-04-01

    The soil aggregation promotes physical protection of organic matter, preservation of which is crucial to improve soil structure, fertility and ensure the agro-ecosystems sustainability. The no-tillage cultivation system has been considered as one of the strategies to increase total soil organic carbono (TOC) contents and soil aggregation, both are closely related and influenced by soil management systems. The aim of this study was to evaluate the distribution of soil aggregates and the total organic carbon inside aggregates, with regard to soil recovery, under 3 different soil management systems, i.e. 10 and 20 years of no-tillage cultivation as compared with soil under natural vegetation (Cerrado). Undisturbed soils (0-5; 5-10; and 10-20 cm depth) were collected from Brazil, Central Region. The soils, Oxisols from Cerrado, were collected from a field under Natural Vegetation-Cerrado (NV), and from fields that were under conventional tillage since 1970s, and 10 and 20 years ago were changed to no-tillage cultivation system (NT-10; NT-20 respectively). The undisturbed samples were sieved (4mm) and the aggregates retained were further fractionated by wet sieving through five sieves (2000, 1000, 500, 250, and 50 μm) with the aggregates distribution expressed as percentage retained by each sieve. The TOC was determined, for each aggregate size, by combustion (Thermo-Finnigan). A predominance of aggregates >2000 μm was observed under NV treatment (92, 91, 82 %), NT-10 (64, 73, 61 %), and NT-20 (71, 79, 63 %) for all three depths (0-5; 5-10; 10-20 cm). In addition greater quantities of aggregates in sizes 1000, 500, 250 and 50 μm under NT-10 and NT-20 treatments, explain the lower aggregate stability under these treatments compared to the soil under NV. The organic C concentration for NV in aggregates >2000 μm was 24,4; 14,2; 8,7 mg/g for each depth (0-5; 5-10; 10-20 cm, respectively), higher than in aggregates sized 250-50 μm (7,2; 5,5; 4,4 mg/g) for all depths

  4. Determination of the carbon content of airborne fungal spores.

    PubMed

    Bauer, Heidi; Kasper-Giebl, Anne; Zibuschka, Franziska; Hitzenberger, Regina; Kraus, Gunther F; Puxbaum, Hans

    2002-01-01

    Airborne fungal spores contribute potentially to the organic carbon of the atmospheric aerosol, mainly in the "coarse aerosol" size range 2.5-10 microm aerodynamic equivalent diameter (aed). Here, we report about a procedure to determine the organic carbon content of fungal spores frequently observed in the atmosphere. Furthermore, we apply a new (carbon/individual) factor to quantify the amount of fungal-spores-derived organic carbon in aerosol collected at a mountain site in Austria. Spores of representatives of Cladosporium sp., Aspergillus sp., Penicillium sp., and Alternaria sp., the four predominant airborne genera, were analyzed for their carbon content using two different analytical procedures. The result was an average carbon content of 13 pg C/spore (RSD, 46%), or expressed as a carbon-per-volume ratio, 0.38 pg C/microm3 (RSD, 30%). These values are comparable to conversion factors for bacteria and some representatives of the zooplankton. Because biopolymers are suspected of interfering with elemental carbon determination by thermal methods, the amount of "fungal carbon" that might be erroneously mistaken for soot carbon was determined using the "two-step combustion" method of Cachier et al. and termed as "apparent elemental carbon" (AEC). This fraction amounted to up to 46% of the initial fungal carbon content. Although the aerosol samples were collected in March under wintry conditions, the organic carbon from fungal spores amounted to 2.9-5.4% of organic carbon in the "coarse mode" size fraction.

  5. Adopting a modified pressure calcimeter with temperature compensation for testing total carbonates in soils

    NASA Astrophysics Data System (ADS)

    Barouchas, Pantelis; Koulos, Vasilios

    2016-04-01

    The total carbonates content of the soil is an important soil quality indicator highly related with soil carbon sequestration and a tool for understanding biogeochemical processes or liming practices. A portable digital pressure calcimeter with multisensory technology was used in order to test total carbonates in soil samples. The concept of the measurement is based on the simultaneous measurement of pressure and temperature after the sample reaction with hydrochloric acid in a closed vessel and a built-in module for automatic temperature compensation, so that performs measurements with higher accuracy. For these purposes two stages of analysis followed in order to document the precision of the methodology: (i) Total carbonates testing in Sand/CaCO3 mixtures and (ii) Total carbonates testing in soil samples. The instrument has a typical mean error of ± 0.3% calcium carbonates content of the soil sample and a recovery more than 98% comparing to certified inter-laboratory soil samples (proficiency tests) for quality assurance. The methodology adopts portable capabilities with soil moisture correction in situ, providing to the end-user the advantages of automatic analysis, fast testing operation, fast re-samples for analysis and productivity.

  6. Assessment of soil organic carbon distribution in Europe scale by spatio-temporal data and geostatistics

    NASA Astrophysics Data System (ADS)

    Aksoy, Ece; Panagos, Panos; Montanarella, Luca

    2013-04-01

    Accuracy in assessing the distribution of soil organic carbon (SOC) is an important issue because SOC is an important soil component that plays key roles in the functions of both natural ecosystems and agricultural systems. The SOC content varies from place to place and it is strongly related with climate variables (temperature and rainfall), terrain features, soil texture, parent material, vegetation, land-use types, and human management (management and degradation) at different spatial scales. Geostatistical techniques allow for the prediction of soil properties using soil information and environmental covariates. In this study, assessment of SOC distribution has been predicted using combination of LUCAS soil samples with local soil data and ten spatio-temporal predictors (slope, aspect, elevation, CTI, CORINE land-cover classification, parent material, texture, WRB soil classification, average temperature and precipitation) with Regression-Kriging method in Europe scale. Significant correlation between the covariates and the organic carbon dependent variable was found.

  7. Current state of heavy metal contents in Vienna soils.

    PubMed

    Pfleiderer, Sebastian; Englisch, Michael; Reiter, Rainer

    2012-12-01

    This study presents the current state of heavy metal contents in both urban and forest soils within the city area of Vienna, Austria. Based on a systematic survey of urban soils and on targeted sampling in forest areas, local and regional anomaly thresholds are derived using statistical methods and considering regional distribution patterns. For urban soils, local anomaly thresholds of elements Cu (60 mg/kg), Hg (0.5 mg/kg), Pb (100 mg/kg) and Zn (200 mg/kg) exceed national guideline values for uncontaminated urban soils and according to Austrian legislation fall into the category "anthropogenic contamination present but no damage to plants, animals or humans detectable". In forest soils within the city, thresholds are very similar to reference values for similar geological settings outside the city, apart from higher concentrations of elements Cr and Ni (threshold values of 107 and 64 mg/kg, respectively). Grouping urban soils according to land use reveals that Cd contents are 25 % higher, Pb contents 36 % higher, in traffic and industrial areas than in parks and like Cu, Hg and Zn, these elements can be shown to be at least partly caused by anthropogenic contamination. A dependency between heavy metal concentrations in soils and underlying geological units is shown within the flysch zone at the western city margin where the contents of elements Co, Cr, Cu, Ni and V are controlled by geology and reveal distinct differences between geological units. In built-up areas, no clear dependency between heavy metal contents in soils and geology is evident as urban soils represent accumulations by anthropogenic activity rather than in situ weathering products of underlying sediments.

  8. Effect of land use change on the carbon cycle in Amazon soils

    NASA Technical Reports Server (NTRS)

    Trumbore, Susan E.; Davidson, Eric A.

    1994-01-01

    The overall goal of this study was to provide a quantitative understanding of the cycling of carbon in the soils associated with deep-rooting Amazon forests. In particular, we wished to apply the understanding gained by answering two questions: (1) what changes will accompany the major land use change in this region, the conversion of forest to pasture? and (2) what is the role of carbon stored deeper than one meter in depth in these soils? To construct carbon budgets for pasture and forest soils we combined the following: measurements of carbon stocks in above-ground vegetation, root biomass, detritus, and soil organic matter; rates of carbon inputs to soil and detrital layers using litterfall collection and sequential coring to estimate fine root turnover; C-14 analyses of fractionated SOM and soil CO2 to estimate residence times; C-13 analyses to estimate C inputs to pasture soils from C-4 grasses; soil pCO2, volumetric water content, and radon gradients to estimate CO2 production as a function of soil depth; soil respiration to estimate total C outputs; and a model of soil C dynamics that defines SOM fractions cycling on annual, decadal, and millennial time scales.

  9. Mechanisms of soil carbon storage in experimental grasslands

    NASA Astrophysics Data System (ADS)

    Steinbeiss, S.; Temperton, V. M.; Gleixner, G.

    2007-10-01

    We investigated the fate of root and litter derived carbon into soil organic matter and dissolved organic matter in soil profiles, in order to explain unexpected positive effects of plant diversity on carbon storage. A time series of soil and soil solution samples was investigated at the field site of The Jena Experiment. In addition to the main biodiversity experiment with C3 plants, a C4 species (Amaranthus retroflexus L.) naturally labeled with 13C was grown on an extra plot. Changes in organic carbon concentration in soil and soil solution were combined with stable isotope measurements to follow the fate of plant carbon into the soil and soil solution. A split plot design with plant litter removal versus double litter input simulated differences in biomass input. After 2 years, the no litter and double litter treatment, respectively, showed an increase of 381 g C m-2 and 263 g C m-2 to 20 cm depth, while 71 g C m-2 and 393 g C m-2 were lost between 20 and 30 cm depth. The isotopic label in the top 5 cm indicated that 11 and 15% of soil organic carbon were derived from plant material on the no litter and the double litter treatment, respectively. Without litter, this equals the total amount of carbon newly stored in soil, whereas with double litter this corresponds to twice the amount of stored carbon. Our results indicate that litter input resulted in lower carbon storage and larger carbon losses and consequently accelerated turnover of soil organic carbon. Isotopic evidence showed that inherited soil organic carbon was replaced by fresh plant carbon near the soil surface. Our results suggest that primarily carbon released from soil organic matter, not newly introduced plant organic matter, was transported in the soil solution and contributed to the observed carbon storage in deeper horizons.

  10. Accessibility, searchability, transparency and engagement of soil carbon data: The International Soil Carbon Network

    NASA Astrophysics Data System (ADS)

    Harden, Jennifer W.; Hugelius, Gustaf; Koven, Charlie; Sulman, Ben; O'Donnell, Jon; He, Yujie

    2016-04-01

    Soils are capacitors for carbon and water entering and exiting through land-atmosphere exchange. Capturing the spatiotemporal variations in soil C exchange through monitoring and modeling is difficult in part because data are reported unevenly across spatial, temporal, and management scales and in part because the unit of measure generally involves destructive harvest or non-recurrent measurements. In order to improve our fundamental basis for understanding soil C exchange, a multi-user, open source, searchable database and network of scientists has been formed. The International Soil Carbon Network (ISCN) is a self-chartered, member-based and member-owned network of scientists dedicated to soil carbon science. Attributes of the ISCN include 1) Targeted ISCN Action Groups which represent teams of motivated researchers that propose and pursue specific soil C research questions with the aim of synthesizing seminal articles regarding soil C fate. 2) Datasets to date contributed by institutions and individuals to a comprehensive, searchable open-access database that currently includes over 70,000 geolocated profiles for which soil C and other soil properties. 3) Derivative products resulting from the database, including depth attenuation attributes for C concentration and storage; C storage maps; and model-based assessments of emission/sequestration for future climate scenarios. Several examples illustrate the power of such a database and its engagement with the science community. First, a simplified, data-constrained global ecosystem model estimated a global sensitivity of permafrost soil carbon to climate change (g sensitivity) of -14 to -19 Pg C °C-1 of warming on a 100 years time scale. Second, using mathematical characterizations of depth profiles for organic carbon storage, C at the soil surface reflects Net Primary Production (NPP) and its allotment as moss or litter, while e-folding depths are correlated to rooting depth. Third, storage of deep C is highly

  11. [Responses of forest soil carbon pool and carbon cycle to the changes of carbon input].

    PubMed

    Wang, Qing-kui

    2011-04-01

    Litters and plant roots are the main sources of forest soil organic carbon (C). This paper summarized the effects of the changes in C input on the forest soil C pool and C cycle, and analyzed the effects of these changes on the total soil C, microbial biomass C, dissoluble organic C, and soil respiration. Different forests in different regions had inconsistent responses to C input change, and the effects of litter removal or addition and of root exclusion or not differed with tree species and regions. Current researches mainly focused on soil respiration and C pool fractions, and scarce were about the effects of C input change on the changes of soil carbon structure and stability as well as the response mechanisms of soil organisms especially soil fauna, which should be strengthened in the future. PMID:21774335

  12. [Responses of forest soil carbon pool and carbon cycle to the changes of carbon input].

    PubMed

    Wang, Qing-kui

    2011-04-01

    Litters and plant roots are the main sources of forest soil organic carbon (C). This paper summarized the effects of the changes in C input on the forest soil C pool and C cycle, and analyzed the effects of these changes on the total soil C, microbial biomass C, dissoluble organic C, and soil respiration. Different forests in different regions had inconsistent responses to C input change, and the effects of litter removal or addition and of root exclusion or not differed with tree species and regions. Current researches mainly focused on soil respiration and C pool fractions, and scarce were about the effects of C input change on the changes of soil carbon structure and stability as well as the response mechanisms of soil organisms especially soil fauna, which should be strengthened in the future.

  13. Water movement in stony soils: The influence of stoniness on soil water content profiles

    NASA Astrophysics Data System (ADS)

    Novak, Viliam; Knava, Karol

    2010-05-01

    WATER MOVEMENT IN STONY SOILS: THE INFLUENCE OF STONINESS ON SOIL WATER CONTENT PROFILES Viliam Novák, Karol Kňava Institute of Hydrology, Slovak Academy of Sciences, Racianska 75, 831 02 Bratislava 3, Slovakia, e-mail: novak@uh.savba.sk Soils containing rock fragments are widespread over the world, on Europe such soil account for 30%, 60% in Mediterranean region. In comparison to fine earth soils (soil particles are less then 2 mm) stony soils contain rock fragments characterized by the low retention capacity and hydraulic conductivity. So, for stony soils -in comparison to the fine-earth soils - is typical lower hydraulic conductivity and retention capacity, which lead to the decrease decrease of infiltration rate and low water retention. So, water movement and its modeling in stony soil would differ from fine earth (usually agricultural) soil. The aim of this contribution is to demonstrate the differences in water movement in homogeneous soil (fine earth) and stony soil. The influence of different stoniness on soil water content and soil water dynamics was studied too. Windthrow at High Tatra mountains in Slovakia (November 2004) cleared nearly 12 000 ha of 80 year conifers and this event initiated complex research of windthrow impact on the ecosystem. The important part of this study was water movement in impacted area. Specific feature of the soil in this area was moraine soil consisting of fine earth, characterized as silty sand, with the relative stone content up to 0.49, increasing with depth. Associated phenomenon to the forest clearing is the decrease of rain interception and higher undercanopy precipitation. Conifers interception capacity can be three times higher than low canopy interception, and can reach up to 40% of annual precipitation in Central Europe. Stones in the soil are decreasing infiltration rate, but paradoxically increased understorey precipitation and followingly the increased cumulative infiltration led to the increase of the soil

  14. Calculating carbon mass balance from unsaturated soil columns treated with CaSO₄₋minerals: test of soil carbon sequestration.

    PubMed

    Han, Young-Soo; Tokunaga, Tetsu K

    2014-12-01

    Renewed interest in managing C balance in soils is motivated by increasing atmospheric concentrations of CO2 and consequent climate change. Here, experiments were conducted in soil columns to determine C mass balances with and without addition of CaSO4-minerals (anhydrite and gypsum), which were hypothesized to promote soil organic carbon (SOC) retention and soil inorganic carbon (SIC) precipitation as calcite under slightly alkaline conditions. Changes in C contents in three phases (gas, liquid and solid) were measured in unsaturated soil columns tested for one year and comprehensive C mass balances were determined. The tested soil columns had no C inputs, and only C utilization by microbial activity and C transformations were assumed in the C chemistry. The measurements showed that changes in C inventories occurred through two processes, SOC loss and SIC gain. However, the measured SOC losses in the treated columns were lower than their corresponding control columns, indicating that the amendments promoted SOC retention. The SOC losses resulted mostly from microbial respiration and loss of CO2 to the atmosphere rather than from chemical leaching. Microbial oxidation of SOC appears to have been suppressed by increased Ca(2+) and SO4(2)(-) from dissolution of CaSO4 minerals. For the conditions tested, SIC accumulation per m(2) soil area under CaSO4-treatment ranged from 130 to 260 g C m(-1) infiltrated water (20-120 g C m(-1) infiltrated water as net C benefit). These results demonstrate the potential for increasing C sequestration in slightly alkaline soils via CaSO4-treatment.

  15. Mechanisms controlling soil carbon sequestration under atmospheric nitrogen deposition

    SciTech Connect

    R.L. Sinsabaugh; D.R. Zak; D.L. Moorhead

    2008-02-19

    Increased atmospheric nitrogen (N) deposition can alter the processing and storage of organic carbon in soils. In 2000, we began studying the effects of simulated atmospheric N deposition on soil carbon dynamics in three types of northern temperate forest that occur across a wide geographic range in the Upper Great Lakes region. These ecosystems range from 100% oak in the overstory (black oak-white oak ecosystem; BOWO) to 0% overstory oak (sugar maple-basswood; SMBW) and include the sugar maple-red oak ecosystem (SMRO) that has intermediate oak abundance. The leaf litter biochemistry of these ecosystems range from highly lignified litter (BOWO) to litter of low lignin content (SMBW). We selected three replicate stands of each ecosystem type and established three plots in each stand. Each plot was randomly assigned one of three levels of N deposition (0, 30 & 80 kg N ha-1 y-1) imposed by adding NaNO3 in six equal increments applied over the growing season. Through experiments ranging from the molecular to the ecosystem scales, we produced a conceptual framework that describes the biogeochemistry of soil carbon storage in N-saturated ecosystems as the product of interactions between the composition of plant litter, the composition of the soil microbial community and the expression of extracellular enzyme activities. A key finding is that atmospheric N deposition can increase or decrease the soil C storage by modifying the expression of extracellular enzymes by soil microbial communities. The critical interactions within this conceptual framework have been incorporated into a new class of simulations called guild decomposition models.

  16. Dynamics of Soil Organic Carbon and Aggregate Stability with Grazing Exclusion in the Inner Mongolian Grasslands.

    PubMed

    Wen, Ding; He, Nianpeng; Zhang, Jinjing

    2016-01-01

    Grazing exclusion (GE) has been deemed as an important approach to enhance the soil carbon storage of semiarid grasslands in China; however, it remains unclear how different organic carbon (OC) components in soils vary with the duration of GE. Here, we observed the changing trends of different OC components in soils with increased GE duration in five grassland succession series plots, ranging from free grazing to 31-year GE. Specifically, we measured microbial biomass carbon (MBC), easily oxidizable OC (EOC), water-soluble OC (WSOC), and OC in water stable aggregates (macroaggregates [250-2000 μm], microaggregates [53-250 μm], and mineral fraction [< 53 μm]) at 0-20 cm soil depths. The results showed that GE significantly enhanced EOC and WSOC contents in soils, but caused a decline of MBC at the three decade scale. Macroaggregate content (F = 425.8, P < 0.001), OC stored in macroaggregates (F = 84.1, P < 0.001), and the mean weight diameter (MWD) of soil aggregates (F = 371.3, P < 0.001) increased linearly with increasing GE duration. These findings indicate that OC stored in soil increases under three-decade GE with soil organic matter (SOM) stability improving to some extent. Long-term GE practices enhance the formation of soil aggregates through higher SOM input and an exclusion of animal trampling. Therefore, the practice of GE may be further encouraged to realize the soil carbon sequestration potential of semi-arid grasslands, China.

  17. Bone formation ability of carbonate apatite-collagen scaffolds with different carbonate contents.

    PubMed

    Matsuura, Ayumu; Kubo, Takayasu; Doi, Kazuya; Hayashi, Kazuhiko; Morita, Kouji; Yokota, Rie; Hayashi, Hidetaka; Hirata, Isao; Okazaki, Masayuki; Akagawa, Yasumasa

    2009-03-01

    Hydroxyapatite and carbonate apatites with different carbonate contents were synthesized, mixed with atelocollagen, and made into sponge scaffolds. The scaffolds were implanted into the bone sockets of the femurs of male New Zealand white rabbits for 2, 3, 12 and 24 weeks. carbonate apatite-collagen scaffold with 4.8 wt% carbonate content appeared to have similar crystallinity and chemical composition to human bone. When the scaffolds were implanted into the rabbit femurs, histological observation indicated that the carbonate apatites-collagen scaffolds with relatively higher carbonate contents were gradually deformed throughout the implantation period, and showed uniform surrounding bone after 24 weeks and could not be distinguished. The carbonate apatite-collagen scaffold with 4.8 wt% carbonate content showed the highest bone area ratio of all of the scaffolds. It is suggested that a carbonate apatite-collagen scaffold with carbonate content similar to that of human bone may have optimal bone formation ability.

  18. Soil respiration characteristics in different land uses and response of soil organic carbon to biochar addition in high-latitude agricultural area.

    PubMed

    Ouyang, Wei; Geng, Xiaojun; Huang, Wejia; Hao, Fanghua; Zhao, Jinbo

    2016-02-01

    The farmland tillage practices changed the soil chemical properties, which also impacted the soil respiration (R s ) process and the soil carbon conservation. Originally, the farmland in northeast China had high soil carbon content, which was decreased in the recent decades due to the tillage practices. To better understand the R s dynamics in different land use types and its relationship with soil carbon loss, soil samples at two layers (0-15 and 15-30 cm) were analyzed for organic carbon (OC), total nitrogen (TN), total phosphorus (TP), total carbon (TC), available nitrogen (AN), available phosphorus (AP), soil particle size distribution, as well as the R s rate. The R s rate of the paddy land was 0.22 (at 0-15 cm) and 3.01 (at 15-30 cm) times of the upland. The average concentrations of OC and clay content in cultivated areas were much lower than in non-cultivated areas. The partial least squares analysis suggested that the TC and TN were significantly related to the R s process in cultivated soils. The upland soil was further used to test soil CO2 emission response at different biochar addition levels during 70-days incubation. The measurement in the limited incubation period demonstrated that the addition of biochar improved the soil C content because it had high concentration of pyrogenic C, which was resistant to mineralization. The analysis showed that biochar addition can promote soil OC by mitigating carbon dioxide (CO2) emission. The biochar addition achieved the best performance for the soil carbon conservation in high-latitude agricultural area due to the originally high carbon content.

  19. Soil respiration characteristics in different land uses and response of soil organic carbon to biochar addition in high-latitude agricultural area.

    PubMed

    Ouyang, Wei; Geng, Xiaojun; Huang, Wejia; Hao, Fanghua; Zhao, Jinbo

    2016-02-01

    The farmland tillage practices changed the soil chemical properties, which also impacted the soil respiration (R s ) process and the soil carbon conservation. Originally, the farmland in northeast China had high soil carbon content, which was decreased in the recent decades due to the tillage practices. To better understand the R s dynamics in different land use types and its relationship with soil carbon loss, soil samples at two layers (0-15 and 15-30 cm) were analyzed for organic carbon (OC), total nitrogen (TN), total phosphorus (TP), total carbon (TC), available nitrogen (AN), available phosphorus (AP), soil particle size distribution, as well as the R s rate. The R s rate of the paddy land was 0.22 (at 0-15 cm) and 3.01 (at 15-30 cm) times of the upland. The average concentrations of OC and clay content in cultivated areas were much lower than in non-cultivated areas. The partial least squares analysis suggested that the TC and TN were significantly related to the R s process in cultivated soils. The upland soil was further used to test soil CO2 emission response at different biochar addition levels during 70-days incubation. The measurement in the limited incubation period demonstrated that the addition of biochar improved the soil C content because it had high concentration of pyrogenic C, which was resistant to mineralization. The analysis showed that biochar addition can promote soil OC by mitigating carbon dioxide (CO2) emission. The biochar addition achieved the best performance for the soil carbon conservation in high-latitude agricultural area due to the originally high carbon content. PMID:26408119

  20. Cadmium Contents of Soils, Durum, and Bread Wheats in Harran Plain, Southeast Turkey

    NASA Astrophysics Data System (ADS)

    Büyükkılıç, Asuman; Mermut, Ahmet; Faz Cano, Angel; Carmona Garces, Doria

    2010-05-01

    Turkey is growing significant amount of durum wheat (Triticum turgidum durum - (Desf.)Husn) which is widely used for making pasta, spaghetti, noodles etc. Objective of this study were to: 1) determine Cd concentrations of the soils, durum and bread wheats grown in the Harran plain, southeast Turkey and 2) evaluate this element in terms of food safety. Soil samples from the selected 16 profiles, grains, roots, and leaves of durum and bread wheats were taken for analyses. Total Cd contents of the soils were below the threshold values. The soils in the northern part of the plain have more than 0.2 ppm of Cd. Carbonate and clay contents are > 15% and 40% respectively and have substantial amounts of Fe-oxy-hydroxides. Three phosphorus fertilizer samples, frequently used in the area, had > 2 ppm of Cd. As expected, the amounts of Cd in bread wheat were lower than durum wheat. However, the Cd contents in durum wheat grains in the area studied were < 50 ?g kg-1 which is less than those in Canada (> 100 ?g kg-1) and similar to the drum grains from Italy. Some samples in Italy even had 71 ?g kg-1. These were attributed to the presence of high amounts of carbonates, Fe-oxy-hydroxides, and clay in the soils we studied. In the surface soil, Zn contents were between 21.5 and 72.8 mg kg-1.This could be another reason for lower contents of Cd in our durum wheat. Our study confirms that durum wheat grown in the Harran plain southeast Turkey has a better quality, therefore advantageous; in terms of food safety from the standpoint of Cd contents.

  1. [Response of Straw and Straw Biochar Returning to Soil Carbon Budget and Its Mechanism].

    PubMed

    Hou, Ya-hong; Wang, Lei; Fu, Xiao-hua; Le, Yi-quan

    2015-07-01

    Direct straw returning and straw carbonization returning are the main measures of straw returning. Because of the differences in structure and nature as well as returning process between straw and straw biochar, the soil respiration and soil carbon budget after returning must have significant differences. In this study, outdoor pot experiment was carried out to study the response of soil respiration and carbon budget to straw and straw biochar returning and its possible mechanism. The results showed that soil respiration of straw biochar returning [mean value 21. 69 µmol.(m2.s)-1] was significantly lower than that of direct straw returning [mean value 65.32 µmol.(m2.s)-1], and its soil organic carbon content ( mean value 20. 40 g . kg-1) and plant biomass (mean value 138. 56 g) were higher than those of direct straw returning (mean values 17. 76 g . kg-1 and 76. 76 g). Considering the carbon loss after the biochar preparation process, its soil carbon budget was also significantly higher than that of direct straw returning, so it was a low carbon mode of straw returning. Direct straw returning significantly promoted soil dehydrogenase activity, soil β-glycosidase activity and soil microorganism quantity, leading to higher soil respiration, but straw biochar did play an obvious role in promoting the microbial activity index. Easily oxidizable carbon (EOC) and biodegradability of straw biochar were lower than those of straw, which showed that straw biochar had higher stability, and was more difficult to degrade for soil microorganisms so its soil microbial activity was generally lower, and could be retained in the soil for a long time.

  2. Sampling for Soil Carbon Stock Assessment in Rocky Agricultural Soils

    NASA Technical Reports Server (NTRS)

    Beem-Miller, Jeffrey P.; Kong, Angela Y. Y.; Ogle, Stephen; Wolfe, David

    2016-01-01

    Coring methods commonly employed in soil organic C (SOC) stock assessment may not accurately capture soil rock fragment (RF) content or soil bulk density (rho (sub b)) in rocky agricultural soils, potentially biasing SOC stock estimates. Quantitative pits are considered less biased than coring methods but are invasive and often cost-prohibitive. We compared fixed-depth and mass-based estimates of SOC stocks (0.3-meters depth) for hammer, hydraulic push, and rotary coring methods relative to quantitative pits at four agricultural sites ranging in RF content from less than 0.01 to 0.24 cubic meters per cubic meter. Sampling costs were also compared. Coring methods significantly underestimated RF content at all rocky sites, but significant differences (p is less than 0.05) in SOC stocks between pits and corers were only found with the hammer method using the fixed-depth approach at the less than 0.01 cubic meters per cubic meter RF site (pit, 5.80 kilograms C per square meter; hammer, 4.74 kilograms C per square meter) and at the 0.14 cubic meters per cubic meter RF site (pit, 8.81 kilograms C per square meter; hammer, 6.71 kilograms C per square meter). The hammer corer also underestimated rho (sub b) at all sites as did the hydraulic push corer at the 0.21 cubic meters per cubic meter RF site. No significant differences in mass-based SOC stock estimates were observed between pits and corers. Our results indicate that (i) calculating SOC stocks on a mass basis can overcome biases in RF and rho (sub b) estimates introduced by sampling equipment and (ii) a quantitative pit is the optimal sampling method for establishing reference soil masses, followed by rotary and then hydraulic push corers.

  3. Soil Organic Carbon Degradation, Barrow, 2013-2014

    DOE Data Explorer

    Gu, Baohua; Yang, Ziming

    2015-03-30

    This dataset provides information about soil organic carbon decomposition in Barrow soil incubation studies. The soil cores were collected from low-center polygon (Area A) and were incubated in the laboratory at different temperatures for up to 60 days. Transformations of soil organic carbon were characterized by UV and FT-IR, and small organic acids in water-soluble carbons were quantified by ion chromatography during the incubation

  4. Existing Soil Carbon Models Do Not Apply to Forested Wetlands.

    SciTech Connect

    Trettin, C C; Song, B; Jurgensen, M F; Li, C

    2001-09-14

    Evaluation of 12 widely used soil carbon models to determine applicability to wetland ecosystems. For any land area that includes wetlands, none of the individual models would produce reasonable simulations based on soil processes. Study presents a wetland soil carbon model framework based on desired attributes, the DNDC model and components of the CENTURY and WMEM models. Proposed synthesis would be appropriate when considering soil carbon dynamics at multiple spatial scales and where the land area considered includes both wetland and upland ecosystems.

  5. Total Contents and Sequential Extraction of Heavy Metals in Soils Irrigated with Wastewater, Akaki, Ethiopia

    NASA Astrophysics Data System (ADS)

    Fitamo, Daniel; Itana, Fisseha; Olsson, Mats

    2007-02-01

    The Akaki River, laden with untreated wastes from domestic, industrial, and commercial sources, serves as a source of water for irrigating vegetable farms. The purpose of this study is to identify the impact of waste-water irrigation on the level of heavy metals and to predict their potential mobility and bioavailability. Zn and V had the highest, whereas Hg the lowest, concentrations observed in the soils. The average contents of As, Co, Cr, Cu, Ni, Zn, V, and Hg of both soils; and Pb and Se from Fluvisol surpassed the mean + 2 SD of the corresponding levels reported for their uncontaminated counterparts. Apparently, irrigation with waste water for the last few decades has contributed to the observed higher concentrations of the above elements in the study soils (Vertisol and Fluvisol) when compared to uncontaminated Vertisol and Fluvisol. On the other hand, Vertisol accommodated comparatively higher average levels of Cr, Cu, Ni, Zn, etc V, and Cd, whereas high contents of Pb and Se were observed in Fluvisol. Alternatively, comparable levels of Co and Hg were found in either soil. Except for Ni, Cr, and Cd in contaminated Vertisol, heavy metals in the soils were not significantly affected by the depth (0-20 and 30-50 cm). When the same element from the two soils was compared, the levels of Cr, Cu, Ni, Pb, Se, Zn, V, Cd at 0-20 cm; and Cr, Ni, Cu, Cd, and Zn at 30-50 cm were significantly different. Organic carbon (in both soils), CEC (Fluvisol), and clay (Vertisol) exhibited significant positive correspondences with the total heavy metal levels. Conversely, Se and Hg contents revealed perceptible associations with carbonate and pH. The exchangeable fraction was dominated by Hg and Cd, whereas the carbonate fraction was abounded with Cd, Pb, and Co. conversely, V and Pb displayed strong affinity to reducible fraction, where as Cr, Cu, Zn, and Ni dominated the oxidizable fraction. Cr, Hg, Se, and Zn (in both soils) showed preference to the residual fraction

  6. Isotopic Approach to Soil Carbonate Dynamics and Implications for Paleoclimatic Interpretations

    USGS Publications Warehouse

    Pendall, E.G.; Harden, J.W.; Trumbore, S.E.; Chadwick, O.A.

    1994-01-01

    The radiocarbon content and stable isotope composition of soil carbonate are best described by a dynamic system in which isotopic reequilibration occurs as a result of recurrent dissolution and reprecipitation. Depth of water penetration into the soil profile, as well as soil age, determines the degree of carbonate isotope reequilibration. We measured ??13C, ??18O and radiocarbon content of gravel rinds and fine (<2 mm) carbonate in soils of 3 .different ages (1000, 3800, and 6300 14 C yr B.P.) to assess the degree to which they record and preserve a climatic signal. In soils developing in deposits independently dated at 3800 and 6300 radiocarbon yr B.P., carbonate radiocarbon content above 40 cm depth suggests continual dissolution and reprecipitation, presumably due to frequent wetting events. Between 40 and 90 cm depth, fine carbonate is dissolved and precipitated as rinds that are not redissolved subsequently. Below 90 cm depth in these soils, radiocarbon content indicates that inherited, fine carbonate undergoes little dissolution and reprecipitation. In the 3800- and 6300-yr-old soils, ??13C in rind and fine carbonate follows a decreasing trend with depth, apparently in equilibrium with modern soil gas, as predicted by a diffusive model for soil CO2. ??18O also decreases with depth due to greater evaporative enrichment above 50 cm depth. In contrast, carbonate isotopes in a 1000-yr-old deposit do not reflect modern conditions even in surficial horizons; this soil has not undergone significant pedogenesis. There appears to be a lag of at least 1000 but less than 3800 yr before carbonate inherited with parent material is modified by ambient climatic conditions. Although small amounts of carbonate are inherited with the parent material, the rate of pedogenic carbonate accumulation indicates that Ca is derived primarily from eolian and rainfall sources. A model describing carbonate input and radiocarbon decay suggests that fine carbonate below 90 cm is mostly

  7. The impact of hazelnuts in land-use changes on soil carbon and in situ soil respiration dynamics.

    PubMed

    Oral, HasanVolkan; Guney, Mert; Kucuker, Mehmet Ali; Onay, Turgut T; Copty, Nadim K; Mater, Baris; Yenigun, Orhan

    2013-11-15

    Our study assessed the impact of hazelnuts (Coryllus avellena L.) in land-use conversion from forest (F) to agricultural land (AL) on various attributes of soil respiration dynamics, such as soil elemental carbon (C%) content, microbial respiration, bulk density, soil pH, electrical conductivity, and seasonal variations. We developed soil C% models to compare soil C% between F and AL soils. Four field trips were conducted in the winter and summer of 2008 and the spring and fall of 2009 in the Karasu region of Turkey. During each trip, 42 sites were visited F (n = 21) and AL (n = 21). Our results showed that hazelnuts plantations in AL could reduce elemental C% by 27% (winter 2008), 16% (summer 2008), 41% (spring 2009), and 22% (fall 2009) in the four seasons studied when compared to F soils. In situ soil respiration was also reduced by 31% (spring 2008), 67% (fall 2008), 88% (spring 2009), and 79% (fall 2009) in AL soils over F soils. The percent of organic matter of AL soils was declined by 36% (winter 2008), 23% (summer 2008), 34% (spring 2009), and 26% (fall 2009) in comparison to F soils. Significant reductions in the correlation between C%-percent clay and C%-electrical conductivity were also recorded for AL soils over F soils. Furthermore, AL soils showed higher bulk density (7.4% and 7%) when compared to F soils. We also found that in situ soil respiration had significant seasonal correlations (p < 0.05) with soil pH (0.537), soil temperature, and percent clay (-0.486) in F soils (summer 2008, spring 2009). Additionally, we found that seasonal variations of four sampling seasons had a moderate impact on in situ respiration and that the differences were statistically significant, except for the winter-summer and spring-fall seasonal pairs. Linear regression C models showed significant differences for F and AL soils.

  8. Modelling carbon and nitrogen turnover in variably saturated soils

    NASA Astrophysics Data System (ADS)

    Batlle-Aguilar, J.; Brovelli, A.; Porporato, A.; Barry, D. A.

    2009-04-01

    Natural ecosystems provide services such as ameliorating the impacts of deleterious human activities on both surface and groundwater. For example, several studies have shown that a healthy riparian ecosystem can reduce the nutrient loading of agricultural wastewater, thus protecting the receiving surface water body. As a result, in order to develop better protection strategies and/or restore natural conditions, there is a growing interest in understanding ecosystem functioning, including feedbacks and nonlinearities. Biogeochemical transformations in soils are heavily influenced by microbial decomposition of soil organic matter. Carbon and nutrient cycles are in turn strongly sensitive to environmental conditions, and primarily to soil moisture and temperature. These two physical variables affect the reaction rates of almost all soil biogeochemical transformations, including microbial and fungal activity, nutrient uptake and release from plants, etc. Soil water saturation and temperature are not constants, but vary both in space and time, thus further complicating the picture. In order to interpret field experiments and elucidate the different mechanisms taking place, numerical tools are beneficial. In this work we developed a 3D numerical reactive-transport model as an aid in the investigation the complex physical, chemical and biological interactions occurring in soils. The new code couples the USGS models (MODFLOW 2000-VSF, MT3DMS and PHREEQC) using an operator-splitting algorithm, and is a further development an existing reactive/density-dependent flow model PHWAT. The model was tested using simplified test cases. Following verification, a process-based biogeochemical reaction network describing the turnover of carbon and nitrogen in soils was implemented. Using this tool, we investigated the coupled effect of moisture content and temperature fluctuations on nitrogen and organic matter cycling in the riparian zone, in order to help understand the relative

  9. Soil organic carbon, macropore networks and preferential transport

    NASA Astrophysics Data System (ADS)

    Larsbo, Mats; Koestel, John; Kätterer, Thomas; Jarvis, Nick

    2016-04-01

    Agricultural management practices such as tillage, crop rotations, residue management and fertilization can have a strong influence on soil organic carbon (SOC) stocks. An increase in SOC content will generally improve soil structure, which in turn determines the solute transport pathways through the soil. The aim of this study was to quantify the architecture of macropore networks in undisturbed soil columns (15 cm high, 12.7 cm diameter) sampled along a transect with natural variations in SOC using X-ray tomography and to relate the network characteristics to the degree of preferential transport in the columns. Two tracer experiments were carried out at constant irrigation rates of 2 and 5 mm h-1. We used the normalised 5% arrival time which reflects the tendency for early arrival of the solutes as a measure of the degree of preferential transport. The soil macropore networks were analysed in cylindrical sub-volumes (8 cm high, 10 cm diameter) located centrally within the soil columns. These sub-volumes were considered unaffected by sampling artefacts. Analyses were also carried out the for whole sample volumes to enable comparisons with the results from the transport experiments. Image processing and analysis were carried out in ImageJ and R. The same grey value threshold was applied to all images after harmonisation of grey values using the PVC column walls and the air outside the columns. This approach resulted in a satisfactory separation between the pore space and the surrounding soil matrix and organic matter. The SOC content along the transect, which varied from 4.2 to 15% , was correlated to all measures of the pore network for the sub-volumes except for the connectivity probability. Columns with high SOC content were associated with large macroporosities (both total and connected), large specific surface areas, large fractal dimensions and small mean pore thicknesses. The SOC content for whole sample volumes was positively correlated to 5% arrival times

  10. Influences of winery-distillery waste compost stability and soil type on soil carbon dynamics in amended soils.

    PubMed

    Bustamante, M A; Said-Pullicino, D; Paredes, C; Cecilia, J A; Moral, R

    2010-10-01

    The application of organic materials to replenish soil organic matter and improve soil structure and fertility has become a common agronomic practice. This research deals with the effects of soil amendment with winery and distillery waste composts on organic carbon (C) mineralisation in two arable soils. A sandy-loam and clay-loam soil were treated and incubated with a number organic materials obtained from the co-composting of different proportions of grape stalk, grape marc, exhausted grape marc and vinasse, with sewage sludge or animal manure. Moreover, the effect of compost stability on C mineralisation dynamics was studied by applying organic materials from different stages of the composting process. The results obtained showed that the addition of exogenous organic matter stimulated microbial growth, enhanced soil respiration and increased water-extractable C contents in both soils, particularly in the days immediately following amendment. The initial composition of the different organic materials used, especially for the mature samples, and the texture of the receiving soil did not influence significantly the C mineralisation final values, with around 11-20% of the added organic C being mineralised over the first 140 days. However, the contribution of organic amendment to the labile organic C pool, maximum rates of soil respiration, as well as the extent of initial disturbance of the soil microbiota were all found to be related to the degree of organic matter stability. Moreover, irrespective of the type and stability of the organic amendment, the mineralogical composition of the receiving soil was found to significantly influence its resilience in such systems.

  11. Influences of winery-distillery waste compost stability and soil type on soil carbon dynamics in amended soils.

    PubMed

    Bustamante, M A; Said-Pullicino, D; Paredes, C; Cecilia, J A; Moral, R

    2010-10-01

    The application of organic materials to replenish soil organic matter and improve soil structure and fertility has become a common agronomic practice. This research deals with the effects of soil amendment with winery and distillery waste composts on organic carbon (C) mineralisation in two arable soils. A sandy-loam and clay-loam soil were treated and incubated with a number organic materials obtained from the co-composting of different proportions of grape stalk, grape marc, exhausted grape marc and vinasse, with sewage sludge or animal manure. Moreover, the effect of compost stability on C mineralisation dynamics was studied by applying organic materials from different stages of the composting process. The results obtained showed that the addition of exogenous organic matter stimulated microbial growth, enhanced soil respiration and increased water-extractable C contents in both soils, particularly in the days immediately following amendment. The initial composition of the different organic materials used, especially for the mature samples, and the texture of the receiving soil did not influence significantly the C mineralisation final values, with around 11-20% of the added organic C being mineralised over the first 140 days. However, the contribution of organic amendment to the labile organic C pool, maximum rates of soil respiration, as well as the extent of initial disturbance of the soil microbiota were all found to be related to the degree of organic matter stability. Moreover, irrespective of the type and stability of the organic amendment, the mineralogical composition of the receiving soil was found to significantly influence its resilience in such systems. PMID:20382012

  12. [Impact of tillage practices on microbial biomass carbon in top layer of black soils].

    PubMed

    Sun, Bing-jie; Jia, Shu-xia; Zhang, Xiao-ping; Liang, Ai-zhen; Chen, Xue-wen; Zhang, Shi-xiu; Liu, Si-yi; Chen, Sheng-long

    2015-01-01

    A study was conducted on a long-term (13 years) tillage and rotation experiment on black soil in northeast China to determine the effects of tillage, time and soil depth on soil microbial biomass carbon (MBC). Tillage systems included no tillage (NT), ridge tillage (RT) and mould-board plough (MP). Soil sampling was done at 0-5, 5-10 and 10-20 cm depths in June, August and September, 2013, and April, 2014 in the corn phase of corn-soybean rota