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Sample records for n2o emission hotspots

  1. Hotspots of N2O and CH4 emissions in tropical ecosystems

    NASA Astrophysics Data System (ADS)

    Castaldi, Simona; Bertolini, Teresa; Santini, Monia; Thongo M'Bou, Armel; De Grandcourt, Agnes; Nicolini, Giacomo; Valentini, Riccardo

    2013-04-01

    At global level, tropics represent the strongest biogenic source of N2O and CH4, with natural ecosystems having a comparable or even dominant role, in terms of source strength, respect to agro-ecosystems. The uncertainty related to both sources is very high, due to the paucity of data and small frequency of sampling in tropical studies. We present data of ongoing measurements of N2O and CH4 fluxes from tropical areas of the African continent spanning from savannas to humid forests and ephemeral wetlands. Natural and managed sites are also compared. A budget at African continental level is presented based on empirical relationships derived from a reanalysis of experimental published studies. Data show that humid tropical forests are the strongest N2O terrestrial source. Both spatial and temporal variability seem to be mainly driven by organic matter inputs. At Regional level annual N2O production follows a sigmoid distribution with rainfall, a key drivers of NPP. In presence of land conversion, agro-ecosystems are significant sources of N2O in the first year following deforestation, but after 10-15 years they strongly reduce their emissions compared with primary forests. Wetlands are the strongest source of CH4 but humid forests, when analysed at landscape level, present lowland hotspots of CH4 emissions which counterbalance the CH4 sink of upland areas. Also the CH4 sink from seasonally dry areas seems weaker than previous estimates.

  2. Decreased N2O reduction by low soil pH causes high N2O emissions in a riparian ecosystem.

    PubMed

    Van den Heuvel, R N; Bakker, S E; Jetten, M S M; Hefting, M M

    2011-05-01

    Quantification of harmful nitrous oxide (N(2)O) emissions from soils is essential for mitigation measures. An important N(2)O producing and reducing process in soils is denitrification, which shows deceased rates at low pH. No clear relationship between N(2)O emissions and soil pH has yet been established because also the relative contribution of N(2)O as the denitrification end product decreases with pH. Our aim was to show the net effect of soil pH on N(2)O production and emission. Therefore, experiments were designed to investigate the effects of pH on NO(3)(-) reduction, N(2)O production and reduction and N(2) production in incubations with pH values set between 4 and 7. Furthermore, field measurements of soil pH and N(2)O emissions were carried out. In incubations, NO(3)(-) reduction and N(2) production rates increased with pH and net N(2)O production rate was highest at pH 5. N(2)O reduction to N(2) was halted until NO(3)(-) was depleted at low pH values, resulting in a built up of N(2)O. As a consequence, N(2)O:N(2) production ratio decreased exponentially with pH. N(2)O reduction appeared therefore more important than N(2)O production in explaining net N(2)O production rates. In the field, a negative exponential relationship for soil pH against N(2)O emissions was observed. Soil pH could therefore be used as a predictive tool for average N(2)O emissions in the studied ecosystem. The occurrence of low pH spots may explain N(2)O emission hotspot occurrence. Future studies should focus on the mechanism behind small scale soil pH variability and the effect of manipulating the pH of soils.

  3. Microcosm N2O emissions wth calibration

    EPA Pesticide Factsheets

    The dataset consists of measurements of soil nitrous oxide emissions from soils under three different amendments: glucose, cellulose, and manure. Data includes the four isotopomers of nitrous oxide (14N15N16O, 15N14N16O, 14N14N18O, 14N14N16O), and the site preference.This dataset is associated with the following publication:Chen , H., D. Williams , P. Deshmukh , F. Birgand, B. Maxwell, and J. Walker. Probing the Biological Sources of Soil N2O Emissions by Quantum Cascade Laser-Based 15N Isotopocule Analysis. SOIL SCIENCE SOCIETY OF AMERICA JOURNAL. Soil Science Society of America, Madison, WI, USA, 100(0): 175-181, (2016).

  4. Soil invertebrate fauna affect N2 O emissions from soil.

    PubMed

    Kuiper, Imke; de Deyn, Gerlinde B; Thakur, Madhav P; van Groenigen, Jan Willem

    2013-09-01

    Nitrous oxide (N2 O) emissions from soils contribute significantly to global warming. Mitigation of N2 O emissions is severely hampered by a lack of understanding of its main controls. Fluxes can only partly be predicted from soil abiotic factors and microbial analyses - a possible role for soil fauna has until now largely been overlooked. We studied the effect of six groups of soil invertebrate fauna and tested the hypothesis that all of them increase N2 O emissions, although to different extents. We conducted three microcosm experiments with sandy soil and hay residue. Faunal groups included in our experiments were as follows: fungal-feeding nematodes, mites, springtails, potworms, earthworms and isopods. In experiment I, involving all six faunal groups, N2 O emissions declined with earthworms and potworms from 78.4 (control) to 37.0 (earthworms) or 53.5 (potworms) mg N2 O-N m(-2) . In experiment II, with a higher soil-to-hay ratio and mites, springtails and potworms as faunal treatments, N2 O emissions increased with potworms from 51.9 (control) to 123.5 mg N2 O-N m(-2) . Experiment III studied the effect of potworm density; we found that higher densities of potworms accelerated the peak of the N2 O emissions by 5 days (P < 0.001), but the cumulative N2 O emissions remained unaffected. We propose that increased soil aeration by the soil fauna reduced N2 O emissions in experiment I, whereas in experiment II N2 O emissions were driven by increased nitrogen and carbon availability. In experiment III, higher densities of potworms accelerated nitrogen and carbon availability and N2 O emissions, but did not increase them. Overall, our data show that soil fauna can suppress, increase, delay or accelerate N2 O emissions from soil and should therefore be an integral part of future N2 O studies.

  5. N2O emissions from a nitrogen-enriched river

    USGS Publications Warehouse

    McMahon, P.B.; Dennehy, K.F.

    1999-01-01

    Nitrous oxide (N2O) emissions from the South Platte River in Colorado were measured using closed chambers in the fall, winter, and summer of 1994- 1995. The South Platte River was enriched in inorganic N (9-800 ??M) derived from municipal wastewater effluent and groundwater return flows from irrigated agricultural fields. River water was as much as 2500% supersaturated with N2O, and median N2O emission rates from the river surface ranged from less than 90 to 32 600 ??g-N m-2 d-1. Seventy-nine percent of the variance in N2O emission rates was explained by concentrations of total inorganic N in river water and by water temperature. The estimated total annual N2O emissions from the South Platte River were 2 x 1013-6 x 1013 ??g-N yr-1. This amount of annual N2O emissions was similar to the estimated annual N2O emissions from all primary municipal wastewater treatment processes in the United States (1). Results from this study indicate that N-enriched rivers could be important anthropogenic sources of N2O to the atmosphere. However, N2O emission measurements from other N-enriched rivers are needed to better quantify this source.Nitrous oxide (N2O) emissions from the South Platte River in Colorado were measured using closed chambers in the fall, winter, and summer of 1994-1995. The South Platte River was enriched in inorganic N (9-800 ??M) derived from municipal wastewater effluent and groundwater return flows from irrigated agricultural fields. River water was as much as 2500% supersaturated with N2O, and median N2O emission rates from the river surface ranged from less than 90 to 32 600 ??g-N m-2 d-1. Seventy-nine percent of the variance in N2O emission rates was explained by concentrations of total inorganic N in river water and by water temperature. The estimated total annual N2O emissions from the South Platte River were 2??1013-6??1013 ??g-N yr-1. This amount of annual N2O emissions was similar to the estimated annual N2O emissions from all primary municipal

  6. Diurnality of soil nitrous oxide (N2O) emissions

    NASA Astrophysics Data System (ADS)

    Gelfand, I.; Moyer, R.; Poe, A.; Pan, D.; Abraha, M.; Chen, J.; Zondlo, M. A.; Robertson, P.

    2015-12-01

    Soil emissions of nitrous oxide (N2O) are important contributors to the greenhouse gas balance of the atmosphere. Agricultural soils contribute ~65% of anthropogenic N2O emissions. Understanding temporal and spatial variability of N2O emissions from agricultural soils is vital for closure of the global N2O budget and the development of mitigation opportunities. Recent studies have observed higher N2O fluxes during the day and lower at night. Understanding the mechanisms of such diurnality may have important consequences for our understanding of the N cycle. We tested the hypothesis that diurnal cycles are driven by root carbon exudes that stimulate denitrification and therefore N2O production. Alternatively, we considered that the cycle could result from higher afternoon temperatures that accelerate soil microbial activity. We removed all plants from a corn field plot and left another plot untouched. We measured soil N2O emissions in each plot using a standard static chamber technique throughout the corn growing season. And also compared static chamber results to ecosystem level N2O emissions as measured by eddy covariance tower equipped with an open-path N2O sensor. We also measured soil and air temperatures and soil water and inorganic N contents. Soil N2O emissions followed soil inorganic N concentrations and in control plot chambers ranged from 10 μg N m-2 hr-1 before fertilization to 13×103 after fertilization. We found strong diurnal cycles measured by both techniques with emissions low during night and morning hours and high during the afternoon. Corn removal had no effect on diurnality, but had a strong effect on the magnitude of soil N2O emissions. Soil temperature exhibited a weak correlation with soil N2O emissions and could not explain diurnal patterns. Further studies are underway to explore additional mechanisms that might contribute to this potentially important phenomena.

  7. Nitrous oxide (N2O) emission from aquaculture: a review.

    PubMed

    Hu, Zhen; Lee, Jae Woo; Chandran, Kartik; Kim, Sungpyo; Khanal, Samir Kumar

    2012-06-19

    Nitrous oxide (N(2)O) is an important greenhouse gas (GHG) which has a global warming potential 310 times that of carbon dioxide (CO(2)) over a hundred year lifespan. N(2)O is generated during microbial nitrification and denitrification, which are common in aquaculture systems. To date, few studies have been conducted to quantify N(2)O emission from aquaculture. Additionally, very little is known with respect to the microbial pathways through which N(2)O is formed in aquaculture systems. This review suggests that aquaculture can be an important anthropogenic source of N(2)O emission. The global N(2)O-N emission from aquaculture in 2009 is estimated to be 9.30 × 10(10) g, and will increase to 3.83 × 10(11)g which could account for 5.72% of anthropogenic N(2)O-N emission by 2030 if the aquaculture industry continues to increase at the present annual growth rate (about 7.10%). The possible mechanisms and various factors affecting N(2)O production are summarized, and two possible methods to minimize N(2)O emission, namely aquaponic and biofloc technology aquaculture, are also discussed. The paper concludes with future research directions.

  8. Microhabitat Effects on N2O Emissions from Floodplain Soils under Controlled Conditions

    NASA Astrophysics Data System (ADS)

    Ley, Martin; Lehmann, Moritz F.; Niklaus, Pascal A.; Kuhn, Thomas; Luster, Jörg

    2016-04-01

    Semi-terrestrial soils such as floodplain soils are considered to be potential hotspots of nitrous oxide (N2O) emissions. The quantitative assessment of N2O release from these hotspots under field conditions, and of the microbial pathways that underlie net N2O production (ammonium oxidation, nitrifier-denitrification, and denitrification) is challenging because of their high spatial and temporal variability. The production and consumption of N2O appears to be linked to the presence or absence of micro-niches, providing specific conditions that may be favorable to either of the relevant microbial pathways. Flood events have been shown to trigger moments of enhanced N2O emission through a close coupling of niches with high and low oxygen availabilities. This coupling might be modulated by microhabitat effects related to soil aggregate formation, root soil interactions and the degradation of organic matter accumulations. In order to assess how these factors can modulate N2O production and consumption under simulated flooding/drying conditions, we have set up a mesocosm experiment with N-rich floodplain soils comprising different combinations of soil aggregate size classes and inert matrix material. These model soils were either planted with basket willow (Salix viminalis L.), mixed with leaf litter, or left untreated. Throughout a simulated flood event, we repeatedly measured the net N2O production rate. In addition, soil water content, redox potential, as well as C and N substrate availability were monitored. In order to gain insight into the sources of, and biogeochemical controls on N2O production, we also measured the bulk δ15N signature of the produced N2O, as well as its intramolecular 15N site preference (SP). In this presentation we focus on a period of enhanced N2O emission during the drying phase after 48 hrs of flooding. We will discuss the observed emission patterns in the context of possible treatment effects. Soils with large aggregates showed a

  9. UV-induced N2O emission from plants

    NASA Astrophysics Data System (ADS)

    Bruhn, Dan; Albert, Kristian R.; Mikkelsen, Teis N.; Ambus, Per

    2014-12-01

    Nitrous oxide (N2O) is an important long-lived greenhouse gas and precursor of stratospheric ozone-depleting mono-nitrogen oxides. The atmospheric concentration of N2O is persistently increasing; however, large uncertainties are associated with the distinct source strengths. Here we investigate for the first time N2O emission from terrestrial vegetation in response to natural solar ultra violet radiation. We conducted field site measurements to investigate N2O atmosphere exchange from grass vegetation exposed to solar irradiance with and without UV-screening. Further laboratory tests were conducted with a range of species to study the controls and possible loci of UV-induced N2O emission from plants. Plants released N2O in response to natural sunlight at rates of c. 20-50 nmol m-2h-1, mostly due to the UV component. The emission response to UV-A is of the same magnitude as that to UV-B. Therefore, UV-A is more important than UV-B given the natural UV-spectrum at Earth's surface. Plants also emitted N2O in darkness, although at reduced rates. The emission rate is temperature dependent with a rather high activation energy indicative for an abiotic process. The prevailing zone for the N2O formation appears to be at the very surface of leaves. However, only c. 26% of the UV-induced N2O appears to originate from plant-N. Further, the process is dependent on atmospheric oxygen concentration. Our work demonstrates that ecosystem emission of the important greenhouse gas, N2O, may be up to c. 30% higher than hitherto assumed.

  10. Nitrogen fertiliser formulation: The impact on N2O emissions

    NASA Astrophysics Data System (ADS)

    Harty, Mary; Krol, Dominika; Carolan, Rachael; McNeill, Gavin; McGeough, Karen; Laughlin, Ronnie; Watson, Catherine; Richards, Karl; Lanigan, Gary; Forrestal, Patrick

    2015-04-01

    Agriculture was responsible for 31% of Ireland's Agricultural Greenhouse Gas (GHG) emissions in 2012, with 39% of these emissions arising from chemical/organic fertilizers in the form of nitrous oxide (N2O). Switching from calcium ammonium nitrate (CAN) to a urea based fertiliser limits the soil residence period of nitrate, the major substrate for denitrification loss in the N2O form. However, urea is susceptible to ammonia (NH3) volatilisation but this risk can be managed using urease inhibitors. The aim of this study was to evaluate the effect of switching from CAN to urea, urea with the urease inhibitor N- (n-butyl) thiophosphoric triamide (trade name Agrotain®) and/or the nitrification inhibitor dicyandiamide (DCD on direct and indirect N2O emissions. The experiment is a two year study (commenced March 2013) at six permanent pasture sites located on the island of Ireland, at Johnstown Castle Co. Wexford, Moorepark Co. Cork and Hillsborough Co. Down, covering a range of soil textures and drainage characteristics. The experiment simulated a grazing environment; annual fertiliser N was applied at different rates (0, 100, 200, 300, 400 or 500 kg N ha-1) in five equal splits, with grass harvested prior to fertilizer application. Direct N2O emissions were quantified regularly using static chambers over 1 year and indirect N2O from ammonia volatilisation was measured using wind tunnels and annual emission factors calculated. Switching from CAN to urea dramatically reduced direct N2O emissions, but had little effect on dry-matter yield. However, there was evidence of pollution swapping of direct for indirect N2O from NH3. In the first year, two urea based formulations successfully reduced both direct and indirect N2O emissions at all sites. Fertiliser formulation strategy has the potential to be a solution for reduction of direct and indirect N2O emissions.

  11. N2O Emission Trends From a Global Atmospheric Inversion

    NASA Astrophysics Data System (ADS)

    Thompson, R.; Chevallier, F.; Zaehle, S.; Dlugokencky, E. J.

    2015-12-01

    Nitrous oxide (N2O) is the third most important long-lived greenhouse gas and contributes strongly to stratospheric ozone depletion through the formation of NO. Concentrations of N2O in the atmosphere have increased by approximately 20% since the pre-industrial era owing largely to the intensification of agriculture and the use of mineral nitrogen fertilizers. Top-down methods can be used to constrain the emissions of N2O using observations of atmospheric concentrations. Inverse modelling is a top-down approach, which relates changes in N2O concentrations to the emissions with the help of an atmospheric transport model. Using the global inverse model, LMDz-PyVar, we estimated N2O emissions from 1996 to 2012 (covering the period when sufficient atmospheric observations are available). Emissions were estimated monthly with a horizontal resolution of 3.25° × 1.875°. From the inversion, we estimate a global mean emission of 17.0 ± 0.8 TgN y-1, however, the emissions varied substantially from year-to-year. The largest inter-annual variability was located in the tropics and subtropics, where it appears to be correlated with ENSO climate variability. We did not find any significant trend in the global emission over 1996 - 2012, however, we did find important trends on continental scales. In South and East Asia, South America and Africa, N2O emissions increased, consistent with increasing use of N-fertilizer. In contrast, in Europe and North America, N2O emissions decreased. In Europe, this is correlated with a decrease in N-fertilizer use, while in North America the decrease is possibly due to climate variability and changes in agricultural practices.

  12. Oceanic N2O emissions in the 21st century

    NASA Astrophysics Data System (ADS)

    Martinez-Rey, J.; Bopp, L.; Gehlen, M.; Tagliabue, A.; Gruber, N.

    2014-12-01

    The ocean is a substantial source of nitrous oxide (N2O) to the atmosphere, but little is known on how this flux might change in the future. Here, we investigate the potential evolution of marine N2O emissions in the 21st century in response to anthropogenic climate change using the global ocean biogeochemical model NEMO-PISCES. We implemented two different parameterizations of N2O production, which differ primarily at low oxygen (O2) conditions. When forced with output from a climate model simulation run under the business-as-usual high CO2 concentration scenario (RCP8.5), our simulations suggest a decrease of 4 to 12% in N2O emissions from 2005 to 2100, i.e., a reduction from 4.03/3.71 to 3.54/3.56 Tg N yr-1 depending on the parameterization. The emissions decrease strongly in the western basins of the Pacific and Atlantic oceans, while they tend to increase above the Oxygen Minimum Zones (OMZs), i.e., in the Eastern Tropical Pacific and in the northern Indian Ocean. The reduction in N2O emissions is caused on the one hand by weakened nitrification as a consequence of reduced primary and export production, and on the other hand by stronger vertical stratification, which reduces the transport of N2O from the ocean interior to the ocean surface. The higher emissions over the OMZ are linked to an expansion of these zones under global warming, which leads to increased N2O production associated primarily with denitrification. From the perspective of a global climate system, the averaged feedback strength associated with the projected decrease in oceanic N2O emissions amounts to around -0.009 W m-2 K-1, which is comparable to the potential increase from terrestrial N2O sources. However, the assesment for a compensation between the terrestrial and marine feedbacks calls for an improved representation of N2O production terms in fully coupled next generation of Earth System Models.

  13. Re-quantifying China's N2O emissions from croplands

    NASA Astrophysics Data System (ADS)

    Zhou, F.; Shang, Z.

    2015-12-01

    Reactive nitrogen (Nr) entering agricultural soils from fertilizer applications worldwide results into a 43%~63% of global anthropogenic N2O emissions (EDGAR, 2014; Saikawa et al., 2014; Tian et al., 2014). This contribution is likely to increase in countries with intensive agricultural systems such as China (Zhou et al., 2014). yet the patterns, trends, and the associated causes of Chinese emissions remains subject to large uncertainty; inventories of China's total agricultural soils N2O emissions at present varied by ~150% (Zhou et al., 2015). The primary sources of this uncertainty are conflicting estimates of emission factors, nitrogen inputs, and the associated environmental conditions, yet none of previous estimates are based upon large-scale measurements and high-resolution activity data. Here, we re-quantify China's N2O emissions from croplands from 1990 to 2012, including direct and indirect pathways, using updated and harmonized N input data, high-resolution environmental factors data, and a comprehensive dataset of global N2O observation networks. The spatially-variable emission factor, and leaching and runoff rates are derived by empirical upscaling of ground-based observations, but validated by ecosystem models and atmospheric inversions of N2O concentration data. N inputs, such as synthetic fertilizer, manure, crop residues, human excretion applied to croplands, are compiled at county-scale, and atmospheric N depositions are simulated by using LMDZ-OR-INCA atmospheric transport chemistry model that has been calibrated by Asian observation networks. We also develop the high-resolution datasets including landuse dynamics (1-km), SOC changes (0.1-deg), climates (0.1-deg), and irrigation rates (city-scale). Three main tasks have been performed in this study: i) the magnitude and spatiotemporal patterns of N2O emissions over China croplands from 1990 to 2012; ii) the attributions of anthropogenic causes of the spatial variations, interannual variability

  14. Microhabitat Effects on N2O Emissions from Floodplain Soils under Controlled Conditions

    NASA Astrophysics Data System (ADS)

    Ley, Martin; Lehmann, Moritz; Niklaus, Pascal; Frey, Beat; Kuhn, Thomas; Luster, Jörg

    2015-04-01

    Semi-terrestrial soils such as floodplain soils are considered to be potential hotspots of nitrous oxide (N2O) emissions. The quantitative assessment of N2O release from these hot spots under field conditions, and of the microbial pathways that underlie net N2O production (ammonium oxidation, nitrifier-denitrification, and denitrification) is challenging in the environment because of the high spatial and temporal variability. The production and consumption of N2O appears to be linked to the presence or absence of micro-niches, providing specific conditions that may be favorable to either of the microbial pathways that produce or consume N2O. The availability of oxygen, reactive organic carbon, and dissolved nitrogen substrates likely play key roles with regards to the net production of N2O. Previous field studies demonstrated, for example, that flooding can trigger "hot moments" of enhanced N2O emission through a close coupling of niches with high and low oxygen availabilities. Such microhabitat effects likely depend on soil aggregate formation, plant soil interactions in the rhizosphere and the degradation of organic matter accumulations. In order to assess how these factors can modulate N2O production and consumption under simulated flooding/drying conditions, we have set up a mesocosm experiment with model soils comprising various mixtures of N-rich floodplain soil aggregates (4000 - 250 µm representing large aggregates, or <250 µm representing small aggregates) and inert matrix material (glass beads of 150 - 250 µm size, or quartz sand of 2000 - 3200 µm size, respectively). Soils containing the different aggregate size groups were either planted with willow (Salix viminalis L.), mixed with leaf litter or left untreated. At several time points before, during and after a simulated flood event, we measure the net efflux rate of N2O. In addition, soil water content, redox potential as well as carbon and nitrogen substrate availability are monitored. In order to

  15. High-resolution measurement of nitrous oxide in the Elbe estuary under hypoxia: Hot-spots of biological N2O production

    NASA Astrophysics Data System (ADS)

    Brase, Lisa; Lendt, Ralf; Sanders, Tina; Dähnke, Kirstin

    2016-04-01

    Nitrous oxide (N2O) is one of the most important greenhouse gases. Its global warming potential exceeds that of CO2 by a factor of ˜300. Estuaries, being sites of intense biological N-turnover, are one of the major natural sources of N2O emissions. On two ship cruises in April and June 2015, concentrations of N2O were measured in the surface water using equilibrator laser based on-line measurements. Based on these high-resolution N2O profiles along the Elbe estuary, N2O saturation and N2O-fluxes between surface water and air were calculated. Additionally, DIN concentrations and dual stable isotopes of nitrate (δ15N and δ18O) were analyzed. Concentration and water-to-air fluxes of N2O were highest in the Hamburg port region and dropped quickly further downstream. Highest water-to-air fluxes were up to 800μM/m2/d and 1600μM/m2/d in April and in June, respectively. Downstream of the port region, an N2O oversaturation of 150-200% was estimated over the entire estuary, with saturation approaching equilibrium (96-100%) only in the North Sea region. N2O production was much higher in June than in April 2015, likely coupled to lower oxygen saturation in the water column in June. Based on these measurements, the port of Hamburg region was identified as a hot-spot of N2O production. High N2O concentration and depleted values of nitrate isotopes suggest that nitrification is a significant source of N2O in the estuary, especially at low oxygen concentration. In the Elbe estuary, hypoxia obviously drastically increased the emissions of the greenhouse gas N2O.

  16. Isotopic Monitoring of N2O Emissions from Wastewater Treatment: Evidence for N2O Production Associated with Anammox Metabolism?

    NASA Astrophysics Data System (ADS)

    Harris, E. J.; Wunderlin, P.; Joss, A.; Emmenegger, L.; Kipf, M.; Wolf, B.; Mohn, J.

    2015-12-01

    Microbial production is the major source of N2O, the strongest greenhouse gas produced within the nitrogen cycle, and the most important stratospheric ozone destructant released in the 21st century. Wastewater treatment is an important and growing source of N2O, with best estimates predicting N2O emissions from this sector will have increased by >25% by 2020. Novel treatment employing partial nitritation-anammox, rather than traditional nitrification-denitrification, has the potential to achieve a neutral carbon footprint due to increased biogas production - if N2O production accounts for <0.5-1% of total nitrogen turnover. As a further motivation for this research, microbial pathways identified from wastewater treatment can be applied to our understanding of N cycling in the natural environment. This study presents the first online isotopic measurements of offgas N2O from a partial-nitritation anammox reactor 1. The measured N2O isotopic composition - in particular the N2O isotopic site preference (SP = δ15Nα - δ15Nβ) - was used to understand N2O production pathways in the reactor. When N2O emissions peaked due to high dissolved oxygen concentrations, low SP showed that N2O was produced primarily via nitrifier denitrification by ammonia oxidizing bacteria (AOBs). N2O production by AOBs via NH2OH oxidation, in contrast, did not appear to be important under any conditions. Over the majority of the one-month measurement period, the measured SP was much higher than expected following our current understanding of N2O production pathways 2. SP reached 41‰ during normal operating conditions and achieved a maximum of 45‰ when nitrite was added under anoxic conditions. These results could be explained by unexpectedly strong heterotrophic N2O reduction despite low dissolved organic matter concentrations, or by an incomplete understanding of isotopic fractionation during N2O production from NH2OH oxidation by AOBs - however the explanation most consistent with all

  17. Uncertainties in United States agricultural N2O emissions: comparing forward model simulations to atmospheric N2O data.

    NASA Astrophysics Data System (ADS)

    Nevison, C. D.; Saikawa, E.; Dlugokencky, E. J.; Andrews, A. E.; Sweeney, C.

    2014-12-01

    Atmospheric N2O concentrations have increased from 275 ppb in the preindustrial to about 325 ppb in recent years, a ~20% increase with important implications for both anthropogenic greenhouse forcing and stratospheric ozone recovery. This increase has been driven largely by synthetic fertilizer production and other perturbations to the global nitrogen cycle associated with human agriculture. Several recent regional atmospheric inversion studies have quantified North American agricultural N2O emissions using top-down constraints based on atmospheric N2O data from the National Oceanic and Atmospheric Administration (NOAA) Global Greenhouse Gas Reference Network, including surface, aircraft and tall tower platforms. These studies have concluded that global N2O inventories such as EDGAR may be underestimating the true U.S. anthropogenic N2O source by a factor of 3 or more. However, simple back-of-the-envelope calculations show that emissions of this magnitude are difficult to reconcile with the basic constraints of the global N2O budget. Here, we explore some possible reasons why regional atmospheric inversions might overestimate the U.S. agricultural N2O source. First, the seasonality of N2O agricultural sources is not well known, but can have an important influence on inversion results, particularly when the inversions are based on data that are concentrated in the spring/summer growing season. Second, boundary conditions can strongly influence regional inversions but the boundary conditions used may not adequately account for remote influences on surface data such as the seasonal stratospheric influx of N2O-depleted air. We will present a set of forward model simulations, using the Community Land Model (CLM) and two atmospheric chemistry tracer transport models, MOZART and the Whole Atmosphere Community Climate Model (WACCM), that examine the influence of terrestrial emissions and atmospheric chemistry and dynamics on atmospheric variability in N2O at U.S. and

  18. Linkage between N2O emission and functional gene abundance in an intensively managed calcareous fluvo-aquic soil.

    PubMed

    Yang, Liuqing; Zhang, Xiaojun; Ju, Xiaotang

    2017-02-24

    The linkage between N2O emissions and the abundance of nitrifier and denitrifier genes is unclear in the intensively managed calcareous fluvo-aquic soils of the North China Plain. We investigated the abundance of bacterial amoA for nitrification and narG, nirS, nirK, and nosZ for denitrification by in situ soil sampling to determine how the abundance of these genes changes instantly during N fertilization events and is related to high N2O emission peaks. We also investigated how long-term incorporated straw and/or manure affect(s) the abundance of these genes based on a seven-year field experiment. The overall results demonstrate that the long-term application of urea-based fertilizer and/or manure significantly enhanced the number of bacterial amoA gene copies leading to high N2O emission peaks after N fertilizer applications. These peaks contributed greatly to the annual N2O emissions in the crop rotation. A significant correlation between annual N2O emissions and narG, nirS, and nirK gene numbers indicates that the abundance of these genes is related to N2O emission under conditions for denitrification, thus partly contributing to the annual N2O emissions. These findings will help to draw up appropriate measures for mitigation of N2O emissions in this 'hotspot' region.

  19. Global and regional emissions estimates for N2O

    NASA Astrophysics Data System (ADS)

    Saikawa, E.; Prinn, R. G.; Dlugokencky, E.; Ishijima, K.; Dutton, G. S.; Hall, B. D.; Langenfelds, R.; Tohjima, Y.; Machida, T.; Manizza, M.; Rigby, M.; O'Doherty, S.; Patra, P. K.; Harth, C. M.; Weiss, R. F.; Krummel, P. B.; van der Schoot, M.; Fraser, P. J.; Steele, L. P.; Aoki, S.; Nakazawa, T.; Elkins, J. W.

    2014-05-01

    We present a comprehensive estimate of nitrous oxide (N2O) emissions using observations and models from 1995 to 2008. High-frequency records of tropospheric N2O are available from measurements at Cape Grim, Tasmania; Cape Matatula, American Samoa; Ragged Point, Barbados; Mace Head, Ireland; and at Trinidad Head, California using the Advanced Global Atmospheric Gases Experiment (AGAGE) instrumentation and calibrations. The Global Monitoring Division of the National Oceanic and Atmospheric Administration/Earth System Research Laboratory (NOAA/ESRL) has also collected discrete air samples in flasks and in situ measurements from remote sites across the globe and analyzed them for a suite of species including N2O. In addition to these major networks, we include in situ and aircraft measurements from the National Institute of Environmental Studies (NIES) and flask measurements from the Tohoku University and Commonwealth Scientific and Industrial Research Organization (CSIRO) networks. All measurements show increasing atmospheric mole fractions of N2O, with a varying growth rate of 0.1-0.7% per year, resulting in a 7.4% increase in the background atmospheric mole fraction between 1979 and 2011. Using existing emission inventories as well as bottom-up process modeling results, we first create globally gridded a priori N2O emissions over the 37 years since 1975. We then use the three-dimensional chemical transport model, Model for Ozone and Related Chemical Tracers version 4 (MOZART v4), and a Bayesian inverse method to estimate global as well as regional annual emissions for five source sectors from 13 regions in the world. This is the first time that all of these measurements from multiple networks have been combined to determine emissions. Our inversion indicates that global and regional N2O emissions have an increasing trend between 1995 and 2008. Despite large uncertainties, a significant increase is seen from the Asian agricultural sector in recent years, most likely

  20. Global and regional emissions estimates for N2O

    NASA Astrophysics Data System (ADS)

    Saikawa, E.; Prinn, R. G.; Dlugokencky, E.; Ishijima, K.; Dutton, G. S.; Hall, B. D.; Langenfelds, R.; Tohjima, Y.; Machida, T.; Manizza, M.; Rigby, M.; O'Doherty, S.; Patra, P. K.; Harth, C. M.; Weiss, R. F.; Krummel, P. B.; van der Schoot, M.; Fraser, P. B.; Steele, L. P.; Aoki, S.; Nakazawa, T.; Elkins, J. W.

    2013-07-01

    We present a comprehensive estimate of nitrous oxide ( N2O) emissions using observations and models from 1995 to 2008. High-frequency records of tropospheric N2O are available from measurements at Cape Grim, Tasmania; Cape Matatula, American Samoa; Ragged Point, Barbados; Mace Head, Ireland; and at Trinidad Head, California using the Advanced Global Atmospheric Gases Experiment (AGAGE) instrumentation and calibrations. The Global Monitoring Division of the National Oceanic and Atmospheric Administration/Earth System Research Laboratory (NOAA/ESRL) has also discrete air samples collected in flasks and in situ measurements from remote sites across the globe and analyzed them for a suite of species including N2O. In addition to these major networks, we include in situ and aircraft measurements from the National Institute for Environmental Studies (NIES) and flask measurements from the Tohoku University and Commonwealth Scientific and Industrial Research Organization (CSIRO) networks. All measurements show increasing atmospheric mole fractions of N2O, with a varying growth rate of 0.1-0.7 % yr-1, resulting in a 7.4% increase in the background atmospheric mole fraction between 1979 and 2011. Using existing emission inventories as well as bottom-up process modeling results, we first create globally-gridded a priori N2O emissions over the 37 yr since 1975. We then use the three-dimensional chemical transport model, Model for Ozone and Related Chemical Tracers version 4 (MOZART v4), and a Bayesian inverse method to estimate global as well as regional annual emissions for five source sectors from 13 regions in the world. This is the first time that all of these measurements from multiple networks have been combined to determine emissions. Our inversion indicates that global and regional N2O emissions have an increasing trend between 1995 and 2008. Despite large uncertainties, a significant increase is seen from the Asian agricultural sector in the recent years, most likely

  1. Global and regional emissions estimates for N2O

    NASA Astrophysics Data System (ADS)

    Saikawa, E.; Prinn, R. G.; Dlugokencky, E. J.; Ishijima, K.; Dutton, G. S.; Hall, B. D.; Langenfelds, R.; Tohjima, Y.; Machida, T.; Manizza, M.; Rigby, M. L.; Odoherty, S. J.; Patra, P. K.; Harth, C.; Weiss, R. F.; Krummel, P. B.; van der Schoot, M.; Fraser, P.; Steele, P.; Aoki, S.; Nakazawa, T.; Elkins, J. W.

    2013-12-01

    We present a comprehensive estimate of nitrous oxide (N2O) emissions using observations and models from 1995 to 2008. High-frequency records of tropospheric N2O are available from measurements at Cape Grim, Tasmania; Cape Matatula, American Samoa; Ragged Point, Barbados; Mace Head, Ireland; and at Trinidad Head, California using the Advanced Global Atmospheric Gases Experiment (AGAGE) instrumentation and calibrations. The Global Monitoring Division of the National Oceanic and Atmospheric Administration/Earth System Research Laboratory (NOAA/ESRL) has also discrete air samples collected in flasks and in situ measurements from remote sites across the globe and analyzed them for a suite of species including N2O. In addition to these major networks, we include in situ and aircraft measurements from the National Institute for Environmental Studies (NIES) and flask measurements from the Tohoku University and Commonwealth Scientific and Industrial Research Organization (CSIRO) networks. All measurements show increasing atmospheric mole fractions of N2O, with a varying growth rate of 0.1-0.7%yr-1, resulting in a 7.4% increase in the background atmospheric mole fraction between 1979 and 2011. Using existing emission inventories as well as bottom-up process modeling results, we first create globally-gridded a priori N2O emissions over the 37 yr since 1975. We then use the three-dimensional chemical transport model, Model for Ozone and Related Chemical Tracers version 4 (MOZART v4), and a Bayesian inverse method to estimate global as well as regional annual emissions for five source sectors from 13 regions in the world. This is the first time that all of these measurements from multiple networks have been combined to determine emissions. Our inversion indicates that global and regional N2O emissions have an increasing trend between 1995 and 2008. Despite large uncertainties, a significant increase is seen from the Asian agricultural sector in the recent years, most likely due

  2. Identifying N2O formation and emissions from a full-scale partial nitritation reactor.

    PubMed

    Mampaey, Kris E; De Kreuk, Merle K; van Dongen, Udo G J M; van Loosdrecht, Mark C M; Volcke, Eveline I P

    2016-01-01

    In this study, N2O formation and emissions from a full-scale partial nitritation (SHARON) reactor were identified through a three-weeks monitoring campaign during which the off-gas was analysed for N2O, O2, CO2 and NO. The overall N2O emission was 3.7% of the incoming ammonium load. By fitting the N2O emission to a theoretical gas stripping profile, the N2O emissions could be assigned to aerobically formed N2O and N2O formed under anoxic conditions. This was further substantiated by liquid N2O measurements. Under standard operation, 70% of the N2O emission was attributed to anoxic N2O formation. Dedicated experiments revealed that low dissolved oxygen concentrations (<1.0 gO2·m(-3)) and longer anoxic periods resulted in an increased N2O emission. Minimising or avoiding anoxic conditions has the highest effect in lowering the N2O emissions. As an additional result, the use of the off-gas N2O concentration measurements to monitor the gas-liquid mass transfer rate coefficient (kLa) during dynamic reactor operation was demonstrated.

  3. Effects of substrates on N2O emissions in an anaerobic ammonium oxidation (anammox) reactor.

    PubMed

    Jin, Yue; Wang, Dunqiu; Zhang, Wenjie

    2016-01-01

    N2O emission in the anaerobic ammonium oxidation (anammox) process is of growing concern. In this study, effects of substrate concentrations on N2O emissions were investigated in an anammox reactor. Extremely high N2O emissions of 1.67 % were led by high NH4-N concentrations. Results showed that N2O emissions have a positive correlation with NH4-N concentrations in the anammox reactor. Reducing NH4-N concentrations by recycling pump resulted in decreasing N2O emissions. In addition, further studies were performed to identify a key biological process that is contributed to N2O emissions from the anammox reactor. Based on the results obtained, Nitrosomonas, which can oxidize ammonia to nitrite, was deemed as the main sources of N2O emissions.

  4. Effects of changing lawn care practices on N2O emissions: A scenario analysis

    NASA Astrophysics Data System (ADS)

    Crane, J. W.; Hornberger, G. M.

    2013-12-01

    Lawn soil emissions of N2O are controlled by a variety of factors, among them the varied lawn care practices employed by homeowners or lawn care professionals. Frequency, intensity, and timing of fertilizer application and irrigation all place controls on soil N2O emissions produced as an intermediary of both nitrification and denitrification. We use a process-based biogeochemical model of C and N dynamics to determine how modifying these lawn care practices affect N2O emissions from lawn soils in Nashville, TN. Closed chamber sampling of N2O emissions is used to calibrate the model and provide a base case allowing additional scenarios to be run. We show that seasonal timing of fertilizer application strongly drives the magnitude of N2O emissions, with early summer application effectively doubling these emissions with no changes to other lawn care practices. Decreasing N fertilizer application intensity causes a fairly direct decrease in N2O emissions, while the frequency of fertilizer applications does not have a so clearly direct impact. Irrigation practices also place controls on N2O emissions, as frequent, intense irrigation increases soil moisture, creates anoxic conditions in the soil and results in elevated N2O emissions. These results suggest that understanding how lawn care affects N2O emissions from lawn soils could provide simple guidelines for lawn care that could substantively reduce lawn N2O emissions.

  5. Gas entrapment and microbial N2O reduction reduce N2O emissions from a biochar-amended sandy clay loam soil

    PubMed Central

    Harter, Johannes; Guzman-Bustamante, Ivan; Kuehfuss, Stefanie; Ruser, Reiner; Well, Reinhard; Spott, Oliver; Kappler, Andreas; Behrens, Sebastian

    2016-01-01

    Nitrous oxide (N2O) is a potent greenhouse gas that is produced during microbial nitrogen transformation processes such as nitrification and denitrification. Soils represent the largest sources of N2O emissions with nitrogen fertilizer application being the main driver of rising atmospheric N2O concentrations. Soil biochar amendment has been proposed as a promising tool to mitigate N2O emissions from soils. However, the underlying processes that cause N2O emission suppression in biochar-amended soils are still poorly understood. We set up microcosm experiments with fertilized, wet soil in which we used 15N tracing techniques and quantitative polymerase chain reaction (qPCR) to investigate the impact of biochar on mineral and gaseous nitrogen dynamics and denitrification-specific functional marker gene abundance and expression. In accordance with previous studies our results showed that biochar addition can lead to a significant decrease in N2O emissions. Furthermore, we determined significantly higher quantities of soil-entrapped N2O and N2 in biochar microcosms and a biochar-induced increase in typical and atypical nosZ transcript copy numbers. Our findings suggest that biochar-induced N2O emission mitigation is based on the entrapment of N2O in water-saturated pores of the soil matrix and concurrent stimulation of microbial N2O reduction resulting in an overall decrease of the N2O/(N2O + N2) ratio. PMID:28008997

  6. Gas entrapment and microbial N2O reduction reduce N2O emissions from a biochar-amended sandy clay loam soil

    NASA Astrophysics Data System (ADS)

    Harter, Johannes; Guzman-Bustamante, Ivan; Kuehfuss, Stefanie; Ruser, Reiner; Well, Reinhard; Spott, Oliver; Kappler, Andreas; Behrens, Sebastian

    2016-12-01

    Nitrous oxide (N2O) is a potent greenhouse gas that is produced during microbial nitrogen transformation processes such as nitrification and denitrification. Soils represent the largest sources of N2O emissions with nitrogen fertilizer application being the main driver of rising atmospheric N2O concentrations. Soil biochar amendment has been proposed as a promising tool to mitigate N2O emissions from soils. However, the underlying processes that cause N2O emission suppression in biochar-amended soils are still poorly understood. We set up microcosm experiments with fertilized, wet soil in which we used 15N tracing techniques and quantitative polymerase chain reaction (qPCR) to investigate the impact of biochar on mineral and gaseous nitrogen dynamics and denitrification-specific functional marker gene abundance and expression. In accordance with previous studies our results showed that biochar addition can lead to a significant decrease in N2O emissions. Furthermore, we determined significantly higher quantities of soil-entrapped N2O and N2 in biochar microcosms and a biochar-induced increase in typical and atypical nosZ transcript copy numbers. Our findings suggest that biochar-induced N2O emission mitigation is based on the entrapment of N2O in water-saturated pores of the soil matrix and concurrent stimulation of microbial N2O reduction resulting in an overall decrease of the N2O/(N2O + N2) ratio.

  7. Emission factors for organic fertilizer-induced N2O emissions from Japanese agricultural soils

    NASA Astrophysics Data System (ADS)

    Sano, T.; Nishina, K.; Sudo, S.

    2013-12-01

    1. Introduction Agricultural fields are significant sources of nitrous oxide (N2O), which is one of the important greenhouse gases with a contribution of 7.9% to the anthropogenic global warming (IPCC, 2007). Direct fertilizer-induced N2O emission from agricultural soil is estimated using the emission factor (EF). National greenhouse gas inventory of Japan defines direct EF for N2O associated with the application of chemical and organic fertilizers as the same value (0.62%) in Japanese agricultural fields. However, it is necessary to estimate EF for organic fertilizers separately, because there are some differences in factors controlling N2O emissions (e.g. nutrient content) between chemical and organic fertilizers. The purpose of this study is to estimate N2O emissions and EF for applied organic fertilizers in Japanese agricultural fields. 2. Materials and Methods We conducted the experiments at 10 prefectural agricultural experimental stations in Japan (Yamagata, Fukushima, Niigata, Ibaraki, Aichi, Shiga, Tokushima, Nagasaki, Kumamoto, and Kagoshima) to consider the variations of cultivation and environmental conditions among regions. Field measurements had been conducted for 2-2.5 years during August 2010-April 2013. Each site set experimental plots with the applications of composted manure (cattle, swine, and poultry), chemical fertilizer, and non-nitrogen fertilizer as a control. The annual amount of applied nitrogen ranged from 16 g-N m-2 y-1 to 60 g-N m-2 y-1 depending on cropping system and cultivated crops (e.g. cabbage, potato) at each site. N2O fluxes were measured using a closed-chamber method. N2O concentrations of gas samples were measured with gas chromatography. The EF value of each fertilizer was calculated as the N2O emission from fertilizer plots minus the background N2O emission (emission from a control plot), and was expressed as a percentage of the applied nitrogen. The soil NH4+ and NO3-, soil temperature, precipitation, and WFPS (water

  8. [Characteristics of N2O emissions from vegetal soils on Fildes peninsula, Antarctica].

    PubMed

    Sun, L; Zhu, R; Xie, Z; Zhao, J; Xing, G; Shi, S; Du, L

    2001-07-01

    The N2O fluxes from the vegetal soils were first measured on the Fildes peninsula, Antarctica, and the total N2O emission was also estimated in the summer 2 months. The daily variations of N2O fluxes appeared single-peak trend under the sunshine or rainy weather conditions but they were irregular under the snow weather conditions and inconsistent with the atmospheric temperatures. The seasonal variations of the N2O fluxes were affected by the temperature and rainfall. The conditions during the transitions between dry and wet seasons improved the N2O emission. The total N2O emissions from moss and lichen soils were 3.7152 kg and 2.5344 kg, respectively. It follows that the vegetal soils are the sources for the atmospheric N2O on the Fildes peninsula, Antarctica.

  9. The effects of nitrogen fertilization on N2O emissions from a rubber plantation

    NASA Astrophysics Data System (ADS)

    Zhou, Wen-Jun; Ji, Hong-Li; Zhu, Jing; Zhang, Yi-Ping; Sha, Li-Qing; Liu, Yun-Tong; Zhang, Xiang; Zhao, Wei; Dong, Yu-Xin; Bai, Xiao-Long; Lin, You-Xin; Zhang, Jun-Hui; Zheng, Xun-Hua

    2016-06-01

    To gain the effects of N fertilizer applications on N2O emissions and local climate change in fertilized rubber (Hevea brasiliensis) plantations in the tropics, we measured N2O fluxes from fertilized (75 kg N ha‑1 yr‑1) and unfertilized rubber plantations at Xishuangbanna in southwest China over a 2-year period. The N2O emissions from the fertilized and unfertilized plots were 4.0 and 2.5 kg N ha‑1 yr‑1, respectively, and the N2O emission factor was 1.96%. Soil moisture, soil temperature, and the area weighted mean ammoniacal nitrogen (NH4+-N) content controlled the variations in N2O flux from the fertilized and unfertilized rubber plantations. NH4+-N did not influence temporal changes in N2O emissions from the trench, slope, or terrace plots, but controlled spatial variations in N2O emissions among the treatments. On a unit area basis, the 100-year carbon dioxide equivalence of the fertilized rubber plantation N2O offsets 5.8% and 31.5% of carbon sink of the rubber plantation and local tropical rainforest, respectively. When entire land area in Xishuangbanna is considered, N2O emissions from fertilized rubber plantations offset 17.1% of the tropical rainforest’s carbon sink. The results show that if tropical rainforests are converted to fertilized rubber plantations, regional N2O emissions may enhance local climate warming.

  10. The effects of nitrogen fertilization on N2O emissions from a rubber plantation

    PubMed Central

    Zhou, Wen-Jun; Ji, Hong-li; Zhu, Jing; Zhang, Yi-Ping; Sha, Li-Qing; Liu, Yun-Tong; Zhang, Xiang; Zhao, Wei; Dong, Yu-xin; Bai, Xiao-Long; Lin, You-Xin; Zhang, Jun-Hui; Zheng, Xun-Hua

    2016-01-01

    To gain the effects of N fertilizer applications on N2O emissions and local climate change in fertilized rubber (Hevea brasiliensis) plantations in the tropics, we measured N2O fluxes from fertilized (75 kg N ha−1 yr−1) and unfertilized rubber plantations at Xishuangbanna in southwest China over a 2-year period. The N2O emissions from the fertilized and unfertilized plots were 4.0 and 2.5 kg N ha−1 yr−1, respectively, and the N2O emission factor was 1.96%. Soil moisture, soil temperature, and the area weighted mean ammoniacal nitrogen (NH4+-N) content controlled the variations in N2O flux from the fertilized and unfertilized rubber plantations. NH4+-N did not influence temporal changes in N2O emissions from the trench, slope, or terrace plots, but controlled spatial variations in N2O emissions among the treatments. On a unit area basis, the 100-year carbon dioxide equivalence of the fertilized rubber plantation N2O offsets 5.8% and 31.5% of carbon sink of the rubber plantation and local tropical rainforest, respectively. When entire land area in Xishuangbanna is considered, N2O emissions from fertilized rubber plantations offset 17.1% of the tropical rainforest’s carbon sink. The results show that if tropical rainforests are converted to fertilized rubber plantations, regional N2O emissions may enhance local climate warming. PMID:27324813

  11. The effects of nitrogen fertilization on N2O emissions from a rubber plantation.

    PubMed

    Zhou, Wen-Jun; Ji, Hong-Li; Zhu, Jing; Zhang, Yi-Ping; Sha, Li-Qing; Liu, Yun-Tong; Zhang, Xiang; Zhao, Wei; Dong, Yu-Xin; Bai, Xiao-Long; Lin, You-Xin; Zhang, Jun-Hui; Zheng, Xun-Hua

    2016-06-21

    To gain the effects of N fertilizer applications on N2O emissions and local climate change in fertilized rubber (Hevea brasiliensis) plantations in the tropics, we measured N2O fluxes from fertilized (75 kg N ha(-1) yr(-1)) and unfertilized rubber plantations at Xishuangbanna in southwest China over a 2-year period. The N2O emissions from the fertilized and unfertilized plots were 4.0 and 2.5 kg N ha(-1) yr(-1), respectively, and the N2O emission factor was 1.96%. Soil moisture, soil temperature, and the area weighted mean ammoniacal nitrogen (NH4(+)-N) content controlled the variations in N2O flux from the fertilized and unfertilized rubber plantations. NH4(+)-N did not influence temporal changes in N2O emissions from the trench, slope, or terrace plots, but controlled spatial variations in N2O emissions among the treatments. On a unit area basis, the 100-year carbon dioxide equivalence of the fertilized rubber plantation N2O offsets 5.8% and 31.5% of carbon sink of the rubber plantation and local tropical rainforest, respectively. When entire land area in Xishuangbanna is considered, N2O emissions from fertilized rubber plantations offset 17.1% of the tropical rainforest's carbon sink. The results show that if tropical rainforests are converted to fertilized rubber plantations, regional N2O emissions may enhance local climate warming.

  12. [Research advances in control of N2O emission from municipal solid waste landfill sites].

    PubMed

    Cai, Chuan-Yu; Li, Bo; Lü, Hao-Hao; Wu, Wei-Xiang

    2012-05-01

    Landfill is one of the main approaches for municipal solid waste treatment, and landfill site is a main emission source of greenhouse gases nitrous oxide (N2O) and methane (CH4). As a high-efficient trace greenhouse gas, N2O has a very high warming potential, with a warming capacity 296 times of CO2, and has a long-term stability in atmosphere, giving greater damage to the ozone layer. Aiming at the researches in the control of N2O emission from municipal solid waste landfill sites, this paper summarized the characteristics and related affecting factors of the N2O emission from the landfill sites, and put forward a series of the measures adaptable to the N2O emission control of present municipal solid waste landfill sites in China. Some further research focuses on the control of N2O emission from the landfill sites were also presented.

  13. Biologically produced volatile compounds: N2O emissions from soils

    NASA Technical Reports Server (NTRS)

    Banin, A.

    1985-01-01

    Tropospheric nitrous concentration has increased by 0.2 0.4% per year over the period 1975 to 1982, amounting to net addition to the atmosphere of 2.8 - 5.6 Tg N2O-N per year. This perturbation, if continued into the future, will affect stratospheric chemical cycles, and the thermal balance of the Earth. In turn it will have direct and indirect global effects on the biosphere. Though the budget and cycles of N2O on Earth are not yet fully resolved, accumulating information and recent modelling efforts permit a more complete evaluation and better definition of gaps in our knowledge.

  14. Phylogenetic and functional potential links pH and N2O emissions in pasture soils

    NASA Astrophysics Data System (ADS)

    Samad, M. D. Sainur; Biswas, Ambarish; Bakken, Lars R.; Clough, Timothy J.; de Klein, Cecile A. M.; Richards, Karl G.; Lanigan, Gary J.; Morales, Sergio E.

    2016-10-01

    Denitrification is mediated by microbial, and physicochemical, processes leading to nitrogen loss via N2O and N2 emissions. Soil pH regulates the reduction of N2O to N2, however, it can also affect microbial community composition and functional potential. Here we simultaneously test the link between pH, community composition, and the N2O emission ratio (N2O/(NO + N2O + N2)) in 13 temperate pasture soils. Physicochemical analysis, gas kinetics, 16S rRNA amplicon sequencing, metagenomic and quantitative PCR (of denitrifier genes: nirS, nirK, nosZI and nosZII) analysis were carried out to characterize each soil. We found strong evidence linking pH to both N2O emission ratio and community changes. Soil pH was negatively associated with N2O emission ratio, while being positively associated with both community diversity and total denitrification gene (nir & nos) abundance. Abundance of nosZII was positively linked to pH, and negatively linked to N2O emissions. Our results confirm that pH imposes a general selective pressure on the entire community and that this results in changes in emission potential. Our data also support the general model that with increased microbial diversity efficiency increases, demonstrated in this study with lowered N2O emission ratio through more efficient conversion of N2O to N2.

  15. Phylogenetic and functional potential links pH and N2O emissions in pasture soils

    PubMed Central

    Samad, M. d. Sainur; Biswas, Ambarish; Bakken, Lars R.; Clough, Timothy J.; de Klein, Cecile A. M.; Richards, Karl G.; Lanigan, Gary J.; Morales, Sergio E.

    2016-01-01

    Denitrification is mediated by microbial, and physicochemical, processes leading to nitrogen loss via N2O and N2 emissions. Soil pH regulates the reduction of N2O to N2, however, it can also affect microbial community composition and functional potential. Here we simultaneously test the link between pH, community composition, and the N2O emission ratio (N2O/(NO + N2O + N2)) in 13 temperate pasture soils. Physicochemical analysis, gas kinetics, 16S rRNA amplicon sequencing, metagenomic and quantitative PCR (of denitrifier genes: nirS, nirK, nosZI and nosZII) analysis were carried out to characterize each soil. We found strong evidence linking pH to both N2O emission ratio and community changes. Soil pH was negatively associated with N2O emission ratio, while being positively associated with both community diversity and total denitrification gene (nir & nos) abundance. Abundance of nosZII was positively linked to pH, and negatively linked to N2O emissions. Our results confirm that pH imposes a general selective pressure on the entire community and that this results in changes in emission potential. Our data also support the general model that with increased microbial diversity efficiency increases, demonstrated in this study with lowered N2O emission ratio through more efficient conversion of N2O to N2. PMID:27782174

  16. Surface nitrification: A major uncertainty in marine N2O emissions

    NASA Astrophysics Data System (ADS)

    Zamora, Lauren M.; Oschlies, Andreas

    2014-06-01

    The ocean is responsible for up to a third of total global nitrous oxide (N2O) emissions, but uncertainties in emission rates of this potent greenhouse gas are high (>100%). Here we use a marine biogeochemical model to assess six major uncertainties in estimates of N2O production, thereby providing guidance in how future studies may most effectively reduce uncertainties in current and future marine N2O emissions. Potential surface N2O production from nitrification causes the largest uncertainty in N2O emissions (estimated up to ~1.6 Tg N yr-1 or 48% of modeled values), followed by the unknown oxygen concentration at which N2O production switches to N2O consumption (0.8 Tg N yr-1 or 24% of modeled values). Other uncertainties are minor, cumulatively changing regional emissions by <15%. If production of N2O by surface nitrification could be ruled out in future studies, uncertainties in marine N2O emissions would be halved.

  17. Surface Nitrification: A Major Uncertainty in Marine N2O Emissions

    NASA Technical Reports Server (NTRS)

    Zamora, Lauren M.; Oschlies, Andreas

    2014-01-01

    The ocean is responsible for up to a third of total global nitrous oxide (N2O) emissions, but uncertainties in emission rates of this potent greenhouse gas are high (approaching 100%). Here we use a marine biogeochemical model to assess six major uncertainties in estimates of N2O production, thereby providing guidance in how future studies may most effectively reduce uncertainties in current and future marine N2O emissions. Potential surface N2O production from nitrification causes the largest uncertainty in N2O emissions (estimated up to approximately 1.6 Tg N/yr (sup -1) or 48% of modeled values), followed by the unknown oxygen concentration at which N2O production switches to N2O consumption (0.8 Tg N/yr (sup -1)or 24% of modeled values). Other uncertainties are minor, cumulatively changing regional emissions by less than 15%. If production of N2O by surface nitrification could be ruled out in future studies, uncertainties in marine N2O emissions would be halved.

  18. Spatiotemporal variations of nitrous oxide (N 2 O) emissions from two reservoirs in SW China

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Long; Liu, Cong-Qiang; Li, Si-Liang; Wang, Fu-Shun; Wang, Bao-Li; Wang, Zhong-Liang

    2011-10-01

    Greenhouse gas emissions from hydroelectric dams have recently given rise to controversies about whether hydropower still provides clean energy. China has a large number of dams used for energy supply and irrigation, but few studies have been carried out on aquatic nitrous oxide (N 2O) variation and its emissions in Chinese river-reservoir systems. In this study, N 2O spatiotemporal variations were investigated monthly in two reservoirs along the Wujiang River, Southwest China, and the emission fluxes of N 2O were estimated. N 2O production in the reservoirs tended to be dominated by nitrification, according to the correlation between N 2O and other parameters. N 2O saturation in the surface water of the Wujiangdu reservoir ranged from 214% to 662%, with an average fluctuation of 388%, while in the Hongjiadu reservoir, it ranged from 201% to 484%, with an average fluctuation of 312%. The dissolved N 2O in both reservoirs was over-saturated with respect to atmospheric equilibrium levels, suggesting that the reservoirs were net sources of N 2O emissions to the atmosphere. The averaged N 2O emission flux in the Wujiangdu reservoir was 0.64 μmol m -2 h -1, while it was 0.45 μmol m -2 h -1 in the Hongjiadu reservoir, indicating that these two reservoirs had moderate N 2O emission fluxes as compared to other lakes in the world. Downstream water of the dams had quite high levels of N 2O saturation, and the estimated annual N 2O emissions from hydropower generation were 3.60 × 10 5 and 2.15 × 10 5 mol N 2O for the Wujiangdu and the Hongjiadu reservoir, respectively. These fluxes were similar to the total N 2O emissions from the reservoir surfaces, suggesting that water released from reservoirs would be another important way for N 2O to diffuse into the atmosphere. It can be concluded that dam construction significantly changes the water environment, especially in terms of nutrient status and physicochemical conditions, which have obvious influences on the N 2O

  19. Effect of high frequency surface and subsurface drip irrigations on N2O emissions in orchards

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fertilized agricultural soil is a source for greenhouse gas nitrous oxide (N2O) emissions. A sustainable agricultural practice needs to consider minimizing N2O emissions while increasing N use efficiency and maintaining crop economic yield and quality. In order to develop a sustainable crop producti...

  20. Reducing N2O emissions from orchard using subsurfce drip irrigation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural soil is the major source for N2O emissions. Minimizing N2O emissions along with increasing N use efficiency, reducing leaching loss, and maintaining crop economic yield and quality can lead to increased sustainability of crop production. The main objective of this research is to evaluat...

  1. Partitioning N2O emissions within the US Corn Belt using an inverse modeling approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) emissions within the US Corn Belt have been estimated to be 2- to 9-11 fold larger than predictions from emission inventories, implying that one or more source 12 categories in bottom-up approaches are underestimated. Here we interpret hourly N2O 13 mixing ratios measured during ...

  2. Potential N2O emissions from leguminous tree plantation soils in the humid tropics

    NASA Astrophysics Data System (ADS)

    Arai, Seiko; Ishizuka, Shigehiro; Ohta, Seiichi; Ansori, Saifuddin; Tokuchi, Naoko; Tanaka, Nagaharu; Hardjono, Arisman

    2008-06-01

    We compared nitrous oxide (N2O) emissions over 1 year from soils of plantations growing acacia, which is a leguminous plant capable of symbiotic nitrogen fixation in root nodules, and secondary forests in Sumatra, Indonesia. N2O emissions from acacia plantation soils fluctuated seasonally, from high in the wetter season to low in the drier season, whereas N2O emissions from secondary forest soils were low throughout the year. Water-filled-pore-space data showed that denitrification contributed substantially to N2O emissions from soils at acacia sites. The average annual N2O flux in acacia plantations was 2.56 kg N ha-1 a-1, which was eight times higher than that from secondary forest soils (0.33 kg N ha-1 a-1). In secondary forests, NH4+ was the dominant form of inorganic nitrogen. However, in acacia plantations, the NH4+: NO3- ratio was relatively lower than that in secondary forests. These results suggest that secondary forests were nitrogen limited, but acacia plantations were less nitrogen limited. Leguminous tree plantations may increase nitrogen cycling, resulting in greater N2O emissions from the soil. However, on a global warming potential basis, N2O emissions from acacia plantation soils accounted for less than 10% of the carbon uptake by plants. Nevertheless, because of the spread of leguminous tree plantations in Asia, the importance of N2O emissions from leguminous tree stands will increase in the coming decades.

  3. Extreme Emission of N2O from Tropical Wetland Soil (Pantanal, South America)

    PubMed Central

    Liengaard, Lars; Nielsen, Lars Peter; Revsbech, Niels Peter; Priemé, Anders; Elberling, Bo; Enrich-Prast, Alex; Kühl, Michael

    2013-01-01

    Nitrous oxide (N2O) is an important greenhouse gas and ozone depleter, but the global budget of N2O remains unbalanced. Currently, ∼25% of the global N2O emission is ascribed to uncultivated tropical soils, but the exact locations and controlling mechanisms are not clear. Here we present the first study of soil N2O emission from the Pantanal indicating that this South American wetland may be a significant natural source of N2O. At three sites, we repeatedly measured in situ fluxes of N2O and sampled porewater nitrate (NO3-) during the low water season in 2008 and 2009. In 2010, 10 sites were screened for in situ fluxes of N2O and soil NO3- content. The in situ fluxes of N2O were comparable to fluxes from heavily fertilized forests or agricultural soils. An important parameter affecting N2O emission rate was precipitation, inducing peak emissions of >3 mmol N2O m−2 day−1, while the mean daily flux was 0.43 ± 0.03 mmol N2O m−2 day−1. Over 170 days of the drained period, we estimated non-wetted drained soil to contribute 70.0 mmol N2O m−2, while rain-induced peak events contributed 9.2 mmol N2O m−2, resulting in a total N2O emission of 79.2 mmol N2O m−2. At the sites of repeated sampling, the pool of porewater nitrate varied (0.002-7.1μmolNO3-gdW-1) with higher concentrations of NO3- (p < 0.05) found in drained soil than in water-logged soil, indicating dynamic shifts between nitrification and denitrification. In the field, O2 penetrated the upper 60 cm of drained soil, but was depleted in response to precipitation. Upon experimental wetting the soil showed rapid O2 depletion followed by N2O accumulation and a peak emission of N2O (2.5 - 3.0mmolN2Om-2day-1). Assuming that the observed emission of N2O from these wetland soils is generally representative to the Pantanal, we suggest that this undisturbed tropical wetland potentially contributes ∼1.7% to the global N2O emission budget, a significant

  4. Extreme emission of n(2)o from tropical wetland soil (pantanal, South america).

    PubMed

    Liengaard, Lars; Nielsen, Lars Peter; Revsbech, Niels Peter; Priemé, Anders; Elberling, Bo; Enrich-Prast, Alex; Kühl, Michael

    2012-01-01

    Nitrous oxide (N(2)O) is an important greenhouse gas and ozone depleter, but the global budget of N(2)O remains unbalanced. Currently, ∼25% of the global N(2)O emission is ascribed to uncultivated tropical soils, but the exact locations and controlling mechanisms are not clear. Here we present the first study of soil N(2)O emission from the Pantanal indicating that this South American wetland may be a significant natural source of N(2)O. At three sites, we repeatedly measured in situ fluxes of N(2)O and sampled porewater nitrate [Formula: see text] during the low water season in 2008 and 2009. In 2010, 10 sites were screened for in situ fluxes of N(2)O and soil [Formula: see text] content. The in situ fluxes of N(2)O were comparable to fluxes from heavily fertilized forests or agricultural soils. An important parameter affecting N(2)O emission rate was precipitation, inducing peak emissions of >3 mmol N(2)O m(-2) day(-1), while the mean daily flux was 0.43 ± 0.03 mmol N(2)O m(-2) day(-1). Over 170 days of the drained period, we estimated non-wetted drained soil to contribute 70.0 mmol N(2)O m(-2), while rain-induced peak events contributed 9.2 mmol N(2)O m(-2), resulting in a total N(2)O emission of 79.2 mmol N(2)O m(-2). At the sites of repeated sampling, the pool of porewater nitrate varied [Formula: see text] with higher concentrations of [Formula: see text] (p < 0.05) found in drained soil than in water-logged soil, indicating dynamic shifts between nitrification and denitrification. In the field, O(2) penetrated the upper 60 cm of drained soil, but was depleted in response to precipitation. Upon experimental wetting the soil showed rapid O(2) depletion followed by N(2)O accumulation and a peak emission of N(2)O [Formula: see text] Assuming that the observed emission of N(2)O from these wetland soils is generally representative to the Pantanal, we suggest that this undisturbed tropical wetland potentially

  5. Simulation of N2O peak emissions on peat soils with SWAP-ANIMO

    NASA Astrophysics Data System (ADS)

    Stolk, P. C.; Hendriks, R. H. A.; Jacobs, C. M. J.; Weststrate, H.; Duyzer, J.

    2009-04-01

    Nitrous oxide (N2O) is a very strong greenhouse gas, with agricultural soils as its main anthropogenic source. Various management practices, like fertilization or tillage, can give rise to pulses of N2O emissions. In spite of their short duration, in the order of a couple of days to weeks, these pulses can constitute major part of total annual nitrous oxide emission. Understanding, predicting and ultimately mitigating these pulses poses a considerable challenge. N2O is mainly produced by nitrifiers and denitrifiers. These require different conditions with respect to aerobicity and available mineral N. Simulation models offer a promising tool to test and further develop process knowledge on N2O production and -emission. SWAP-ANIMO is a process oriented biogeochemical model, originally developed for the simulation of nitrate leaching, that has recently been extended with an N2O module. It includes production and consumption of N2O by denitrification, production of N2O by nitrification and transport by diffusion and convection in the soil water and soil air. Here we present the validation of N2O surface flux simulations, with daily measurements of fluxes from grassland on peat in The Netherlands. As a first step to evaluate the simulation of the processes in the soil, we compare observed and simulated soil N2O concentration profiles.

  6. A new high-resolution N2O emission inventory for China in 2008.

    PubMed

    Zhou, Feng; Shang, Ziyin; Ciais, Philippe; Tao, Shu; Piao, Shilong; Raymond, Peter; He, Canfei; Li, Bengang; Wang, Rong; Wang, Xuhui; Peng, Shushi; Zeng, Zhenzhong; Chen, Han; Ying, Na; Hou, Xikang; Xu, Peng

    2014-01-01

    The amount and geographic distribution of N2O emissions over China remain largely uncertain. In this study, county-level and 0.1° × 0.1° gridded anthropogenic N2O emission inventories for China (PKU-N2O) in 2008 are developed based on high-resolution activity data and regional emission factors (EFs) and parameters. These new estimates are compared with previous inventories, and with two sensitivity tests: one that uses high-resolution activity data but the default IPCC methodology (S1) and the other that uses regional EFs and parameters but starts from coarser-resolution activity data. The total N2O emissions are 2150 GgN2O/yr (interquartile range from 1174 to 2787 GgN2O/yr). Agriculture contributes 64% of the total, followed by energy (17%), indirect emissions (12%), wastes (5%), industry (2.8%), and wildfires (0.2%). Our national emission total is 17% greater than that of the EDGAR v4.2 global product sampled over China and is also greater than the GAINS-China, NDRC, and S1 estimates by 10%, 50%, and 17%, respectively. We also found that using uniform EFs and parameters or starting from national/provincial data causes systematic spatial biases compared to PKU-N2O. Spatial analysis shows nonlinear relationships between N2O emission intensities and urbanization. Per-capita and per-GDP N2O emissions increase gradually with an increase in the urban population fraction from 0.3 to 0.9 among 2884 counties, and N2O emission density increases with urban expansion.

  7. Lowering N2O emissions from soils using eucalypt biochar: the importance of redox reactions

    NASA Astrophysics Data System (ADS)

    Quin, P.; Joseph, S.; Husson, O.; Donne, S.; Mitchell, D.; Munroe, P.; Phelan, D.; Cowie, A.; van Zwieten, L.

    2015-11-01

    Agricultural soils are the primary anthropogenic source of atmospheric nitrous oxide (N2O), contributing to global warming and depletion of stratospheric ozone. Biochar addition has shown potential to lower soil N2O emission, with the mechanisms remaining unclear. We incubated eucalypt biochar (550 °C) - 0, 1 and 5% (w/w) in Ferralsol at 3 water regimes (12, 39 and 54% WFPS) - in a soil column, following gamma irradiation. After N2O was injected at the base of the soil column, in the 0% biochar control 100% of expected injected N2O was released into headspace, declining to 67% in the 5% amendment. In a 100% biochar column at 6% WFPS, only 16% of the expected N2O was observed. X-ray photoelectron spectroscopy identified changes in surface functional groups suggesting interactions between N2O and the biochar surfaces. We have shown increases in -O-C = N /pyridine pyrrole/NH3, suggesting reactions between N2O and the carbon (C) matrix upon exposure to N2O. With increasing rates of biochar application, higher pH adjusted redox potentials were observed at the lower water contents. Evidence suggests that biochar has taken part in redox reactions reducing N2O to dinitrogen (N2), in addition to adsorption of N2O.

  8. Lowering N2O emissions from soils using eucalypt biochar: the importance of redox reactions

    PubMed Central

    Quin, P; Joseph, S; Husson, O; Donne, S; Mitchell, D; Munroe, P; Phelan, D; Cowie, A; Van Zwieten, L

    2015-01-01

    Agricultural soils are the primary anthropogenic source of atmospheric nitrous oxide (N2O), contributing to global warming and depletion of stratospheric ozone. Biochar addition has shown potential to lower soil N2O emission, with the mechanisms remaining unclear. We incubated eucalypt biochar (550 °C) – 0, 1 and 5% (w/w) in Ferralsol at 3 water regimes (12, 39 and 54% WFPS) – in a soil column, following gamma irradiation. After N2O was injected at the base of the soil column, in the 0% biochar control 100% of expected injected N2O was released into headspace, declining to 67% in the 5% amendment. In a 100% biochar column at 6% WFPS, only 16% of the expected N2O was observed. X-ray photoelectron spectroscopy identified changes in surface functional groups suggesting interactions between N2O and the biochar surfaces. We have shown increases in -O-C = N /pyridine pyrrole/NH3, suggesting reactions between N2O and the carbon (C) matrix upon exposure to N2O. With increasing rates of biochar application, higher pH adjusted redox potentials were observed at the lower water contents. Evidence suggests that biochar has taken part in redox reactions reducing N2O to dinitrogen (N2), in addition to adsorption of N2O. PMID:26615820

  9. Contributions of agricultural plants and soils to N2O emission in a farmland

    NASA Astrophysics Data System (ADS)

    Li, J.; Lee, X.; Yu, Q.; Tong, X.; Qin, Z.; MacDonald, B.

    2011-06-01

    The goal of this study was to quantify the roles of plants and soil in the N2O budget of a cropland in North China. Plant and soil N2O fluxes were measured with transparent and dark plant chambers and soil chambers, respectively, in three adjacent fields of fertilized cotton, fertilized maize and unfertilized soybean. During the observation period, the soil flux was 448 ± 89, 230 ± 74 and 90 ± 14 μg N2O m-2 h-1 in cotton, maize and soybean fields, respectively. The plant flux was 54 ± 43 and 16 ± 41 μg N2O m-2 h-1, about 10 % and 26 % to the total ecosystem flux, for the cotton and the soybean field, respectively. Ignoring the contribution of plants would cause an obvious underestimation on the ecosystem N2O flux. The influence of sunlight on plant N2O flux was insignificant. However, in the cotton field, the responses of the plant N2O flux to air temperature and soil ammonium content were significant under sunlight but insignificant under darkness, suggesting that stomatal activity might influence the release process. In the cotton field, temperature sensitivity of plant N2O emission was 1.13, much lower than the value of soil flux (5.74). No relationship was found between plant N2O flux and soil nitrate content. It was implied that nitrate reduction in plants might not be the main source of plant N2O emission under field conditions. The seasonal patterns of the soil and plant N2O emissions were similarly affected by fertilization, indicating that plants might serve as a passive conduit transporting N2O produced in the soil.

  10. Dynamics and emissions of N2O in groundwater: A review.

    PubMed

    Jurado, Anna; Borges, Alberto V; Brouyère, Serge

    2017-01-30

    This work reviews the concentrations, the dynamics and the emissions of nitrous oxide (N2O) in groundwater. N2O is an important greenhouse gas (GHG) and the primary stratospheric ozone depleting substance. The major anthropogenic source that contributes to N2O generation in aquifers is agriculture because the use of fertilizers has led to the widespread groundwater contamination by inorganic nitrogen (N) (mainly nitrate, NO3(-)). Once in the aquifer, this inorganic N is transported and affected by several geochemical processes that produce and consume N2O. An inventory of dissolved N2O concentrations is presented and the highest concentration is about 18.000 times higher than air-equilibrated water (up to 4004μg N L(-1)). The accumulation of N2O in groundwater is mainly due to denitrification and to lesser extent to nitrification. Their occurrence depend on the geochemical (e.g., NO3(-), dissolved oxygen, ammonium and dissolved organic carbon) as well as hydrogeological parameters (e.g., groundwater table fluctuations and aquifer permeability). The coupled understanding of both parameters is necessary to gain insight on the dynamics and the emissions of N2O in groundwater. Overall, groundwater indirect N2O emissions seem to be a minor component of N2O emissions to the atmosphere. Further research might be devoted to evaluate the groundwater contribution to the indirect emissions of N2O because this will help to better constraint the N2O global budget and, consequently, the N budget.

  11. Marine animals significantly increase tundra N2O and CH4 emissions in maritime Antarctica

    NASA Astrophysics Data System (ADS)

    Zhu, Renbin; Liu, Yashu; Xu, Hua; Ma, Dawei; Jiang, Shan

    2013-12-01

    studies on greenhouse gas emissions from animals concentrated on domestic animals, with limited data available from wild animals. The number of marine animals is potentially large in coastal Antarctica. In this paper, N2O and CH4 emissions were investigated from a penguin colony, a seal colony, a skua colony, the adjacent animal-lacking tundra, and background tundra sites to test the effects of marine animals on their fluxes in maritime Antarctica. Extremely high N2O emissions occurred in the penguin puddles (mean 392 µg N2O m-2 h-1) and seal wallows (mean 579 µg N2O m-2 h-1). The N2O emissions from animal colony tundra (13-57 µg N2O m-2 h-1) are much higher than those from the animal-lacking tundra, whereas the background tundra showed negligible N2O fluxes. Penguin puddles and seal wallows were stronger CH4 emitters than animal colony tundra soils, while animal-lacking tundra soils were strong CH4 sinks. Overall high N2O and CH4 emissions were modulated by soil physical and chemical processes associated with marine animal activities: sufficient supply of the nutrients NH4+-N and NO3--N, total nitrogen, and total organic carbon from marine animal excreta, animal tramp, and high soil water-filled pore space. Laboratory incubation experiments further confirmed that penguin and seal colony soils produced much higher N2O and CH4 emissions than animal-lacking tundra soils. Our results indicate that marine animal colonies are the hot spots for N2O and CH4 emissions in maritime Antarctica, and even at the global scale, and current climate warming will further increase their emissions.

  12. Symbiotic relationships between soil fungi and plants reduce N2O emissions from soil

    PubMed Central

    Bender, S Franz; Plantenga, Faline; Neftel, Albrecht; Jocher, Markus; Oberholzer, Hans-Rudolf; Köhl, Luise; Giles, Madeline; Daniell, Tim J; van der Heijden, Marcel GA

    2014-01-01

    N2O is a potent greenhouse gas involved in the destruction of the protective ozone layer in the stratosphere and contributing to global warming. The ecological processes regulating its emissions from soil are still poorly understood. Here, we show that the presence of arbuscular mycorrhizal fungi (AMF), a dominant group of soil fungi, which form symbiotic associations with the majority of land plants and which influence a range of important ecosystem functions, can induce a reduction in N2O emissions from soil. To test for a functional relationship between AMF and N2O emissions, we manipulated the abundance of AMF in two independent greenhouse experiments using two different approaches (sterilized and re-inoculated soil and non-mycorrhizal tomato mutants) and two different soils. N2O emissions were increased by 42 and 33% in microcosms with reduced AMF abundance compared to microcosms with a well-established AMF community, suggesting that AMF regulate N2O emissions. This could partly be explained by increased N immobilization into microbial or plant biomass, reduced concentrations of mineral soil N as a substrate for N2O emission and altered water relations. Moreover, the abundance of key genes responsible for N2O production (nirK) was negatively and for N2O consumption (nosZ) positively correlated to AMF abundance, indicating that the regulation of N2O emissions is transmitted by AMF-induced changes in the soil microbial community. Our results suggest that the disruption of the AMF symbiosis through intensification of agricultural practices may further contribute to increased N2O emissions. PMID:24351937

  13. Isotopic constraints on marine and terrestrial N2O emissions during the last deglaciation

    NASA Astrophysics Data System (ADS)

    Schilt, Adrian; Brook, Edward J.; Bauska, Thomas K.; Baggenstos, Daniel; Fischer, Hubertus; Joos, Fortunat; Petrenko, Vasilii V.; Schaefer, Hinrich; Schmitt, Jochen; Severinghaus, Jeffrey P.; Spahni, Renato; Stocker, Thomas F.

    2014-12-01

    Nitrous oxide (N2O) is an important greenhouse gas and ozone-depleting substance that has anthropogenic as well as natural marine and terrestrial sources. The tropospheric N2O concentrations have varied substantially in the past in concert with changing climate on glacial-interglacial and millennial timescales. It is not well understood, however, how N2O emissions from marine and terrestrial sources change in response to varying environmental conditions. The distinct isotopic compositions of marine and terrestrial N2O sources can help disentangle the relative changes in marine and terrestrial N2O emissions during past climate variations. Here we present N2O concentration and isotopic data for the last deglaciation, from 16,000 to 10,000 years before present, retrieved from air bubbles trapped in polar ice at Taylor Glacier, Antarctica. With the help of our data and a box model of the N2O cycle, we find a 30 per cent increase in total N2O emissions from the late glacial to the interglacial, with terrestrial and marine emissions contributing equally to the overall increase and generally evolving in parallel over the last deglaciation, even though there is no a priori connection between the drivers of the two sources. However, we find that terrestrial emissions dominated on centennial timescales, consistent with a state-of-the-art dynamic global vegetation and land surface process model that suggests that during the last deglaciation emission changes were strongly influenced by temperature and precipitation patterns over land surfaces. The results improve our understanding of the drivers of natural N2O emissions and are consistent with the idea that natural N2O emissions will probably increase in response to anthropogenic warming.

  14. Isotopic constraints on marine and terrestrial N2O emissions during the last deglaciation.

    PubMed

    Schilt, Adrian; Brook, Edward J; Bauska, Thomas K; Baggenstos, Daniel; Fischer, Hubertus; Joos, Fortunat; Petrenko, Vasilii V; Schaefer, Hinrich; Schmitt, Jochen; Severinghaus, Jeffrey P; Spahni, Renato; Stocker, Thomas F

    2014-12-11

    Nitrous oxide (N2O) is an important greenhouse gas and ozone-depleting substance that has anthropogenic as well as natural marine and terrestrial sources. The tropospheric N2O concentrations have varied substantially in the past in concert with changing climate on glacial-interglacial and millennial timescales. It is not well understood, however, how N2O emissions from marine and terrestrial sources change in response to varying environmental conditions. The distinct isotopic compositions of marine and terrestrial N2O sources can help disentangle the relative changes in marine and terrestrial N2O emissions during past climate variations. Here we present N2O concentration and isotopic data for the last deglaciation, from 16,000 to 10,000 years before present, retrieved from air bubbles trapped in polar ice at Taylor Glacier, Antarctica. With the help of our data and a box model of the N2O cycle, we find a 30 per cent increase in total N2O emissions from the late glacial to the interglacial, with terrestrial and marine emissions contributing equally to the overall increase and generally evolving in parallel over the last deglaciation, even though there is no a priori connection between the drivers of the two sources. However, we find that terrestrial emissions dominated on centennial timescales, consistent with a state-of-the-art dynamic global vegetation and land surface process model that suggests that during the last deglaciation emission changes were strongly influenced by temperature and precipitation patterns over land surfaces. The results improve our understanding of the drivers of natural N2O emissions and are consistent with the idea that natural N2O emissions will probably increase in response to anthropogenic warming.

  15. Symbiotic relationships between soil fungi and plants reduce N2O emissions from soil.

    PubMed

    Bender, S Franz; Plantenga, Faline; Neftel, Albrecht; Jocher, Markus; Oberholzer, Hans-Rudolf; Köhl, Luise; Giles, Madeline; Daniell, Tim J; van der Heijden, Marcel Ga

    2014-06-01

    N2O is a potent greenhouse gas involved in the destruction of the protective ozone layer in the stratosphere and contributing to global warming. The ecological processes regulating its emissions from soil are still poorly understood. Here, we show that the presence of arbuscular mycorrhizal fungi (AMF), a dominant group of soil fungi, which form symbiotic associations with the majority of land plants and which influence a range of important ecosystem functions, can induce a reduction in N2O emissions from soil. To test for a functional relationship between AMF and N2O emissions, we manipulated the abundance of AMF in two independent greenhouse experiments using two different approaches (sterilized and re-inoculated soil and non-mycorrhizal tomato mutants) and two different soils. N2O emissions were increased by 42 and 33% in microcosms with reduced AMF abundance compared to microcosms with a well-established AMF community, suggesting that AMF regulate N2O emissions. This could partly be explained by increased N immobilization into microbial or plant biomass, reduced concentrations of mineral soil N as a substrate for N2O emission and altered water relations. Moreover, the abundance of key genes responsible for N2O production (nirK) was negatively and for N2O consumption (nosZ) positively correlated to AMF abundance, indicating that the regulation of N2O emissions is transmitted by AMF-induced changes in the soil microbial community. Our results suggest that the disruption of the AMF symbiosis through intensification of agricultural practices may further contribute to increased N2O emissions.

  16. Instream Large Wood: Dentrification Hotspots With Low N2O Production

    EPA Science Inventory

    The maintenance and restoration of forested riparian cover is important for watershed nitrogen (N) cycling. Forested riparian zones provide woody debris to streams that may stimulate in-stream denitrification and nitrous oxide (N2O) production. We examined the effects of woody an...

  17. Woody Debris: Denitrification Hotspots and N2O Production in Fluvial Systems

    EPA Science Inventory

    The maintenance and restoration of forested riparian cover is important for watershed nitrogen (N) cycling. Forested riparian zones provide woody debris to streams that may stimulate in-stream denitrification and control nitrous oxide (N2O) production. We examined the effects of ...

  18. N2O emission from organic barley cultivation as affected by green manure treatment

    NASA Astrophysics Data System (ADS)

    Nadeem, S.; Hansen, S.; Bleken, M.; Dörsch, P.

    2012-04-01

    Legumes are an important source of nitrogen in stockless organic cereal production. However, substantial amounts of N can be lost from legume-grass leys prior to or after incorporation as green manure (GM). Here we report N2O emissions from a field experiment in SE Norway exploring different green manure management strategies: mulching versus removal of grass-clover herbage during a whole growing season and replacement as biogas residue to a subsequent barley crop. Grass-clover ley had significantly higher N2O emissions as compared with a non fertilized cereal reference during the GM year (2009). Mulching of herbage induced significantly more N2O emission (+ 0.37 kg N2O-N ha-1) throughout the growing season than removing herbage. In spring 2010, all plots were ploughed (with and without GM) resulting in generally higher N2O emissions during barley production. Addition of biogas residue (80 kg N ha-1) in 2010 to previously non mulched GM and unfertilized cereal plots (2009) had no significant effect on cumulative N2O emissions relative to a treatment receiving the same amount of N in form of mulched aboveground GM. Ley management (mulching vs. removing biomass in 2009) had no effect on N2O emissions during barley production in 2010. In general, organic amendments (previously mulched or harvested GM, biorest) increased N2O emissions relative to a reference treatment with low mineral N fertilisation (80 kg N ha-1). Organic cereal production emitted 95 g N2O-N kg-1 N yield in barley grain, which was substantially higher than in the reference treatment with 80 kg mineral N fertilization in 2010 (47 g N2O-N kg-1 N yield in barley grain).

  19. Emissions of N2O and NO from fertilized fields: Summary of available measurement data

    NASA Astrophysics Data System (ADS)

    Bouwman, A. F.; Boumans, L. J. M.; Batjes, N. H.

    2002-12-01

    Information from 846 N2O emission measurements in agricultural fields and 99 measurements for NO emissions was summarized to assess the influence of various factors regulating emissions from mineral soils. The data indicate that there is a strong increase of both N2O and NO emissions accompanying N application rates, and soils with high organic-C content show higher emissions than less fertile soils. A fine soil texture, restricted drainage, and neutral to slightly acidic conditions favor N2O emission, while (though not significant) a good soil drainage, coarse texture, and neutral soil reaction favor NO emission. Fertilizer type and crop type are important factors for N2O but not for NO, while the fertilizer application mode has a significant influence on NO only. Regarding the measurements, longer measurement periods yield more of the fertilization effect on N2O and NO emissions, and intensive measurements (≥1 per day) yield lower emissions than less intensive measurements (2-3 per week). The available data can be used to develop simple models based on the major regulating factors which describe the spatial variability of emissions of N2O and NO with less uncertainty than emission factor approaches based on country N inputs, as currently used in national emission inventories.

  20. Effects of temperature on nitrous oxide (N2O) emission from intensive aquaculture system.

    PubMed

    Paudel, Shukra Raj; Choi, Ohkyung; Khanal, Samir Kumar; Chandran, Kartik; Kim, Sungpyo; Lee, Jae Woo

    2015-06-15

    This study examines the effects of temperature on nitrous oxide (N2O) emissions in a bench-scale intensive aquaculture system rearing Koi fish. The water temperature varied from 15 to 24 °C at interval of 3 °C. Both volumetric and specific rate for nitrification and denitrification declined as the temperature decreased. The concentrations of ammonia and nitrite, however, were lower than the inhibitory level for Koi fish regardless of temperature. The effects of temperature on N2O emissions were significant, with the emission rate and emission factor increasing from 1.11 to 1.82 mg N2O-N/d and 0.49 to 0.94 mg N2O-N/kg fish as the temperature decreased from 24 to 15 °C. A global map of N2O emission from aquaculture was established by using the N2O emission factor depending on temperature. This study demonstrates that N2O emission from aquaculture is strongly dependent on regional water temperatures as well as on fish production.

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

    PubMed

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

    2004-11-01

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

  2. Frozen cropland soil in northeast China as source of N2O and CO2 emissions.

    PubMed

    Miao, Shujie; Qiao, Yunfa; Han, Xiaozeng; Brancher Franco, Roberta; Burger, Martin

    2014-01-01

    Agricultural soils are important sources of atmospheric N2O and CO2. However, in boreal agro-ecosystems the contribution of the winter season to annual emissions of these gases has rarely been determined. In this study, soil N2O and CO2 fluxes were measured for 6 years in a corn-soybean-wheat rotation in northeast China to quantify the contribution of wintertime N2O and CO2 fluxes to annual emissions. The treatments were chemical fertilizer (NPK), chemical fertilizer plus composted pig manure (NPKOM), and control (Cont.). Mean soil N2O fluxes among all three treatments in the winter (November-March), when soil temperatures are below -7°C for extended periods, were 0.89-3.01 µg N m(-2) h(-1), and in between the growing season and winter (October and April), when freeze-thaw events occur, 1.73-5.48 µg N m(-2) h(-1). The cumulative N2O emissions were on average 0.27-1.39, 0.03-0.08 and 0.03-0.11 kg N2O_N ha(-1) during the growing season, October and April, and winter, respectively. The average contributions of winter N2O efflux to annual emissions were 6.3-12.1%. In all three seasons, the highest N2O emissions occurred in NPKOM, while NPK and Cont. emissions were similar. Cumulative CO2 emissions were 2.73-4.94, 0.13-0.20 and 0.07-0.11 Mg CO2-C ha(-1) during growing season, October and April, and winter, respectively. The contribution of winter CO2 to total annual emissions was 2.0-2.4%. Our results indicate that in boreal agricultural systems in northeast China, CO2 and N2O emissions continue throughout the winter.

  3. Spatial and temporal variability of N2O emissions in a subtropical forest catchment in China

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Mulder, J.; Wu, L. P.; Meng, X. X.; Wang, Y. H.; Dörsch, P.

    2013-03-01

    Subtropical forests in southern China have received chronically large amounts of atmogenic nitrogen (N), causing N saturation. Recent studies suggest that a significant proportion of the N input is returned to the atmosphere, in part as nitrous oxide (N2O). We measured N2O emission fluxes by closed chamber technique throughout two years in a Masson pine-dominated headwater catchment with acrisols (pH ~ 4) at Tieshanping (Chongqing, SW China) and assessed the spatial and temporal variability in two landscape elements typical for this region: a mesic forested hillslope (HS) and a hydrologically connected, terraced groundwater discharge zone (GDZ) in the valley bottom. High emission rates of up to 1800 μg N2O-N m-2 h-1 were recorded on the HS shortly after rain storms during monsoonal summer, whereas emission fluxes during the dry winter season were generally low. Overall, N2O emission was lower in GDZ than on HS, rendering the mesic HS the dominant source of N2O in this landscape. Temporal variability of N2O emissions on HS was largely explained by soil temperature (ST) and moisture, pointing at denitrification as a major process for N removal and N2O production. The concentration of nitrate (NO3-) in pore water on HS was high even in the rainy season, apparently never limiting denitrification and N2O production. The concentration of NO3- decreased along the terraced GDZ, indicating efficient N removal, but with moderate N2O-N loss. The extrapolated annual N2O fluxes from soils on HS (0.54 and 0.43 g N2O-N m-2 yr-1 for a year with a wet and a dry summer, respectively) are among the highest N2O fluxes reported from subtropical forests so far. Annual N2O-N emissions amounted to 8-10% of the annual atmogenic N deposition, suggesting that forests on acid soils in southern China are an important, hitherto overlooked component of the anthropogenic N2O budget.

  4. Spatial and temporal variability of N2O emissions in a subtropical forest catchment in China

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Mulder, J.; Wu, L. P.; Meng, X. X.; Wang, Y. H.; Dörsch, P.

    2012-10-01

    Subtropical forests in South China have received chronically large amounts of atmogenic nitrogen (N) causing N saturation. Recent studies suggest that a significant proportion of the N input is returned to the atmosphere, in part as nitrous oxide (N2O). We measured N2O emission fluxes by closed chamber technique throughout two years in a Masson pine-dominated headwater catchment with acrisols (pH ~ 4) at TieShanPing (Chongqing, SW China) and assessed the spatial and temporal variability in two landscape elements typical for this region: a mesic forested hill slope (HS) and a hydrologically connected, terraced groundwater discharge zone (GDZ) in the valley bottom. High emission rates of up to 1800 μg N2O-N m-2 h-1 were recorded on the HS shortly after rain storms during monsoonal summer, whereas emission fluxes during the dry winter season were generally low. Overall, N2O emission was lower in GDZ than in HS, rendering the mesic HS the dominant source of N2O in this landscape. Temporal variability of N2O emissions on HS was largely explained by soil temperature and moisture, pointing at denitrification as a major process for N removal and N2O production. The concentration of nitrate (NO3-) in pore water on HS was high even in the rainy season, apparently never limiting denitrification and N2O production. The concentration of NO3- decreased along the terraced GDZ, indicating efficient N removal, but with moderate N2O-N loss. The extrapolated annual N2O fluxes from soils on HS (0.50 and 0.41 g N2O-N m-2 yr-1 for a year with a wet and a dry summer, respectively) are among the highest N2O fluxes reported from subtropical forests so far. Annual N2O-N emissions amounted to 8-10% of the annual atmogenic N-deposition, suggesting that forests on acid soils in South China are an important, hitherto overlooked component of the anthropogenic N2O budget.

  5. Contrasting denitrifier communities relate to contrasting N2O emission patterns from acidic peat soils in arctic tundra.

    PubMed

    Palmer, Katharina; Biasi, Christina; Horn, Marcus A

    2012-05-01

    Cryoturbated peat circles (that is, bare surface soil mixed by frost action; pH 3-4) in the Russian discontinuous permafrost tundra are nitrate-rich 'hotspots' of nitrous oxide (N(2)O) emissions in arctic ecosystems, whereas adjacent unturbated peat areas are not. N(2)O was produced and subsequently consumed at pH 4 in unsupplemented anoxic microcosms with cryoturbated but not in those with unturbated peat soil. Nitrate, nitrite and acetylene stimulated net N(2)O production of both soils in anoxic microcosms, indicating denitrification as the source of N(2)O. Up to 500 and 10 μM nitrate stimulated denitrification in cryoturbated and unturbated peat soils, respectively. Apparent maximal reaction velocities of nitrite-dependent denitrification were 28 and 18 nmol N(2)O g(DW)(-1) h(-1), for cryoturbated and unturbated peat soils, respectively. Barcoded amplicon pyrosequencing of narG, nirK/nirS and nosZ (encoding nitrate, nitrite and N(2)O reductases, respectively) yielded ≈49 000 quality-filtered sequences with an average sequence length of 444 bp. Up to 19 species-level operational taxonomic units were detected per soil and gene, many of which were distantly related to cultured denitrifiers or environmental sequences. Denitrification-associated gene diversity in cryoturbated and in unturbated peat soils differed. Quantitative PCR (inhibition-corrected per DNA extract) revealed higher copy numbers of narG in cryoturbated than in unturbated peat soil. Copy numbers of nirS were up to 1000 × higher than those of nirK in both soils, and nirS nirK(-1) copy number ratios in cryoturbated and unturbated peat soils differed. The collective data indicate that the contrasting N(2)O emission patterns of cryoturbated and unturbated peat soils are associated with contrasting denitrifier communities.

  6. Contrasting denitrifier communities relate to contrasting N2O emission patterns from acidic peat soils in arctic tundra

    PubMed Central

    Palmer, Katharina; Biasi, Christina; Horn, Marcus A

    2012-01-01

    Cryoturbated peat circles (that is, bare surface soil mixed by frost action; pH 3–4) in the Russian discontinuous permafrost tundra are nitrate-rich ‘hotspots' of nitrous oxide (N2O) emissions in arctic ecosystems, whereas adjacent unturbated peat areas are not. N2O was produced and subsequently consumed at pH 4 in unsupplemented anoxic microcosms with cryoturbated but not in those with unturbated peat soil. Nitrate, nitrite and acetylene stimulated net N2O production of both soils in anoxic microcosms, indicating denitrification as the source of N2O. Up to 500 and 10 μ nitrate stimulated denitrification in cryoturbated and unturbated peat soils, respectively. Apparent maximal reaction velocities of nitrite-dependent denitrification were 28 and 18 nmol N2O gDW−1 h−1, for cryoturbated and unturbated peat soils, respectively. Barcoded amplicon pyrosequencing of narG, nirK/nirS and nosZ (encoding nitrate, nitrite and N2O reductases, respectively) yielded ≈49 000 quality-filtered sequences with an average sequence length of 444 bp. Up to 19 species-level operational taxonomic units were detected per soil and gene, many of which were distantly related to cultured denitrifiers or environmental sequences. Denitrification-associated gene diversity in cryoturbated and in unturbated peat soils differed. Quantitative PCR (inhibition-corrected per DNA extract) revealed higher copy numbers of narG in cryoturbated than in unturbated peat soil. Copy numbers of nirS were up to 1000 × higher than those of nirK in both soils, and nirS nirK−1 copy number ratios in cryoturbated and unturbated peat soils differed. The collective data indicate that the contrasting N2O emission patterns of cryoturbated and unturbated peat soils are associated with contrasting denitrifier communities. PMID:22134649

  7. Effects of crop management, soil type, and climate on N2O emissions from Austrian Soils

    NASA Astrophysics Data System (ADS)

    Zechmeister-Boltenstern, Sophie; Sigmund, Elisabeth; Kasper, Martina; Kitzler, Barbara; Haas, Edwin; Wandl, Michael; Strauss, Peter; Poetzelsberger, Elisabeth; Dersch, Georg; Winiwarter, Wilfried; Amon, Barbara

    2015-04-01

    Within the project FarmClim ("Farming for a better climate") we assessed recent N2O emissions from two selected regions in Austria. Our aim was to deepen the understanding of Austrian N2O fluxes regarding region specific properties. Currently, N2O emissions are estimated with the IPCC default emission factor which only considers the amount of N-input as an influencing factor for N2O emissions. We evaluated the IPCC default emission factor for its validity under spatially distinct environmental conditions. For this two regions for modeling with LandscapeDNDC have been identified in this project. The benefit of using LandscapeDNDC is the detailed illustration of microbial processes in the soil. Required input data to run the model included daily climate data, vegetation properties, soil characteristics and land management. The analysis of present agricultural practices was basis for assessing the hot spots and hot moments of nitrogen emissions on a regional scale. During our work with LandscapeDNDC we were able to adapt specific model algorithms to Austrian agricultural conditions. The model revealed a strong dependency of N2O emissions on soil type. We could estimate how strongly soil texture affects N2O emissions. Based on detailed soil maps with high spatial resolution we calculated region specific contribution to N2O emissions. Accordingly we differentiated regions with deviating gas fluxes compared to the predictions by the IPCC inventory methodology. Taking region specific management practices into account (tillage, irrigation, residuals) calculation of crop rotation (fallow, catch crop, winter wheat, barley, winter barley, sugar beet, corn, potato, onion and rapeseed) resulted in N2O emissions differing by a factor of 30 depending on preceding crop and climate. A maximum of 2% of N fertilizer input was emitted as N2O. Residual N in the soil was a major factor stimulating N2O emissions. Interannual variability was affected by varying N-deposition even in case

  8. Emissions of N2O from peat soils under different cropping systems

    NASA Astrophysics Data System (ADS)

    Norberg, Lisbet; Berglund, Örjan; Berglund, Kerstin

    2016-04-01

    Drainage of peatlands for agriculture use leads to an increase in nitrogen turnover rate causing emissions of N2O to the atmosphere. Agriculture contributes to a substantial part of the anthropogenic emissions of N2O therefore mitigation options for the farmers are important. Here we present a field study with the aim to investigate if the choice of cropping system can mitigate the emission of N2O from cultivated organic soils. The sites used in the study represent fen peat soils with a range of different soil properties located in different parts of southern Sweden. All sites are on active farms with good drainage. N2O emissions from the soil under two different crops grown on the same field, with the same soil type, drainage intensity and weather conditions, are compared by gas sampling. The crops included are oat, barley, carrot, potato and grassland. Three or four sampling occasions during the growing season in 2010 were carried out with static chambers. The N2O emission is calculated from the linear increase of gas concentration in the chamber headspace during the incubation time of 40 minutes. Parallel to the gas sampling soil temperature and soil moisture are measured and some soil properties determined. The result from the gas sampling and measurements show no significant difference in seasonal average N2O emission between the compared crops at any site. There are significant differences in N2O emissions between the compared crops at some of the single sampling occasions but the result vary and no crop can be pointed out as a mitigation option. The seasonal average N2O emissions varies from 16±17 to 1319±1971 μg N2O/m2/h with peaks up to 3317 μg N2O/m2/h. The N2O emission rate from peat soils are determined by other factors than the type of crops grown on the field. The emission rates vary during the season and especially between sites. Although all sites are fen peat soil the soil properties are different, e.g. carbon content varies between 27-43% and

  9. A New High-Resolution N2O Emission Inventory for China in 2008

    NASA Astrophysics Data System (ADS)

    Shang, Z.; Zhou, F.; Ciais, P.; Tao, S.; Piao, S.; Raymond, P. A.; He, C.; Li, B.; Wang, R.; Wang, X.; Peng, S.; Zeng, Z.; Chen, H.; Ying, N.; Hou, X.; Xu, P.

    2014-12-01

    The amount and geographic distribution of N2O emissions over China remain largely uncertain. Most of existing emission inventories use uniform emission factors (EFs) and the associated parameters and apply spatial proxies to downscale national or provincial data, resulting in the introduction of spatial bias. In this study, county-level and 0.1° × 0.1° gridded anthropogenic N2O emission inventories for China (PKU-N2O) in 2008 are developed based on high-resolution activity data and regional EFs and parameters. These new estimates are compared with estimates from EDGAR v4.2, GAINS-China, National Development and Reform Commission of China (NDRC), and with two sensitivity tests: one that uses high-resolution activity data but the default IPCC methodology (S1) and the other that uses regional EFs and parameters but starts from coarser-resolution activity data. The total N2O emissions are 2150 GgN2O/yr (interquartile range from 1174 to 2787 GgN2O/yr). Agriculture contributes 64% of the total, followed by energy (17%), indirect emissions (12%), wastes (5%), industry (2.8%), and wildfires (0.2%). Our national emission total is 17% greater than that of the EDGAR v4.2 global product sampled over China and is also greater than the GAINS-China, NDRC, and S1 estimates by 10%, 50%, and 17%, respectively. We also found that using uniform EFs and parameters or starting from national/provincial data causes systematic spatial biases compared to PKU-N2O. In addition, the considerable differences between the relative contributions of the six sectors across the six Agro-Climate Zones primarily reflect the different distributions of industrial activities and land use. Eastern China (8.7% area of China) is the largest contributor of N2O emissions and accounts for nearly 25% of the total. Spatial analysis also shows nonlinear relationships between N2O emission intensities and urbanization. Per-capita and per-GDP N2O emissions increase gradually with an increase in the urban

  10. N2O emission from organic barley cultivation as affected by green manure management

    NASA Astrophysics Data System (ADS)

    Nadeem, S.; Hansen, S.; Azzaroli Bleken, M.; Dörsch, P.

    2012-02-01

    Legumes are an important source of nitrogen in stockless organic cereal production. However, substantial amounts of N can be lost from legume-grass leys prior to or after incorporation as green manure (GM). Here we report N2O emissions from a field experiment in SE Norway exploring different green manure management strategies: mulching versus removal of grass-clover herbage during a whole growing season and replacement as biogas residue to a subsequent barley crop. Grass-clover ley had small but significantly higher N2O emissions as compared with a non-fertilized cereal reference during the year of green manure (GM) production in 2009. Mulching of herbage induced significantly more N2O emission (+0.37 kg N2O-N ha-1) throughout the growing season than removing herbage. In spring 2010 all plots were ploughed (with and without GM) and sown with barley, resulting in generally higher N2O emissions than during the previous year. Application of biogas residue (110 kg N ha-1) before sowing did not increase emissions neither when applied to previous ley plots nor when applied to previously unfertilized cereal plots. Ley management (mulching vs. removing biomass in 2009) had no effect on N2O emissions during barley production in 2010. In general, GM ley (mulched or harvested) increased N2O emissions relative to a cereal reference with low mineral N fertilisation (80 kg N ha-1). Organic cereal production emitted 95 g N2O-N kg-1 N yield in barley grain, which was substantially higher than in the cereal reference treatment with 80 kg mineral N fertilization in 2010 (47 g N2O-N kg-1 N yield in barley grain).

  11. N2O emission from organic barley cultivation as affected by green manure management

    NASA Astrophysics Data System (ADS)

    Nadeem, S.; Hansen, S.; Azzaroli Bleken, M.; Dörsch, P.

    2012-07-01

    Legumes are an important source of nitrogen in stockless organic cereal production. However, substantial amounts of N can be lost from legume-grass leys prior to or after incorporation as green manure (GM). Here we report N2O emissions from a field experiment in SE Norway exploring different green manure management strategies: mulching versus removal of grass-clover herbage during a whole growing season and return as biogas residue to a subsequent barley crop. Grass-clover ley had small but significantly higher N2O emissions as compared with a non-fertilised cereal reference during the year of green manure (GM) production in 2009. Mulching of herbage induced significantly more N2O emission (+0.37 kg N2O-N ha-1) throughout the growing season than removing herbage. In spring 2010, all plots were ploughed (with and without GM) and sown with barley, resulting in generally higher N2O emissions than during the previous year. Application of biogas residue (60 kg NH4+-N + 50 kg organic N ha-1) before sowing did not increase emissions neither when applied to previous ley plots nor when applied to previously unfertilised cereal plots. Ley management (mulching vs. removing biomass in 2009) had no effect on N2O emissions during barley production in 2010. In general, GM ley (mulched or harvested) increased N2O emissions relative to a cereal reference with low mineral N fertilisation (80 kg N ha-1). Based on measurements covering the growing season 2010, organic cereal production emitted 95 g N2O-N kg-1 N yield in barley grain, which was substantially higher than in the cereal reference treatment with 80 kg mineral N fertilisation (47 g N2O-N kg-1 N yield in barley grain).

  12. Global N2O emissions - with a focus on natural soil

    NASA Astrophysics Data System (ADS)

    Saikawa, E.; Schlosser, C. A.; Rigby, M. L.; Prinn, R. G.; Weiss, R. F.; Fraser, P.; Krummel, P. B.; Steele, P.; Odoherty, S. J.; Simmonds, P.; Dlugokencky, E. J.; Elkins, J. W.; Dutton, G. S.; Hall, B. D.; Tohjima, Y.; Machida, T.; Nakazawa, T.; Aoki, S.; Ishijima, K.

    2011-12-01

    Nitrous oxide (N2O) emissions weighted by ozone depletion potential currently dominate emissions of ozone depleting substances, and N2O is now the third most significant long-lived anthropogenic greenhouse gas after CO2 and CH4. Despite its impact on stratospheric ozone destruction, it is not regulated under the Montreal Protocol, and global observations show a continuous N2O mole fraction increase of 0.2 to 0.3% per year. Sinks and sources of N2O still have large uncertainties but previous studies have estimated that soil emissions share more than a half of the global total. Because the variability in soil emissions could potentially have important implications for regional and global climate, and vice versa, it is essential to better understand the processes and feedbacks associated with soil N2O emissions. To achieve this goal and quantify global soil N2O emissions, we have included nitrification-denitrification processes (DNDC) into the Community Land Model (CLM) version 3.5. Using three different bias-corrected, reanalysis-based meteorological datasets (NCC, CAS and GOLD), we constructed a suite of global gridded soil N2O emissions estimates from 1975 through the mid-2000s. We evaluate our global soil N2O flux estimates against: 1) an existing emissions inventory (GEIA), 2) another process model (NASA-CASA), and 3) observations from an existing forest N2O flux dataset in the Amazon and in the United States. Both the global and regional totals agree well and the model reproduces the observed seasonal cycles of N2O emissions. Next, we input these emission estimates to a 3-dimensional atmospheric chemical transport model - the Model for OZone And Related Tracers (MOZART) version 4 - to analyze the impact of monthly and inter-annual variability in soil emissions on atmospheric observations. Using these emissions as an initial estimate, we also determine new regional and global N2O emissions by inverse modeling from 1995 through 2009. Data from the Advanced Global

  13. A toy model for estimating N2O emissions from natural soils

    NASA Technical Reports Server (NTRS)

    Fung, Inez

    1992-01-01

    A model of N2O emissions from natural soils, whose ultimate objective is to evaluate what contribution natural ecosystems make to the global N2O budget and how the contribution would change with global change, is presented. Topics covered include carbon and nitrogen available in the soil, delivery of nitrifiable N, soil water and oxygen status, soil water budget model, effects of drainage, nitrification and denitrification potentials, soil fertility, N2O production, and a model evaluation. A major implication of the toy model is that the tropics account for more than 80 percent of global emission.

  14. High N2O emission in an N-saturated subtropical forest, southwest China

    NASA Astrophysics Data System (ADS)

    Dörsch, P.; Zhu, J.; Mulder, J.

    2012-04-01

    Nitrogen (N)-saturated forests in subtropical China are significant N sinks, despite low forest growth rates. In a forested headwater catchment at Tieshanping, Chongqing, SW China, with 4 g N m-2a-1 atmogenic deposition (60% of which as NH4+-N) and leaching of only 0.6 g N m-2 a-1 (NO3--N dominated), we applied state-of-the-art field and laboratory methodologies to investigate the nature of the N sinks. The study included the determination of spatiotemporal patterns of N2O emission, a 15N labeling experiment and laboratory incubations to determine nitrification and denitrification characteristics and their gaseous product stoichiometries. Emission of N2O occurred predominantly during the wet season (summer), driven by rain episodes. N2O emission rates were particularly high along a hill slope (HS) with a thin organic surface layer overlaying an argic B horizon causing transient interflow during storm flow conditions. Lower N2O emission rates were observed at the foot slope in a colluvium-derived groundwater discharge zone (GDZ). Laboratory incubation experiments suggested that the difference in N2O emission rate is primarily due to higher N2O/N2 product ratios of denitrification in the HS topsoil being exposed to frequent drying-rewetting. Lower N2O/N2 product ratios in soils of the GDZ, in turn, could be attributed to more stable anoxia, lower NO3- availability and higher pH as compared with the hillslope, all of which favor the expression of N2O reductase. Estimated annual N2O emission for the relatively dry hydrological year 2009-2010 was 0.4 g N m-2, which is equivalent to approximately 10% of the annual input of reactive N. Measurements during summer 2009 indicated that N2O emissions can be even higher during wet years. A 15NO3- labeling experiment conducted on HS soils during summer revealed that between 75 and 86% of the N2O emission derived from denitrification during the first 6 days after label addition, accounting for 8-15% of the applied NO3--N. Our

  15. Dolomite application to acidic soils: a promising option for mitigating N2O emissions.

    PubMed

    Shaaban, Muhammad; Peng, Qi-An; Hu, Ronggui; Wu, Yupeng; Lin, Shan; Zhao, Jinsong

    2015-12-01

    Soil acidification is one of the main problems to crop productivity as well as a potent source of atmospheric nitrous oxide (N2O). Liming practice is usually performed for the amelioration of acidic soils, but the effects of dolomite application on N2O emissions from acidic soils are still not well understood. Therefore, a laboratory study was conducted to examine N2O emissions from an acidic soil following application of dolomite. Dolomite was applied to acidic soil in a factorial design under different levels of moisture and nitrogen (N) fertilizer. Treatments were as follows: dolomite was applied as 0, 1, and 2 g kg(-1) soil (named as CK, L, and H, respectively) under two levels of moisture [i.e., 55 and 90 % water-filled pore space (WFPS)]. All treatments of dolomite and moisture were further amended with 0 and 200 mg N kg(-1) soil as (NH4)2SO4. Soil properties such as soil pH, mineral N (NH4 (+)-N and NO3 (-)-N), microbial biomass carbon (MBC), dissolved organic carbon (DOC), and soil N2O emissions were analyzed throughout the study period. Application of N fertilizer rapidly increased soil N2O emissions and peaked at 0.59 μg N2O-N kg(-1) h(-1) under 90 % WFPS without dolomite application. The highest cumulative N2O flux was 246.32 μg N2O-N kg(-1) under 90 % WFPS without dolomite addition in fertilized soil. Addition of dolomite significantly (p ≤ 0.01) mitigated N2O emissions as soil pH increased, and H treatment was more effective for mitigating N2O emissions as compared to L treatment. The H treatment decreased the cumulative N2O emissions by up to 73 and 67 % under 55 and 90 % WFPS, respectively, in fertilized soil, and 60 and 68 % under 55 and 90 % WFPS, respectively, in unfertilized soil when compared to those without dolomite addition. Results demonstrated that application of dolomite to acidic soils is a promising option for mitigating N2O emissions.

  16. Impact of Aquatic and Terrestrial Emissions on Atmospheric N2O Variability

    NASA Astrophysics Data System (ADS)

    Nevison, C. D.; Riddick, S. N.; Saikawa, E.; Hess, P. G.

    2013-12-01

    Atmospheric concentrations of the greenhouse gas nitrous oxide (N2O) have increased by about 20% since the preindustrial era, an increase that has been driven largely by use of anthropogenic nitrogen fertilizers. The N2O source associated with agriculture was historically underestimated by assessments that considered only direct emissions from fertilized fields, but more recently it has been recognized that 'indirect' emissions associated with N leaching and runoff to rivers and may account for as much as half of total agricultural N2O emissions. Meanwhile, recent regional atmospheric N2O inversions have inferred large North American agricultural N2O sources that are difficult to reconcile with global budget constraints. At the same time, it is not clear whether the inversions can detect indirect N2O emissions associated with nitrogen leaching and runoff. Here, we will present forward model simulations aimed at quantifying the relative magnitude, spatial distribution and timing of direct and indirect agricultural N2O emissions. The model simulations will be based on the Community Land Model (CLM), with new agricultural and trace N gas parameterizations, coupled to the River Transport Model (RTM), with a module for estimating river N transport and N2O production associated with in-stream sediment denitrification. The coupled CLM-RTM N2O fluxes will be used to force atmospheric chemistry tracer transport model (ACTM) simulations, with direct and indirect emissions carried as separate tracers. The ACTM results will be used to evaluate the impact of both types of emissions on site-specific variability in atmospheric N2O at United States monitoring sites and to assess the likelihood that current atmospheric monitoring networks can detect these signals. Locations of selected NOAA monitoring sites for atmospheric N2O over the continental United States, showing both aircraft (triangles) and surface flask or tower sites (filled circles). Site locations are superimposed on a

  17. [Effects of applying controlled release fertilizers on N2O emission from a lateritic red soil].

    PubMed

    Du, Ya-qin; Zheng, Li-xing; Fan, Xiao-lin

    2011-09-01

    Static closed chamber technique and contrast method were adopted to study the effects of three coated compound fertilizers (N:P2O5:K2O = 19:8.6:10.5, high N; 14.4:14.4:14.4, balanced NPK; and 12.5:9.6:20.2, high K) on the NO2O emission from a lateritic red soil under the condition of no crop planting, taking uncoated compound fertilizers (N:P2O5:K2O = 20:9:11, high N; 15:15:15, balanced NPK; and 13:10:21, high K) as the contrasts. Different formula of fertilizer NPK induced significant difference in the N2O emission. Under the application of uncoated compound fertilizers, the cumulative N2O emission was in the order of balanced NPK > or = high N > high K. Applying coated compound fertilizers decreased the N2O emission significantly, and the emission amount under the application of high N, balanced NPK, and high K was 34.4%, 30.5%, and 89.3% of the corresponding uncoated compound fertilizers, respectively. Comparing with the application of uncoated compound fertilizers, applying coated compound fertilizers also decreased the daily N2O flux significantly, and delayed and shortened the N2O peak, suggesting that coated fertilizers could reduce soil nitrogen loss and the global warming potential induced by N2O emission.

  18. Optimizing rice plant photosynthate allocation reduces N2O emissions from paddy fields

    PubMed Central

    Jiang, Yu; Huang, Xiaomin; Zhang, Xin; Zhang, Xingyue; Zhang, Yi; Zheng, Chengyan; Deng, Aixing; Zhang, Jun; Wu, Lianhai; Hu, Shuijin; Zhang, Weijian

    2016-01-01

    Rice paddies are a major source of anthropogenic nitrous oxide (N2O) emissions, especially under alternate wetting-drying irrigation and high N input. Increasing photosynthate allocation to the grain in rice (Oryza sativa L.) has been identified as an effective strategy of genetic and agronomic innovation for yield enhancement; however, its impacts on N2O emissions are still unknown. We conducted three independent but complementary experiments (variety, mutant study, and spikelet clipping) to examine the impacts of rice plant photosynthate allocation on paddy N2O emissions. The three experiments showed that N2O fluxes were significantly and negatively correlated with the ratio of grain yield to total aboveground biomass, known as the harvest index (HI) in agronomy (P < 0.01). Biomass accumulation and N uptake after anthesis were significantly and positively correlated with HI (P < 0.05). Reducing photosynthate allocation to the grain by spikelet clipping significantly increased white root biomass and soil dissolved organic C and reduced plant N uptake, resulting in high soil denitrification potential (P < 0.05). Our findings demonstrate that optimizing photosynthate allocation to the grain can reduce paddy N2O emissions through decreasing belowground C input and increasing plant N uptake, suggesting the potential for genetic and agronomic efforts to produce more rice with less N2O emissions. PMID:27378420

  19. Optimizing rice plant photosynthate allocation reduces N2O emissions from paddy fields

    NASA Astrophysics Data System (ADS)

    Jiang, Yu; Huang, Xiaomin; Zhang, Xin; Zhang, Xingyue; Zhang, Yi; Zheng, Chengyan; Deng, Aixing; Zhang, Jun; Wu, Lianhai; Hu, Shuijin; Zhang, Weijian

    2016-07-01

    Rice paddies are a major source of anthropogenic nitrous oxide (N2O) emissions, especially under alternate wetting-drying irrigation and high N input. Increasing photosynthate allocation to the grain in rice (Oryza sativa L.) has been identified as an effective strategy of genetic and agronomic innovation for yield enhancement; however, its impacts on N2O emissions are still unknown. We conducted three independent but complementary experiments (variety, mutant study, and spikelet clipping) to examine the impacts of rice plant photosynthate allocation on paddy N2O emissions. The three experiments showed that N2O fluxes were significantly and negatively correlated with the ratio of grain yield to total aboveground biomass, known as the harvest index (HI) in agronomy (P < 0.01). Biomass accumulation and N uptake after anthesis were significantly and positively correlated with HI (P < 0.05). Reducing photosynthate allocation to the grain by spikelet clipping significantly increased white root biomass and soil dissolved organic C and reduced plant N uptake, resulting in high soil denitrification potential (P < 0.05). Our findings demonstrate that optimizing photosynthate allocation to the grain can reduce paddy N2O emissions through decreasing belowground C input and increasing plant N uptake, suggesting the potential for genetic and agronomic efforts to produce more rice with less N2O emissions.

  20. Nitrous Oxide (N2O) Emissions by Termites: Does the Feeding Guild Matter?

    PubMed

    Brauman, Alain; Majeed, Muhammad Zeeshan; Buatois, Bruno; Robert, Alain; Pablo, Anne-Laure; Miambi, Edouard

    2015-01-01

    In the tropics, termites are major players in the mineralization of organic matter leading to the production of greenhouse gases including nitrous oxide (N2O). Termites have a wide trophic diversity and their N-metabolism depends on the feeding guild. This study assessed the extent to which N2O emission levels were determined by termite feeding guild and tested the hypothesis that termite species feeding on a diet rich in N emit higher levels of N2O than those feeding on a diet low in N. An in-vitro incubation approach was used to determine the levels of N2O production in 14 termite species belonging to different feeding guilds, collected from a wide range of biomes. Fungus-growing and soil-feeding termites emit N2O. The N2O production levels varied considerably, ranging from 13.14 to 117.62 ng N2O-N d(-1) (g dry wt.)(-1) for soil-feeding species, with Cubitermes spp. having the highest production levels, and from 39.61 to 65.61 ng N2O-N d(-1) (g dry wt.)(-1) for fungus-growing species. Wood-feeding termites were net N2O consumers rather than N2O producers with a consumption ranging from 16.09 to 45.22 ng N2O-N d(-1) (g dry wt.)(-1). Incubating live termites together with their mound increased the levels of N2O production by between 6 and 13 fold for soil-feeders, with the highest increase in Capritermes capricornis, and between 14 and 34 fold for fungus-growers, with the highest increase in Macrotermes muelleri. Ammonia-oxidizing (amoA-AOB and amoA-AOA) and denitrifying (nirK, nirS, nosZ) gene markers were detected in the guts of all termite species studied. No correlation was found between the abundance of these marker genes and the levels of N2O production from different feeding guilds. Overall, these results support the hypothesis that N2O production rates were higher in termites feeding on substrates with higher N content, such as soil and fungi, compared to those feeding on N-poor wood.

  1. Nitrous Oxide (N2O) Emissions by Termites: Does the Feeding Guild Matter?

    PubMed Central

    Buatois, Bruno; Robert, Alain; Pablo, Anne-Laure; Miambi, Edouard

    2015-01-01

    In the tropics, termites are major players in the mineralization of organic matter leading to the production of greenhouse gases including nitrous oxide (N2O). Termites have a wide trophic diversity and their N-metabolism depends on the feeding guild. This study assessed the extent to which N2O emission levels were determined by termite feeding guild and tested the hypothesis that termite species feeding on a diet rich in N emit higher levels of N2O than those feeding on a diet low in N. An in-vitro incubation approach was used to determine the levels of N2O production in 14 termite species belonging to different feeding guilds, collected from a wide range of biomes. Fungus-growing and soil-feeding termites emit N2O. The N2O production levels varied considerably, ranging from 13.14 to 117.62 ng N2O-N d-1 (g dry wt.)-1 for soil-feeding species, with Cubitermes spp. having the highest production levels, and from 39.61 to 65.61 ng N2O-N d-1 (g dry wt.)-1 for fungus-growing species. Wood-feeding termites were net N2O consumers rather than N2O producers with a consumption ranging from 16.09 to 45.22 ng N2O-N d-1 (g dry wt.)-1. Incubating live termites together with their mound increased the levels of N2O production by between 6 and 13 fold for soil-feeders, with the highest increase in Capritermes capricornis, and between 14 and 34 fold for fungus-growers, with the highest increase in Macrotermes muelleri. Ammonia-oxidizing (amoA-AOB and amoA-AOA) and denitrifying (nirK, nirS, nosZ) gene markers were detected in the guts of all termite species studied. No correlation was found between the abundance of these marker genes and the levels of N2O production from different feeding guilds. Overall, these results support the hypothesis that N2O production rates were higher in termites feeding on substrates with higher N content, such as soil and fungi, compared to those feeding on N-poor wood. PMID:26658648

  2. Attenuation of N2O emission rates from agricultural soil at different dicyandiamide concentrations.

    PubMed

    Verma, Amitosh; Tyagi, Larisha; Singh, S N

    2008-02-01

    An experiment was conducted to assess the role of different concentrations of dicyandiamide (DCD), a potent nitrification inhibitor, on temporal changes in nitrous oxide emission from sandy loam agricultural soil. It was found that with increasing concentration of DCD i.e. from 6 to 12% of nitrogen applied in the form of urea, there was a decrease in the both average and peak N(2)O emissions. However, from 14% DCD treated soil, there was a non-significant alteration in the N(2)O emission. Maximum average N(2)O efflux of 217.55 microg m(-2) h(-1) was noted from control plots. As compared to control, there was an attenuation of 50, 58, 65, and 91% average N(2)O efflux from 6, 8, 10 and 12% DCD applied pots, respectively, whereas, there was a negative average of N(2)O efflux from the soil with 14% DCD treatment. The soil N content also showed a significant correlation with N(2)O emission. Therefore, 12% DCD treatment has been found to be the best with regard to attenuation of nitrous oxide from sandy loam agricultural soils.

  3. Predicting N2O emissions from nitrifying and denitrifying biofilms: a modeling study.

    PubMed

    Sabba, Fabrizio; Picioreanu, Cristian; Boltz, Joshua P; Nerenberg, Robert

    2017-02-01

    Wastewater treatment plants can be significant sources of nitrous oxide (N2O), a potent greenhouse gas. While our understanding of N2O emissions from suspended-growth processes has advanced significantly, less is known about emissions from biofilm processes. Biofilms may behave differently due to their substrate gradients and microbial stratification. In this study, we used mathematical modeling to explore the mechanisms of N2O emissions from nitrifying and denitrifying biofilms. Our ammonia-oxidizing bacteria biofilm model suggests that N2O emissions from biofilm can be significantly greater than from suspended-growth systems. The driving factor is the diffusion of hydroxylamine, a nitrification intermediate, from the aerobic to the anoxic regions of the biofilm. The presence of nitrite-oxidizing bacteria further increased emissions. For denitrifying biofilms, our results suggest that emissions are generally greater than for suspended-growth systems. However, the magnitude of the difference depends on the bulk dissolved oxygen, chemical oxygen demand, and nitrate concentrations, as well as the biofilm thickness. Overall, the accumulation and diffusion of key intermediates, i.e. hydroxylamine and nitrite, distinguish biofilms from suspended-growth systems. Our research suggests that the mechanisms of N2O emissions from biofilms are much more complex than suspended-growth systems, and that emissions may be higher in many cases.

  4. Detailed regional predictions of N2O and NO emissions from a tropical highland rainforest

    NASA Astrophysics Data System (ADS)

    Gharahi Ghehi, N.; Werner, C.; Hufkens, K.; Kiese, R.; Van Ranst, E.; Nsabimana, D.; Wallin, G.; Klemedtsson, L.; Butterbach-Bahl, K.; Boeckx, P.

    2013-01-01

    Tropical forest soils are a significant source for the greenhouse gas N2O as well as for NO, a precursor of tropospheric ozone. However, current estimates are uncertain due to the limited number of field measurements. Furthermore, there is considerable spatial and temporal variability of N2O and NO emissions due to the variation of environmental conditions such as soil properties, vegetation characteristics and meteorology. In this study we used a process-based model (ForestDNDC-tropica) to estimate N2O and NO emissions from tropical highland forest (Nyungwe) soils in southwestern Rwanda. To extend the model inputs to regional scale, ForestDNDC-tropica was linked to an exceptionally large legacy soil dataset. There was agreement between N2O and NO measurements and the model predictions though the ForestDNDC-tropica resulted in considerable lower emissions for few sites. Low similarity was specifically found for acidic soil with high clay content and reduced metals, indicating that chemo-denitrification processes on acidic soils might be under-represented in the current ForestDNDC-tropica model. The results showed that soil bulk density and pH are the most influential factors driving spatial variations in soil N2O and NO emissions for tropical forest soils. The area investigated (1113 km2) was estimated to emit ca. 439 ± 50 t N2O-N yr-1 (2.8-5.5 kg N2O-N ha-1 yr-1) and 244 ± 16 t NO-N yr-1 (0.8-5.1 kg N ha-1 yr-1). Consistent with less detailed studies, we confirm that tropical highland rainforest soils are a major source of atmospheric N2O and NO.

  5. Effects of dicyandiamide and dolomite application on N2O emission from an acidic soil.

    PubMed

    Shaaban, Muhammad; Wu, Yupeng; Peng, Qi-an; Lin, Shan; Mo, Yongliang; Wu, Lei; Hu, Ronggui; Zhou, Wei

    2016-04-01

    Soil acidification is a major problem for sustainable agriculture since it limits productivity of several crops. Liming is usually adopted to ameliorate soil acidity that can trigger soil processes such as nitrification, denitrification, and loss of nitrogen (N) as nitrous oxide (N2O) emissions. The loss of N following liming of acidic soils can be controlled by nitrification inhibitors (such as dicyandiamide). However, effects of nitrification inhibitors following liming of acidic soils are not well understood so far. Here, we conducted a laboratory study using an acidic soil to examine the effects of dolomite and dicyandiamide (DCD) application on N2O emissions. Three levels of DCD (0, 10, and 20 mg kg(-1); DCD0, DCD10, and DCD20, respectively) were applied to the acidic soil under two levels of dolomite (0 and 1 g kg(-1)) which were further treated with two levels of N fertilizer (0 and 200 mg N kg(-1)). Results showed that N2O emissions were highest at low soil pH levels in fertilizer-treated soil without application of DCD and dolomite. Application of DCD and dolomite significantly (P ≤ 0.001) reduced N2O emissions through decreasing rates of NH4 (+)-N oxidation and increasing soil pH, respectively. Total N2O emissions were reduced by 44 and 13% in DCD20 and dolomite alone treatments, respectively, while DCD20 + dolomite reduced N2O emissions by 54% when compared with DCD0 treatment. The present study suggests that application of DCD and dolomite to acidic soils can mitigate N2O emissions.

  6. Nitrous oxide emission hotspots from organic soils in Europe

    NASA Astrophysics Data System (ADS)

    Leppelt, T.; Dechow, R.; Gebbert, S.; Freibauer, A.; Lohila, A.; Augustin, J.; Drösler, M.; Fiedler, S.; Glatzel, S.; Höper, H.; Järveoja, J.; Lærke, P. E.; Maljanen, M.; Mander, Ü.; Mäkiranta, P.; Minkkinen, K.; Ojanen, P.; Regina, K.; Strömgren, M.

    2014-06-01

    Organic soils are a main source of direct nitrous oxide (N2O) emissions, an important greenhouse gas (GHG). Observed N2O emissions from organic soils are highly variable in space and time which causes high uncertainties in national emission inventories. Those uncertainties could be reduced when relating the upscaling process to a priori identified key drivers by using available N2O observations from plot scale in empirical approaches. We used the empirical fuzzy modelling approach MODE to identify main drivers for N2O and utilize them to predict the spatial emission pattern of European organic soils. We conducted a meta study with a total amount of 659 annual N2O measurements which was used to derive separate models for different land use types. We applied our models to available, spatial explicit input driver maps to upscale N2O emissions on European level and compared the inventory with recently published IPCC emission factors. The final statistical models explained up to 60% of the N2O variance. Our study results showed that cropland and grasslands emitted the highest N2O fluxes 0.98 ± 1.08 and 0.58 ± 1.03 g N2O-N m-2 a-1, respectively. High fluxes from cropland sites were mainly controlled by low soil pH-value and deep drained groundwater tables. Grassland hotspot emissions were strongly related to high amount of N-fertilizer inputs and warmer winter temperatures. In contrast N2O fluxes from natural peatlands were predominantly low (0.07±0.27 g N2O-N m-2 a-1) and we found no relationship with the tested drivers. The total inventory for direct N2O emissions from organic soils in Europe amount up to 149.5 Gg N2O-N a-1, which included also fluxes from forest and peat extraction sites and exceeds the inventory calculated by IPCC emission factors of 87.4 Gg N2O-N a-1. N2O emissions from organic soils represent up to 13% of total European N2O emissions reported in the European Union (EU) greenhouse gas inventory of 2011 from only 7% of the EU area. Thereby the

  7. Effect of long-term compost and inorganic fertilizer application on background N2O and fertilizer-induced N2O emissions from an intensively cultivated soil.

    PubMed

    Ding, Weixin; Luo, Jiafa; Li, Jie; Yu, Hongyan; Fan, Jianling; Liu, Deyan

    2013-11-01

    The influence of inorganic fertilizer and compost on background nitrous oxide (N2O) and fertilizer-induced N2O emissions were examined over a maize-wheat rotation year from June 2008 to May 2009 in a fluvo-aquic soil in Henan Province of China where a field experiment had been established in 1989 to evaluate the long-term effects of manure and fertilizer on soil organic status. The study involved five treatments: compost (OM), fertilizer NPK (nitrogen-phosphorus-potassium, NPK), half compost N plus half fertilizer N (HOM), fertilizer NK (NK), and control without any fertilizer (CK). The natural logarithms of the background N2O fluxes were significantly (P<0.05) correlated with soil temperature, but not with soil moisture, during the maize or wheat growing season. The 18-year application of compost alone and inorganic fertilizer not only significantly (P<0.05) increased soil organic carbon (SOC) by 152% and 10-43% (respectively), but also increased background N2O emissions by 106% and 48-76% (respectively) compared with the control. Total N in soils was a better indicator for predicting annual background N2O emission than SOC. The estimated emission factor (EF) of mineralized N, calculated by dividing annual N2O emission by mineralized N was 0.13-0.19%, significantly (P<0.05) lower than the EF of added N (0.30-0.39%). The annual N2O emission in the NPK, HOM and OM soils amended with 300 kg ha(-1) organic or inorganic N was 1427, 1325 and 1178 g N ha(-1), respectively. There was a significant (P<0.05) difference between the NPK and OM. The results of this study indicate that soil indigenous N was less efficiently converted into N2O compared with exogenous N. Increasing SOC by compost application, then partially increasing N supply to crops instead of adding inorganic N fertilizer, may be an effective measure to mitigate N2O emissions from arable soils in the North China plain.

  8. Simulating N2O emissions in different tillage systems of irrigated corn using RZ-Shaw model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) is potent greenhouse gas (GHG) and agriculture is a global source of N2O emissions from soil fertility management. Yet emissions vary by agronomic practices and environmental factors that govern soil moisture and temperature. Ecosystem models are important tools to estimate N2O e...

  9. Rainfall reduction amplifies the stimulatory effect of nitrogen addition on N2O emissions from a temperate forest soil

    NASA Astrophysics Data System (ADS)

    Geng, Shicong; Chen, Zhijie; Han, Shijie; Wang, Fang; Zhang, Junhui

    2017-02-01

    Soil is a significant source of atmospheric N2O, and soil N2O emissions at a global scale are greatly affected by environment changes that include continuous deposition of atmospheric nitrogen and changing precipitation distribution. However, to date, field simulations of multiple factors that control the interaction between nitrogen deposition and precipitation on forest soil N2O emissions are scarce. In this study, we conducted a 2-year continuous assessment of N2O emissions from November 2012 to October 2014 at a nitrogen addition and rainfall reduction manipulation platform in an old broad-leaved Korean pine mixed forest at Changbai Mountain in northeastern China. We found that N2O emissions from control plots were 1.25 ± 0.22 kg N2O-N ha‑1 a‑1. Nitrogen addition significantly increased N2O emissions, with the emission factor of 1.59%. A 30% reduction in rainfall decreased N2O emissions by 17–45%. However, in combination, nitrogen addition and rainfall reduction increased N2O emissions by 58–140%, with the emission factor of 3.19%, and had a larger promotional effect than the addition of nitrogen alone. Our results indicated that drought slightly decreases forest soil N2O emission; however, with increasing deposition of atmospheric N in temperate forest soils, the effect of drought might become altered to increase N2O emission.

  10. Rainfall reduction amplifies the stimulatory effect of nitrogen addition on N2O emissions from a temperate forest soil

    PubMed Central

    Geng, Shicong; Chen, Zhijie; Han, Shijie; Wang, Fang; Zhang, Junhui

    2017-01-01

    Soil is a significant source of atmospheric N2O, and soil N2O emissions at a global scale are greatly affected by environment changes that include continuous deposition of atmospheric nitrogen and changing precipitation distribution. However, to date, field simulations of multiple factors that control the interaction between nitrogen deposition and precipitation on forest soil N2O emissions are scarce. In this study, we conducted a 2-year continuous assessment of N2O emissions from November 2012 to October 2014 at a nitrogen addition and rainfall reduction manipulation platform in an old broad-leaved Korean pine mixed forest at Changbai Mountain in northeastern China. We found that N2O emissions from control plots were 1.25 ± 0.22 kg N2O-N ha−1 a−1. Nitrogen addition significantly increased N2O emissions, with the emission factor of 1.59%. A 30% reduction in rainfall decreased N2O emissions by 17–45%. However, in combination, nitrogen addition and rainfall reduction increased N2O emissions by 58–140%, with the emission factor of 3.19%, and had a larger promotional effect than the addition of nitrogen alone. Our results indicated that drought slightly decreases forest soil N2O emission; however, with increasing deposition of atmospheric N in temperate forest soils, the effect of drought might become altered to increase N2O emission. PMID:28233839

  11. Quantification of nitrous oxide (N2O) emissions and soluble microbial product (SMP) production by a modified AOB-NOB-N2O-SMP model.

    PubMed

    Kim, MinJeong; Wu, Guangxue; Yoo, ChangKyoo

    2017-03-01

    A modified AOB-NOB-N2O-SMP model able to quantify nitrous oxide (N2O) emissions and soluble microbial product (SMP) production during wastewater treatment is proposed. The modified AOB-NOB-N2O-SMP model takes into account: (1) two-step nitrification by ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), (2) N2O production by AOB denitrification under oxygen-limited conditions and (3) SMP production by microbial growth and endogenous respiration. Validity of the modified model is demonstrated by comparing the simulation results with experimental data from lab-scale sequencing batch reactors (SBRs). To reliably implement the modified model, a model calibration that adjusts model parameters to fit the model outputs to the experimental data is conducted. The results of this study showed that the modeling accuracy of the modified AOB-NOB-N2O-SMP model increases by 19.7% (NH4), 51.0% (NO2), 57.8% (N2O) and 16.7% (SMP) compared to the conventional model which does not consider the two-step nitrification and SMP production by microbial endogenous respiration.

  12. [Vertical distribution characteristics of N2O emission in tea garden and its adjacent woodland].

    PubMed

    Fan, Li-chao; Han, Wen-yan; Li, Xin; Li, Zhi-xin

    2015-09-01

    In this study, we determined the vertical distribution of N2O emission rates in tea soils and its adjacent woodland soils. The results showed that total nitrogen contents, N2O fluxes and cumulative emissions in the tea garden and woodland decreased with the increasing depth of the soil layer, and their average values were greater in tea garden than in woodland. Generally, pH, soil water soluble organic nitrogen (WSON), soil microbial biomass nitrogen (MBN), NO(3-)-N and NH(4+)-N contents had a downward trend with the increasing depth of soil layer. The WSON, MBN, NO(3-)-N and NH(4+)-N contents from each soil layer were greater in tea garden than in woodland, but the pH value in tea garden was lower than that in woodland. The N2O emission rate was significantly positively related with TN, MBN and NH(4+)-N contents, but not with pH value. The N2O emission rate was significantly correlated with WSON content in woodland, but not in tea garden. The N20 emission rate was significantly correlated with NO(3-)-N concentration in tea garden, but not in woodland. WSON/TN and N2O-N/SMBN were averagely greater than in tea garden in woodland, and SMBN/TN was opposite. These results indicated that tea soil was not conducive to accumulate nitrogen pool, maintain soil quality and its sustainable use compared to woodland.

  13. Assessment of N2O emissions from rapeseed cultivation in Poland by various approaches

    NASA Astrophysics Data System (ADS)

    Syp, Alina; Faber, Antoni; Kozak, Małgorzata

    2016-10-01

    The aim of this study was to compare four tools for calculation of nitrous oxide (N2O) emissions under the renewable energy directive. All the tools follow the methodology of the international panel on climate change. The first calculations of N2O fluxes were based on the Tier 1 method using the BioGrace tool. The second and the third ones followed the Tier 2 methodology, applying the global nitrous oxide calculator and the Lesschen emission factors, respectively. The last assessment was performed in accordance with the Tier 3 approach by using the denitrification- decomposition model. The N2O fluxes were calculated for rapeseed cultivation in a 4-year crop rotation in Poland. The same input data were applied in all methods. The average of N2O emissions varied in the range of 1.99-3.78 kg N2O ha-1 y-1, depending on the approach used (Lesschen emission factors > denitrificationdecomposition > global nitrous oxide calculator > BioGrace). This paper illustrates that, at country level, the Lesschen emission factors method worked as well as the denitrification-decomposition model for Poland. The advantage of this approach is the simplicity of collecting the necessary data, in contrast to process-based modelling. Moreover, the Tier 2 method provides mitigation measures similar to the denitrification-decomposition model, related to crop type, climatic conditions, and management practices.

  14. N2O emissions and carbon sequestration in a nitrogen-fertilized Douglas fir stand

    NASA Astrophysics Data System (ADS)

    Jassal, Rachhpal S.; Black, T. Andrew; Chen, Baozhang; Roy, Real; Nesic, Zoran; Spittlehouse, D. L.; Trofymow, J. A.

    2008-12-01

    This study investigated how nitrogen (N) fertilization with 200 kg N ha-1 of a 58-year-old West Coast Douglas fir stand influenced its net greenhouse gas (GHG) global warming potential (GWP) in the first year after fertilization. Effects of fertilization on GHG GWP were calculated considering changes in soil N2O emissions, measured using the static chamber technique and the soil N2O gradient technique; eddy covariance (EC) measured net ecosystem productivity (NEP); and energy requirements of fertilizer production, transport, and its aerial spreading. We found significant N2O losses in fertilized plots compared to a small uptake in nonfertilized plots. Chamber-measured N loss in the fertilized plots was about 16 kg N2O ha-1 in the first year, which is equivalent to 10 kg N ha-1 or 5% of the applied fertilizer N. Soil N2O emissions measured using the gradient technique, however, exceeded the chamber measurements by about 50%. We also compared a polymer-coated slow-release urea with regular urea and found that the former delayed N2O emissions but the year-end total loss was about the same as that from regular urea. Change in NEP due to fertilization was determined by relating annual NEP for the nonfertilized stand to environmental controls using an empirical and a process-based model. Annual NEP increased by 64%, from 326 g C m-2, calculated assuming that the stand was not fertilized, to the measured value of 535 g C m-2 with fertilization. At the end of the year, net change in GHG GWP was -2.28 t CO2 ha-1 compared to what it would have been without fertilization, thereby indicating favorable effect of fertilization even in the first year after fertilization with significant emissions of N2O.

  15. Nitrogen and phosphorus addition impact soil N2O emission in a secondary tropical forest of South China

    PubMed Central

    Wang, Faming; Li, Jian; Wang, Xiaoli; Zhang, Wei; Zou, Bi; Neher, Deborah A.; Li, Zhian

    2014-01-01

    Nutrient availability greatly regulates ecosystem processes and functions of tropical forests. However, few studies have explored impacts of N addition (aN), P addition (aP) and N×P interaction on tropical forests N2O fluxes. We established an N and P addition experiment in a tropical forest to test whether: (1) N addition would increase N2O emission and nitrification, and (2) P addition would increase N2O emission and N transformations. Nitrogen and P addition had no effect on N mineralization and nitrification. Soil microbial biomass was increased following P addition in wet seasons. aN increased 39% N2O emission as compared to control (43.3 μgN2O-N m−2h−1). aP did not increase N2O emission. Overall, N2O emission was 60% greater for aNP relative to the control, but significant difference was observed only in wet seasons, when N2O emission was 78% greater for aNP relative to the control. Our results suggested that increasing N deposition will enhance soil N2O emission, and there would be N×P interaction on N2O emission in wet seasons. Given elevated N deposition in future, P addition in this tropical soil will stimulate soil microbial activities in wet seasons, which will further enhance soil N2O emission. PMID:25001013

  16. Spatially explicit estimates of N2 O emissions from croplands suggest climate mitigation opportunities from improved fertilizer management.

    PubMed

    Gerber, James S; Carlson, Kimberly M; Makowski, David; Mueller, Nathaniel D; Garcia de Cortazar-Atauri, Iñaki; Havlík, Petr; Herrero, Mario; Launay, Marie; O'Connell, Christine S; Smith, Pete; West, Paul C

    2016-10-01

    With increasing nitrogen (N) application to croplands required to support growing food demand, mitigating N2 O emissions from agricultural soils is a global challenge. National greenhouse gas emissions accounting typically estimates N2 O emissions at the country scale by aggregating all crops, under the assumption that N2 O emissions are linearly related to N application. However, field studies and meta-analyses indicate a nonlinear relationship, in which N2 O emissions are relatively greater at higher N application rates. Here, we apply a super-linear emissions response model to crop-specific, spatially explicit synthetic N fertilizer and manure N inputs to provide subnational accounting of global N2 O emissions from croplands. We estimate 0.66 Tg of N2 O-N direct global emissions circa 2000, with 50% of emissions concentrated in 13% of harvested area. Compared to estimates from the IPCC Tier 1 linear model, our updated N2 O emissions range from 20% to 40% lower throughout sub-Saharan Africa and Eastern Europe, to >120% greater in some Western European countries. At low N application rates, the weak nonlinear response of N2 O emissions suggests that relatively large increases in N fertilizer application would generate relatively small increases in N2 O emissions. As aggregated fertilizer data generate underestimation bias in nonlinear models, high-resolution N application data are critical to support accurate N2 O emissions estimates.

  17. Emissions of NO and N2O in wetland microcosms for swine wastewater treatment.

    PubMed

    Zhang, Shunan; Liu, Feng; Xiao, Runlin; Li, Yong; Zhou, Juan; Wu, Jinshui

    2015-12-01

    Nitric oxide (NO) and nitrous oxide (N2O) emitted from wetland systems contribute an important proportion to the global warming effect. In this study, four wetland microcosms vegetated with Myriophyllum elatinoides (WM), Alternanthera philoxeroides (WA), Eichhornia crassipes (WE), or without vegetation (NW) were compared to investigate the emissions of NO and N2O during nitrogen (N) removal process when treating swine wastewater. After 30-day incubation, TN removal rates of 96.4, 74.2, 97.2, and 47.3 % were observed for the WM, WA, WE, and NW microcosms, respectively. Yet, no significant difference was observed in WM and WE (p > 0.05). The average NO and N2O emissions in WE was significantly higher than those in WM, WA, and NW (p < 0.05). In addition, the emission of N2O in WE accounted for 2.10 % of initial TN load and 2.17 % of the total amount of TN removal, compared with less than 1 % in the other microcosms. These findings indicate that wetland vegetated with M. elatinoides may be an optimal system for swine wastewater treatment, based on its higher removal of N and lower emissions of NO and N2O.

  18. Multivariate regulation of soil CO2 and N2 O pulse emissions from agricultural soils.

    PubMed

    Liang, Liyin L; Grantz, David A; Jenerette, G Darrel

    2016-03-01

    Climate and land-use models project increasing occurrence of high temperature and water deficit in both agricultural production systems and terrestrial ecosystems. Episodic soil wetting and subsequent drying may increase the occurrence and magnitude of pulsed biogeochemical activity, affecting carbon (C) and nitrogen (N) cycles and influencing greenhouse gas (GHG) emissions. In this study, we provide the first data to explore the responses of carbon dioxide (CO2 ) and nitrous oxide (N2 O) fluxes to (i) temperature, (ii) soil water content as percent water holding capacity (%WHC), (iii) substrate availability throughout, and (iv) multiple soil drying and rewetting (DW) events. Each of these factors and their interactions exerted effects on GHG emissions over a range of four (CO2 ) and six (N2 O) orders of magnitude. Maximal CO2 and N2 O fluxes were observed in environments combining intermediate %WHC, elevated temperature, and sufficient substrate availability. Amendments of C and N and their interactions significantly affected CO2 and N2 O fluxes and altered their temperature sensitivities (Q10 ) over successive DW cycles. C amendments significantly enhanced CO2 flux, reduced N2 O flux, and decreased the Q10 of both. N amendments had no effect on CO2 flux and increased N2 O flux, while significantly depressing the Q10 for CO2 , and having no effect on the Q10 for N2 O. The dynamics across DW cycles could be attributed to changes in soil microbial communities as the different responses to wetting events in specific group of microorganisms, to the altered substrate availabilities, or to both. The complex interactions among parameters influencing trace gas fluxes should be incorporated into next generation earth system models to improve estimation of GHG emissions.

  19. Quantifying Uncertainties in N2O Emission Due to N Fertilizer Application in Cultivated Areas

    PubMed Central

    Philibert, Aurore; Loyce, Chantal; Makowski, David

    2012-01-01

    Nitrous oxide (N2O) is a greenhouse gas with a global warming potential approximately 298 times greater than that of CO2. In 2006, the Intergovernmental Panel on Climate Change (IPCC) estimated N2O emission due to synthetic and organic nitrogen (N) fertilization at 1% of applied N. We investigated the uncertainty on this estimated value, by fitting 13 different models to a published dataset including 985 N2O measurements. These models were characterized by (i) the presence or absence of the explanatory variable “applied N”, (ii) the function relating N2O emission to applied N (exponential or linear function), (iii) fixed or random background (i.e. in the absence of N application) N2O emission and (iv) fixed or random applied N effect. We calculated ranges of uncertainty on N2O emissions from a subset of these models, and compared them with the uncertainty ranges currently used in the IPCC-Tier 1 method. The exponential models outperformed the linear models, and models including one or two random effects outperformed those including fixed effects only. The use of an exponential function rather than a linear function has an important practical consequence: the emission factor is not constant and increases as a function of applied N. Emission factors estimated using the exponential function were lower than 1% when the amount of N applied was below 160 kg N ha−1. Our uncertainty analysis shows that the uncertainty range currently used by the IPCC-Tier 1 method could be reduced. PMID:23226430

  20. N2O emission characteristics and its affecting factors in rain-fed potato fields in Wuchuan County, China

    NASA Astrophysics Data System (ADS)

    Wang, Liwei; Wang, Cheng; Pan, Zhihua; Xu, Hui; Gao, Lin; Zhao, Peiyi; Dong, Zhiqiang; Zhang, Jingting; Cui, Guohui; Wang, Sen; Han, Guolin; Zhao, hui

    2016-12-01

    Representing an important greenhouse gas, nitrous oxide (N2O) emission from cultivated land is a hot topic in current climate change research. This study examined the influences of nitrogen fertilisation, temperature and soil moisture on the ammonia monooxygenase subunit A (amoA) gene copy numbers and N2O emission characteristics. The experimental observation of N2O fluxes was based on the static chamber-gas chromatographic method. The ammonia-oxidising bacteria (AOB) and ammonia-oxidising archaea (AOA) gene copy numbers in different periods were measured by real-time polymerase chain reaction (PCR). The results indicated that rain-fed potato field was a N2O source, and the average annual N2O emission was approximately 0.46 ± 0.06 kgN2O-N/ha/year. N2O emissions increased significantly with increase in fertilisation, temperatures below 19.6 °C and soil volumetric water content under 15%. Crop rotation appreciably decreases N2O emissions by 34.4 to 52.4% compared to continuous cropping in rain-fed potato fields. The significant correlation between N2O fluxes and AOB copy numbers implied that N2O emissions were primarily controlled by AOB in rain-fed potato fields. The research has important theoretical and practical value for understanding N2O emissions from rain-fed dry farmland fields.

  1. Future N2O from US agriculture: projecting effects of changing land use, agricultural technology, and climate on N2O emissions

    SciTech Connect

    Scott, M J.; Sands, Ronald D. ); Rosenberg, Norman J. ); Izaurralde, R Cesar C. )

    2002-12-02

    The objective of this paper is to detailed supply relationships for nitrous oxide (N2O) emissions from U.S. agriculture for the purpose of conducting policy-sensitive emissions modeling of this greenhouse gas. The basic tool used is the emissions framework of the Intergovernmental Panel on Climate Change (IPCC) Phase II guidelines developed by the IPCC and Organization for Economic Cooperation and Development (OECD) for national emissions inventories. The inventory method has been modified based on the results of an updated literature review and analysis. The supply relationships developed in this project are used to estimate emissions of N2O for U.S. agriculture through the year 2080 under baseline conditions and a policy to restrain emissions growth.

  2. Sulfide-driven autotrophic denitrification significantly reduces N2O emissions.

    PubMed

    Yang, Weiming; Zhao, Qing; Lu, Hui; Ding, Zhi; Meng, Liao; Chen, Guang-Hao

    2016-03-01

    The Sulfate reduction-Autotrophic denitrification-Nitrification Integrated (SANI) process build on anaerobic carbon conversion through biological sulfate reduction and autotrophic denitrification by using the sulfide byproduct from the previous reaction. This study confirmed extra decreases in N2O emissions from the sulfide-driven autotrophic denitrification by investigating N2O reduction, accumulation, and emission in the presence of different sulfide/nitrate (S/N) mass ratios at pH 7 in a long-term laboratory-scale granular sludge autotrophic denitrification reactor. The N2O reduction rate was linearly proportional to the sulfide concentration, which confirmed that no sulfide inhibition of N2O reductase occurred. At S/N = 5.0 g-S/g-N, this rate resulted by sulfide-driven autotrophic denitrifying granular sludge (average granule size = 701 μm) was 27.7 mg-N/g-VSS/h (i.e., 2 and 4 times greater than those at 2.5 and 0.8 g-S/g-N, respectively). Sulfide actually stimulates rather than inhibits N2O reduction no matter what granule size of sulfide-driven autotrophic denitrifying sludge engaged. The accumulations of N2O, nitrite and free nitrous acid (FNA) with average granule size 701 μm of sulfide-driven autotrophic denitrifying granular sludge engaged at S/N = 5.0 g-S/g-N were 4.7%, 11.4% and 4.2% relative to those at 3.0 g-S/g-N, respectively. The accumulation of FNA can inhibit N2O reduction and increase N2O accumulation during sulfide-driven autotrophic denitrification. In addition, the N2O gas emission level from the reactor significantly increased from 14.1 ± 0.5 ppmv (0.002% of the N load) to 3707.4 ± 36.7 ppmv (0.405% of the N load) as the S/N mass ratio in the influent decreased from 2.1 to 1.4 g-S/g-N over the course of the 120-day continuous monitoring period. Sulfide-driven autotrophic denitrification may significantly reduce greenhouse gas emissions from biological nutrient removal when sulfur conversion processes are applied.

  3. Nitrous oxide (N2O) emissions from California based on 2010 CalNex airborne measurements

    NASA Astrophysics Data System (ADS)

    Xiang, Bin; Miller, Scot M.; Kort, Eric A.; Santoni, Gregory W.; Daube, Bruce C.; Commane, Roisin; Angevine, Wayne M.; Ryerson, Tom B.; Trainer, Michael K.; Andrews, Arlyn E.; Nehrkorn, Thomas; Tian, Hanqin; Wofsy, Steven C.

    2013-04-01

    Nitrous oxide (N2O) is an important gas for climate and for stratospheric chemistry, with a lifetime exceeding 100 years. Global concentrations have increased steadily since the 18th century, apparently due to human-associated emissions, principally from the application of nitrogen fertilizers. However, quantitative studies of agricultural emissions at large spatial scales are lacking, inhibited by the difficulty of measuring small enhancements in atmospheric concentration. Here we derive regional emission rates for N2O in the agricultural heartland of California based on analysis of in-situ airborne atmospheric observations collected using a new quantum cascade laser spectrometer. The data were obtained on board the NOAA WP-3 research aircraft during the CalNex (California Research at the Nexus of Air Quality and Climate Change) program in late spring 2010. We coupled the WRF (weather research and forecasting) model, a meso-scale meteorology model, with the STILT (stochastic time-inverted Lagrangian transport) model, a Lagrangian particle dispersion model, to link our in-situ airborne observations to surface emissions. We then used a variety of statistical methods to identify source areas and to optimize emission rates. Our results are consistent with the view that fertilizer application is the largest source of N2O in the Central Valley. The spatial distribution of surface emissions, based on California land use and activity maps, was very different than indicated in the leading emission inventory (EDGAR 4.0). Our estimated total emission flux of N2O for California in May and June was 3 - 4 times larger than the annual mean given for the state by EDGAR and other inventories, indicating a strong seasonal variation. We estimated the statewide total annual emissions of N2O to be 0.042 ± 0.011 Tg N/year, roughly equivalent to inventory values if we account for seasonal variations using observations obtained in the midwestern United States. This state total N2O

  4. Evaluating Soil Oxygen as a Control on N2O Emissions from Ruminant Urine Patches under Different Irrigation Frequencies

    NASA Astrophysics Data System (ADS)

    Owens, J.; Clough, T. J.; Laubach, J.; Hunt, J.; Venterea, R. T.; Phillips, R. L.

    2015-12-01

    Urine patches from grazing ruminant animals are a significant source of nitrous oxide (N2O) emissions, and irrigation is increasingly used to improve forage quality and yield for grazing cattle. The objective of this study was to test whether irrigation frequency influenced N2O emissions from urine patches on a free-draining grazed pasture soil. It was hypothesized that greater irrigation frequency would increase soil moisture thereby lowering soil oxygen (O2), and that these O2-limited conditions would increase the potential for N2O to be reduced to nitrogen gas (N2), resulting in lower N2O emissions. A field trial tested the effects of two irrigation frequencies and urine deposition on N2O fluxes measured daily for 35 days. Denitrification potential measurements using the acetylene inhibition technique were completed to infer N2O/(N2O+N2) ratios, and soil O2 concentrations were measured continuously at three depths within the soil profile. While a more frequent irrigation treatment resulted in a lower N2O/(N2O+N2) ratio, this did not give rise to lower N2O emissions. Nitrous oxide fluxes were not influenced by irrigation frequency, and approximately 0.09% of the nitrogen applied as urine was emitted as N2O from both irrigation treatments. Neither N2O nor soil O2 varied with individual irrigation events. Soil O2 ranged from 17 to 20% expect following urine deposition, where it temporarily decreased to 13%. Soil O2 measurements failed to explain N2O emissions, but a relationship was derived between N2O fluxes and estimates of soil gas diffusivity (Dp/Do). This work is the first to show how soil O2 concentrations vary under a urine patch and under different irrigation treatments, and supports Dp/Do as robust predictor of N2O emissions in situ.

  5. Biofuel cropping system impacts on soil C, microbial communities and N2O emissions

    NASA Astrophysics Data System (ADS)

    McGowan, Andrew R.

    Substitution of cellulosic biofuel in place of gasoline or diesel could reduce greenhouse gas (GHG) emissions from transportation. However, emissions of nitrous oxide (N2O) and changes in soil organic carbon (SOC) could have a large impact on the GHG balance of cellulosic biofuel, thus there is a need to quantify these responses in cellulosic biofuel crops. The objectives of this study were to: (i) measure changes in yield, SOC and microbial communities in potential cellulosic biofuel cropping systems (ii) measure and characterize the temporal variation in N2O emissions from these systems (iii) characterize the yield and N2O response of switchgrass to N fertilizer and to estimate the costs of production. Sweet sorghum, photoperiod-sensitive sorghum, and miscanthus yielded the highest aboveground biomass (20-32 Mg ha-1). The perennial grasses sequestered SOC over 4 yrs, while SOC stocks did not change in the annual crops. Root stocks were 4-8 times higher in the perennial crops, suggesting greater belowground C inputs. Arbuscular mycorrhizal fungi (AMF) abundance and aggregate mean weight diameter were higher in the perennials. No consistent significant differences were found in N2O emissions between crops, though miscanthus tended to have the lowest emissions. Most N2O was emitted during large events of short duration (1-3 days) that occurred after high rainfall events with high soil NO3-. There was a weak relationship between IPCC Tier 1 N2O estimates and measured emissions, and the IPCC method tended to underestimate emissions. The response of N2O to N rate was nonlinear in 2 of 3 years. Fertilizer induced emission factor (EF) increased from 0.7% at 50 kg N ha-1 to 2.6% at 150 kg N ha-1. Switchgrass yields increased with N inputs up to 100-150 kg N ha-1, but the critical N level for maximum yields decreased each year, suggesting N was being applied in excess at higher N rates. Yield-scaled costs of production were minimized at 100 kg N ha-1 ($70.91 Mg-1

  6. A geostatistical approach to identify and mitigate agricultural nitrous oxide emission hotspots.

    PubMed

    Turner, P A; Griffis, T J; Mulla, D J; Baker, J M; Venterea, R T

    2016-12-01

    Anthropogenic emissions of nitrous oxide (N2O), a trace gas with severe environmental costs, are greatest from agricultural soils amended with nitrogen (N) fertilizer. However, accurate N2O emission estimates at fine spatial scales are made difficult by their high variability, which represents a critical challenge for the management of N2O emissions. Here, static chamber measurements (n=60) and soil samples (n=129) were collected at approximately weekly intervals (n=6) for 42-d immediately following the application of N in a southern Minnesota cornfield (15.6-ha), typical of the systems prevalent throughout the U.S. Corn Belt. These data were integrated into a geostatistical model that resolved N2O emissions at a high spatial resolution (1-m). Field-scale N2O emissions exhibited a high degree of spatial variability, and were partitioned into three classes of emission strength: hotspots, intermediate, and coldspots. Rates of emission from hotspots were 2-fold greater than non-hotspot locations. Consequently, 36% of the field-scale emissions could be attributed to hotspots, despite representing only 21% of the total field area. Variations in elevation caused hotspots to develop in predictable locations, which were prone to nutrient and moisture accumulation caused by terrain focusing. Because these features are relatively static, our data and analyses indicate that targeted management of hotspots could efficiently reduce field-scale emissions by as much 17%, a significant benefit considering the deleterious effects of atmospheric N2O.

  7. Evaluation of intensive '4R' strategies for decreasing N2O emissions in rainfed corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ‘4R’ approach of using the ‘right’ rate, source, timing and placement is an accepted framework for increasing crop N use efficiency. However, modifying one 4R component by itself does not consistently reduce nitrous oxide (N2O) emissions. Our objective was to determine if split application tim...

  8. Nitrite intensity explains N management effects on N2O emissions in maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is typically assumed that the dependence of nitrous oxide (N2O) emissions on soil nitrogen (N) availability is best quantified in terms of ammonium (NH4+) and/or nitrate (NO3-) concentrations. In contrast, nitrite (NO2-) is seldom measured separately from NO3- despite its role as a central substr...

  9. Measurements of N2O emissions from different vegetable fields on the North China Plain

    NASA Astrophysics Data System (ADS)

    Diao, Tiantian; Xie, Liyong; Guo, Liping; Yan, Hongliang; Lin, Miao; Zhang, He; Lin, Jia; Lin, Erda

    2013-06-01

    Few studies have measured the N2O emission fluxes from vegetable fields. In order to identify the characteristics and the influencing factors of N2O emissions from different vegetable fields, we measured N2O emissions for a full year from four typical fields, including an open-ground vegetable field that has produced vegetables for over 20 years (OV20), a recently developed open-ground vegetable field that was converted from a maize field three years earlier (OV3), a recently developed greenhouse vegetable field that was converted from a maize field 3 years earlier (GV3) and a typical local maize field (Maize). Four different fertilization treatments were set additionally in the recently developed open-ground vegetable field. These were: no fertilizer or manure (OV3_CK), manure only (OV3_M) and the combination of manure with different rates of chemical fertilizer application (OV3_MF1 and OV3_MF3). The results showed that N2O emission fluxes fluctuated between 0.3 ± 0.1 and 912.4 ± 80.0 mg N2O-N m-2 h-1 with the highest emission peak occurring after fertilization followed by irrigation. Nitrogen application explained 64.6-84.5% of the N2O emission in the vegetable fields. The magnitude of the emission peaks depended on the nitrogen application rate and the duration of the emission peaks was mainly associated with soil temperature when appropriate irrigation was given after fertilization. The N2O emission peaks occurred later and lasted for a longer period when the soil temperature was <24 °C in May. However, emission peaks occurred earlier and lasted for a shorter period when the soil temperature was around 25-33 °C from June to August. The annual N2O emissions from the fertilized vegetable fields were 1.68-2.38 times higher than that from the maize field, which had an emission value of 2.88 ± 0.10 kg N ha-1 a-1. The N2O emission factor (EF) of manure nitrogen was 0.07% over the whole year, but was 0.11% and 0.02% in the spring cucumber season and the autumn

  10. N2O Emissions in Southeastern Amazonia: The Effect of Agricultural Intensification

    NASA Astrophysics Data System (ADS)

    O'Connell, C.; Brando, P. M.; Cerri, C. E.; Coe, M. T.; Davidson, E. A.; Galford, G. L.; Macedo, M.; Neill, C.; Venterea, R. T.

    2014-12-01

    The Amazon is not only an exceptionally biodiverse and carbon-rich tract of tropical forest, it is also a case study in land use change. Over the last 30 years, Amazonia has been home to extraordinary growth in agricultural production, in part from agricultural expansion, but also due to more intense management on Amazonia's existing croplands. We use a year-long campaign and approximately 500 field chamber measurements to estimate how cropland intensification in Mato Grosso, Brazil affects the emission of nitrous oxide (N2O) and soil N dynamics. In this system, soybean cropland intensification occurs when double cropping is introduced, in which maize is planted directly after soybean harvest and fertilized twice with inorganic N. We find that dry season N2O emissions in single-cropped (soybean only) fields, double-cropped (soybean/maize) fields and reference tropical forest are uniformly near zero, or ~0-0.5 ngN/cm^2/hr. Surprisingly, wet season emissions rates remain low as well, between 1-4 ngN/cm^2/hr, for both cropland types and reference forest. By contrast, isolated post-fertilization spikes in N2O emissions are large, with a maximum increase of ~800% and a mean increase of ~400%, though these flux increases resolve rapidly and rates return to their low baseline within days. Finally, we explore the role that soil moisture, soil N availability, and soil C availability play in regulating N2O fluxes in reference forest, soybean fields and intensified soybean-maize fields. Open questions surround how the Amazon's land resources can be leveraged to increase agricultural production at the least harm to the environment. Here, we quantify the consequences of land use change on N2O, a powerful greenhouse gas, in a critical ecosystem undergoing novel agricultural intensification. These results may inform both greenhouse gas accounting and our understanding of the effects of Amazonia's changing agricultural landscape on the nitrogen cycle.

  11. Effect of granulated wood ash fertilization on N2O emissions in boreal peat forests

    NASA Astrophysics Data System (ADS)

    Liimatainen, Maarit; Martikainen, Pertti J.; Hytönen, Jyrki; Maljanen, Marja

    2016-04-01

    Peatlands cover one third of the land surface area in Finland and over half of that are drained for forestry. Natural peatlands are either small sources of nitrous oxide (N2O) or they can also act as a sinks of N2O. When peatlands are drained, oxygen concentration in the peat increases, organic matter decomposition accelerates and N2O emissions may increase significantly, especially in nutrient rich peat soils. Hence drainage and land-use changes can have a big impact on N2O fluxes in peatlands. The annual consumption of wood chips is to be increased to 13.5 M m3 from the present 8.7 M m3 in Finland. This will also increase the amount of wood ash in the power plants. Wood ash contains considerable amounts of mineral nutrients but lacks nitrogen. Therefore, it has been used as a fertilizer in nitrogen rich peatland forests lacking other nutrients. Recycling of ash would also return the nutrients lost during biomass harvesting back to the forests. We studied the effects of granulated wood ash as a fertilizer in peat soils drained for forestry. Ash is nowadays granulated mainly to facilitate its handling and spreading. Granulation also stabilizes the ash decreasing the solubility of most of the nutrients and minimizing harmful effects of ash spread over the vegetation. Granulated wood ash increases soil pH less than loose ash. Drainage of peatland forests increases microbial activity in the soil which is furthermore intensified with the addition of ash promoting organic matter decomposition and possibly affecting N2O emissions. We studied the effect of granulated wood ash on N2O fluxes in three different peat forests in Finland in both field and laboratory experiments. In the field, N2O emissions were not affected by granulated wood ash fertilization but the soil respiration rate increased. However, in the laboratory studies we observed a clear decrease in N2O production due to wood ash addition, although changes in pH values were only minor. We studied what could

  12. Urea Fertilizer Decreases N2O Emissions Compared to Anhydrous Ammonia in Corn Cropping Systems in Minnesota

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantifying nitrous oxide (N2O) emissions from corn and soybean fields under different fertilizer regimes is essential to developing national inventories of greenhouse gas (GHG) emissions. The objective of this study was to compare N2O emissions in plots managed for more than 15 yr under continuous ...

  13. Nitrous Oxide (N2O) Emissions from California based on 2010 CalNex Airborne Measurements

    NASA Astrophysics Data System (ADS)

    Xiang, B.; Miller, S.; Kort, E. A.; Santoni, G. W.; Daube, B.; Commane, R.; Angevine, W. M.; Ryerson, T. B.; Trainer, M.; Andrews, A. E.; Nehrkorn, T.; Tian, H.; Wofsy, S. C.

    2012-12-01

    Nitrous oxide (N2O) is an important gas for climate and for stratospheric chemistry, with an atmospheric lifetime exceeding 100 years. Global concentrations have increased steadily since the 18th century, apparently due to human-associated emissions, principally from application of nitrogen fertilizers. However, quantitative studies of agricultural emissions at large spatial scales are lacking, inhibited by the difficulty of measuring small enhancements of atmospheric concentrations. Here we derive regional emission rates for N2O in the Central Valley of California, based on analysis of in-situ airborne atmospheric observations collected using a quantum cascade laser spectrometer. The data were obtained on board the NOAA P-3 research aircraft during the CalNex (California Research at the Nexus of Air Quality and Climate Change) program in May and June, 2010. We coupled WRF (Weather Research and Forecasting) model to STILT (Stochastic Time-Inverted Lagrangian Transport) to link our in-situ observations to surface emissions, and then used a variety of statistical methods to identify source areas and to extract optimized emission rates from the inversion. Our results support the view that fertilizer application is the largest source of N2O in the Central Valley. But the spatial distribution of derived surface emissions, based on California land use and activity maps, was very different than indicated in the leading emissions inventory (EDGAR 4.0), and our estimated total emission flux of N2O for California during the study period was 3 - 4 times larger than EDGAR and other inventories.

  14. Quantifying N2O emissions and production pathways from fresh waste during the initial stage of disposal to a landfill.

    PubMed

    Wang, Xiaojun; Jia, Mingsheng; Zhang, Han; Pan, Songqing; Kao, Chih Ming; Chen, Shaohua

    2016-08-11

    Intensive nitrous oxide (N2O) emissions usually occur at the working face of landfills. However, the specific amounts and contributions of the multiple pathways to N2O emissions are poorly understood. N2O emissions and the mutual conversions of N-species in both open and sealed simulated landfill reactors filled with fresh refuse were examined during a 100-h incubation period, and N2O sources were calculated using (15)N isotope labelling. N2O peak fluxes were above 70μgNkg(-1) waste h(-1) for both treatments. The sealed incubation reactors became a N2O sink when N2O in the ambient environment was sufficient. The total amount of N2O emissions under sealed conditions was 2.15±0.56mgNkg(-1) waste, which was higher than that under open conditions (1.91±0.34mgNkg(-1) waste). The NO2(-) peak appeared prior to the peak in N2O flux. The degree and duration of total nitrogen reduction in open incubations were larger and longer than those of sealed incubations and could possibly be due to oxygen supplementation. Denitrification (DF) was a major source of N2O generation during these incubations. The contribution of the DF pathway decreased from 89.2% to 61.3% during the open incubations. The effects of nitrification (NF) and nitrification-coupled denitrification (NCD) increased during the increasing phase and the decreasing phase of N2O flux, contributing 24.1-37.4% and 31.7-34.4% of total N2O emissions, respectively. In sealed treatments, the DF pathway accounted for more than 90% of the total N2O emission during the entire incubation.

  15. [Effects of leachate irrigation and cover soil type on N2O emission from municipal solid waste landfill].

    PubMed

    He, Pin-Jing; Chen, Miao; Zhang, Hou-Hu; Shao, Li-Ming

    2008-07-01

    By the method of static chamber, the seasonal and diurnal variations of N2O fluxes in two full-scale municipal solid waste (MSW) landfills covered with sandy and clay soils were measured to study the effects of leachate irrigation and cover soil type on the landfill N2O emission. The results showed that the N2O flux in the MSW landfill covered with sandy soil was (242 +/- 576) microg N2O-N x m(-2) x h(-1) in summer, being 3.2 times (P > 0.05) as high as that in spring [(74.4 +/- 314) microg N2O-N x m(-2) x h(-1), while the N2O flux in the MSW landfill covered with clay soil was (591 +/- 767) microg N2O-N x m(-2) x h(-1) in summer, being 2.2 times (P < 0.05) as high as that in spring [(269 +/- 335) microg N2O-N x m(-2) x h(-1)]. Leachate irrigation promoted the N2O emission from the soil cover of the landfill covered with sandy soil, and the N2O flux in the landfill was 1 time higher than that of the control (P > 0.05). Under leachate irrigation, the average N2O flux in spring and summer in the landfill covered with sand soil was (211 +/- 460) microg N2O-N x m(-2) x h(-1), being only 1/2 of that [(430 +/- 605) microg N2O-N x m(-2) x h(-1)] in the landfill covered with clay soil without leachate irrigation (P > 0.05 ). Therefore, no matter leachate irrigation was conducted or not, the N2O emission from MSW landfill could be minimized by covering with infertile sandy soil.

  16. Comparison of N2O Emissions from Soils at Three Temperate Agricultural Sites

    NASA Technical Reports Server (NTRS)

    Frolking, S. E.; Moiser, A. R.; Ojima, D. S.; Li, C.; Parton, W. J.; Potter, C. S.; Priesack, E.; Stenger, R.; Haberbosch, C.; Dorsch, P.; Peterson, David L. (Technical Monitor)

    1997-01-01

    Nitrous oxide (N2O) flux simulations by four models were compared with year-round field measurements from five temperate agricultural sites in three countries. The field sites included an unfertilized, semi-arid rangeland with low N2O fluxes in eastern Colorado, USA; two fertilizer treatments (urea and nitrate) on a fertilized grass ley cut for silage in Scotland; and two fertilized, cultivated crop fields in Germany where N2O loss during the winter was quite high. The models used were daily trace gas versions of the CENTURY model, DNDC, ExpertN, and the NASA-Ames version of the CASA model. These models included similar components (soil physics, decomposition, plant growth, and nitrogen transformations), but in some cases used very different algorithms for these processes. All models generated similar results for the general cycling of nitrogen through the agro-ecosystems, but simulated nitrogen trace gas fluxes were quite different. In most cases the simulated N20 fluxes were within a factor of about 2 of the observed annual fluxes, but even when models produced similar N2O fluxes they often produced very different estimates of gaseous N loss as nitric oxide (NO), dinitrogen (N2), and ammonia (NH3). Accurate simulation of soil moisture appears to be a key requirement for reliable simulation of N2O emissions. All models simulated the general pattern of low background fluxes with high fluxes following fertilization at the Scottish sites, but they could not (or were not designed to) accurately capture the observed effects of different fertilizer types on N2O flux. None of the models were able to reliably generate large pulses of N2O during brief winter thaws that were observed at the two German sites. All models except DNDC simulated very low N2O fluxes for the dry site in Colorado. The US Trace Gas Network (TRAGNET) has provided a mechanism for this model and site intercomparison. Additional intercomparisons are needed with these and other models and additional data

  17. [Quantifying direct N2O emissions from paddy fields during rice growing season in China: model establishment].

    PubMed

    Zou, Jian-Wen; Qin, Yan-Mei; Liu, Shu-Wei

    2009-02-15

    Various water management regimes, such as continuous flooding (F), flooding-midseason drainage-reflooding (F-D-F), and flooding-midseason drainage-reflooding-moist intermittent irrigation but without water logging (F-D-F-M), are currently practiced in paddy rice production in China. These water regimes have incurred a sensitive change in direct N2O emission from rice paddy fields. In order to establish statistical models quantifying the country-specific emission factor and background emission of N2O in paddy fields during the rice growing season, we compiled and statistically analyzed field data on 71 N2O measurements from 17 field studies that were published in peer-reviewed Chinese and English journals. For each field study, we documented the seasonal N2O emission, the type and amount of organic amendment and fertilizer nitrogen application, the water management regime, the drainage duration, the field location and cropping season. Seasonal total N2O was, on average, equivalent to 0.02% of the nitrogen applied in the continuous flooding rice paddies. Under the water regime of F-D-F or the F-D-F-M, seasonal N2O emissions increased with N fertilizer applied in rice paddies. Applying an Ordinary Least Square (OLS) linear regression model resulted in an emission factor of 0.42% for N2O, and in unpronounced background N2 O emission under the water regime of F-D-F. Under the F-D-F-M water regime, N2O emission factor and N2O-N background emission were estimated to be 0.73% and 0.79 kg x hm(-2) during the paddy rice growing season, respectively. After considering three different water regimes in rice paddies in China, the emission factor of N for N2O and N2O-N background emission averaged 0.54% and 0.43 kg x hm(-2). The results of this study suggest that paddy rice relative to upland crop production could have contributed to mitigating N2O emissions from agriculture in China. The emission factor of N for N2O and its background emissions can be directly adopted to develop

  18. Comparing N2O emissions at varying N rates from irrigated and rainfed corn in the US Midwest

    NASA Astrophysics Data System (ADS)

    Millar, N.; Kahmark, K.; Basso, B.; Robertson, G. P.

    2011-12-01

    Global N2O emissions from agriculture are estimated to be ~2.8 Pg CO2e yr-1 accounting for 60% of total anthropogenic emissions. N2O is the largest contributor to the GHG burden of cropping systems in the US, with annual estimated emissions of ~0.5 Tg primarily due to N fertilizer inputs and other soil management activities. Currently 23 million acres of corn, soybean and wheat are irrigated annually in the US with increased N2O emissions due to the practice likely under-reported in GHG inventories. Here we compare N2O emissions and yield from irrigated and rainfed corn at varying N rates between 0 and 246 kg N ha-1 from the Kellogg Biological Station in SW Michigan. Initial results show that N2O emissions increase with increasing N rate and are significantly higher from irrigated corn compared to rainfed corn at the same N rate. At increasing N rates daily emissions following an irrigation event were between 2.4 - 77.5 g N2O-N ha-1 from irrigated corn and 1.6 - 13.0 g N2O-N ha-1 from rainfed corn. Emissions data from automated and static chambers will be presented and trade-offs between N2O emissions, N fertilizer rate, crop yield and irrigation practice will be evaluated from an environmental and economic standpoint.

  19. Can subsoil denitrification reduce groundwater nitrate pollution and atmospheric N2O emissions?

    NASA Astrophysics Data System (ADS)

    Mofizur Rahman Jahangir, Mohammad; Khalil, Mohammad Ibrahim; Cardenas, Laura; Hatch, David; Johnston, Paul; Richards, Karl

    2010-05-01

    Denitrification, a biological nitrate removal pathway, can control the availability of NO3- for leaching to the receptors but it is not only a natural pathway for excess NO3- elimination but also contributes to the emissions of N2O, a potent greenhouse gas. Denitrification potential and N2:N2O+N2 ratios were investigated in intact soil cores collected at 0-10, 45-55 and 120-130 cm soil depths where groundwater table was approximately 2 m below ground level. The soil was a moderately well drained loam to clay loam Gleysol under a grazing pasture in South Eastern Ireland. Three individual experiments were carried out by amending the soil with (i) 90 mg NO3--N as KNO3, (ii) -(i) + 150 mg glucose-C, (iii) -(i) + 150 mg DOC, kg-1 dry soil. An automated laboratory incubation system was used to simultaneously measure N2O and N2 at 15°C at 3% moisture content above field capacity. N2O fluxes differed significantly (p

  20. NO versus N2O emissions from an NH4(+)-amended Bermuda grass pasture

    NASA Technical Reports Server (NTRS)

    Hutchinson, G. L.; Brams, E. A.

    1992-01-01

    An enclosure technique is used to monitor soil NO and N2O emissions during early summer regrowth of Bermuda grass (Cynodon dactylon) on sandy loam in a humid, subtropical region of southern Texas. The evolution of both gases was substantially higher from plots harvested at the beginning of the experiment and fertilized five days later with 52 kg N/ha as (NH4)2SO4 than from plots not harvested or fertilized. Emission of NO, but not N2O, was stimulated by clipping and removing the grass, probably because eliminating the shading provided by the dense grass canopy changed these plots from cooler to warmer than unharvested plots, thereby stimulating the activity of soil microorganisms responsible for NO production. Neither gas flux was significantly affected by application of N until the next rainfall dissolved and moved the surface-applied fertilizer into the soil. Immediately thereafter, emissions of NO and N2O increased dramatically to peaks of 160 and 12 g N/ha/d, respectively, and then declined at rates that closely parallel the nitrification rate of added NH4(+), indicating that the gases resulted from the activity of nitrifying microorganisms, rather than denitrifiers. Nitric oxide emissions during the nine-week measurement period averaged 7.2 times greater than N2O emissions and accounted for 3.2 percent of the added N. The data indicate that humid, subtropical grasslands, which not only have large geographical extent but also have been subject to intense anthropogenic disturbance, contribute significantly to the global atmospheric NO(x) budget.

  1. N 2O emissions at municipal solid waste landfill sites: Effects of CH 4 emissions and cover soil

    NASA Astrophysics Data System (ADS)

    Zhang, Houhu; He, Pinjing; Shao, Liming

    Municipal solid waste landfills are the significant anthropogenic sources of N 2O due to the cooxidation of ammonia by methane-oxidizing bacteria in cover soils. Such bacteria could be developed through CH 4 fumigation, as evidenced by both laboratory incubation and field measurement. During a 10-day incubation with leachate addition, the average N 2O fluxes in the soil samples, collected from the three selected landfill covers, were multiplied by 1.75 ( p < 0.01), 3.56 ( p < 0.01), and 2.12 ( p < 0.01) from the soil samples preincubated with 5% CH 4 for three months when compared with the control, respectively. Among the three selected landfill sites, N 2O fluxes in two landfill sites were significantly correlated with the variations of the CH 4 emissions without landfill gas recovery ( p < 0.001). N 2O fluxes were also elevated by the increase of the CH 4 emissions with landfill gas recovery in another landfill site ( p > 0.05). The annual average N 2O flux was 176 ± 566 μg N 2O-N m -2 h -1 ( p < 0.01) from sandy soil-covered landfill site, which was 72% ( p < 0.05) and 173% ( p < 0.01) lower than the other two clay soil covered landfill sites, respectively. The magnitude order of N 2O emissions in three landfill sites was also coincident by the results of laboratory incubation, suggesting the sandy soil cover could mitigate landfill N 2O emissions.

  2. Response of N2O emissions to biochar amendment in a cultivated sandy loam soil during freeze-thaw cycles.

    PubMed

    Liu, Xiang; Wang, Quan; Qi, Zhiming; Han, Jiangang; Li, Lanhai

    2016-10-17

    In the last decade, an increasing number of studies have reported that soil nitrous oxide (N2O) emissions can be reduced by adding biochar. However, the effect of biochar amendment on soil N2O emissions during freeze-thaw cycle (FTC) is still unknown. In this laboratory study, biochar (0%, 2% and 4%, w/w) was added into a cultivated sandy loam soil and then treated with 15 times of FTC (each FTC consisted of freeze at -5/-10 °C for 24 h and thaw at 5/10 °C for 24 h), to test whether biochar can mitigate soil N2O emissions during FTC, and estimate the relationships between N2O emissions and soil inorganic nitrogen contents/microbial biomass content/enzyme activities. The results showed that biochar amendment suppressed soil N2O emissions by 19.9-69.9% as compared to soils without biochar amendment during FTC. However, N2O emissions were only significantly correlated to soil nitrate nitrogen (NO3(-)-N) contents, which decreased after biochar amendment, indicating that the decreased soil nitrification by adding biochar played an important role in mitigating N2O emissions during FTC. Further studies are needed to estimate the effectiveness of biochar amendment on reducing freeze-thaw induced N2O emissions from different soils under field conditions.

  3. Evaluating four N2O emission algorithms in RZWQM2 in response to N rate on an irrigated corn field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) emissions from agricultural soils are major contributors to greenhouse gases. Correctly assessing the effects of the interactions between agricultural practices and environmental factors on N2O emissions is required for better crop and nitrogen (N) management. We used an enhanced...

  4. Response of N2O emissions to biochar amendment in a cultivated sandy loam soil during freeze-thaw cycles

    PubMed Central

    Liu, Xiang; Wang, Quan; Qi, Zhiming; Han, Jiangang; Li, Lanhai

    2016-01-01

    In the last decade, an increasing number of studies have reported that soil nitrous oxide (N2O) emissions can be reduced by adding biochar. However, the effect of biochar amendment on soil N2O emissions during freeze-thaw cycle (FTC) is still unknown. In this laboratory study, biochar (0%, 2% and 4%, w/w) was added into a cultivated sandy loam soil and then treated with 15 times of FTC (each FTC consisted of freeze at −5/−10 °C for 24 h and thaw at 5/10 °C for 24 h), to test whether biochar can mitigate soil N2O emissions during FTC, and estimate the relationships between N2O emissions and soil inorganic nitrogen contents/microbial biomass content/enzyme activities. The results showed that biochar amendment suppressed soil N2O emissions by 19.9–69.9% as compared to soils without biochar amendment during FTC. However, N2O emissions were only significantly correlated to soil nitrate nitrogen (NO3−-N) contents, which decreased after biochar amendment, indicating that the decreased soil nitrification by adding biochar played an important role in mitigating N2O emissions during FTC. Further studies are needed to estimate the effectiveness of biochar amendment on reducing freeze-thaw induced N2O emissions from different soils under field conditions. PMID:27748462

  5. Linkage between N2O emission and functional gene abundance in an intensively managed calcareous fluvo-aquic soil

    NASA Astrophysics Data System (ADS)

    Yang, Liuqing; Zhang, Xiaojun; Ju, Xiaotang

    2017-02-01

    The linkage between N2O emissions and the abundance of nitrifier and denitrifier genes is unclear in the intensively managed calcareous fluvo-aquic soils of the North China Plain. We investigated the abundance of bacterial amoA for nitrification and narG, nirS, nirK, and nosZ for denitrification by in situ soil sampling to determine how the abundance of these genes changes instantly during N fertilization events and is related to high N2O emission peaks. We also investigated how long-term incorporated straw and/or manure affect(s) the abundance of these genes based on a seven-year field experiment. The overall results demonstrate that the long-term application of urea-based fertilizer and/or manure significantly enhanced the number of bacterial amoA gene copies leading to high N2O emission peaks after N fertilizer applications. These peaks contributed greatly to the annual N2O emissions in the crop rotation. A significant correlation between annual N2O emissions and narG, nirS, and nirK gene numbers indicates that the abundance of these genes is related to N2O emission under conditions for denitrification, thus partly contributing to the annual N2O emissions. These findings will help to draw up appropriate measures for mitigation of N2O emissions in this ‘hotspot’ region.

  6. Linkage between N2O emission and functional gene abundance in an intensively managed calcareous fluvo-aquic soil

    PubMed Central

    Yang, Liuqing; Zhang, Xiaojun; Ju, Xiaotang

    2017-01-01

    The linkage between N2O emissions and the abundance of nitrifier and denitrifier genes is unclear in the intensively managed calcareous fluvo-aquic soils of the North China Plain. We investigated the abundance of bacterial amoA for nitrification and narG, nirS, nirK, and nosZ for denitrification by in situ soil sampling to determine how the abundance of these genes changes instantly during N fertilization events and is related to high N2O emission peaks. We also investigated how long-term incorporated straw and/or manure affect(s) the abundance of these genes based on a seven-year field experiment. The overall results demonstrate that the long-term application of urea-based fertilizer and/or manure significantly enhanced the number of bacterial amoA gene copies leading to high N2O emission peaks after N fertilizer applications. These peaks contributed greatly to the annual N2O emissions in the crop rotation. A significant correlation between annual N2O emissions and narG, nirS, and nirK gene numbers indicates that the abundance of these genes is related to N2O emission under conditions for denitrification, thus partly contributing to the annual N2O emissions. These findings will help to draw up appropriate measures for mitigation of N2O emissions in this ‘hotspot’ region. PMID:28233823

  7. [Effects of typical herbicides on soil respiration and N2O emissions from soil added with different nitrogen fertilizers].

    PubMed

    Sun, Qing; Shi, Chun-Xing; Shi, Kun; Yan, Ru-Bin; Jiang, Jing-Yan; Wu, Yi-Zhong

    2012-06-01

    To investigate the effects of typical herbicides on soil respiration and N2O emissions from soil added with different nitrogen fertilizers, a laboratory incubation experiment was carried out using a modified gas chromatograph (Agilent 4890D) method. The results showed that with (NH4)2SO4 amendment, soil respiration and N2O emissions from the Atrazine and Paraquat treatments had no significant difference in comparison to the control (P > 0.05). Glyphosate significantly inhibited soil respiration by 21.5% (P < 0.05) and had no obvious influence on N2O emissions (P > 0.05). Tribenuron-methyl significantly promoted soil respiration with the increase of 14.3% (P < 0.05) and also had no obvious influence on N2O emissions (P > 0.05). Acetochlor significantly increased soil respiration and N2O emissions (P < 0.05) with the increase of 6.1% and 45.1%, respectively. With urea application, Atrazine and Acetochlor had no significant influence on soil respiration and N2O emissions (P > 0.05). Paraquat increased N2O emissions significantly (P < 0.05)with the increase of 43.5% and had no significant influence on soil respiration ( P > 0.05). Glyphosate significantly inhibited soil respiration by 17.5% (P < 0.05), and had no significant influence on N2O emissions (P > 0.05). Tribenuron-methyl enhanced soil respiration and N2O emissions significantly (P < 0.05), and its soil respiration and N2O emissions were 1.3 and 1.6 times higher than those from the control. Due to the complexity of effects of different herbicides on microbial physiological metabolism, long-term in-situ studies need to be carried out to better understand the effect of various herbicides on greenhouse gas emissions.

  8. Assessment of N2O emission from a photobioreactor treating ammonia-rich swine wastewater digestate.

    PubMed

    Mezzari, Melissa P; da Silva, Márcio L B; Nicoloso, Rodrigo S; Ibelli, Adriana M G; Bortoli, Marcelo; Viancelli, Aline; Soares, Hugo M

    2013-12-01

    This study investigated the interactions between naturally occurring bacteria and the microalgae Chlorella vulgaris within a lab scale photobioreactor treating ammonia-rich swine wastewater digestate effluent. Nitrification and denitrification were assessed by targeting ammonia monoxygenases (amoA), nitrate (narG), nitrite (nirS), nitric oxide (norB) and nitrous oxide (nosZ) reductases genes. Oxygen produced from microalgae photosynthesis stimulated nitrification. Under limiting carbon availability (i.e., <1.44 for mg TOC/mg NO2-N and 1.72 for mg TOC/mg NO3-N), incomplete denitrification led to accumulation of NO2 and NO3. Significant N2O emission (up to 118 μg N2O-N) was linked to NO2 metabolism in Chlorella. The addition of acetate as external carbon source recovered heterotrophic denitrification activity suppressing N2O emission. Effluent methane concentrations trapped within photobioreactor was removed concomitantly with ammonia. Overall, closed photobioreactors can be built to effectively remove nitrogen and mitigate simultaneously greenhouse gases emissions that would occur otherwise in open microalgae-based wastewater treatment systems.

  9. Global trends in terrestrial denitrification and N2O emissions for the period 1900-2050

    NASA Astrophysics Data System (ADS)

    Bouwman, L.; Beusen, A.; Griffioen, J.; Van Groenigen, J.; Hefting, M.; Oenema, O.; Van Puijenbroek, P.; Seitzinger, S.; Slomp, C. P.; Stehfest, E.

    2012-12-01

    Estimates of global terrestrial denitrification and nitrous oxide (N2O) emission are presented for the period 1900 to 2000 and scenarios for the period 2000-2050 based on the Millennium Ecosystem Assessment. Soil nitrogen (N) budgets are used in a global distributed flow-path model with 0.5 by 0.5 degree resolution, representing denitrification and N2O emissions from soils, groundwater and riparian zones. Total agricultural and natural N inputs from N fertilizers, animal manure, biological N fixation and N deposition increased from ~155 to ~345 Tg of N yr-1 (Tg = teragram; 1 Tg = 1012 g) between 1900 and 2000; depending on the scenario, inputs will further increase to ~408 to ~510 Tg of N yr-1 in 2050. In the period 1900-2000, the soil N budget surplus (inputs minus withdrawal by plants) increased from 118 to 202 Tg yr-1, and this may remain stable or further increase to 275 Tg per year in 2050, depending on the scenario. Estimates indicate that N2 production from denitrification increased from 52 to 96 Tg yr-1 between 1900 and 2000, and N2O-N emissions from 10 to 12 Tg of N yr-1. The major part (70%) of global N2 and N2O-N (92%) production occurred in soils in 2000. A further increase of denitrification is foreseen to 142 Tg N2-N and 16 Tg of N2O-N yr-1 in 2050. Our results indicate that riparian buffer zones are an important source of N2O. Soils are key sites for denitrification and are much more important than groundwater and riparian zones in controlling the N flow to rivers and the oceans. The total (temporary) storage in deep groundwater between 1900 and 2000 amounts to around 376 Tg of N. Despite the removal of N through denitrification, the N flow from diffuse sources on land to rivers increased from 38 to 65 Tg of N yr-1 between 1900 and 2000, with a further increase of up to 84 Tg of N yr-1 in 2050. The major causes of uncertainty in our estimates are the difficulties associated with measurements and models of denitrification. With the projected increase

  10. NO and N2O emissions from agricultural fields in the North China Plain: Origination and mitigation.

    PubMed

    Zhang, Yuanyuan; Mu, Yujing; Zhou, Yizhen; Tian, Di; Liu, Junfeng; Zhang, Chenglong

    2016-05-01

    Agricultural soil has been recognized as a major source of atmospheric NO and N2O emissions which have important impacts on regional and global environments. Here we comparably investigated the effects of ammonium, nitrate fertilizers and nitrification inhibitor dicyandiamide (DCD) addition on NO and N2O emissions from the agricultural soil in the North China Plain (NCP). Compared with the ammonium fertilizer application, the reductions of NO emissions caused by nitrate fertilizer and DCD addition were 100% and 93%, and of N2O emissions were 54% and 74%, respectively. Remarkable reductions of NO and N2O emissions were also observed from five different agricultural soils in the NCP by replacing ammonium with nitrate fertilizer, indicating that nitrification is the predominant process for the emissions of NO and N2O from the soils in the vast area of NCP. NO emission peaks were found to be several days later than N2O peaks after the application of ammonium fertilizer and flooding irrigation, implying that most of NO initially produced via nitrification process might be fast reduced to N2O under the high soil moisture condition. Interestingly, the relative contribution of denitrification to N2O emission showed obviously time-dependent, e.g., evident N2O emission caused by the application of nitrate was only observed after the basal fertilization for the maize and the topdressing for the wheat. Replacing ammonium with nitrate fertilizer and mixing with the nitrification inhibitor are verified to be effective measures for mitigating NO and N2O emissions from arable soils in the NCP.

  11. Verifying the UK N_{2}O emission inventory with tall tower measurements

    NASA Astrophysics Data System (ADS)

    Carnell, Ed; Meneguz, Elena; Skiba, Ute; Misselbrook, Tom; Cardenas, Laura; Arnold, Tim; Manning, Alistair; Dragosits, Ulli

    2016-04-01

    Nitrous oxide (N2O) is a key greenhouse gas (GHG), with a global warming potential ˜300 times greater than that of CO2. N2O is emitted from a variety of sources, predominantly from agriculture. Annual UK emission estimates are reported, to comply with government commitments under the United Nations Framework Convention on Climate Change (UNFCCC). The UK N2O inventory follows internationally agreed protocols and emission estimates are derived by applying emission factors to estimates of (anthropogenic) emission sources. This approach is useful for comparing anthropogenic emissions from different countries, but does not capture regional differences and inter-annual variability associated with environmental factors (such as climate and soils) and agricultural management. In recent years, the UK inventory approach has been refined to include regional information into its emissions estimates (e.g. agricultural management data), in an attempt to reduce uncertainty. This study attempts to assess the difference between current published inventory methodology (default IPCC methodology) and a revised approach, which incorporates the latest thinking, using data from recent work. For 2013, emission estimates made using the revised approach were 30 % lower than those made using default IPCC methodology, due to the use of lower emission factors suggested by recent projects (www.ghgplatform.org.uk, Defra projects: AC0116, AC0213 and MinNO). The 2013 emissions estimates were disaggregated on a monthly basis using agricultural management (e.g. sowing dates), climate data and soil properties. The temporally disaggregated emission maps were used as input to the Met Office atmospheric dispersion model NAME, for comparison with measured N2O concentrations, at three observation stations (Tacolneston, E England; Ridge Hill, W England; Mace Head, W Ireland) in the UK DECC network (Deriving Emissions linked to Climate Change). The Mace Head site, situated on the west coast of Ireland, was

  12. High-Resolution Upscaling of Closed Chamber Fluxes for N2o Emissions from China's Agricultural Soils

    NASA Astrophysics Data System (ADS)

    Zhou, F.; Shang, Z.; Ciais, P.; Piao, S.; Raymond, P. A.; Tao, S.; Zeng, Z.

    2014-12-01

    Moving from local toward global N2O emissions brings up numerous issues related to data processing, aggregation, tradeoffs between model quality and data quality, and prioritization of data collection and/or compilation efforts. We studied these issues in the context of modelling China's N2O emissions from agricultural soils. We developed a spatially-explicit model (PKU-N2O-Agr model) for high-resolution mapping of N2O emissions based on the idea of Hole-in-the-Pipe Model. We collected 709 site-year records (504 for upland and 205 for paddy) at 106 experimental sites across China from 1994 to 2013 and calibrated the observed N2O flux by using the Bayesian Recursive Regression Tree algorithm. The calibrated PKU-N2O-Agr model is applied to simulate China's N2O emissions from upland and paddy cropland at 1-km spatial resolution and to examine the variable importance and sensitivity for N2O emissions as well as scaling dependence of the effect-response relationships. The N2O emissions in 2008 are 615 GgN2O/yr and ~25% lower than PKU-N2O and EDGAR v4.2 global product sampled over China. The average coefficients of determination between observed and simulated results were 0.91 for upland and 0.92 for paddy cropland, which indicate the using a simplified data-driven approach with data of high resolution could produce accurate and reliable results. Emission factors (considering background emissions) for paddy and upland soils are 0.6% and 0.8% of N inputs, which are 2 times of IPCC default but half of the mean of observations, respectively. SOC is the most important for capturing the variability of N2O emissions from upland, whereas N inflow is the critical factor for paddy cropland. Different with previous works, the marginal sensitivities of environmental factors on agricultural N2O emissions are calculated, which is of great use for verifying process-based simulation model when being applied in China (e.g., DNDC). Both critical factors and the effect

  13. Optimal estimation of regional N2O emissions using a three-dimensional global model

    NASA Astrophysics Data System (ADS)

    Huang, J.; Golombek, A.; Prinn, R.

    2004-12-01

    In this study, we use the MATCH (Model of Atmospheric Transport and Chemistry) model and Kalman filtering techniques to optimally estimate N2O emissions from seven source regions around the globe. The MATCH model was used with NCEP assimilated winds at T62 resolution (192 longitude by 94 latitude surface grid, and 28 vertical levels) from July 1st 1996 to December 31st 2000. The average concentrations of N2O in the lowest four layers of the model were then compared with the monthly mean observations from six national/global networks (AGAGE, CMDL (HATS), CMDL (CCGG), CSIRO, CSIR and NIES), at 48 surface sites. A 12-month-running-mean smoother was applied to both the model results and the observations, due to the fact that the model was not able to reproduce the very small observed seasonal variations. The Kalman filter was then used to solve for the time-averaged regional emissions of N2O for January 1st 1997 to June 30th 2000. The inversions assume that the model stratospheric destruction rates, which lead to a global N2O lifetime of 130 years, are correct. It also assumes normalized emission spatial distributions from each region based on previous studies. We conclude that the global N2O emission flux is about 16.2 TgN/yr, with {34.9±1.7%} from South America and Africa, {34.6±1.5%} from South Asia, {13.9±1.5%} from China/Japan/South East Asia, {8.0±1.9%} from all oceans, {6.4±1.1%} from North America and North and West Asia, {2.6±0.4%} from Europe, and {0.9±0.7%} from New Zealand and Australia. The errors here include the measurement standard deviation, calibration differences among the six groups, grid volume/measurement site mis-match errors estimated from the model, and a procedure to account approximately for the modeling errors.

  14. Contributions of Autotrophic and Heterotrophic Nitrifiers to Soil NO and N2O Emissions

    PubMed Central

    Tortoso, A. C.; Hutchinson, G. L.

    1990-01-01

    Soil emission of gaseous N oxides during nitrification of ammonium represents loss of an available plant nutrient and has an important impact on the chemistry of the atmosphere. We used selective inhibitors and a glucose amendment in a factorial design to determine the relative contributions of autotrophic ammonium oxidizers, autotrophic nitrite oxidizers, and heterotrophic nitrifiers to nitric oxide (NO) and nitrous oxide (N2O) emissions from aerobically incubated soil following the addition of 160 mg of N as ammonium sulfate kg−1. Without added C, peak NO emissions of 4 μg of N kg−1 h−1 were increased to 15 μg of N kg−1 h−1 by the addition of sodium chlorate, a nitrite oxidation inhibitor, but were reduced to 0.01 μg of N kg−1 h−1 in the presence of nitrapyrin [2-chloro-6-(trichloromethyl)-pyridine], an inhibitor of autotrophic ammonium oxidation. Carbon-amended soils had somewhat higher NO emission rates from these three treatments (6, 18, and 0.1 μg of N kg−1 h−1 after treatment with glucose, sodium chlorate, or nitrapyrin, respectively) until the glucose was exhausted but lower rates during the remainder of the incubation. Nitrous oxide emission levels exhibited trends similar to those observed for NO but were about 20 times lower. Periodic soil chemical analyses showed no increase in the nitrate concentration of soil treated with sodium chlorate until after the period of peak NO and N2O emissions; the nitrate concentration of soil treated with nitrapyrin remained unchanged throughout the incubation. These results suggest that chemoautotrophic ammonium-oxidizing bacteria are the predominant source of NO and N2O produced during nitrification in soil. PMID:16348220

  15. Regulation of denitrification at the cellular level: a clue to the understanding of N2O emissions from soils

    PubMed Central

    Bakken, Lars R.; Bergaust, Linda; Liu, Binbin; Frostegård, Åsa

    2012-01-01

    Denitrifying prokaryotes use NOx as terminal electron acceptors in response to oxygen depletion. The process emits a mixture of NO, N2O and N2, depending on the relative activity of the enzymes catalysing the stepwise reduction of NO3− to N2O and finally to N2. Cultured denitrifying prokaryotes show characteristic transient accumulation of NO2−, NO and N2O during transition from oxic to anoxic respiration, when tested under standardized conditions, but this character appears unrelated to phylogeny. Thus, although the denitrifying community of soils may differ in their propensity to emit N2O, it may be difficult to predict such characteristics by analysis of the community composition. A common feature of strains tested in our laboratory is that the relative amounts of N2O produced (N2O/(N2+N2O) product ratio) is correlated with acidity, apparently owing to interference with the assembly of the enzyme N2O reductase. The same phenomenon was demonstrated for soils and microbial communities extracted from soils. Liming could be a way to reduce N2O emissions, but needs verification by field experiments. More sophisticated ways to reduce emissions may emerge in the future as we learn more about the regulation of denitrification at the cellular level. PMID:22451108

  16. Global metaanalysis of the nonlinear response of soil nitrous oxide (N2O) emissions to fertilizer nitrogen.

    PubMed

    Shcherbak, Iurii; Millar, Neville; Robertson, G Philip

    2014-06-24

    Nitrous oxide (N2O) is a potent greenhouse gas (GHG) that also depletes stratospheric ozone. Nitrogen (N) fertilizer rate is the best single predictor of N2O emissions from agricultural soils, which are responsible for ∼ 50% of the total global anthropogenic flux, but it is a relatively imprecise estimator. Accumulating evidence suggests that the emission response to increasing N input is exponential rather than linear, as assumed by Intergovernmental Panel on Climate Change methodologies. We performed a metaanalysis to test the generalizability of this pattern. From 78 published studies (233 site-years) with at least three N-input levels, we calculated N2O emission factors (EFs) for each nonzero input level as a percentage of N input converted to N2O emissions. We found that the N2O response to N inputs grew significantly faster than linear for synthetic fertilizers and for most crop types. N-fixing crops had a higher rate of change in EF (ΔEF) than others. A higher ΔEF was also evident in soils with carbon >1.5% and soils with pH <7, and where fertilizer was applied only once annually. Our results suggest a general trend of exponentially increasing N2O emissions as N inputs increase to exceed crop needs. Use of this knowledge in GHG inventories should improve assessments of fertilizer-derived N2O emissions, help address disparities in the global N2O budget, and refine the accuracy of N2O mitigation protocols. In low-input systems typical of sub-Saharan Africa, for example, modest N additions will have little impact on estimated N2O emissions, whereas equivalent additions (or reductions) in excessively fertilized systems will have a disproportionately major impact.

  17. Global metaanalysis of the nonlinear response of soil nitrous oxide (N2O) emissions to fertilizer nitrogen

    PubMed Central

    Shcherbak, Iurii; Millar, Neville; Robertson, G. Philip

    2014-01-01

    Nitrous oxide (N2O) is a potent greenhouse gas (GHG) that also depletes stratospheric ozone. Nitrogen (N) fertilizer rate is the best single predictor of N2O emissions from agricultural soils, which are responsible for ∼50% of the total global anthropogenic flux, but it is a relatively imprecise estimator. Accumulating evidence suggests that the emission response to increasing N input is exponential rather than linear, as assumed by Intergovernmental Panel on Climate Change methodologies. We performed a metaanalysis to test the generalizability of this pattern. From 78 published studies (233 site-years) with at least three N-input levels, we calculated N2O emission factors (EFs) for each nonzero input level as a percentage of N input converted to N2O emissions. We found that the N2O response to N inputs grew significantly faster than linear for synthetic fertilizers and for most crop types. N-fixing crops had a higher rate of change in EF (ΔEF) than others. A higher ΔEF was also evident in soils with carbon >1.5% and soils with pH <7, and where fertilizer was applied only once annually. Our results suggest a general trend of exponentially increasing N2O emissions as N inputs increase to exceed crop needs. Use of this knowledge in GHG inventories should improve assessments of fertilizer-derived N2O emissions, help address disparities in the global N2O budget, and refine the accuracy of N2O mitigation protocols. In low-input systems typical of sub-Saharan Africa, for example, modest N additions will have little impact on estimated N2O emissions, whereas equivalent additions (or reductions) in excessively fertilized systems will have a disproportionately major impact. PMID:24927583

  18. Estimating CH4 and N2O Emissions Using Tower Measurements in California

    NASA Astrophysics Data System (ADS)

    Jeong, S.; Zhao, C.; Hsu, Y.; Andrews, A. E.; Bianco, L.; Vaca, P.; Dlugokencky, E. J.; Wilczak, J. M.; Fischer, M. L.

    2011-12-01

    Based on an inverse modeling approach, we report spatio-temporally-resolved emissions for major non-CO2 greenhouse gases (CH4 and N2O) in California's Central Valley using measurements from a collaborative tower network. This large dataset, for the first time, allows quantification of the seasonal and inter-annual variations in California emissions, facilitating validation of uncertain state-wide annual emission totals that will be subject to future regulation by AB-32. Seasonally varying regional methane emissions (~100km) are estimated by scaling high-resolution (10-km scale) CH4 emission maps (initially tied to estimated state totals) for major known sources using a Bayesian inversion model to provide optimal agreement with aggregate mixing ratio data measured at the CARB-CEC-LBNL-NOAA 5-tower network. Two years of continuous CH4 measurements from the Walnut Grove (WGC) tall-tower indicate that annual CH4 emissions north of WGC (the southern end of the Sacramento Valley) are 2 - 3 times greater than the un-scaled inventory, with stronger summertime emissions that are likely driven by agriculture. South of WGC (in the Northern San Joaquin Valley) emissions are 0.9 - 1.5 times greater than the un-scaled inventory with small seasonal variation, where dairy emissions are expected to be dominant. Preliminary measurements from the 5-tower network suggest that long term data collected from those sites will greatly increase the ability to quantify and apportion CH4 emissions at 50 - 100 km scales over the entire Valley. Two years of daily N2O flask measurements from WGC indicate that N2O emissions are 2 - 3 times higher than the EDGAR3.2 emission inventory in Central California. Applying these scaling factors to the remainder of the California landscape suggests that total non-CO2 GHG's constitute 15 - 25% of California's total GHG emissions, and hence that mitigation of non-CO2 GHG emissions could meaningfully reduce California's overall GHG burden.

  19. N2O and NO emissions during autotrophic nitrogen removal in a granular sludge reactor--a simulation study.

    PubMed

    Van Hulle, S W H; Callens, J; Mampaey, K E; van Loosdrecht, M C M; Volcke, E I P

    2012-01-01

    This contribution deals with NO and N2O emissions during autotrophic nitrogen removal in a granular sludge reactor. Two possible model scenarios describing this emission by ammonium- oxidizing biomass have been compared in a simulation study of a granular sludge reactor for one-stage partial nitritation--Anammox. No significant difference between these two scenarios was noticed. The influence of the bulk oxygen concentration, granule size, reactor temperature and ammonium load on the NO and N2O emissions has been assessed. The simulation results indicate that emission maxima of NO and N2O coincide with the region for optimal Anammox conversion. Also, most of the NO and N2O are present in the off-gas, owing to the limited solubility of both gases. The size of granules needs to be large enough not to limit optimal Anammox activity, but not too large as this implies an elevated production of N2O. Temperature has a significant influence on N2O emission, as a higher temperature results in a better N-removal efficiency and a lowered N2O production. Statistical analysis of the results showed that there is a strong correlation between nitrite accumulation and N2O production. Further, three regions of operation can be distinguished: a region with high N2O, NO and nitrite concentration; a region with high N2 concentrations and, as such, high removal percentages; and a region with high oxygen and nitrate concentrations. There is some overlap between the first two regions, which is in line with the fact that maximum emission of NO and N2O coincides with the region for optimal Anammox conversion.

  20. Modelling the effect of aggregates on N2O emission from denitrification in an agricultural peat soil

    NASA Astrophysics Data System (ADS)

    Stolk, P. C.; Hendriks, R. F. A.; Jacobs, C. M. J.; Moors, E. J.; Kabat, P.

    2011-09-01

    Nitrous oxide (N2O) emissions are highly variable in time, with high peak emissions lasting a few days to several weeks and low background emissions. This temporal variability is poorly understood which hampers the simulation of daily N2O emissions. In structured soils, like clay and peat, aggregates hamper the diffusion of oxygen, which leads to anaerobic microsites in the soil, favourable for denitrification. Diffusion of N2O out of the aggregates is also hampered, which leads to delayed emissions and increased reduction of N2O to N2. In this model simulation study we investigate the effect of aggregates in soils on the N2O emissions. We present a parameterization to simulate the effects of aggregates on N2O production by denitrification and on N2O reduction. The parameterization is based on the mobile-immobile model concept. It was implemented in a field-scale hydrological-biogeochemical model combination. We compared the simulated fluxes with observed fluxes from a fertilized and drained peat soil under grass. The results of this study show that aggregates strongly affect the simulated N2O emissions: peak emissions are lower, whereas the background emissions are slightly higher. Including the effect of aggregates caused a 40% decrease in the simulated annual emissions relative to the simulations without accounting for the effects of aggregates. The new parameterization significantly improved the model performance regarding simulation of observed daily N2O fluxes; r2 and RMSE improved from 0.11 and 198 g N2O-N ha-1 d-1 to 0.41 and 40 g N2O-N ha-1 d-1, respectively. Our analyses of the model results show that aggregates have a larger impact on the reduction than on the production of N2O. Reduction of N2O is more sensitive to changes in the drivers than production of N2O and is in that sense the key to understanding N2O emissions from denitrification. The effects of changing environmental conditions on reduction of N2O relative to N2O production strongly depend on

  1. Effects of Biochar Addition on CO2 and N2O Emissions following Fertilizer Application to a Cultivated Grassland Soil

    PubMed Central

    Chen, Jingjing; Kim, Hyunjin; Yoo, Gayoung

    2015-01-01

    Carbon (C) sequestration potential of biochar should be considered together with emission of greenhouse gases when applied to soils. In this study, we investigated CO2 and N2O emissions following the application of rice husk biochars to cultivated grassland soils and related gas emissions tos oil C and nitrogen (N) dynamics. Treatments included biochar addition (CHAR, NO CHAR) and amendment (COMPOST, UREA, NO FERT). The biochar application rate was 0.3% by weight. The temporal pattern of CO2 emissions differed according to biochar addition and amendments. CO2 emissions from the COMPOST soils were significantly higher than those from the UREA and NO FERT soils and less CO2 emission was observed when biochar and compost were applied together during the summer. Overall N2O emission was significantly influenced by the interaction between biochar and amendments. In UREA soil, biochar addition increased N2O emission by 49% compared to the control, while in the COMPOST and NO FERT soils, biochar did not have an effect on N2O emission. Two possible mechanisms were proposed to explain the higher N2O emissions upon biochar addition to UREA soil than other soils. Labile C in the biochar may have stimulated microbial N mineralization in the C-limited soil used in our study, resulting in an increase in N2O emission. Biochar may also have provided the soil with the ability to retain mineral N, leading to increased N2O emission. The overall results imply that biochar addition can increase C sequestration when applied together with compost, and might stimulate N2O emission when applied to soil amended with urea. PMID:26020941

  2. Improved global estimation of N2O emission from nitrification using a process-based model and meta-analysis

    NASA Astrophysics Data System (ADS)

    Inatomi, M. I.; Hajima, T.; Ito, A.

    2015-12-01

    Nitrous oxide (N2O) is recognized as one of the important anthropogenic greenhouse gases and also stratospheric ozone-depleting substances. Natural soil and fertilizer in croplands are large sources of N2O to the atmosphere, and so their global estimation is of great importance for prediction and mitigation. Two major processes of N2O production, i.e. nitrification and denitrification, were identified and parameterized using the leaky-pipe scheme. However, their biogeochemical mechanisms are very complicated and it is difficult to fully include them into process-based models, leading to substantial estimation uncertainty. In croplands, estimation is even more difficult because it depends on the amount, composition, and timing of nitrogenous fertilizer input. In this study, we focused on N2O emission from nitrification, which can play a dominant role in aerobic soils. In the present terrestrial nitrogen cycle models, fractionation of nitrogen in gross nitrification is parameterized in very simplified manner. First, we conducted a meta-analysis of the fraction of N2O emission from gross nitrification in relation to temperature, moisture (water-filled pore space), and pH, for a wide variety of soils including arable lands. We obtained typical values of N2O emission ratio from gross nitrification for different soil textures. Second, we assessed sensitivity of N2O emission to the assumption of nitrification fractionation, using a process-based model VISIT. We changed the value of N2O fraction in gross nitrification in different manners: default constant ratio, meta-analysis-based ratio, and parameterizations used in other models (DNDC and DLEM). We investigate how much the assumption of nitrification N2O emission affects global estimation of N2O budget and other parts of nitrogen cycle.

  3. Source portioning of N_{2}O emissions after long term elevation of soil temperature in a permanent grassland soil

    NASA Astrophysics Data System (ADS)

    Jansen-Willems, Anne; Lanigan, Gary; Clough, Timothy; Andresen, Louise; Müller, Christoph

    2016-04-01

    Several methods, such as source portioning, have been used to quantify the contributions of individual N pools to N2O emissions. These methods however, assume the absence of hybrid reactions such as co-denitrification, which were previously identified as important. A straight forward method portioning N2O fluxes into four different production processes, including a hybrid reaction, was therefore developed. This method portioned the N2O fluxes in nitrification, denitrification, oxidation of organic matter and co-denitrification, using data on 45R and 46R of the N2O flux and the 15N content of the NO3- and NH4+ in the soil. This newly developed method was used to analyse the N2O emissions from incubated soil, which was previously subjected to 6 years of elevated soil temperature of +0, +1, +2 or +3 ° C. N2O emissions were measured and analysed at four time points in the six days following, NO315NH4 Gly or 15NO3NH4 Gly, label addition. The oxidation of organic N was found to be the main source of N2O fluxes at all sampling dates, comprising between 63 and 85% of the total N2O flux. The percentage contribution made by organic N to N2O fluxes increased over the sampling period, rising from a minimum of 40% in the control treatment, to virtually 100% across all treatments by Day 6. Compared to the control treatment, denitrification contributed less to N2O from soil subjected to +2 and +3 ° C warming (p <0.0001 and p=0.002, respectively). Co-denitrification only contributed to the N2O flux during the first day after substrate addition. The highest amount of N2O produced via co-denitrification was found under the control treatment. From soil subjected to +2 and +3 ° C treatments, the contribution of co-denitrification was minor. However, these differences in co-denitrification were not significant. This research showed the importance of the oxidation of organic N in N2O emissions. It should therefore not be omitted as a potential source in source portioning. Emissions

  4. Minimizing N2O emissions and carbon footprint on a full-scale activated sludge sequencing batch reactor.

    PubMed

    Rodriguez-Caballero, A; Aymerich, I; Marques, Ricardo; Poch, M; Pijuan, M

    2015-03-15

    A continuous, on-line quantification of the nitrous oxide (N2O) emissions from a full-scale sequencing batch reactor (SBR) placed in a municipal wastewater treatment plant (WWTP) was performed in this study. In general, N2O emissions from the biological wastewater treatment system were 97.1 ± 6.9 g N2O-N/Kg [Formula: see text] consumed or 6.8% of the influent [Formula: see text] load. In the WWTP of this study, N2O emissions accounted for over 60% of the total carbon footprint of the facility, on average. Different cycle configurations were implemented in the SBR aiming at reaching acceptable effluent values. Each cycle configuration consisted of sequences of aerated and non-aerated phases of different time length being controlled by the ammonium set-point fixed. Cycles with long aerated phases showed the largest N2O emissions, with the consequent increase in carbon footprint. Cycle configurations with intermittent aeration (aerated phases up to 20-30 min followed by short anoxic phases) were proven to effectively reduce N2O emissions, without compromising nitrification performance or increasing electricity consumption. This is the first study in which a successful operational strategy for N2O mitigation is identified at full-scale.

  5. Using stable isotopes to follow excreta N dynamics and N2O emissions in animal production systems.

    PubMed

    Clough, T J; Müller, C; Laughlin, R J

    2013-06-01

    Nitrous oxide (N2O) is a potent greenhouse gas and the dominant anthropogenic stratospheric ozone-depleting emission. The tropospheric concentration of N2O continues to increase, with animal production systems constituting the largest anthropogenic source. Stable isotopes of nitrogen (N) provide tools for constraining emission sources and, following the temporal dynamics of N2O, providing additional insight and unequivocal proof of N2O source, production pathways and consumption. The potential for using stable isotopes of N is underutilised. The intent of this article is to provide an overview of what these tools are and demonstrate where and how these tools could be applied to advance the mitigation of N2O emissions from animal production systems. Nitrogen inputs and outputs are dominated by fertiliser and excreta, respectively, both of which are substrates for N2O production. These substrates can be labelled with 15N to enable the substrate-N to be traced and linked to N2O emissions. Thus, the effects of changes to animal production systems to reduce feed-N wastage by animals and fertiliser wastage, aimed at N2O mitigation and/or improved animal or economic performance, can be traced. Further 15N-tracer studies are required to fully understand the dynamics and N2O fluxes associated with excreta, and the biological contribution to these fluxes. These data are also essential for the new generation of 15N models. Recent technique developments in isotopomer science along with stable isotope probing using multiple isotopes also offer exciting capability for addressing the N2O mitigation quest.

  6. Historical Pattern and Future Trajectories of Terrestrial N2O Emission driven by Multi-factor Global Changes

    NASA Astrophysics Data System (ADS)

    Lu, C.; Tian, H.; Yang, J.; Zhang, B.; Xu, R.

    2015-12-01

    Nitrous oxide (N2O) is among the most important greenhouse gases only next to carbon dioxide (CO2) and methane (CH4) due to its long life time and high radiative forcing (with a global warming potential 265 times as much as CO2 at 100-year time horizon). The Atmospheric concentration of N2O has increased by 20% since pre-industrial era, and this increase plays a significant role in shaping anthropogenic climate change. However, compared to CO2- and CH4-related research, fewer studies have been performed in assessing and predicting the spatiotemporal patterns of N2O emission from natural and agricultural soils. Here we used a coupled biogeochemical model, DLEM, to quantify the historical and future changes in global terrestrial N2O emissions resulting from natural and anthropogenic perturbations including climate variability, atmospheric CO2 concentration, nitrogen deposition, land use and land cover changes, and agricultural land management practices (i.e., synthetic nitrogen fertilizer use, manure application, and irrigation etc.) over the period 1900-2099. We focused on inter-annual variation and long-term trend of terrestrial N2O emission driven by individual and combined environmental changes during historical and future periods. The sensitivity of N2O emission to climate, atmospheric composition, and human activities has been examined at biome-, latitudinal, continental and global scales. Future projections were conducted to identify the hot spots and hot time periods of global N2O emission under two emission scenarios (RCP2.6 and RCP8.5). It provides a modeling perspective for understanding human-induced N2O emission growth and developing potential management strategies to mitigate further atmospheric N2O increase and climate warming.

  7. Micrometeorological measurements over 3 years reveal differences in N2 O emissions between annual and perennial crops.

    PubMed

    Abalos, Diego; Brown, Shannon E; Vanderzaag, Andrew C; Gordon, Robert J; Dunfield, Kari E; Wagner-Riddle, Claudia

    2016-03-01

    Perennial crops can deliver a wide range of ecosystem services compared to annual crops. Some of these benefits are achieved by lengthening the growing season, which increases the period of crop water and nutrient uptake, pointing to a potential role for perennial systems to mitigate soil nitrous oxide (N2 O) emissions. Employing a micrometeorological method, we tested this hypothesis in a 3-year field experiment with a perennial grass-legume mixture and an annual corn monoculture. Given that N2 O emissions are strongly dependent on the method of fertilizer application, two manure application options commonly used by farmers for each crop were studied: injection vs. broadcast application for the perennial; fall vs. spring application for the annual. Across the 3 years, lower N2 O emissions (P < 0.001) were measured for the perennial compared to the annual crop, even though annual N2 O emissions increased tenfold for the perennial after ploughing. The percentage of N2 O lost per unit of fertilizer applied was 3.7, 3.1 and 1.3 times higher for the annual for each consecutive year. Differences in soil organic matter due to the contrasting root systems of these crops are probably a major factor behind the N2 O reduction. We found that a specific manure management practice can lead to increases or reductions in annual N2 O emissions depending on environmental variables. The number of freeze-thaw cycles during winter and the amount of rainfall after fertilization in spring were key factors. Therefore, general manure management recommendations should be avoided because interannual weather variability has the potential to determine if a specific practice is beneficial or detrimental. The lower N2 O emissions of perennial crops deserve further research attention and must be considered in future land-use decisions. Increasing the proportion of perennial crops in agricultural landscapes may provide an overlooked opportunity to regulate N2 O emissions.

  8. Projections of oceanic N2O emissions in the 21st century using the IPSL Earth system model

    NASA Astrophysics Data System (ADS)

    Martinez-Rey, J.; Bopp, L.; Gehlen, M.; Tagliabue, A.; Gruber, N.

    2015-07-01

    The ocean is a substantial source of nitrous oxide (N2O) to the atmosphere, but little is known about how this flux might change in the future. Here, we investigate the potential evolution of marine N2O emissions in the 21st century in response to anthropogenic climate change using the global ocean biogeochemical model NEMO-PISCES. Assuming nitrification as the dominant N2O formation pathway, we implemented two different parameterizations of N2O production which differ primarily under low-oxygen (O2) conditions. When forced with output from a climate model simulation run under the business-as-usual high-CO2 concentration scenario (RCP8.5), our simulations suggest a decrease of 4 to 12 % in N2O emissions from 2005 to 2100, i.e., a reduction from 4.03/3.71 to 3.54/3.56 TgN yr-1 depending on the parameterization. The emissions decrease strongly in the western basins of the Pacific and Atlantic oceans, while they tend to increase above the oxygen minimum zones (OMZs), i.e., in the eastern tropical Pacific and in the northern Indian Ocean. The reduction in N2O emissions is caused on the one hand by weakened nitrification as a consequence of reduced primary and export production, and on the other hand by stronger vertical stratification, which reduces the transport of N2O from the ocean interior to the ocean surface. The higher emissions over the OMZ are linked to an expansion of these zones under global warming, which leads to increased N2O production, associated primarily with denitrification. While there are many uncertainties in the relative contribution and changes in the N2O production pathways, the increasing storage seems unequivocal and determines largely the decrease in N2O emissions in the future. From the perspective of a global climate system, the averaged feedback strength associated with the projected decrease in oceanic N2O emissions amounts to around -0.009 W m-2 K-1, which is comparable to the potential increase from terrestrial N2O sources. However

  9. Partitioning Residue-derived and Residue-induced Emissions of N2O Using 15N-labelled Crop Residues

    NASA Astrophysics Data System (ADS)

    Farrell, R. E.; Carverhill, J.; Lemke, R.; Knight, J. D.

    2014-12-01

    Estimates of N2O emissions in Canada indicate that 17% of all agriculture-based emissions are associated with the decomposition of crop residues. However, research specific to the western Canadian prairies (including Saskatchewan) has shown that the N2O emission factor for N sources in this region typically ranges between 0.2 and 0.6%, which is well below the current IPCC default emission factor of 1.0%. Thus, it stands to reason that emissions from crop residues should also be lower than those calculated using the current IPCC emission factor. Current data indicates that residue decomposition, N mineralization and N2O production are affected by a number of factors such as C:N ratio and chemical composition of the residue, soil type, and soil water content; thus, a bench-scale incubation study was conducted to examine the effects of soil type and water content on N2O emissions associated with the decomposition of different crop residues. The study was carried out using soils from the Black, Dark Brown, Brown, and Gray soil zones and was conducted at both 50% and 70% water-filled pore space (WFPS); the soils were amended with 15N-labeled residues of wheat, pea, canola, and flax, or with an equivalent amount of 15N-labeled urea; 15N2O production was monitored using a Picarro G5101-i isotopic N2O analyzer. Crop residue additions to the soils resulted in both direct and indirect emissions of N2O, with residue derived emissions (RDE; measured as 15N2O) generally exceeding residue-induced emissions (RIE) at 50% WFPS—with RDEs ranging from 42% to 88% (mean = 58%) of the total N2O. Conversely, at 70% WFPS, RDEs were generally lower than RIEs—ranging from 21% to 83% (mean = 48%). Whereas both water content and soil type had an impact on N2O production, there was a clear and consistent trend in the emission factors for the residues; i.e., emissions were always greatest for the canola residue and lowest for the wheat residue and urea fertilizer; and intermediate for pea

  10. Micrometeorological measurements of N2O and CH4 emissions from a municipal solid waste landfill.

    PubMed

    McBain, Matthew C; Warland, Jon S; McBride, Raymond A; Wagner-Riddle, Claudia

    2005-10-01

    Micrometeorological measurements of methane (CH4) and nitrous oxide (N2O) emissions were made at the decommissioned Park Road Landfill in Grimsby, Ontario, Canada between June and August 2002. The influence of precipitation, air temperature, wind speed and barometric pressure on the temporal variability of landfill biogas emissions was assessed. Gas flux measurements were obtained using a micrometeorological mass balance measurement technique [integrated horizontal flux (IHF)] in conjunction with two tunable diode laser trace gas analyser (TDLTGA) systems. This method allows for continuous, non-intrusive measurements of gas flux at high temporal resolution. Mean fluxes of N2O were negligible over the duration of the study (-0.23 to 0.02 microg m(-2) s(-1)). In contrast, mean emissions of CH4 were much greater (80.4 to 450.8 microg m(-2) s(-1)) and varied both spatially and temporally. Spatial variations in CH4 fluxes were observed between grass kill areas (biogas 'hot spots') and the densely grass-covered areas of the landfill. Temporal variations in CH4 fluxes were also observed, due at least in part to barometric pressure, wind speed and precipitation effects.

  11. Evaluating Observational Constraints on N2O Emissions via Information Content Analysis Using GEOS-Chem and its Adjoint

    NASA Astrophysics Data System (ADS)

    Wells, K. C.; Millet, D. B.; Bousserez, N.; Henze, D. K.; Chaliyakunnel, S.; Griffis, T. J.; Dlugokencky, E. J.; Prinn, R. G.; O'Doherty, S.; Weiss, R. F.; Dutton, G. S.; Elkins, J. W.; Krummel, P. B.; Langenfelds, R. L.; Steele, P.

    2015-12-01

    Nitrous oxide (N2O) is a long-lived greenhouse gas with a global warming potential approximately 300 times that of CO2, and plays a key role in stratospheric ozone depletion. Human perturbation of the nitrogen cycle has led to a rise in atmospheric N2O, but large uncertainties exist in the spatial and temporal distribution of its emissions. Here we employ a 4D-Var inversion framework for N2O based on the GEOS-Chem chemical transport model and its adjoint to derive new constraints on the space-time distribution of global land and ocean N2O fluxes. Based on an ensemble of global surface measurements, we find that emissions are overestimated over Northern Hemisphere land areas and underestimated in the Southern Hemisphere. Assigning these biases to particular land or ocean regions is more difficult given the long lifetime of N2O. To quantitatively evaluate where the current N2O observing network provides local and regional emission constraints, we apply a new, efficient information content analysis technique involving radial basis functions. The technique yields optimal state vector dimensions for N2O source inversions, with model grid cells grouped in space and time according to the resolution that can actually be provided by the network of global observations. We then use these optimal state vectors in an analytical inversion to refine current top-down emission estimates.

  12. Effects of flooding cycles in the Pantanal on the turnover of soil nitrogen pools and emission of N2O

    NASA Astrophysics Data System (ADS)

    Liengaard, L.; Nielsen, L. P.; Revsbech, N. P.; Elberling, B.; Priemé, A.; Prast, A. E.; Kühl, M.

    2011-06-01

    The global nitrous oxide (N2O) budget remains unbalanced. Currently, ~25 % of the global N2O emission is ascribed to uncultivated tropical soils, but the exact locations and controlling mechanisms are not clear. In this study, we present the first detailed study of the dynamics of soil nitrogen pools and flux of N2O from the world's largest wetland Pantanal, South America. At three long-term measurement sites we measured porewater pH, NO3-, NH4+ , N2O and O2 as well as N2O dynamics in soil slurry, and in situ fluxes of N2O and CO2. The pool of inorganic nitrogen changed (7.1-92 μg NH4+-N g dw-1, and 0.1-201 μg NO3--N g dw-1) with the seasonal flooding and drying cycles, indicating dynamic shifts between ammonification, nitrification and denitrification. In the field, O2 penetrated to a depth of 60 cm in dry soil, but O2 was rapidly depleted in response to precipitation. Soil pH fluctuated from pH 7-7.5 in flooded soil to pH 3.5-4.5 in the same drained soil. Microsensor measurements showed rapid N2O accumulation reaching >500-1000 Pa in soil slurries due to incomplete denitrification. In situ fluxes of N2O were comparable to heavily fertilized forest or agricultural soils. The dominating parameter affecting N2O emission rate was precipitation inducing peak emissions of >3 mmol N2O m-2 d-1, while the mean daily flux was 0.43 mmol N2O m-2 d-1. Single measurement based screening of in situ activity at 10 Pantanal sites during dry conditions averaged 0.39 mmol N2O m-2 d-1. The in situ N2O fluxes were only weakly correlated (r2 = 0.177) with NO3- and pH value, showing a tendency (p = 0.063) for NO3- concentration to be positively correlated with the in situ N2O flux and a weaker tendency (p = 0.138) for the pH value to be negatively correlated with the in situ N2O flux. Over 170 days of the drained period we estimated non-wetted drained soil to contribute 70.0 mmol N2O m-2, while rain induced peak events contributed 9.2 mmol N2O m-2, resulting in a total N2O emission

  13. Effects of different vegetation zones on CH4 and N2O emissions in coastal wetlands: a model case study.

    PubMed

    Liu, Yuhong; Wang, Lixin; Bao, Shumei; Liu, Huamin; Yu, Junbao; Wang, Yu; Shao, Hongbo; Ouyang, Yan; An, Shuqing

    2014-01-01

    The coastal wetland ecosystems are important in the global carbon and nitrogen cycle and global climate change. For higher fragility of coastal wetlands induced by human activities, the roles of coastal wetland ecosystems in CH4 and N2O emissions are becoming more important. This study used a DNDC model to simulate current and future CH4 and N2O emissions of coastal wetlands in four sites along the latitude in China. The simulation results showed that different vegetation zones, including bare beach, Spartina beach, and Phragmites beach, produced different emissions of CH4 and N2O in the same latitude region. Correlation analysis indicated that vegetation types, water level, temperature, and soil organic carbon content are the main factors affecting emissions of CH4 and N2O in coastal wetlands.

  14. Controlling factors of nitrous oxide (N2O) emissions at the field-scale in an agricultural slope

    NASA Astrophysics Data System (ADS)

    Vilain, Guillaume; Garnier, Josette; Tallec, Gaëlle; Tournebize, Julien; Cellier, Pierre; Flipo, Nicolas

    2010-05-01

    Agricultural practices widely contribute to the atmospheric nitrous oxide (N2O) concentration increase and are the major source of N2O which account for 24% of the global annual emission (IPCC, 2007). Soil nitrification and denitrification are the microbial processes responsible for the production of N2O, which also depends on soil characteristics and management. Besides their control by various factors, such as climate, soil conditions and management (content of NO3- and NH4+, soil water content, presence of degradable organic material…), the role of topography is less known although it can play an important role on N2O emissions (Izaurralde et al., 2004). Due to the scarcity of data on N2O direct vs. indirect emission rate from agriculture in the Seine Basin (Garnier et al., 2009), one of the objectives of the study conducted here was to determine the N2O emission rates of the various land use representative for the Seine Basin, in order to better assess the direct N2O emissions, and to explore controlling factor such as meteorology, topography, soil properties and crop successions. The main objective of this study was at the same time to characterize N2O fluxes variability along a transect from an agricultural plateau to a river and to analyze the influence of landscape position on these emissions. We conducted this study in the Orgeval catchment (Seine basin, France; between 48°47' and 48°55' N, and 03°00' and 03°55' E) from May 2008 to August 2009 on two agricultural fields cropped with wheat, barley, oats, corn. N2O fluxes were monitored from weekly to bimonthly using static manual chambers placed along the chosen transect in five different landscape positions from the plateau to the River. This study has shown that soil moisture (expressed as Water Filled Pore Space) and NO3- soil concentrations explained most of the N2O flux variability during the sampling period. Most of N2O was emitted directly after N fertilization application during a relatively

  15. Natural and Anthropogenic Controls over Global Terrestrial N2O Emission Growth at a Century-Long Time Scale

    NASA Astrophysics Data System (ADS)

    Lu, C.; Tian, H.; Kamaljit, K.; Zhang, B.

    2014-12-01

    The Atmospheric concentration of nitrous oxide (N2O) has increased by 20% relative to pre-industrial level. It has attracted growing attention since N2O has long life time and radiative forcing 265 times higher than CO2 at 100-year time horizon. Global N2O emission from terrestrial ecosystem is among the most important contributors to the increase of atmospheric N2O. However, compared to CO2- and CH4-related research, less intensive studies have been performed in assessing the spatiotemporal patterns of terrestrial N2O emission and attributing its changes to both natural and anthropogenic disturbances across the globe. Here we integrated gridded time-series data of climate variability, atmospheric CO2 concentration, nitrogen deposition, land use and land cover changes, and agricultural land management practices (i.e., synthetic nitrogen fertilizer use, manure application, and irrigation etc.) to a process-based land ecosystem model, DLEM, for answering the above questions. During 1900-2010, the inter-annual variation and long-term trend of terrestrial N2O emission driven by individual and combined environmental changes have been examined. Through this, we distinguished and quantified the relative contributions of changes in climate, atmospheric composition, and human activities to N2O emission growth at biome-, latitudinal, continental and global scales. The impacts of climate variability, and increasing nitrogen input, particularly nitrogen fertilizer use along with enhanced food production, have been paid special attention. Hot spots and hot time periods of global N2O emission are identified in this study. It provides clue for scientific community and policy makers to develop potential management strategies for mitigating atmospheric N2O increase and climate warming.

  16. N2O and NO2 Emissions from Heavy-Duty Diesel Trucks with Advanced Emission Controls

    NASA Astrophysics Data System (ADS)

    Preble, C.; Harley, R.; Kirchstetter, T.

    2014-12-01

    Diesel engines are the largest source of nitrogen oxides (NOx) emissions nationally, and also a major contributor to the black carbon (BC) fraction of fine particulate matter (PM). Recently, diesel particle filter (DPF) and selective catalytic reduction (SCR) emission control systems that target exhaust PM and NOx have become standard equipment on new heavy-duty diesel trucks. However, the deliberate catalytic oxidation of engine-out nitric oxide (NO) to nitrogen dioxide (NO2) in continuously regenerating DPFs leads to increased tailpipe emission of NO2. This is of potential concern due to the toxicity of NO2 and the resulting increases in atmospheric formation of other air pollutants such as ozone, nitric acid, and fine PM. While use of SCR reduces emissions of both NO and NO2, it may lead to increased emissions of nitrous oxide (N2O), a potent greenhouse gas. Here we report results from on-road measurements of heavy-duty diesel truck emissions conducted at the Port of Oakland and the Caldecott Tunnel in the San Francisco Bay Area. Emission factors (g pollutant per kg of diesel) were linked via recorded license plates to individual truck attributes, including engine model year and installed emission control equipment. Between 2009 and 2013, the fraction of DPF-equipped trucks at the Port of Oakland increased from 2 to 99%, and median engine age decreased from 11 to 6 years. Over the same period, fleet-average emission factors for black carbon and NOx decreased by 76 ± 22% and 53 ± 8%, respectively. However, direct emissions of NO2 increased, and consequently the NO2/NOx emission ratio increased from 0.03 ± 0.02 to 0.18 ± 0.03. Older trucks retrofitted with DPFs emitted approximately 3.5 times more NO2 than newer trucks equipped with both DPF and SCR. Preliminary data from summer 2014 measurements at the Caldecott Tunnel suggest that some older trucks have negative emission factors for N2O, and that for newer trucks, N2O emission factors have changed sign and

  17. Emissions of N2O, CH4 and CO2 from tropical forest soils

    NASA Technical Reports Server (NTRS)

    Keller, Michael; Kaplan, Warren A.; Wofsy, Steven C.

    1986-01-01

    Emissions of nitrous oxide, methane, and carbon dioxide were measured at diverse locations in tropical forests of Brazil, Ecuador, and Puerto Rico using a static open chamber technique. Mean fluxes to the atmosphere were 1.7 x 10 to the 10th, -0.7 x 10 to the 10th, and 1.5 x 10 to the 14th molecules/sq cm per s for N2O, CH4, and CO2, respectively. The data indicate that tropical forests contribute a significant fraction of the global source for atmospheric N2O, about 40 percent of the current source, and possibly 75 percent of the preindustrial source. Methane is consumed by soils on average, but the sink is an insignificant part (less than 5 percent) of the atmospheric cycle for the gas. Emissions of CO2 from forest soils are higher at equatorial sites than at middle or high latitudes, as expected from ecological considerations. Soils emit CO2 at rates more than twice as large as the rate of carbon infall in litter; hence much of the emitted CO2 must arise from root metabolism.

  18. Mitigation of soil N2O emission by inoculation with a mixed culture of indigenous Bradyrhizobium diazoefficiens

    NASA Astrophysics Data System (ADS)

    Akiyama, Hiroko; Hoshino, Yuko Takada; Itakura, Manabu; Shimomura, Yumi; Wang, Yong; Yamamoto, Akinori; Tago, Kanako; Nakajima, Yasuhiro; Minamisawa, Kiwamu; Hayatsu, Masahito

    2016-09-01

    Agricultural soil is the largest source of nitrous oxide (N2O), a greenhouse gas. Soybean is an important leguminous crop worldwide. Soybean hosts symbiotic nitrogen-fixing soil bacteria (rhizobia) in root nodules. In soybean ecosystems, N2O emissions often increase during decomposition of the root nodules. Our previous study showed that N2O reductase can be used to mitigate N2O emission from soybean fields during nodule decomposition by inoculation with nosZ++ strains [mutants with increased N2O reductase (N2OR) activity] of Bradyrhizobium diazoefficiens. Here, we show that N2O emission can be reduced at the field scale by inoculation with a mixed culture of indigenous nosZ+ strains of B. diazoefficiens USDA110 group isolated from Japanese agricultural fields. Our results also suggested that nodule nitrogen is the main source of N2O production during nodule decomposition. Isolating nosZ+ strains from local soybean fields would be more applicable and feasible for many soybean-producing countries than generating mutants.

  19. Mitigation of soil N2O emission by inoculation with a mixed culture of indigenous Bradyrhizobium diazoefficiens

    PubMed Central

    Akiyama, Hiroko; Hoshino, Yuko Takada; Itakura, Manabu; Shimomura, Yumi; Wang, Yong; Yamamoto, Akinori; Tago, Kanako; Nakajima, Yasuhiro; Minamisawa, Kiwamu; Hayatsu, Masahito

    2016-01-01

    Agricultural soil is the largest source of nitrous oxide (N2O), a greenhouse gas. Soybean is an important leguminous crop worldwide. Soybean hosts symbiotic nitrogen-fixing soil bacteria (rhizobia) in root nodules. In soybean ecosystems, N2O emissions often increase during decomposition of the root nodules. Our previous study showed that N2O reductase can be used to mitigate N2O emission from soybean fields during nodule decomposition by inoculation with nosZ++ strains [mutants with increased N2O reductase (N2OR) activity] of Bradyrhizobium diazoefficiens. Here, we show that N2O emission can be reduced at the field scale by inoculation with a mixed culture of indigenous nosZ+ strains of B. diazoefficiens USDA110 group isolated from Japanese agricultural fields. Our results also suggested that nodule nitrogen is the main source of N2O production during nodule decomposition. Isolating nosZ+ strains from local soybean fields would be more applicable and feasible for many soybean-producing countries than generating mutants. PMID:27633524

  20. Denitrifier communities in tank bromeliads and prospected N2O emissions from tank substrate upon increasing N-deposition

    NASA Astrophysics Data System (ADS)

    Suleiman, Marcel; Brandt, Franziska; Brenzinger, Kristof; Martinson, Guntars; Braker, Gesche

    2014-05-01

    It is well known that tropical rainforest soils with total emissions of 1.34 Tg N/yr from the tropics, play a significant role in the global N2O emissions scenarios. Significant contributions were reported particularly for tropical rainforest soils in South and Central America due to the large areas covered by rainforest in this region. In tropical rainforests of the Americas tank bromeliads constitute a prominent group of plants and were shown to significantly contribute to the production of the greenhouse gas methane from tropical forests. It is, however, essentially unknown whether and how bromeliads may contribute to the production of N2O, another important greenhouse gas. It is also unknown whether N2O emissions relate to atmospheric N-deposition and whether an increase in emissions is to be expected upon the prospected increase in N-deposition. We studied the propensity of tank substrate of the bromeliad Werauhia gladioliflora to emit N2O and how this potential is related to the underlying denitrifier communities. In tropical forests of Costa Rica Werauhia gladioliflora is very abundant with 9.85 specimen m-2. Incubation of the tank substrate with increasing amounts of fertilizer to reflect predicted N-deposition scenarios resulted in proportionally increasing net N2O production. Based on the abundance of Werauhia gladioliflora we estimated annual emissions of 395 µg N2O-N m-2 day-1 for N-deposition levels to date which is in the range of tropical soils. At a surplus of N 70% of N2O produced were not reduced leading to accumulation of N2O which agreed well with the finding that 95% of the denitrifiers detected lacked a gene encoding a N2O-reductase and are therefore unable to reduce N2O to dinitrogen. Generally, denitrifiers were highly abundant and ready to denitrify immediately after provision of a nitrogen source because carbon is non-limiting in tank substrate. Our results suggest that tank bromeliad substrate may be a significant source of N2O in

  1. Subsurface N cycling under variable paddy flood management: what role does it play in N2O emissions?

    NASA Astrophysics Data System (ADS)

    Verhoeven, Elizabeth; Pierreux, Sofie; Decock, Charlotte; Romani, Marco; Sleutel, Steven; Six, Johan

    2016-04-01

    There is increasing pressure to grow rice with less water in order to save water and mitigate methane (CH4) emissions. However, there is frequently a trade-off with yield declines and increased nitrous oxide (N2O) emissions, potentially increasing the global warming potential of the system. A field trial in Northern Italy was established with two water regimes: continuously flooded (flooded) and alternate wetting and drying (AWD), to investigate the impact of such water management on N2O emissions and N cycling along a depth profile. Surface gas fluxes were complimented by depth profile measurements of soil gas, inorganic N, DOC, dissolved gas concentrations, redox potential and moisture. Sampling was concentrated around two periods during the 2015 growing season which were hypothesized to show significant variation in N dynamics; a fertilization event and final season drainage. For N cycling and N2O emissions, stable isotope measurements were taken to obtain process-level information in situ. During the first field campaign, maximum mean daily N2O emissions did not peak at fertilization but rather a week earlier, demonstrating a greater response to soil conditions (i.e. higher redox and lower moisture) than inorganic N concentrations. This was especially the case in the AWD treatment where emissions peaked at 82.3 ± 126.0 g N2O-N ha-1 d-1 relative to a peak of 2.83 ± 1.1 g N2O-N ha-1 d-1 in the flooded treatment. Considering the upper depths (0-15 cm), peak emissions corresponded well to higher redox potentials in the AWD treatment (72-406 mV versus -100 to -12 mV for AWD and flooded treatments, respectively). These emissions also correlated well to pore space N2O concentrations at 5 and 12.5 cm, suggesting important production of N2O at these depths and subsequent diffusion to the soil surface. Pore space and dissolved N2O concentrations were much lower in the flooded treatment and no such spikes were observed. No significant N2O emissions were observed in

  2. CH4 and N2O emissions embodied in international trade of meat

    NASA Astrophysics Data System (ADS)

    Caro, Dario; LoPresti, Anna; Davis, Steven J.; Bastianoni, Simone; Caldeira, Ken

    2014-11-01

    Although previous studies have quantified carbon dioxide emissions embodied in products traded internationally, there has been limited attention to other greenhouse gases such as methane (CH4) and nitrous oxide (N2O). Following IPCC guidelines, we estimate non-CO2 emissions from beef, pork and chicken produced in 237 countries over the period 1990-2010, and assign these emissions to the country where the meat is ultimately consumed. We find that, between 1990 and 2010, an average of 32.8 Mt CO2-eq emissions (using 100 year global warming potentials) are embodied in beef, pork and chicken traded internationally. Further, over the 20 year period, the quantity of CO2-eq emissions embodied in traded meat increased by 19%. The largest trade flows of emissions embodied in meat were from Brazil and Argentina to Russia (2.8 and 1.4 Mt of CO2-eq, respectively). Trade flows within the European region are also substantial: beef and pork exported from France embodied 3.3 Mt and 0.4 Mt of CO2-eq, respectively. Emissions factor of meat production (i.e. CO2-eq emissions per kg of meat) produced depend on ambient temperature, development level, livestock category (e.g. cattle, pork, and chicken) and livestock management practices. Thus, trade may result in an overall increase of GHG emissions when meat-consuming countries import meat from countries with a greater emissions intensity of meat production rather than producing the meat domestically. Comparing the emissions intensity of meat production of trading partners, we assess trade flows according to whether they tend to reduce or increase global emissions from meat production.

  3. Mitigation of nitrous oxide (N2 O) emission from swine wastewater treatment in an aerobic bioreactor packed with carbon fibers.

    PubMed

    Yamashita, Takahiro; Yamamoto-Ikemoto, Ryoko; Yokoyama, Hiroshi; Kawahara, Hirofumi; Ogino, Akifumi; Osada, Takashi

    2015-03-01

    Mitigation of nitrous oxide (N2 O) emission from swine wastewater treatment was demonstrated in an aerobic bioreactor packed with carbon fibers (CF reactor). The CF reactor had a demonstrated advantage in mitigating N2 O emission and avoiding NOx (NO3  + NO2 ) accumulation. The N2 O emission factor was 0.0003 g N2 O-N/gTN-load in the CF bioreactor compared to 0.03 gN2 O-N/gTN-load in an activated sludge reactor (AS reactor). N2 O and CH4 emissions from the CF reactor were 42 g-CO2 eq/m(3) /day, while those from the AS reactor were 725 g-CO2 eq/m(3) /day. The dissolved inorganic nitrogen (DIN) in the CF reactor removed an average of 156 mg/L of the NH4 -N, and accumulated an average of 14 mg/L of the NO3 -N. In contrast, the DIN in the AS reactor removed an average 144 mg/L of the NH4 -N and accumulated an average 183 mg/L of the NO3 -N. NO2 -N was almost undetectable in both reactors.

  4. Analysis of N2O isotopic composition at a tall tower in central Switzerland to identify emission sources and hot spots

    NASA Astrophysics Data System (ADS)

    Ibraim, E.; Mohn, J.; Harris, E. J.; Henne, S.; Eyer, S.; Denk, T.; Wolf, B.; Tuzson, B.; Emmenegger, L.; Butterbach-Bahl, K.; Six, J.

    2015-12-01

    The isotopic composition of nitrous oxide (N2O) provides important information on N2O sources, because microbial processes exhibit characteristic isotopic signatures [1]. Therefore, quasi-continuous measurements of ambient N2O concentration and isotopic composition in combination with atmospheric modelling can be used to identify local and regional emission hotspots and disentangle production pathways [2]. Quantum cascade laser absorption spectroscopy (QCLAS) in combination with preconcentration allows simultaneous and high-precision analysis of the four main stable N2O isotopologues (14N14N16O, 14N15N16O, 15N14N16O and 14N14N18O) at ambient mixing ratios [3]. In the presented project, we will initiate quasi-continuous measurements of N2O isotopologues at the Beromünster tall tower in Central Switzerland [4]. For the two inlet heights 12 and 212 m, maximum changes in the N2O mixing ratios of 50 and 10 ppb are anticipated, which would result in delta value changes in the order of 3 and 0.6 ‰, assuming a 20 ‰ depletion in delta values for the main source processes. To resolve differences in N2O isotopic composition at the highest inlet the repeatability of delta value measurements has to be improved to < 0.1 ‰. In an ongoing laboratory phase we significantly enhanced the long-term stability of the laser spectrometer by reducing the dependency of cell temperature on ambient temperature changes from 100 mK K-1 to 10 mK K-1. Thereby, the required precision level is maintained for a 10 times longer period, which results in an accuracy of < 0.1‰ for the targeted isotope ratios. In addition, a novel preconcentration device [5] was set up and optimized with respect to temporal resolution. First results from the Beromünster tall tower, which are anticipated for fall 2015, will be presented and followed by atmospheric transport simulations and a biogeochemical soil model developed at IMK-IFU to simulate N2O isotopomer surface fluxes. References[1] S. Toyoda et al

  5. On-road measurement of NH3 and N2O emissions from a Euro V heavy-duty vehicle

    NASA Astrophysics Data System (ADS)

    Suarez-Bertoa, Ricardo; Mendoza-Villafuerte, Pablo; Bonnel, Pierre; Lilova, Velizara; Hill, Leslie; Perujo, Adolfo; Astorga, Covadonga

    2016-08-01

    The use of selective catalytic reduction systems (SCR) to abate NOx vehicular emissions brings new concerns on the emissions of the byproducts NH3 and N2O. Therefore, NH3 and N2O on-road emissions from a Euro V truck equipped with a SCR were measured in real time using a QCL-IR. Results bring to light possibility to perform this kind of real time measurements for other pollutants besides, hydrocarbons, NOx, CO and CO2. The capability to measure NH3 and N2O in a second-by-second basis will allow applying the currently agreed regulatory emissions evaluation for gaseous compounds. Average N2O emission factors calculated applying the current PEMS-based data analysis to all available windows from the tests ranged from 0.063 g/kWh to 0.139 g/kWh. Average NH3 concentrations ranged from 0.9 ppm to 5.7 ppm. Although calculated average N2O and NH3 emissions were within current limits, NOx emissions were substantially higher than Euro V limits under the studied conditions.

  6. Affect of dairy cow manure, urine, and slurry on N<2>O, CO<2>, and CH<4> emissions from Pasture

    NASA Astrophysics Data System (ADS)

    Dorich, C.; Varner, R. K.; Contosta, A.; Li, C.

    2012-12-01

    Agriculture is responsible for roughly 25% of total anthropogenic emission of greenhouse gases (GHG) globally. These agricultural emissions are primarily in the form of methane (CH<4>) and nitrous oxide (N<2>O) where they account for roughly 40 and 80 percent of anthropogenic emissions of their gas, respectively. Measuring and modeling of these gases has remained difficult however as management varies between farms and N<2>O fluxes have been difficult to link to climate and site conditions. Most of these N<2>O fluxes occur during soil freeze-thaw and wetting-drying cycles as well as fertilizer addition moments, all of which are difficult to measure and harder yet to model. Thus the N<2>O flux remains poorly understood and may be underestimated in literature. This provides a problem in agriculture emissions as N use efficiency has been suggested as a proxy for farm scale emissions. On a farm scale these large fluxes of N<2>O from soil "hot moments" can account for up to 60% of the total GHG emissions and thus it is essential to capture the full flux. At the University of New Hampshire Agriculture Experiment Station's (NHAES) organic dairy farm a manure fertilizer experiment was conducted. Manure, urine, and slurry from the UNH dairy farms were collected, analyzed, and applied to pasture plots in May 2012 in order to examine N<2>O flux hot moments. Sites were measured at least bi-weekly with manual static flux chambers taken with soil temperature and moisture along with measurements for soil inorganic N, soil C:N, plant biomass and C:N, and soil pH. Gas samples were analyzed for CO<2>, CH<4>, and N<2>O. Emissions were compared with other fluxes from the farm ecosystem including; corn silage, free stall bedding, composting and solid manure, and a manure slurry tank.

  7. Biochar and denitrification in soils: when, how much and why does biochar reduce N2O emissions?

    PubMed Central

    Cayuela, Maria Luz; Sánchez-Monedero, Miguel Angel; Roig, Asunción; Hanley, Kelly; Enders, Akio; Lehmann, Johannes

    2013-01-01

    Agricultural soils represent the main source of anthropogenic N2O emissions. Recently, interactions of black carbon with the nitrogen cycle have been recognized and the use of biochar is being investigated as a means to reduce N2O emissions. However, the mechanisms of reduction remain unclear. Here we demonstrate the significant impact of biochar on denitrification, with a consistent decrease in N2O emissions by 10–90% in 14 different agricultural soils. Using the 15N gas-flux method we observed a consistent reduction of the N2O/(N2 + N2O) ratio, which demonstrates that biochar facilitates the last step of denitrification. Biochar acid buffer capacity was identified as an important aspect for mitigation that was not primarily caused by a pH shift in soil. We propose the function of biochar as an “electron shuttle” that facilitates the transfer of electrons to soil denitrifying microorganisms, which together with its liming effect would promote the reduction of N2O to N2. PMID:23615819

  8. [Effects of conservation tillage on soil CO2 and N2O emission during the following winter-wheat season].

    PubMed

    Pan, Ying; Hu, Zheng-Hu; Wu, Yang-Zhou; Sun, Yin-Yin; Sheng, Lu; Chen, Shu-Tao; Xiao, Qi-Tao

    2014-07-01

    In order to study the effect of conservation tillage on soil CO2 and N2O emissions in the following crop-growing season, field experiments were conducted in the winter wheat-growing season. Four treatments were conventional tillage (T), no-tillage with no straw cover (NT), no-tillage with straw cover (NTS), and conventional tillage with straw incorporation (TS), respectively. The CO2 and N2O fluxes were measured using a static chamber-gas chromatograph technique. The results showed that in the following winter wheat-growing season, conservation tillage did not change the seasonal pattern of CO2 and N2O emission fluxes from soil, and had no significant effect on crop biomass. Conservation tillage significantly reduced the accumulative amount of CO2 and N2O. Compared with the T treatment, the accumulative amount of CO2 under TS, NT, and NTS treatments were reduced by 5.95% (P = 0.132), 12.94% (P = 0.007), and 13.91% (P = 0.004), respectively, and the accumulative amount of N2O were significantly reduced by 31.23% (P = 0.000), 61.29% (P = 0.000), and 33.08% (P = 0.000), respectively. Our findings suggest that conservation tillage significantly reduced CO2 and N2O emission from soil in the following winter wheat-growing season.

  9. Global trends and uncertainties in terrestrial denitrification and N2O emissions

    PubMed Central

    Bouwman, A. F.; Beusen, A. H. W.; Griffioen, J.; Van Groenigen, J. W.; Hefting, M. M.; Oenema, O.; Van Puijenbroek, P. J. T. M.; Seitzinger, S.; Slomp, C. P.; Stehfest, E.

    2013-01-01

    Soil nitrogen (N) budgets are used in a global, distributed flow-path model with 0.5° × 0.5° resolution, representing denitrification and N2O emissions from soils, groundwater and riparian zones for the period 1900–2000 and scenarios for the period 2000–2050 based on the Millennium Ecosystem Assessment. Total agricultural and natural N inputs from N fertilizers, animal manure, biological N2 fixation and atmospheric N deposition increased from 155 to 345 Tg N yr−1 (Tg = teragram; 1 Tg = 1012 g) between 1900 and 2000. Depending on the scenario, inputs are estimated to further increase to 408–510 Tg N yr−1 by 2050. In the period 1900–2000, the soil N budget surplus (inputs minus withdrawal by plants) increased from 118 to 202 Tg yr−1, and this may remain stable or further increase to 275 Tg yr−1 by 2050, depending on the scenario. N2 production from denitrification increased from 52 to 96 Tg yr−1 between 1900 and 2000, and N2O–N emissions from 10 to 12 Tg N yr−1. The scenarios foresee a further increase to 142 Tg N2–N and 16 Tg N2O–N yr−1 by 2050. Our results indicate that riparian buffer zones are an important source of N2O contributing an estimated 0.9 Tg N2O–N yr−1 in 2000. Soils are key sites for denitrification and are much more important than groundwater and riparian zones in controlling the N flow to rivers and the oceans. PMID:23713114

  10. Potential N2O Emissions from the Tanks of Bromeliads Suggest an Additional Source of N2O in the Neotropics.

    PubMed

    Suleiman, Marcel; Brandt, Franziska B; Brenzinger, Kristof; Martinson, Guntars O; Braker, Gesche

    2016-12-06

    We studied the propensity of the tank bromeliad Werauhia gladioliflora to emit the greenhouse gas nitrous oxide (N2O) at current and at increased N deposition levels in the range of predicted future scenarios. Potential production rates and net accumulation of N2O from tank substrate corresponded to N availability. N2O was produced in excess at all N levels due to a low level of N2O reductase activity which agreed well with a low abundance of N2O reducers compared to nitrite reducers. Transcriptional activation, however, indicated that expression of denitrification genes may be enhanced with increasing N supply eventually leading to more efficient N2O turnover with potential for adaptation of denitrifier communities to higher N levels. Our findings indicate that tank bromeliads may constitute a novel source of N2O in Neotropical forest canopies but further studies are required to understand the size and significance of in situ N2O fluxes from tank bromeliads to the environment.

  11. Modeling N2O Emissions From Temperate Agroecosystems: A Literature Review Using Monte Carlo Sampling

    NASA Astrophysics Data System (ADS)

    Tonitto, C.

    2006-12-01

    In this work, we model annual N2O flux based on field experiments in temperate agroecosystems reported in the literature. Understanding potential N2O flux as a consequence of ecosystem management is important for mitigating global change. While loss of excess N as N2 has no environmental consequences, loss as N2O contributes to the greenhouse effect; over a 100 year time horizon N2O has 310 times the global warming potential (GWP) of CO2. Nitrogen trace gas flux remains difficult to accurately quantify under field conditions due to temporal and spatial limitations of sampling. Trace gas measurement techniques often rely on small chambers sampled at regular intervals. This measurement scheme can undersample stochastic events, such as high precipitation, which correspond to periods of high N trace gas flux. We apply Monte Carlo sampling of field measurements to project N2O losses under different crops and soil textures. Three statistical models are compared: 1) annual N2O flux as a function of process rates derived from temporally aggregated field observations, 2) annual N2O flux incorporating the probability of precipitation events, and 3) annual N2O flux as a function of crop growth. Using the temporally aggregated model, predicted annual N2O flux was highest for corn and wheat, which receive higher fertilizer inputs relative to barley and ryegrass. Within a cropping system, clayey soil textures resulted in the highest N2O flux. The incorporation of precipitation events in the model has the greatest effect on clayey soils. Relative to the aggregated model the inclusion of precipitation events changed predicted mean annual N2O flux from 31 to 49 kg N ha-1 for corn grown on clay loam and shifted the 75% confidence interval (CI) from 20-42 to 38-61 kg N ha-1. In contrast, comparisons between the aggregated and precipitation event models resulted in indistinguishable predictions of mean annual N2O loss for corn grown on silty loam and loam soils. Similarly, application

  12. Tracing changes of N2O emission pathways in a permanent grassland under elevated atmospheric CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Gorenflo, Andre; Moser, Gerald; Brenzinger, Kristof; Elias, Dafydd; McNamara, Neill; Clough, Tim; Maček, Irena; Vodnik, Dominik; Braker, Gesche; Schimmelpfennig, Sonja; Gerstner, Judith; Müller, Christoph

    2015-04-01

    The increase of greenhouse gases (GHG) in the atmosphere is of concern due to its effect on global temperatures. Nitrous oxide (N2O) with a Global Warming Potential of 298 over a 100 year period is of particular concern because strong feedback effects of elevated atmospheric CO2 on N2O emissions have been observed. However, so far the changes in processes which are responsible for such a feedback effect are only poorly understood. Our study was carried out in situ in a long-term Free Air Carbon dioxide Enrichment (FACE) study on permanent grassland at atmospheric CO2 concentrations 20% above ambient which expected at the middle of this century. We performed an in situ 15N tracing with differentially labelled NH4NO3 to trace the main N2O emission pathways. Over a period of more than one year we monitored at least weakly the N2O emissions with the closed chamber technique and analyzed the 15N signature of the N2O. The observed gaseous emissions under ambient and elevated atmospheric CO2 were associated with the observed gross N transformations and the microbial activities to identify the main emission pathways under ambient and elevated CO2.

  13. Bioenergy residues applied as soil amendments: N2O emissions and C sequestration potential

    NASA Astrophysics Data System (ADS)

    Cayuela, M.; Kuikman, P.; Oenema, O.; Bakker, R.; van Groenigen, J.

    2009-12-01

    most stable residues with the lowest CO2 loss between 0.5 and 5.8 % of total added C. Regarding N2O emissions, first generation biofuel residues led to the highest total N2O emissions (between 2.5 - 6.0% of added N). Second generation biofuel residues emitted between 1.0-2.0% of added N, whereas anaerobic digestates led to emissions lower than 1% of added N. The two biochars used in this study led to negative N2O emissions, i.e. lower than the blank soil. We conclude that, at least in the short term, the effects of biofuel residues on the combined greenhouse gas balance of the soil ranges from beneficial (biochar) via mixed (digestates, second generation biofuels) to manifestly detrimental (first generation biofuels). These effects should be taken into account in life cycle analyses of biofuel production.

  14. Constraining N2O emissions over the last century by firn air isotope measurements in both hemispheres

    NASA Astrophysics Data System (ADS)

    Prokopiou, Markella; Sapart, Celia; Martinerie, Patricia; Witrant, Emmanuel; Ishijima, Kentaro; Magand, Sophie; Kaiser, Jan; van de Wal, Roderik; Röckmann, Thomas

    2014-05-01

    N2O is a greenhouse gas that it is responsible for increased radiative forcing of the climate system. In addition to this, it is primarily destroyed in the stratosphere providing an important source of NOx, which in turn plays an important role in ozone depletion. Large uncertainties remain as to the actual strength of the individual sources of N2O. Knowledge of the historical record, of the temporal evolution of N2O emissions, can provide insight on how its sources and sinks altered during the industrial period. Data from air trapped in firn enables us to better determine the source/sink strength emissions over time. In this study we analyze firn measurements on 15N, 18O and position dependent 15N isotopic composition of N2O, from both hemispheres, combining new and previously published data, in order to constrain the N2O budget. From the Northern Hemisphere we use data from North Greenland Ice core Project (NGRIP) and North Eemian Ice core Project (NEEM) and for the Southern Hemisphere we use data from Berkner Island (BI), Dronning Maud Land (DML) and Dome Concordia (DOME C). Results show that the isotopic composition of 15N, 18O of N2O is presently more depleted which indicates a strong depleting source contribution probably originating from agricultural activities. The LGGE-GIPSA firn air diffusion model allows single site reconstructions, as well as using all data together in a multi-site inversion, in order to reconstruct the temporal evolution of N2O and its isotopic composition. We investigate the consistency between the different datasets and present a best-guess isotope history based on the firn air data. A simple two-box atmospheric model is applied in order to simulate the N2O atmospheric contribution from different sources and sinks.

  15. Footprint methods to separate N2O emission rates from adjacent paddock areas

    NASA Astrophysics Data System (ADS)

    Mukherjee, Sandipan; McMillan, Andrew M. S.; Sturman, Andrew P.; Harvey, Mike J.; Laubach, Johannes

    2015-03-01

    Using micrometeorological techniques to measure greenhouse gas emissions from differently treated adjacent plots is a promising avenue to verify the effect of mitigation strategies at the field scale. In pursuing such an approach, it is crucial to accurately characterize the source area of the fluxes measured at each sampling point. Hence, a comprehensive footprint analysis method is required so that emission rates can be obtained for a specific field within a biochemically heterogeneous area. In this study, a footprint analysis method is developed to estimate the emission for an experiment where the flux of N2O is measured from several control and treated plots. The emission rate of an individual plot is estimated using an inverse footprint fraction approach where the footprint fractions are obtained from an analytical footprint model. A numerical solution for obtaining the background flux for such a multiplot measurement system is also provided. Results of the footprint analysis method are assessed, first, by comparing footprint fractions obtained from both an analytical footprint model and a "forward" simulation of a backward Lagrangian stochastic (bLs) model; and second, by comparing the emission rates of a control plot obtained from the footprint analysis method and from the "backward" simulation of the bLs model. It is found that the analytical footprint fractions compare well with the values obtained from the bLs model (correlation coefficient of 0.58 and 0.66 within p value <0.001). An average of 4.3 % of the measured fluxes is found to be contributed by sources outside the measured area and, excluding this outside area contribution to the measured flux, footprint corrected emission rates within the defined domain are found to increase by 2.1 to 5.8 % of the measured flux. Also, the proposed method of emission rate estimation is found to work well under a wide range of atmospheric stability.

  16. Nitrous oxide emission budgets and land-use-driven hotspots for organic soils in Europe

    NASA Astrophysics Data System (ADS)

    Leppelt, T.; Dechow, R.; Gebbert, S.; Freibauer, A.; Lohila, A.; Augustin, J.; Drösler, M.; Fiedler, S.; Glatzel, S.; Höper, H.; Järveoja, J.; Lærke, P. E.; Maljanen, M.; Mander, Ü.; Mäkiranta, P.; Minkkinen, K.; Ojanen, P.; Regina, K.; Strömgren, M.

    2014-12-01

    Organic soils are a main source of direct emissions of nitrous oxide (N2O), an important greenhouse gas (GHG). Observed N2O emissions from organic soils are highly variable in space and time, which causes high uncertainties in national emission inventories. Those uncertainties could be reduced when relating the upscaling process to a priori-identified key drivers by using available N2O observations from plot scale in empirical approaches. We used the empirical fuzzy modelling approach MODE to identify main drivers for N2O and utilize them to predict the spatial emission pattern of European organic soils. We conducted a meta-study with a total amount of 659 annual N2O measurements, which was used to derive separate models for different land use types. We applied our models to available, spatially explicit input driver maps to upscale N2O emissions at European level and compared the inventory with recently published IPCC emission factors. The final statistical models explained up to 60% of the N2O variance. Our study results showed that cropland and grasslands emitted the highest N2O fluxes 0.98 ± 1.08 and 0.58 ± 1.03 g N2O-N m-2 a-1, respectively. High fluxes from cropland sites were mainly controlled by low soil pH value and deep-drained groundwater tables. Grassland hotspot emissions were strongly related to high amount of N-fertilizer inputs and warmer winter temperatures. In contrast, N2O fluxes from natural peatlands were predominantly low (0.07 ± 0.27 g N2O-N m-2 a-1) and we found no relationship with the tested drivers. The total inventory for direct N2O emissions from organic soils in Europe amount up to 149.5 Gg N2O-N a-1, which also included fluxes from forest and peat extraction sites and exceeds the inventory calculated by IPCC emission factors of 87.4 Gg N2O-N a-1. N2O emissions from organic soils represent up to 13% of total European N2O emissions reported in the European Union (EU) greenhouse gas inventory of 2011 from only 7% of the EU area

  17. CO2 and N2O emissions from Lou soils of greenhouse tomato fields under aerated irrigation

    NASA Astrophysics Data System (ADS)

    Hou, Huijing; Chen, Hui; Cai, Huanjie; Yang, Fan; Li, Dan; Wang, Fangtong

    2016-05-01

    The change of O2 content in soil caused by aerated irrigation (AI) must inevitably affect the production and emissions of CO2 and N2O from soils. This paper described in-situ observation of CO2 and N2O emissions from AI soils with static chamber-GC technique, in order to reveal the effects of AI on CO2 and N2O emissions from soils of greenhouse tomato fields in autumn-winter season. CO2 and N2O emissions from AI soils mainly concentrated in the blooming and fruit setting period compared to other periods. AI increased cumulative emissions of CO2 and N2O by 11.8% (p = 0.394) and 10.0% (p = 0.480), respectively, compared to the control. The integrative global warming potential of CO2 and N2O on a 100-year horizon for the AI treatment was 6430.60 kg ha-1, increased by 11.7% compared with that for the control (p = 0.356). Both the emissions of CO2 and N2O from AI soils had the exponential positive correlation with soil water-filled pore space (WFPS). The highest peak of CO2 and N2O fluxes from AI soils was observed at 46.7% and 47.5% WFPS, with WFPS ranging from 43.3% to 51.5% and from 45.6% to 52.3% during the whole growth stage, respectively. In addition, the average yield for the AI treatment (34.52 t ha-1) was significantly greater (17.4%) compared with that of the control (p = 0.018). These results suggest that AI do not significantly increase the integrative greenhouse effect caused by CO2 and N2O from soils of greenhouse tomato fields, but significantly increase the tomato yield. The research results provide certain theoretical foundation and scientific basis for accurately evaluating the farmland ecological effect of AI technique.

  18. Climate, duration, and N placement determine N2O emissions in reduced tillage systems: a meta-analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    No-tillage management is being promoted in agro-ecosystems to reduce erosion and sequester additional soil C. The impact of no tillage on N2O emissions, however, has been variable with increases as well as decreases in emissions. Here we report on the short and long term impact of tillage operations...

  19. Mechanism study on the influence of in situ SOx removal on N2O emission in CFB boiler

    NASA Astrophysics Data System (ADS)

    Wu, Lingnan; Qin, Wu; Hu, Xiaoying; Dong, Changqing; Yang, Yongping

    2015-04-01

    The influence of in situ deSOx process on N2O emission in CFB boiler was studied using density functional theory calculations. The competitive adsorption of SO2 and N2O on pure CaO (1 0 0) surface was first studied and the reaction priority was determined. Results showed that SO2 was more likely to adsorb on CaO (1 0 0) surface O anion site, which hindered the catalytic decomposition of N2O on CaO (1 0 0) surface and sulfurized the CaO (1 0 0) surface under reducing atmosphere. Then a partially sulfurized CaO (1 0 0) surface was established to study the catalytic activity of deSOx reaction intermediate on N2O decomposition. The O atom transfer process and the surface recovery process were two key steps for N2O decomposition and the rate-determining step was the latter one. The sulfurization of the surface could deactivate its catalytic activity on N2O decomposition compared with pure CaO (1 0 0) surface but it was still better than that of pure CaS (1 0 0) surface. The free Gibbs energy was calculated to incorporate the temperature dependence of respective reactions. When temperature was higher than 373 K, the surface recovery was more likely to proceed via the LH route.

  20. Mechanistic approach to understand increased N2O emission followed by biochar application to the organic poor field soil

    NASA Astrophysics Data System (ADS)

    Yoo, G.; Lee, Y.; Seo, J.; Kim, J.; Kim, Y.

    2015-12-01

    Biochar, which is a by-product of pyrolysis, is widely accepted as a climate change mitigation strategy if it is applied to soils. A lot of researches have reported that application of biochar reduced the emission of N2O due to better aeration and increased pH. However, in the dry, organic poor, and heavily fertilized Korean field soil, we observed rather an increase in N2O emission in our previous researches. To explain this inconsistent trend, we conducted a research investigating the mechanisms of N2O emission. The main mechanisms of N2O emission from soils are nitrification and denitrification, among which we exclude the possibility of denitrification process because the soil water condition at our sampling dates was dry. To confirm our assumption that the increased N2O emission from the soil is mainly from the enhanced nitrification due to biochar addition, we used the nitrification inhibitor (DCD: Dicyandiamide). The experiment was performed in the pepper field located in Gyeonggi-do, Korea where we already observed an increase in N2O emission followed by biochar amendment in the previous year. Treatments include the control, biochar treatment (BC, 2 ton ha-1), DCD treatment (DCD, 10% of N fertilizer w/w), and biochar and DCD co-treatment (BC+DCD). All the treatments were received with N:P2O5:K2O (225 : 112 : 149 kg ha-1). Daily average of N2O emission rate was increased in the BC treatment by 154% and the emission was reduced to the control level in the BC+DCD treatment. From this result, we could confirm that the increased N2O emission from the biochar application is from the nitrification process. The field experiment will be prolonged to Aug 2015 and for the further analysis, the basic soil physicochemical parameters (TC, TN, pH, hot water extractable C, available N) and microbial parameters (fluorescein diacetate hydrolysis assay, microbial biomass C, and assay of nitrifiers) will be measured.

  1. Post-harvest N2O emissions were not affected by various types of oilseed straw incorporated into soil

    NASA Astrophysics Data System (ADS)

    Köbke, Sarah; Senbayram, Mehmet; Hegewald, Hannes; Christen, Olaf; Dittert, Klaus

    2015-04-01

    Oilseed rape post-harvest N2O emissions are seen highly critical as so far they are considered as one of the most crucial drawbacks in climate-saving bioenergy production systems. N2O emissions may substantially counterbalance the intended savings in CO2 emissions. Carbon-rich crop residues in conjunction with residual soil nitrate are seen as a key driver since they may serve as energy source for denitrification and, they may alter soil-borne N2O emissions. As oilseed rape straw is known to have high N/C ratio compared to other crop residues, its soil incorporation may specifically trigger post-harvest N2O emissions. Therefore, the aim of the present study was to determine post-harvest N2O emissions in soils amended with various types of oilseed rape straw (with different N/C ratio) and barley straw in field and incubation experiments. In the incubation experiment, oilseed rape or 15N labelled barley straw were mixed with soil at a rate of 1.3 t DM ha-1 and studied for 43 days. Treatments consisted of non-treated control soil (CK), 15N labelled barley straw (BST), oilseed rape straw (RST), 15N labelled barley straw + N (BST+N), or oilseed rape straw + N (RST+N). N fertilizer was applied to the soil surface as ammonium-nitrate at a rate of 100 kg N ha-1 and soil moisture was adjusted to 80% water-holding capacity. In the field experiment, during the vegetation period 15N labelled fertilizer (15NH415NO3) was used to generate 15N labelled oilseed rape straw (up to 5 at%). Here, the three fertilizer treatments consisted of 5 kg N ha-1 (RST-5), 150 kg N ha-1 (RST-150) and 180 kg N ha-1 (RST-180). Post-harvest N2O emissions were determined during the period of August 2013 to February 2014 by using static flux chambers. In the incubation trial, cumulative N2O emissions were 5, 29, 40 g N2O-N ha-1 148 days-1 in non-fertilized control, BST and RST treatments, respectively. Here, emissions were slightly higher in RST than BST (p

  2. [N2O emission from an intensively managed greenhouse vegetable field in Nanjing suburb, Jiangsu Province of East China].

    PubMed

    Jia, Jun-Xiang; Zhang, Man; Xiong, Zheng-Qin; Li, Ye

    2012-03-01

    By using static opaque chamber and gas chromatography, this paper studied the dynamic changes of N2O fluxes and their relationships with soil temperature, soil moisture content, and soil nitrate and ammonium contents in an intensively managed greenhouse celery-Tung choy-Bok choy-amaranth rotation field and in a bare fallow land in Nanjing suburb. The cumulative N2O emission from the rotation vegetable field was as high as 137.2 kg N x hm(-2), being significantly higher than that from the bare fallow land (29.2 kg N x hm(-2)), and the N2O-N emission factor of the rotation vegetable field ecosystem was up to 4.6%. In the rotation field, the planting of Tung choy had the greatest contribution to the annual cumulative N2O emission, occupying 53.5% of the total, followed by the planting of Bok choy (31.9%), celery field (4.5%), and amaranth (4.8%). The N2O flux of the rotation field had significant positive correlation with soil temperature, the Q10 being 2.80, but no significant correlations with soil moisture content and soil nitrate and ammonium contents.

  3. Improving estimates of N2O emissions for western and central Europe using a Bayesian inversion approach

    NASA Astrophysics Data System (ADS)

    Thompson, R. L.; Gerbig, C.; Roedenbeck, C.; Heimann, M.

    2009-04-01

    The nitrous oxide (N2O) mixing ratio has been increasing in the atmosphere since the industrial revolution, from 270 ppb in 1750 to 320 ppb in 2007 with a steady growth rate of around 0.26% since the early 1980's. The increase in N2O is worrisome for two main reasons. First, it is a greenhouse gas; this means that its atmospheric increase translates to an enhancement in radiative forcing of 0.16 ± 0.02 Wm-2 making it currently the fourth most important long-lived greenhouse gas and is predicted to soon overtake CFC's to become the third most important. Second, it plays an important role in stratospheric ozone chemistry. Human activities are the primary cause of the atmospheric N2O increase. The largest anthropogenic source of N2O is from the use of N-fertilizers in agriculture but fossil fuel combustion and industrial processes, such as adipic and nitric acid production, are also important. We present a Bayesian inversion approach for estimating N2O fluxes over central and western Europe using high frequency in-situ concentration data from the Ochsenkopf tall tower (50 °01′N, 11 °48′, 1022 masl). For the inversion, we employ a Lagrangian-type transport model, STILT, which provides source-receptor relationships at 10 km using ECMWF meteorological data. The a priori flux estimates used were from IER, for anthropogenic, and GEIA, for natural fluxes. N2O fluxes were retrieved monthly at 2 x 2 degree spatial resolution for 2007. The retrieved N2O fluxes showed significantly more spatial heterogeneity than in the a priori field and considerable seasonal variability. The timing of peak emissions was different for different regions but in general the months with the strongest emissions were May and August. Overall, the retrieved flux (anthropogenic and natural) was lower than in the a priori field.

  4. Optimum sampling time and frequency for measuring N2O emissions from a rain-fed cereal cropping system.

    PubMed

    Reeves, Steven; Wang, Weijin

    2015-10-15

    Annual cumulative nitrous oxide (N2O) emissions from soil have historically been calculated from intermittent data measured manually via the static chamber method. The temporal variability in emissions, both diurnally and between days, introduces uncertainty into the up-scaling of static chamber data. This study assessed the most appropriate time of the day to sample and the best sampling frequency to ensure reliable estimates of annual cumulative emissions. Sub-daily N2O emissions were measured using automatic gas sampling chambers over three years in a sub-tropical cereal crop system. The sub-daily dataset was divided into eight time periods per day to assess the best sampling time of the day. Daily mean N2O emissions were subsampled from the dataset to simulate different sampling frequencies, including pre-set and rainfall-based scenarios. Annual cumulative N2O emissions were calculated for these scenarios and compared to the 'actual' annual cumulative emissions. The results demonstrated that manual sampling between mid-morning (09:00) and midday (12:00), and late evening (21:00) and midnight (24:00) best approximated the daily mean N2O emission. Factoring in the need to sample during daylight hours, gas sampling from mid-morning to midday was the most appropriate sampling time. Overall, triweekly sampling provided the most accurate estimate (± 4% error) of annual cumulative N2O emissions, but was undesirable due to its labour intensive high sampling frequency. Weekly sampling with triweekly sampling in the two weeks following rainfall events was the most efficient sampling schedule, as it had similar accuracy (± 5% error) to the triweekly sampling, the smallest variability in outcomes and approximately half the sampling times of triweekly sampling. Inter-annual rainfall variability affected the accuracy and variability of estimations of annual cumulative emissions, but did not affect the overall trends in sampling frequency accuracy. This study demonstrated

  5. Use of Stable Isotope Techniques to Differentiate Between Processes Contributing to N2O Emissions From Soils

    NASA Astrophysics Data System (ADS)

    Baggs, E. M.; Wrage, N.; Richter, M.; Shaw, E. J.

    2004-12-01

    N2O is produced biologically in soils during denitrification, nitrification, nitrifier denitrification and dissimilatory reduction of nitrate to ammonium (DNRA). These processes may occur simultaneously in different microsites of the same soil but there is often uncertainty associated with which process is predominantly contributing to measured emissions. Recent advances in stable isotope techniques facilitating direct measurement of 15N-N2O and natural abundance 15N218O allows determination of the source of N2O and an accurate quantification (15N enrichment) or estimation in natural systems (natural abundance) of emissions from each source. Here we will introduce the techniques we have developed and present selected results from studies where they have been applied. We are able to directly determine the respective contributions of nitrification and denitrification in soil by measurement of 15N-N2O after application of (a) 15NH415NO3 and (b) 14NH415NO3 (10 atom % excess 15N) to different replicates, where 15N-N2O measured from (b) replicates are attributed to denitrification and 15N-N2O measured from (a) replicates minus 15N-N2O from (b) replicates are attributed to nitrification, provided that dissimilatory 15NO3- reduction or immobilisation and remineralisation of 15NO3- are negligible. Addition of C2H2 (0.01 % v/v) to inhibit autotrophic ammonia oxidation enables us to differentiate between autotrophic and heterotrophic nitrified N2O. We have shown heterotrophic nitrification to be contributing to N2O emissions from a clay loam soil at 50 % water-filled pore space (WFPS) and evidence for aerobic denitrification at 20 % WFPS after application of 200 kg N ha-1. We have further developed this technique to determine the contribution of nitrifier denitrification by addition of 100 kPa O2 to inhibit anaerobic processes, and derivation of the nitrifier denitrification emission on a difference basis. In culture studies we have quantified 15N-N2O production during

  6. Modelling site-specific N2O emission factors from Austrian agricultural soils for targeted mitigation measures (NitroAustria)

    NASA Astrophysics Data System (ADS)

    Amon, Barbara; Zechmeister-Boltenstern, Sophie; Kasper, Martina; Foldal, Cecilie; Schiefer, Jasmin; Kitzler, Barbara; Schwarzl, Bettina; Zethner, Gerhard; Anderl, Michael; Sedy, Katrin; Gaugitsch, Helmut; Dersch, Georg; Baumgarten, Andreas; Haas, Edwin; Kiese, Ralf

    2016-04-01

    Results from a previous project "FarmClim" highlight that the IPCC default emission factor is not able to reflect region specific N2O emissions from Austrian arable soils. The methodology is limited in identifying hot spots and hot moments of N2O emissions. When estimations are based on default emission factors no recommendations can be given on optimisation measures that would lead to a reduction of soil N2O emissions. The better the knowledge is about Nitrogen and Carbon budgets in Austrian agricultural managed soils the better the situation can be reflected in the Austrian GHG emission inventory calculations. Therefore national and regionally modelled emission factors should improve the evidence for national deviation from the IPCC default emission factors and reduce the uncertainties. The overall aim of NitroAustria is to identify the drivers for N2O emissions on a regional basis taking different soil types, climate, and agricultural management into account. We use the LandscapeDNDC model to update the N2O emission factors for N fertilizer and animal manure applied to soils. Key regions in Austria were selected and region specific N2O emissions calculated. The model runs at sub-daily time steps and uses data such as maximum and minimum air temperature, precipitation, radiation, and wind speed as meteorological drivers. Further input data are used to reflect agricultural management practices, e.g., planting/harvesting, tillage, fertilizer application, irrigation and information on soil and vegetation properties for site characterization and model initialization. While at site scale, arable management data (crop cultivation, rotations, timings etc.) is obtained by experimental data from field trials or observations, at regional scale such data need to be generated using region specific proxy data such as land use and management statistics, crop cultivations and yields, crop rotations, fertilizer sales, manure resulting from livestock units etc. The farming

  7. Legumes or nitrification inhibitors to reduce N2O emissions in subtropical cereal cropping systems? A simulation study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The DAYCENT biogeochemical model was used to investigate how the use of fertilisers coated with nitrification inhibitors and the introduction of legumes in the crop rotation can affect subtropical cereal production and N2O emissions. The model was validated using comprehensive multi-seasonal, high-f...

  8. Potential impact of atmospheric N deposition on soil N2O emission varies with different soil N regimes

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Yi, M.; Koike, T.

    2011-12-01

    Future increases in nitrogen (N) deposition has the potential to change belowground nutrient dynamics, especially N cycle, and thereby can alter the soil-atmosphere exchange of nitrous oxide (N2O) which is one of the major greenhouse gases. Moreover, we considered that their effect on soil N2O emission varies with different soil N levels because N2O is a by-product of the biological nitrification process in aerobic soil environments and of the biological denitrification process in anaerobic soil environments. To understand the changes in soil N2O flux under different soil N, we carried out simulated N addition experiment in three-year-old hybrid larch F1 (F1: Larix gmelinii var. japonica × Larix kaempferi) plantation during two growing seasons 2008 - 2009. The hybrid larch F1 was developed to make up for several problems of larch species, e.g. a high susceptibility to disease or grazing damage by insects and fungi, and a large number of this seedlings are planted recently in northern Japan. Based on soil analysis, we selected two sites which have different soil N concentration, i.e. low-N and high-N concentrations. Nitrogen input was initiated at the onset of our experiment, and included four treatments with four replications: Low-N soil + Zero-N control, Low-N soil + 50 kg-N addition, High-N soil + Zero-N control and High-N soil + 50 kg-N addition. The N was added as ammonium nitrate (NH4NO3) solution distributed in four occasions during each growing season. Gas and soil samples were taken from each plot on ten occasions at a time during each growing season. Collected N2O concentrations were determined by a gas chromatograph (GC-14B; Shimadzu, Kyoto, Japan) equipped with an electron capture detector, while total-N and inorganic-N concentrations were obtained by a NC analyzer (Sumigraph NC-1000; Sumica Chemical Analysis Service Ltd., Osaka, Japan) and an auto analyzer (AACS-4; BL-TEC Inc., Osaka, Japan), respectively. Before the N addition, initial total-N in High

  9. N2O and N2 emissions from contrasting soil environments - interactive effects of soil nitrogen, hydrology and microbial communities

    NASA Astrophysics Data System (ADS)

    Christiansen, Jesper; Elberling, Bo; Ribbons, Relena; Hedo, Javier; José Fernández Alonso, Maria; Krych, Lukasz; Sandris Nielsen, Dennis; Kitzler, Barbara

    2016-04-01

    Reactive nitrogen (N) in the environment has doubled relative to the natural global N cycle with consequences for biogeochemical cycling of soil N. Also, climate change is expected to alter precipitation patterns and increase soil temperatures which in Arctic environments may accelerate permafrost thawing. The combination of changes in the soil N cycle and hydrological regimes may alter microbial transformations of soil N with unknown impacts on N2O and N2 emissions from temperate and Arctic soils. We present the first results of soil N2O and N2 emissions, chemistry and microbial communities over soil hydrological gradients (upslope, intermediate and wet) across a global N deposition gradient. The global gradient covered an N-limited high Arctic tundra (Zackenberg-ZA), a pacific temperate rain forest (Vancouver Island-VI) and an N saturated forest in Austria (Klausenleopoldsdorf-KL). The N2O and N2 emissions were measured from intact cores at field moisture in a He-atmosphere system. Extractable NH4+ and NO3-, organic and microbial C and N and potential enzyme-activities were determined on soil samples. Soil genomic DNA was subjected to MiSeq-based tag-encoded 16S rRNA and ITS gene amplicon sequencing for the bacterial and fungal community structure. Similar soil moisture levels were observed for the upslope, intermediate and wet locations at ZA, VI and KL, respectively. Extractable NO3- was highest at the N rich KL and lowest at ZA and showed no trend with soil moisture similar to NH4+. At ZA and VI soil NH4+ was higher than NO3- indicating a tighter N cycling. N2O emissions increased with soil moisture at all sites. The N2O emissions for the wet locations ranked similarly to NO3- with the largest response to soil moisture at KL. N2 emissions were remarkably similar across the sites and increased with soil wetness. Microbial C and N also increased with soil moisture and were overall lowest at the N rich KL site. The potential activity of protease enzyme was site

  10. 40 CFR Table Aa-2 to Subpart Aa of... - Kraft Lime Kiln and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Kraft Lime Kiln and Calciner Emissions... and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O Fuel Fossil fuel-based emissions factors (kg/mmBtu HHV) Kraft lime kilns CH4 N2O Kraft calciners CH4 N2O Residual Oil 0.0003 Distillate...

  11. 40 CFR Table Aa-2 to Subpart Aa of... - Kraft Lime Kiln and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Kraft Lime Kiln and Calciner Emissions... and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O Fuel Fossil fuel-based emissions factors (kg/mmBtu HHV) Kraft lime kilns CH4 N2O Kraft calciners CH4 N2O Residual Oil 0.0003 Distillate...

  12. 40 CFR Table Aa-2 to Subpart Aa of... - Kraft Lime Kiln and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Kraft Lime Kiln and Calciner Emissions... and Calciner Emissions Factors for Fossil Fuel-Based CH4 and N2O Fuel Fossil fuel-based emissions factors (kg/mmBtu HHV) Kraft lime kilns CH4 N2O Kraft calciners CH4 N2O Residual Oil 0.0003 Distillate...

  13. Development of an Open-Path N2O Flux Measurement System for Understanding Agricultural and Soil Emissions

    NASA Astrophysics Data System (ADS)

    Gomez, A.; Silver, J.; Massick, S.; Ochoa, E.; Stanton, A. C.

    2015-12-01

    Nitrous oxide is the third most important greenhouse gas, with an atmospheric lifetime of ~114 years and a global warming impact ~300 times greater than that of CO2. The main cause of nitrous oxide's atmospheric increase is anthropogenic emissions, and over 80% of the current global anthropogenic flux is related to agriculture, including associated land-use change. An accurate assessment of N2O emissions from agriculture is vital not only for understanding the global N2O balance and its impact on climate and also for designing crop systems with lower GHG emissions. This work focuses on the early development of an open path N2O instrument for field deployment, based on quantum cascade laser absorption. With a targeted precision of 0.1 ppb at 10 Hz, this instrument will enable eddy covariance measurements to determine vertical fluxes of N2O. Details of the instrument design, which emphasizes ruggedness and high thermal stability, will be presented along with initial results from outdoor testing of the instrument.

  14. Effect of different agronomic practises on greenhouse gas emissions, especially N2O and nutrient cycling

    NASA Astrophysics Data System (ADS)

    Koal, Philipp; Schilling, Rolf; Gerl, Georg; Pritsch, Karin; Munch, Jean Charles

    2014-05-01

    In order to achieve a reduction of greenhouse gas emissions, management practises need to be adapted by implementing sustainable land use. At first, reliable field data are required to assess the effect of different farming practises on greenhouse gas budgets. The conducted field experiment covers and compares two main aspects of agricultural management, namely an organic farming system and an integrated farming system, implementing additionally the effects of diverse tillage systems and fertilisation practises. Furthermore, the analysis of the alterable biological, physical and chemical soil properties enables a link between the impact of different management systems on greenhouse gas emissions and the monitored cycle of matter, especially the nitrogen cycle. Measurements were carried out on long-term field trials at the Research Farm Scheyern located in a Tertiary hilly landscape approximately 40 km north of Munich (South Germany). The long-term field trials of the organic and integrated farming system were started in 1992. Since then, parcels in a field (each around 0,2-0,4 ha) with a particular interior plot set-up have been conducted. So the 20 years impacts of different tillage and fertilisation practises on soil properties including trace gases were examined. Fluxes of CH4, N2O and CO2 are monitored since 2007 for the integrated farming system trial and since 2012 for the organic farming system trial using an automated system which consists of chambers (per point: 4 chambers, each covering 0,4 m2 area) with a motor-driven lid, an automated gas sampling unit, an on-line gas chromatographic analysis system, and a control and data logging unit (Flessa et al. 2002). Each chamber is sampled 3-4 times in 24 hours. The main outcomes are the analysis of temporal and spatial dynamics of greenhouse gas fluxes as influenced by management practice events (fertilisation and tillage) and weather effects (drying-rewetting, freezing-thawing, intense rainfall and dry periods

  15. Scheduling fertilizer applications as a simple mitigation option for reducing N2O emission in intensively managed mown grassland systems

    NASA Astrophysics Data System (ADS)

    Neftel, Albrecht; Calanca, Pierluigi; Felber, Raphael; Grant, Robert; Conen, Franz

    2014-05-01

    A general principle in all proposed N2O mitigation options is the fertilization according to plants' requirements. Meanwhile the amount of N fertilization allowed is regulated in many countries. Due to the high pressure from food security and the need for economic efficiency the given limits are generally used up. In mown grassland systems a simple mitigation option is to optimize the timing of the fertilizer applications. Application of fertilizer, both organic manure and mineral fertilizer, is generally scheduled after each cut in a narrow time window. In practice, the delay between cut and fertilizer application is determined by weather conditions, management conditions and most important by the planning and experience of the individual farmer. Many field experiments have shown that enhanced N2O emissions tend to occur after cuts but before the application of fertilizer, especially when soils are characterized by a high WFPS. These findings suggest that the time of fertilizer application has an important implications for the N2O emission rate and that scheduling fertilization according to soil conditions might be a simple, cheap and efficient measure to mitigate N2O emissions. In this paper we report on results from a sensitivity analysis aiming at quantifying the effects of the timing of the fertilizer applications on N2O emissions from intensively managed, mown grasslands. Simulations for different time schedules were carried out with the comprehensive ecosystem model "ECOSYS" . To our knowledge this aspect has not been systematically investigated from a scientific point of view, but might have been always there within the experiences of attentive environmentally concerned farmers.

  16. Effects of agricultural practices on greenhouse gas emissions (N2O, CH4 and CO2) from corn fields

    NASA Astrophysics Data System (ADS)

    Hui, D.; Wang, J.; Jima, T.; Dennis, S.; Stockert, C.; Smart, D.; Bhattarai, S.; Brown, K.; Sammis, T.; Reddy, C.

    2012-12-01

    The United States is, by far, the largest producer of corn (Zea mays L.) in the world. Recent increases in fertilizer cost and concerns over global climate change have farmers and others interested in more efficient fertilization management and greenhouse gas emissions reductions. To seek the best management practices, we conducted field experiments during the 2012 growing season at Tennessee State University Agricultural Research and Demonstration Center in Nashville, TN. Six treatments were applied including regular URAN application [2 times], multiple URAN applications [4 times], denitrification inhibitor with regular URAN application, and chicken litter plus regular URAN application in no-tilled plots, and URAN application plus bio-char in tilled plots, all compared to regular URAN application in conventional tilled plots. Each treatment was replicated six times (blocks). We measured N2O, CO2 and CH4 emissions using a closed chamber method after rainfall events, fertilizer applications or every two weeks whichever was shorter. Corresponding soil NH4+-N and NO3--N, soil temperature and moisture were also measured during the gas sampling. Plant physiology and growth were measured about every two weeks. While preliminary results indicate that N2O and CO2 fluxes were significantly influenced by the agricultural practices on some days, particularly after rainfall events, CH4 flux was not influenced by the treatments during most of the days. Plots with bio-char showed significantly lower N2O emissions. We also measured N2O flux in a commercial corn field using the Eddy Covariance (EC) technique to ground verify the chamber based N2O emissions at the field scale. Results obtained with the EC technique seem comparable with the chamber method.

  17. Effects of Eriophorum vaginatum on N_{2}O emissions at a restored peatland

    NASA Astrophysics Data System (ADS)

    Brummell, Martin; Lazcano, Cristina; Strack, Maria

    2016-04-01

    Restoration of peatlands extracted for horticultural peat production includes both deliberate and accidental introduction of a wide range of plant species, including vascular plants and bryophytes. The roots of vascular plants provide a channel for the movement of greenhouse gases (GHG) including N2O in many soil ecosystems, and may stimulate production of N2O or have other effects via the release of root exudates that are then taken up by soil microorganisms such as heterotrophic denitrifiers. Here we carried out a field study in order to evaluate the effects of Eriophorum vaginatum, an abundant sedge at the harvested peatland at Seba Beach, Alberta, Canada, (53° 27'17.2"N 114° 52'52.0"W) where restoration efforts began in late 2012, and is the dominant ground cover in some areas. We hypothesized that E. vaginatum would increase net N2O production from peat compared to areas of bare peat or moss. We measured net GHG exchange for CO2, CH4, and N2O over one growing season (May-September 2015) using static chambers within this peatland to compare between plots containing E. vaginatum and plots lacking vascular plants. Plots were located along a transect of increasing water table, in order to discriminate between the effects of E. vaginatum and the prevailing hydrological conditions on N2O fluxes. Net fluxes of N2O from the peat to the atmosphere were observed throughout the experimental area, as well as fluxes in the opposite direction, in which the peat removed N2O from the atmosphere inside the chamber. Non-zero fluxes were highly variable in both occurrence and magnitude, though a small number of plots accounted for the majority of measured fluxes. Neither aboveground biomass of E. vaginatum nor its presence in a plot was correlated with either frequency or direction of N2O flux measurements. Other factors, such as water table fluctuations and temperature may be stronger drivers of these microbially-mediated processes than vegetation at this stage of the

  18. Plant species diversity reduces N2O but not CH4 emissions from constructed wetlands under high nitrogen levels.

    PubMed

    Han, Wenjuan; Shi, Mengmeng; Chang, Jie; Ren, Yuan; Xu, Ronghua; Zhang, Chongbang; Ge, Ying

    2017-02-01

    Constructed wetlands (CWs) have been widely used for treating wastewater. CWs also are the sources of greenhouse gas (GHG) due to high pollutant load. It has been reported that plant species diversity can enhance nitrogen (N) removal efficiency in CWs for treating wastewater. However, the influence of plant species diversity on GHG emissions from CWs in habitats with high N levels still lack research. This study established four species richness levels (1, 2, 3, 4) and 15 species compositions by using 75 simulated vertical flow CWs microcosms to investigate the effects of plant species diversity on the GHG emissions and N removal efficiency of CWs with a high N level. Results showed plant species richness reduced nitrous oxide (N2O) emission and N (NO3(-)-N, NH4(+)-N, and TIN) concentrations in wastewater, but had no effect on methane (CH4) emission. Especially, among the 15 compositions of plant species, the four-species mixture emitted the lowest N2O and had under-depletion of N (DminTIN < 0). The presence of Oenanthe javanica had a significantly negative effect on the N2O emission but had no effect on N removal efficiency. The presence of Rumex japonicus significantly reduced the N (NO3(-)-N and TIN) concentrations in wastewater but had no effect on the N2O and CH4 emissions. The N concentrations and GHG emissions in the community of R. japonicus × Phalaris arundinacea were as low as those in the four-species mixture. Assembling plant communities with relatively high species richness (four-species mixture) or particular composition (R. japonicus × P. arundinacea) could enhance the N removal efficiency and reduce the GHG emissions from CWs for treating wastewater with a high N level.

  19. Effect of fertilization on N2O emissions from a marginal soil used for perennial grass bioenergy production

    NASA Astrophysics Data System (ADS)

    Stoof, Cathelijne; Karim, Imtiaz; Mason, Cedric; Tadipatri, Dhanya; Cary, Ian; Crawford, Ryan; Hansen, Julie; Crawford, Jamie; Mayton, Hilary; Steenhuis, Tammo; Richards, Brian

    2014-05-01

    Marginal lands constitute the primary land base available for development of bioenergy feedstocks in New York and the northeastern USA. Many of these soils are marginal because seasonal wetness prevents profitable row crop cultivation, but they are potentially suitable for perennial bioenergy feedstocks like switchgrass. Using these frequently wet soils for bioenergy production has multiple environmental and socio-economic benefits, yet little is known about how sustainable this practice is regarding greenhouse gas emissions - particularly in relation to the application of fertilizers. In a 2.2-ha field study near Ithaca, NY, USA, we are therefore monitoring greenhouse gas production from marginal silty clay loam soils cultivated with switchgrass. Here, we present results of our 2013 monitoring campaign, in which we assessed the effect of surface-applied granular ammonium sulfate-fertilizer (0, 56 and 112 kg N/ha) on N2O emissions along a natural catena from organic matter-rich wet lowland soil to drier midslope and upslope soils with higher rock fragment content. Sampling was done at 1 /2-week intervals around fertilization in June extending to 3-week intervals around harvest in September, giving a total of 15 sampling events. Emissions were sampled in a factorial design using four replicate static chambers per plot, and soil moisture, soil temperature and perched water table depth was assessed likewise. As expected, N2O emissions increased with N-fertilizer application. This effect of fertilization was much stronger than the effect of soil type or slope position. The greatest N2O fluxes were observed a few days after fertilization; we will explore and present the effects of rainfall, air temperature, soil moisture and soil temperature as potential drivers of smaller peaks occurring post-fertilization. Since the non-fertilized plots had negligible N2O emissions while still producing switchgrass at 6 Mg/ha, unfertilized switchgrass production is naturally most

  20. Synthetic fertilizer management for China's cereal crops has reduced N2O emissions since the early 2000s.

    PubMed

    Sun, Wenjuan; Huang, Yao

    2012-01-01

    China has implemented a soil testing and fertilizer recommendation (STFR) program to reduce the over-usage of synthetic nitrogen (N) fertilizer on cereal crops since the late 1990 s. Using province scale datasets, we estimated an annual reduction rate of 2.5-5.1 kg N ha(-1) from 1998 to 2008 and improving grain yields, which were attributed to the balanced application of phosphate and potassium fertilization. Relative to the means for 1998-2000, the synthetic N fertilizer input and the corresponding N-induced N(2)O production in cereal crops were reduced by 22 ± 0.7 Tg N and 241 ± 4 Gg N(2)O-N in 2001-2008. Further investigation suggested that the N(2)O emission related to wheat and maize cultivation could be reduced by 32-43 Gg N(2)O-N per year in China (26%-41% of the emissions in 2008) if the STFR practice is implemented universally in the future.

  1. Soil trace gas emissions (CH4 and N2O) offset the CO2 uptake in poplar short rotation coppice

    NASA Astrophysics Data System (ADS)

    Zenone, Terenzio; Zona, Donatella; Gelfand, Iya; Gielen, Bert; camino serrano, Marta; Ceulemans, Reinhart

    2015-04-01

    The need for renewable energy sources will lead to a considerable expansion in the planting of dedicated fast-growing biomass crops across Europe. Among them poplar (Populus spp) is the most widely planted as short rotation coppice (SRC) and an increase in the surface area of large-scale SRC poplar plantations might thus be expected. In this study we report the greenhouse gas fluxes (GHG) of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) measured using the eddy covariance technique in a SRC plantation for bioenergy production during the period 2010-2013. The plantation was established in April 2010 on 18.4 ha of former agricultural land with a density of 8000 plants ha-1; the above-ground biomass was harvested on February 2012 and 2014.The whole GHG balance of the four years of the study was 1.90 (± 1.37) Mg CO2eq ha-1; this indicated that soil trace gas emissions offset the CO2 uptake by the plantation. CH4 and N2O almost equally contributed to offset the CO2 uptake of -5.28 (±0.67) Mg CO2eq ha-1 with an overall emission of 3.56 (± 0.35) Mg CO2eq ha-1 of N2O and of 3.53 (± 0.85) Mg CO2eq ha-1 of CH4. N2O emissions mostly occurred during a single peak a few months after the site was converted into SRC and represented 44% of the entire N2O loss during the entire study. Accurately capturing these emission events proved to be critical for correct estimates of the GHG balance. The self-organizing map (SOM) technique graphically showed the relationship between the CO2 fluxes and the principal environmental variables but failed to explain the variability of the soil trace gas emissions. The nitrogen content in the soil and the water table depth were the two drivers that best explained the variability in N2O and CH4 respectively. This study underlines the importance of the "non-CO2 GHG" on the overall balance as well as the impact of the harvest on the CO2 uptake rate. Further long-term investigations of soil trace gas emissions should also monitor the N

  2. Hormesis, hotspots and emissions trading.

    PubMed

    Wiener, Jonathan B

    2004-06-01

    Instrument choice--the comparison of technology standards, performance standards, taxes and tradable permits--has been a major topic in environmental law and environmental economics. Most analyses assume that emissions and health effects are positively and linearly related. If they are not, this complicates the instrument choice analysis. This article analyses the effects of a nonlinear dose-response function on instrument choice. In particular, it examines the effects of hormesis (high-dose harm but low-dose benefit) on the choice between fixed performance standards and tradable emissions permits. First, the article distinguishes the effects of hormesis from the effects of local emissions. Hormesis is an attribute of the dose-response or exposure-response relationship. Hotspots are an attribute of the emissions-exposure relationship. Some pollutants may be hormetic and cause local emissions-exposure effects; others may be hormetic without causing local emissions-exposure effects. It is only the local exposure effects of emissions that pose a problem for emissions trading. Secondly, the article shows that the conditions under which emissions trading would perform less well or even perversely under hormesis, depend on how stringent a level of protection is set. Only when the regulatory standard is set at the nadir of the hormetic curve would emissions trading be seriously perverse (assuming other restrictive conditions as well), and such a standard is unlikely. Moreover, the benefits of the overall programme may justify the risk of small perverse effects around this nadir. Thirdly, the article argues that hotspots can be of concern for two distinct reasons, harmfulness and fairness. Lastly, the paper argues that the solution to these problems may not be to abandon market-based incentive instruments and their cost-effectiveness gains, but to improve them further by moving from emissions trading and emissions taxes to risk trading and risk taxes. In short, the article

  3. DMPP-added nitrogen fertilizer affects soil N2O emission and microbial activity in Southern Italy

    NASA Astrophysics Data System (ADS)

    Vitale, Luca; De Marco, Anna; Maglione, Giuseppe; Polimeno, Franca; Di Tommasi, Paul; Magliulo, Vincenzo

    2014-05-01

    Arable sites contributes to global N2O emission due to massive utilization of nitrogen fertilizers. N2O derives from the biological processes such as nitrification and denitrification influenced by soil nitrogen availability. The use of nitrogen fertilizers added with nitrification inhibitors represents one among the proposed strategy to reduce soil N2O emission form arable sites. The aim of this work was to evaluate the effects of 3,4-dimethylphyrazole phosphate (DMPP), a nitrification inhibitor, on N2O emission and microbial activity of a soil cropped to potato in Southern Italy. The experiment was a randomized block design with two treatments applied and three replicates: control (C) and DMPP (Entec®, K+S Nitrogen) plots, both supplied with the same amount of ammonium nitrate. The nitrogen fertilizer was supplied in three events: at 0 Day After Sowing (DAS; 100 kg N ha-1), at 57 DAS (30 kg N ha-1), and at 71 DAS (30 kg N ha-1). Soil N2O emission was monitored by both dynamic and static chambers. Static chambers were located both on hills and furrows whereas dynamic chambers were located on furrows. Air samples were collected from chambers at different times and analysed by a gas chromatograph (SRI 8610C, Gas Chromatograph). Fluxes were estimated as a linear interpolation of N2O changes over a 30 min time. Microbial biomass and basal respiration were determined as CO2 evolution, analysed by means of an IRGA (Li6200, Licor), on 2 g of fresh soil over a 4h incubation time. Microbial biomass was determined by Substrate Induced Respiration method. Data show no statistical differences in N2O fluxes measured with either dynamic chambers between C and DMPP plots in studied period. However, after the first fertilization event, when the fertilizer was applied as 100 kg N ha-1, the average N2O fluxes measured with static chambers were higher in DMPP plots compared to C plots. In the same period, the microbial biomass significantly decreased in DMPP plots as compared to C

  4. Greenhouse Gas (CH4, CO2 and N2O) Emission Levels by Wastewater Treatment Plant (WWTP) Ponds in Brazil

    NASA Astrophysics Data System (ADS)

    Rossete, A. L. M.; Sundefeld Junior, G.; Aparicio, C.; Baldi, G. G.; Montes, C. R.; Piveli, R. P.; Melfi, A. J.

    2015-12-01

    This study measured greenhouse gas emissions (GHG) by Facultative Ponds on Wastewater Treatment Plants. The most studied GHGs include CO2, CH4and N2O. The level of GHG (CO2, CH4 and N2O) emissions by WWTPs in Australian-type stabilization ponds was measured in the city of Lins (22º21'S, 49º50'W), state of São Paulo (SP), Brazil. GHG collection was carried outusing a collection chamber installed at the center of the facultative pond's final third. The effluent's pH and temperature (ET) were registered by probes, and meteorological information regarding air temperature (AT) and solar radiation (SR) were obtained from INMET, Brazil. GHG collection was carried out for 72 consecutive hours in June 2014, on an hourly basis, once every 5 minutes, for the first 30 minutes, and once every 10 minutes from 30 to 50 minutesand subsequently analyzed by gas chromatograph (GC).After three days of data collection, the average AT, SR, ET and pH values were, respectively, 18oC, 2583kJm-2, 23oC and 8.2. Average values for GHG emission levels (CH4, CO2 and N2O) were 79.01; 100.65 and 0.0 mg m-2 h-1, respectively. GHG emission levels were divided into light periods (morning, afternoon and evening)in order to verify the periods with the highest GHG emissions.The highest CH4 emission levels were measured between morning and early afternoon. The maximum CO2 emissions were observed from evening to early morning. N2O emissions were constant and values were close to the ones found in the atmosphere, which shows the emission of N2O by facultative ponds does not contribute to greenhouse gases emissions.The results enabled us to characterize and quantify GHG emission levels per Facultative Pond on Wastewater Treatment Plant. Acknowledgment to FAPESP and SABESP, Brazil.

  5. Anthropogenic effects on greenhouse gas (CH4 and N2O) emissions in the Guadalete River Estuary (SW Spain).

    PubMed

    Burgos, M; Sierra, A; Ortega, T; Forja, J M

    2015-01-15

    Coastal areas are subject to a great anthropogenic pressure because more than half of the world's population lives in its vicinity causing organic matter inputs, which intensifies greenhouse gas emissions into the atmosphere. Dissolved concentrations of CH4 and N2O have been measured seasonally during 2013 in the Guadalete River Estuary, which flows into the Cadiz Bay (southwestern Spanish coast). It has been intensely contaminated since 1970. Currently it receives wastewater effluents from cities and direct discharges from nearby agriculture crop. Eight sampling stations have been established along 18 km of the estuary. CH4 and N2O were measured using a gas chromatograph connected to an equilibration system. Additional parameters such as organic matter, dissolved oxygen, nutrients and chlorophyll were determinate as well, in order to understand the relationship between physicochemical and biological processes. Gas concentrations increased from the River mouth toward the inner part, closer to the wastewater treatment plant discharge. Values varied widely within 21.8 and 3483.4 nM for CH4 and between 9.7 and 147.6 nM for N2O. Greenhouse gas seasonal variations were large influenced by the precipitation regime, masking the temperature influence. The Guadatete Estuary acted as a greenhouse gas source along the year, with mean fluxes of 495.7 μmol m(-2)d(-1) and 92.8 μmol m(-2)d(-1) for CH4 and N2O, respectively.

  6. Nitrogen loss from high N-input vegetable fields - a) direct N2O emissions b) Spatiotemporal variability of N species (N2O, NH4+, NO3-) in soils

    NASA Astrophysics Data System (ADS)

    Pfab, H.; Ruser, R.; Palmer, I.; Fiedler, S.

    2009-04-01

    Nitrous oxide is a climate relevant trace gas. It contributes 7.9 % to the total anthropogenic greenhouse gas emission and it is also involved in stratospheric ozone depletion. Approximately 85 % of the anthropogenic N2O emissions result from agricultural activities, more than 50 % are produced during microbial N-turnover processes in soils. Especially soils with high N-input (N-fertilizer and high amount of N in plant residues) like vegetable cropped soils are assumed to cause high N2O losses. The aims of the study presented were (i) to quantify the N2O loss from a vegetable field (lettuce-cauliflower crop rotation), (ii) to calculate an emission factor for the study site in Southwest Germany and to compare this factor with the default value provided by the IPCC (2006) and (iii) to test the emission reduction potential (Ammonium Sulfate Nitrate fertilizer, ASN either by reduced N-fertilization) in comparison with common N doses used for good agricultural practice or by the use of a nitrification inhibitor (DMPP), a banded N-application (lettuce) or a depot fertilization measure (pseudo-CULTAN in order to suppress nitrification). N2O fluxes determined with the closed chamber method were highly variable in time with strongly increased flux rates after N-fertilization in combination with rainfall or irrigation measures and after the incorporation of cauliflower crop residues. Using the mean soil nitrate contents of the top soil of our investigated treatments (0-25 cm depth), we could explain approximately 60 % of the variability of the cumulative N2O losses during the vegetation period of lettuce and cauliflower. The cumulative N2O emissions ranged between 0,99 kg N2O-N ha-1 from the unfertilized control plots (vegetation period) and 6,81 kg N2O-N ha-1 from the plots with the highest N-dose. Based on the guidelines of the IPCC (2006), we calculated an emission factor around 0,9 % for the cropping season. This value is in good agreement with the default value of the

  7. The Great Cormorant (Phalacrocorax carbo) colony as a "hot spot" of nitrous oxide (N2O) emission in central Japan

    NASA Astrophysics Data System (ADS)

    Mizota, Chitoshi; Noborio, Kosuke; Mori, Yoshiaki

    2012-09-01

    Unusual high soil fluxes up to ca. 500 mg N2O m-2 h-1 emission were associated with a continued breeding/roosting colony of Great Cormorant in central Japan. This flux is nearly two-orders of magnitude higher than those hitherto documented. The flux was markedly dependent upon the soil surface temperature, i.e., higher in April-October during the prevailing high air temperatures, as compared with November to March. Integrated input of fecal N at rearing and fledging stages of chicks followed by coupled mineralization, nitrification and subsequently denitrification processes under humid and temperate regimes is responsible for such an unusual flux. The Great Cormorant colony serves as a "hot spot" of N2O emission of natural origin.

  8. Effects of nitrogen fertilization on soil N2O emissions and soil respiration in temperate grassland in Inner Mongolia, China

    NASA Astrophysics Data System (ADS)

    Dong, Y.; Qi, Y.; Peng, Q.

    2012-04-01

    Nitrogen addition to soil can play a vital role in influencing nitrogen balance and the losses of soil carbon by respiration in N-deficient terrestrial ecosystems. The aim of this study was to clarify the effects of different levels of nitrogen fertilization (HN:200 kg N ha-1y-1, MN:100 kg N ha-1y-1 and LN:50 kg N ha-1y-1) on soil N2O emissions and soil respiration compared with non-fertilization(CK, 0 kg N ha-1y-1), from July 2007 to September 2008, in temperate grassland in Inner Mongolia, China. Several N fertilizer forms were included(CAN:calcium ammonium nitrate, AS:ammonium sulphate and NS:sodium nitrate) and a static closed chamber method was used as gas fluxes measurement. Our data showed that peak N2O fluxes induced by N treatments were concentrated in short periods (2 to 3 weeks) after fertilization in summer and in soil thawing periods in early spring; there were similarly low N2O fluxes from all treatments in the remaining seasons of the year. The three N levels increased annual N2O emissions significantly(P<0.05) in the order of MN>HN>LN compared with the CK(control) treatment in year 1; in year 2, the elevation of annual N2O emissions was significant (P<0.05) by HN and MN treatments but was insignificant by LN treatments (P>0.05). The three N forms also had strong effects on N2O emissions. Significantly (P<0.05) higher annual N2O emissions were observed in the soils of CAN and AS fertilizer treatments than in the soils of NS fertilizer treatments in both measured years, but the difference between CAN and AS was not significant (P>0.05). Annual N2O emission factors (EF) ranged from 0.060 to 0.298% for different N fertilizer treatments in the two observed years, with an overall EF value of 0.125%. The EF values were by far less than the mean default EF proposed by the Intergovernmental Panel on Climate Change(IPCC). Our results also showed that N fertilization did not change the seasonal patterns of soil respiration, which were mainly controlled by soil

  9. [Effect of organic material incorporation in rice season on N2O emissions from following winter wheat growing season].

    PubMed

    Zou, Jian-wen; Huang, Yao; Zong, Liang-gang; Zheng, Xun-hua; Wang, Yue-si

    2006-07-01

    In a field experiment, five fertilizer treatments including chemical fertilizer (CF), rapeseed cake + chemical fertilizer (RC + CF), wheat straw + chemical fertilizer (WS + CF), cow manure + chemical fertilizer (CM + CF), and pig manure + chemical fertilizer (PM + CF), were dedicated to examine the effect of organic materials incorporation in the rice season on N2O emissions from the following winter wheat season and to assess the climatic impacts from CH4 and N2O emissions in a rice-wheat rotation. Organic material was incorporated at the same rate (225 g x m(-2)) for organic treatments at the depth of 10 cm in the soil as the basal fertilizer just before rice transplanting. An identical synthetic nitrogen fertilizer was adopted for all treatments. Results show that the seasonal amount of N20 emissions from the following wheat season differed with organic material applied in rice season. No pronounced difference in N20 emissions was found between the CF and RC + CF treatments. In contrast with the CF treatment, however, N2O emission was decreased by 15% for the WS + CF treatment, but increased by 29% and 16% for the CM + CF and PM + CF treatments, respectively. Over the entire annual rotation cycle, N2O amount was increased by 17% for the CM + CF treatment, 7% for the PM + CF treatment, and 6% for the RC + CF treatment, but decreased by 16% for the WS + CF treatment in comparison with the CF treatment. Based on total emissions of CH4 in rice season and N2O over the entire rotation cycle, the estimation of combined Global Warming Potentials (GWPs) for CH4 and N20 shows that over a 20 years horizon or a 500 years horizon, the value of annual total GWPs was ranked in the order of RC + CF > WS + CF > CM + CF > PM + CF > CF or RC + CF > CM + CF > PM + CF > WS + CF > CF. The highest, middle and the lowest value of the GWPs per unit crop grain yield occurred for the crop residue, farmyard manure and pure synthetic fertilizer treatments, respectively. Compared to the

  10. Estimating agricultural N2O emissions in France: comparison of a spatialized agro-ecosytem model (CERES-EGC) and a terrestrial biosphere model (O-CN)

    NASA Astrophysics Data System (ADS)

    Massad, R. S.; Prieur, V.; Boukari, E.; Lehuger, S.; Chaumartin, F.; Schultz, M.; Gabrielle, B.

    2012-04-01

    Nitrous oxide (N2O) is a major greenhouse gas and air pollutant. Considered over a 100 year period, it has 298 times more impact 'per unit weight' (Global warming potential) than carbon dioxide. The parties to the United Nations Framework Convention on Climate Change (UNFCCC), including France, are committed to estimate their national nitrous oxide (N2O) budgets and to establish regional programmes of N2O emissions reductions. Agricultural activities are gradually coming into focus as a major GHG emission sector; precise regional estimates of current N2O emissions from arable land are being needed, along with possible means for mitigating emissions. The use of biogeochemical simulation models to estimate N2O fluxes from agricultural soils has obvious benefits. These models provide a unique potential to mechanistically predict N2O emissions from arable soils on both the plot-scale and the regional/national scale on daily time resolutions. In this study we apply two biogeochemical simulation models: CERES-EGC and O-CN all over France for the year 2007 in the perspective of producing an inventory of N2O emissions from croplands. Simulated total N2O emissions from agricultural soils sum up to 20.4 Gg N-N2O/yr with the CERES-EGC model and to 95.1 Gg N-N2O/yr with the O-CN model. Even though the total emissions are largely different between the two models, the temporal and spatial distributions are comparable. When compared to the EDGAR 4.2 emission database we note that O-CN overestimates the annual emissions by approximately a factor of two, whereas CERES-EGC underestimates those emissions. These differences can be explained to a certain extent by the difference in land-use types considered in each of the models and the inventories.

  11. Predicting field N2O emissions and controlling factors in a Swiss grassland using a mid-infrared spectrometer

    NASA Astrophysics Data System (ADS)

    Lee, Juhwan; Six, Johan

    2014-05-01

    Infrared reflectance spectroscopy, alternative to conventional analysis methods, is used to analyze soil physical and chemical properties. The objective of this study was to evaluate the potential of mid-infrared (MIR) spectroscopic technique to determine the spatial and temporal changes and variability in controlling factors of soil N2O emissions under various management practices. In this study, we selected an intensively managed grassland in Chamau, Switzerland as a pilot site. The perennial grassland is situated in the pre-alpine lowlands of Switzerland at 400 m a.s.l., and managed for forage production. Management practices include 4 to 6 times mowing per year. One to two weeks after mowing, the grassland is fertilized with cattle slurry. Gas and soil (0-20 cm depth) samples were collected from April to September 2013. The soil samples were air-dried and ball-milled for spectrum measurements in the MIR (= 4000-400 cm-1). We developed and tested a site-specific calibration model to quantify soil factors affecting daily N2O emissions, namely mineral N concentrations, dissolved organic carbon, pH, and gravimetric water content. Soil MIR databases could be applied to large-scale biogeochemical modeling of N2O emissions to improve our understanding of related mechanisms, encompassing its high spatial and temporal variation. We also discuss potential MIR spectroscopy applications in regional soil assessment and GHG accounting under climate change.

  12. Partitioning N2O emissions within the U.S. Corn Belt using an inverse modeling approach

    NASA Astrophysics Data System (ADS)

    Chen, Zichong; Griffis, Timothy J.; Millet, Dylan B.; Wood, Jeffrey D.; Lee, Xuhui; Baker, John M.; Xiao, Ke; Turner, Peter A.; Chen, Ming; Zobitz, John; Wells, Kelley C.

    2016-08-01

    Nitrous oxide (N2O) emissions within the US Corn Belt have been previously estimated to be 200-900% larger than predictions from emission inventories, implying that one or more source categories in bottom-up approaches are underestimated. Here we interpret hourly N2O concentrations measured during 2010 and 2011 at a tall tower using a time-inverted transport model and a scale factor Bayesian inverse method to simultaneously constrain direct and indirect agricultural emissions. The optimization revealed that both agricultural source categories were underestimated by the Intergovernmental Panel on Climate Change (IPCC) inventory approach. However, the magnitude of the discrepancies differed substantially, ranging from 42 to 58% and from 200 to 525% for direct and indirect components, respectively. Optimized agricultural N2O budgets for the Corn Belt were 319 ± 184 (total), 188 ± 66 (direct), and 131 ± 118 Gg N yr-1 (indirect) in 2010, versus 471 ± 326, 198 ± 80, and 273 ± 246 Gg N yr-1 in 2011. We attribute the interannual differences to varying moisture conditions, with increased precipitation in 2011 amplifying emissions. We found that indirect emissions represented 41-58% of the total agricultural budget, a considerably larger portion than the 25-30% predicted in bottom-up inventories, further highlighting the need for improved constraints on this source category. These findings further support the hypothesis that indirect emissions are presently underestimated in bottom-up inventories. Based on our results, we suggest an indirect emission factor for runoff and leaching ranging from 0.014 to 0.035 for the Corn Belt, which represents an upward adjustment of 1.9-4.6 times relative to the IPCC and is in agreement with recent bottom-up field studies.

  13. Linking N2O emissions from biochar-amended soil to the structure and function of the N-cycling microbial community

    NASA Astrophysics Data System (ADS)

    Harter, Johannes; Krause, Hans-Martin; Schuettler, Stefanie; Ruser, Reiner; Fromme, Markus; Scholten, Thomas; Kappler, Andreas; Behrens, Sebastian

    2014-05-01

    Nitrous oxide (N2O) contributes 8% to global greenhouse gas emissions. Agricultural sources represent about 60% of anthropogenic N2O emissions. Most agricultural N2O emissions are due to increased fertilizer application. A considerable fraction of nitrogen fertilizers are converted to N2O by microbially-mediated processes. Soil amended with biochar has been demonstrated to reduce N2O emissions in the field and in laboratory experiments. Although N2O emission mitigation following soil biochar amendment has been reported frequently the underlying processes and specific role of the nitrogen cycling microbial community in decreasing soil N2O emissions has not been subject of systematic investigation. To investigate the impact of biochar on the microbial community of nitrogen-transforming microorganisms we performed a microcosm study with arable soil amended with different amounts (0%, 2% and 10% (w/w)) of high-temperature wood derived biochar. By quantifying the abundance and activity of functional marker genes of microbial nitrogen fixation (nifH), nitrification (amoA) and denitrification (nirK, nirS and nosZ) using quantitative real-time PCR we found that biochar addition enhanced microbial nitrous oxide reduction and increased the abundance of microorganisms capable of N2-fixation. Soil biochar amendment increased the relative gene and transcript copy numbers of the nosZ-encoded bacterial N2O reductase, suggesting a mechanistic link to the observed reduction in N2O emissions. Our findings contribute to a better understanding of the impact of biochar on the nitrogen cycling microbial community and the consequences of soil biochar amendment for microbial nitrogen transformation processes and N2O emissions from soil.

  14. The influence of N-fertilization regimes on N2O emissions and denitrification in rain-fed cropland during the rainy season.

    PubMed

    Dong, Zhixin; Zhu, Bo; Zeng, Zebin

    2014-11-01

    The effects of nitrogen fertilization regimes on N2O emissions and denitrification rates were evaluated by in situ field incubation experiments with intact soil cores and the acetylene block technique. Intact soil cores were collected from long-term field experiments involving several N fertilization regimes, including single synthetic N fertilizer (N), organic manure (OM), synthetic N, P, K fertilizer (NPK), organic manure with synthetic fertilizer (OMNPK), crop straw residue with synthetic fertilizer (SRNPK) and no nitrogen fertilizer (NF). N2O was sampled from the head space of the cylinders to determine the daily N2O emission and denitrification rate. The results showed that the N2O emissions were greatly influenced by the specific fertilization regime even when the same nitrogen rate was applied. The mean N2O emissions and denitrification rates from the N, OM, NPK, OMNPK and SRNPK treatment were 2.22, 2.66, 1.94, 2.53, 1.67 and 4.63, 5.96, 4.15, 5.41, 3.65 mg per m(2) per day, respectively. The application of OM significantly increased the N2O emission and denitrification compared to the application of NPK because of the high soil organic carbon (SOC) content of OM. However, SRNPK increased the SOC content and decreased the N2O emissions significantly compared to the OM and OMNPK treatments because the addition of crop straw with a high C/N ratio to soil with a low inorganic N content induced N immobilization. The contents of soil nitrate and ammonium were the main limiting factors for N2O emissions in a positive regression as follows: Ln (N2O) = 2.511 + 1.258 × Ln ([NH4(+)] + [NO3(-)]). Crop straw residue combined with synthetic fertilizer is recommended as an optimal strategy for mitigating N2O emissions and denitrification-induced N loss in rain-fed croplands.

  15. Emissions of N2O from tropical forest soils - Response to fertilization with NH4(+), NO3(-), and PO4(3-)

    NASA Technical Reports Server (NTRS)

    Keller, M.; Kaplan, W. A.; Wofsy, S. C.; Da Costa, Jose Maria

    1988-01-01

    Undisturbed oxisols in a central Amazon tropical forest were fertilized with ammonium, nitrate, or phosphate. Enhanced emissions of N2O were observed for all treatments within one day of fertilization, with the response NO3(-) much greater than NH4(+) much greater than PO4(3-). Approximately, 0.5 percent of applied NO3(-) was converted to N2O within two weeks after application, with less than 0.1 percent of the NH4(+) converted to N2O. These experiments reveal a potentially large source of N2O from microbial reduction of NO3(-) in the clay soils of Amazonia.

  16. CO(2) and N(2)O emissions in a soil chronosequence at a glacier retreat zone in Maritime Antarctica.

    PubMed

    Thomazini, A; Mendonça, E S; Teixeira, D B; Almeida, I C C; La Scala, N; Canellas, L P; Spokas, K A; Milori, D M B P; Turbay, C V G; Fernandes, R B A; Schaefer, C E G R

    2015-07-15

    Studies of C cycle alterations are extremely important to identify changes due to climate change, especially in the polar ecosystem. The objectives of this study were to (i) examine patterns of soil CO2-C and N2O-N emissions, and (ii) evaluate the quantity and quality of soil organic matter across a glacier retreat chronosequence in the Maritime Antarctica. Field measurements were carried out during January and February 2010 (summer season) along a retreating zone of the White Eagle Glacier, at King George Island, Maritime Antarctica. Soil samples (0-10cm) were collected along a 500-m transect at regular intervals to determine changes in soil organic matter. Field CO2-C emission measurements and soil temperature were carried out at regular intervals. In addition, greenhouse gas production potentials were assessed through 100days laboratory incubations. Soils exposed for a longer time tended to have greater concentrations of soluble salts and possess sandier textures. Total organic C (3.59gkg(-1)), total N (2.31gkg(-1)) and labile C (1.83gkg(-1)) tended to be lower near the glacier front compared with sites away from it, which is correlated with decreasing degree of humification of the soil organic matter with exposure time. Soil CO2-C emissions tended to increase with distance from the glacier front. On average, the presence of vegetation increased CO2-C emissions by 440%, or the equivalent of 0.633g of CO2-C m(-2)h(-1). Results suggest that newly exposed landsurfaces undergo soil formation with increasing labile C input from vegetation, accompanied by increasing soil CO2-C emissions. Despite the importance of exposure time on CO2-C production and emissions, there was no similar trend in soil N2O-N production potentials as a function of glacial retreat. For N2O, instead, the maximum production occurred in sites with the first stages of vegetation growth.

  17. Effects of Soil Temperature, Flooding, and Organic Matter Addition on N2O Emissions from a Soil of Hongze Lake Wetland, China

    PubMed Central

    Lu, Yan; Xu, Hongwen

    2014-01-01

    The objectives of this study were to test the effects of soil temperature, flooding, and raw organic matter input on N2O emissions in a soil sampled at Hongze Lake wetland, Jiangsu Province, China. The treatments studied were—peat soil (I), peat soil under flooding (II), peat soil plus raw organic matter (III), and peat soil under flooding plus organic matter. These four treatments were incubated at 20°C and 35°C. The result showed that temperature increase could enhance N2O emissions rate and cumulative emissions significantly; moreover, the flooded soil with external organic matter inputs showed the lowest cumulative rise in N2O emissions due to temperature increment. Flooding might inhibit soil N2O emissions, and the inhibition was more pronounced after organic matter addition to the original soil. Conversely, organic matter input explained lower cumulative N2O emissions under flooding. Our results suggest that complex interactions between flooding and other environmental factors might appear in soil N2O emissions. Further studies are needed to understand potential synergies or antagonisms between environmental factors that control N2O emissions in wetland soils. PMID:25133216

  18. Effects of soil temperature, flooding, and organic matter addition on N2O emissions from a soil of Hongze Lake wetland, China.

    PubMed

    Lu, Yan; Xu, Hongwen

    2014-01-01

    The objectives of this study were to test the effects of soil temperature, flooding, and raw organic matter input on N2O emissions in a soil sampled at Hongze Lake wetland, Jiangsu Province, China. The treatments studied were-peat soil (I), peat soil under flooding (II), peat soil plus raw organic matter (III), and peat soil under flooding plus organic matter. These four treatments were incubated at 20°C and 35°C. The result showed that temperature increase could enhance N2O emissions rate and cumulative emissions significantly; moreover, the flooded soil with external organic matter inputs showed the lowest cumulative rise in N2O emissions due to temperature increment. Flooding might inhibit soil N2O emissions, and the inhibition was more pronounced after organic matter addition to the original soil. Conversely, organic matter input explained lower cumulative N2O emissions under flooding. Our results suggest that complex interactions between flooding and other environmental factors might appear in soil N2O emissions. Further studies are needed to understand potential synergies or antagonisms between environmental factors that control N2O emissions in wetland soils.

  19. [Effects of no-tillage and fertilization on paddy soil CH4 and N2O emissions and their greenhouse effect in central China].

    PubMed

    Dai, Guang-zhao; Li, Cheng-fang; Cao, Cou-gui; Zhan, Ming; Tong, Le-ga; Mei, Shao-hua; Zhai, Zhong-bing; Fan, Duan-yang

    2009-09-01

    By using static chamber-gas chromatographic techniques, the CH4 and N2O emissions from the paddy soil in southeast Hubei were measured. Four treatments were installed, i.e., no-tillage plus no-fertilization (NT0), conventional tillage plus no-fertilization (CT0), no-tillage plus fertilization (NTC), and conventional tillage plus fertilization (CTC). In all treatments, the CH4 emission had a seasonal variation of increasing first and decreasing then, while the N2O emission had no significant seasonal variation. Fertilization increased the CH4 and N2O emissions significantly. NT0 increased the CH4 emission and decreased the N2O emission significantly, compared with CT0; NTC only decreased the CH4 emission and increased the N2O emission slightly, compared with CTC. The analysis on the integrated greenhouse effect of CH4 and N2O showed that NT0 increased the effect by 25.9%, compared with CT0, while NTC decreased the effect by 10.1%, compared with CTC. Therefore, a reasonable arrangement of fertilization and no-tillage could reduce the integrated greenhouse effect of CH4 and N2O from paddy field.

  20. Pulse increase of soil N2O emission in response to N addition in a temperate forest on Mt Changbai, northeast China.

    PubMed

    Bai, Edith; Li, Wei; Li, Shanlong; Sun, Jianfei; Peng, Bo; Dai, Weiwei; Jiang, Ping; Han, Shijie

    2014-01-01

    Nitrogen (N) deposition has increased significantly globally since the industrial revolution. Previous studies on the response of gaseous emissions to N deposition have shown controversial results, pointing to the system-specific effect of N addition. Here we conducted an N addition experiment in a temperate natural forest in northeastern China to test how potential changes in N deposition alter soil N2O emission and its sources from nitrification and denitrification. Soil N2O emission was measured using closed chamber method and a separate incubation experiment using acetylene inhibition method was carried out to determine denitrification fluxes and the contribution of nitrification and denitrification to N2O emissions between Jul. and Oct. 2012. An NH4NO3 addition of 50 kg N/ha/yr significantly increased N2O and N2 emissions, but their "pulse emission" induced by N addition only lasted for two weeks. Mean nitrification-derived N2O to denitrification-derived N2O ratio was 0.56 in control plots, indicating higher contribution of denitrification to N2O emissions in the study area, and this ratio was not influenced by N addition. The N2O to (N2+N2O) ratio was 0.41-0.55 in control plots and was reduced by N addition at one sampling time point. Based on this short term experiment, we propose that N2O and denitrification rate might increase with increasing N deposition at least by the same fold in the future, which would deteriorate global warming problems.

  1. Quantitative importance of denitrification and N2O emission in an N-saturated subtropical forest catchment, southwest China

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Dörsch, P.; Mulder, J.

    2009-04-01

    Anthropogenic emission of nitrogen in the environment has increased rapidly, due to fast economic growth. This has resulted in increased deposition rates of reactive nitrogen, primarily as NOx (from fossil fuel combustion) and NH3 (from fertilizer production and animal husbandry). In response, temperate and boreal forests may develop nitrogen saturation, characterized by increased leaching of nitrate. In addition, elevated emission of N2 and N2O, due to nitrification and denitrification, may occur. To date, few studies exist quantifying the nitrogen balance, including N2 and N2O production, in nitrogen-saturated, monsoonal, sub-tropical forest ecosystems in south-west China. Since nitrate contributes to the eutrophication of stream water, and N2O is a potent greenhouse gas, it is important to quantitatively understand the role of nitrification and denitrification in the nitrogen cycle. Several subtropical forests in southwest China, receiving elevated nitrogen deposition (30-73 kg N ha-1 a-1; Zhang. et al., 2008), are characterized by high temperature and soil moisture content in much of the growing season. This may cause a much stronger intensity of denitrification compared with that in temperate and boreal forests. In turn this may lead to decreased nitrate leaching and a higher potential of N2O emission. In my PhD project, I will investigate the nitrogen cycle in a forest catchment (TieShanPing; TSP), which is near one of the biggest cities, Chongqing, in southwest China. Previous research suggests high nitrogen deposition (3.52 gN m-2 a-1), but low nitrogen flux (0.57 gN m-2 a-1) in runoff (Chen & Mulder, 2007). Tree growth, and thus plant N uptake, is limited and nitrate fluxes below the root zone are relatively large, suggesting ‘N-saturation'. Based on this, we hypothesize that significant amounts of nitrogen are emitted as gases, with denitrification playing an important role, and N2 and N2O (especially N2) being major components of the emitted gases

  2. 40 CFR Table Jj-7 to Subpart Jj of... - Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N)

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) 0.07 Deep bedding for cattle and swine (no mix) 0.01 Manure Composting (in vessel) 0.006 Manure... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Manure Management... N2O-N/kg Kjdl N) Manure management system component N2O emission factor Uncovered anaerobic lagoon...

  3. Biogenic emissions of CO2 and N2O at multiple depths increase exponentially during a simulated soil thaw for a northern prairie Mollisol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil respiration occurs at depths below the surface, but belowground data are lacking to support multilayer models of soil CO2 and N2O emissions. In particular, Q10s for CO2 and N2O within soil profiles are needed to determine if temperature sensitivities calculated at the surface are similar to th...

  4. Effects of water regime during rice-growing season on annual direct N(2)O emission in a paddy rice-winter wheat rotation system in southeast China.

    PubMed

    Liu, Shuwei; Qin, Yanmei; Zou, Jianwen; Liu, Qiaohui

    2010-01-15

    Annual paddy rice-winter wheat rotation constitutes one of the typical cropping systems in southeast China, in which various water regimes are currently practiced during the rice-growing season, including continuous flooding (F), flooding-midseason drainage-reflooding (F-D-F), and flooding-midseason drainage-reflooding and moisture but without waterlogging (F-D-F-M). We conducted a field experiment in a rice-winter wheat rotation system to gain an insight into the water regime-specific emission factors and background emissions of nitrous oxide (N(2)O) over the whole annual cycle. While flooding led to an unpronounced N(2)O emission during the rice-growing season, it incurred substantial N(2)O emission during the following non-rice season. During the non-rice season, N(2)O fluxes were, on average, 2.61 and 2.48 mg N(2)O-Nm(-)(2) day(-1) for the 250 kg N ha(-1) applied plots preceded by the F and F-D-F water regimes, which are 56% and 49% higher than those by the F-D-F-M water regime, respectively. For the annual rotation system experienced by continuous flooding during the rice-growing season, the relationship between N(2)O emission and nitrogen input predicted the emission factor and background emission of N(2)O to be 0.87% and 1.77 kg N(2)O-Nha(-1), respectively. For the plots experienced by the water regimes of F-D-F and F-D-F-M, the emission factors of N(2)O averaged 0.97% and 0.85%, with background N(2)O emissions of 2.00 kg N(2)O-Nha(-1) and 1.61 kg N(2)O-Nha(-1) for the annual rotation system, respectively. Annual direct N(2)O-N emission was estimated to be 98.1 Gg yr(-1) in Chinese rice-based cropping systems in the 1990s, consisting of 32.3 Gg during the rice-growing season and 65.8 Gg during the non-rice season, which accounts for 25-35% of the annual total emission from croplands in China.

  5. Factors Related with CH4 and N2O Emissions from a Paddy Field: Clues for Management implications

    PubMed Central

    Wang, Chun; Lai, Derrick Y. F.; Sardans, Jordi; Wang, Weiqi; Zeng, Congsheng; Peñuelas, Josep

    2017-01-01

    Paddy fields are major sources of global atmospheric greenhouse gases, including methane (CH4) and nitrous oxide (N2O). The different phases previous to emission (production, transport, diffusion, dissolution in pore water and ebullition) despite well-established have rarely been measured in field conditions. We examined them and their relationships with temperature, soil traits and plant biomass in a paddy field in Fujian, southeastern China. CH4 emission was positively correlated with CH4 production, plant-mediated transport, ebullition, diffusion, and concentration of dissolved CH4 in porewater and negatively correlated with sulfate concentration, suggesting the potential use of sulfate fertilizers to mitigate CH4 release. Air temperature and humidity, plant stem biomass, and concentrations of soil sulfate, available N, and DOC together accounted for 92% of the variance in CH4 emission, and Eh, pH, and the concentrations of available N and Fe3+, leaf biomass, and air temperature 95% of the N2O emission. Given the positive correlations between CH4 emission and DOC content and plant biomass, reduce the addition of a carbon substrate such as straw and the development of smaller but higher yielding rice genotypes could be viable options for reducing the release of greenhouse gases from paddy fields to the atmosphere. PMID:28081161

  6. Emission and control of N2O and composition of ash derived from cattle manure combustion using a pilot-scale fluidized bed incinerator.

    PubMed

    Oshita, Kazuyuki; Kawaguchi, Koji; Takaoka, Masaki; Matsukawa, Kazutsugu; Fujimori, Takashi; Fujiwara, Taku

    2015-10-06

    This study investigates the emission of nitrous oxide (N2O) and discusses the reduction of N2O emissions during the 24-h combustion of cattle manure using a pilot-scale fluidized bed incinerator under various experimental conditions. The results of these experiments were then validated against previously reported data. In addition, the characteristics of cattle manure incineration ash and their changes under different combustion conditions were estimated. In incineration experiments with composted cattle manure, N2O concentrations using multi-stage combustion were 75% lower than the concentrations resulting from normal combustion without additional auxiliary fuel, since N2O could be decomposed in the high-temperature zone formed by the inlet of the secondary combustion air. The N2O emission factor under normal combustion conditions (800°C) was 6.0% g-N2O-N/g-N. This result is similar to the values found in previous studies at the same temperature. The N2O emission factor was decreased to 1.6% g-N2O-N/g-N using a multi-stage combustion procedure. The current Japanese N2O emission factor of 0.1% g-N2O-N/g-N is an underestimate for some conditions and should be uniquely specified for each condition. Finally, cattle manure ash contains ample fertilizer elements, little Fe, Al and Zn, but abundant Cl. Therefore if Cl could be removed by some kind of pretreatment, cattle manure ash could be used as a favourable fertilizer.

  7. Urbanisation-related land use change from forest and pasture into turf grass modifies soil nitrogen cycling and increases N2O emissions

    NASA Astrophysics Data System (ADS)

    van Delden, Lona; Rowlings, David W.; Scheer, Clemens; Grace, Peter R.

    2016-11-01

    Urbanisation is becoming increasingly important in terms of climate change and ecosystem functionality worldwide. We are only beginning to understand how the processes of urbanisation influence ecosystem dynamics, making peri-urban environments more vulnerable to nutrient losses. Brisbane in South East Queensland has the most extensive urban sprawl of all Australian cities. This research estimated the environmental impact of land use change associated with urbanisation by examining soil nitrogen (N) turnover and subsequent nitrous oxide (N2O) emissions using a fully automated system that measured emissions on a sub-daily basis. There was no significant difference in soil N2O emissions between the native dry sclerophyll eucalypt forest and an extensively grazed pasture, wherefrom only low annual emissions were observed amounting to 0.1 and 0.2 kg N2O ha-1 yr-1, respectively. The establishment of a fertilised turf grass lawn increased soil N2O emissions 18-fold (1.8 kg N2O ha-1 yr-1), with highest emissions occurring in the first 2 months after establishment. Once established, the turf grass lawn presented relatively low N2O emissions for the rest of the year, even after fertilisation and rain events. Soil moisture was significantly higher, and mineralised N accumulated in the fallow plots, resulting in the highest N2O emissions (2.8 kg N2O ha-1 yr-1) and significant nitrate (NO3-) losses, with up to 63 kg N ha-1 lost from a single rain event due to reduced plant cover removal. The study concludes that urbanisation processes creating peri-urban ecosystems can greatly modify N cycling and increase the potential for losses in the form of N2O and NO3-.

  8. Linking N2O emissions from biochar-amended soil to the structure and function of the N-cycling microbial community

    PubMed Central

    Harter, Johannes; Krause, Hans-Martin; Schuettler, Stefanie; Ruser, Reiner; Fromme, Markus; Scholten, Thomas; Kappler, Andreas; Behrens, Sebastian

    2014-01-01

    Nitrous oxide (N2O) contributes 8% to global greenhouse gas emissions. Agricultural sources represent about 60% of anthropogenic N2O emissions. Most agricultural N2O emissions are due to increased fertilizer application. A considerable fraction of nitrogen fertilizers are converted to N2O by microbiological processes (that is, nitrification and denitrification). Soil amended with biochar (charcoal created by pyrolysis of biomass) has been demonstrated to increase crop yield, improve soil quality and affect greenhouse gas emissions, for example, reduce N2O emissions. Despite several studies on variations in the general microbial community structure due to soil biochar amendment, hitherto the specific role of the nitrogen cycling microbial community in mitigating soil N2O emissions has not been subject of systematic investigation. We performed a microcosm study with a water-saturated soil amended with different amounts (0%, 2% and 10% (w/w)) of high-temperature biochar. By quantifying the abundance and activity of functional marker genes of microbial nitrogen fixation (nifH), nitrification (amoA) and denitrification (nirK, nirS and nosZ) using quantitative PCR we found that biochar addition enhanced microbial nitrous oxide reduction and increased the abundance of microorganisms capable of N2-fixation. Soil biochar amendment increased the relative gene and transcript copy numbers of the nosZ-encoded bacterial N2O reductase, suggesting a mechanistic link to the observed reduction in N2O emissions. Our findings contribute to a better understanding of the impact of biochar on the nitrogen cycling microbial community and the consequences of soil biochar amendment for microbial nitrogen transformation processes and N2O emissions from soil. PMID:24067258

  9. Linking N2O emissions from biochar-amended soil to the structure and function of the N-cycling microbial community.

    PubMed

    Harter, Johannes; Krause, Hans-Martin; Schuettler, Stefanie; Ruser, Reiner; Fromme, Markus; Scholten, Thomas; Kappler, Andreas; Behrens, Sebastian

    2014-03-01

    Nitrous oxide (N2O) contributes 8% to global greenhouse gas emissions. Agricultural sources represent about 60% of anthropogenic N2O emissions. Most agricultural N2O emissions are due to increased fertilizer application. A considerable fraction of nitrogen fertilizers are converted to N2O by microbiological processes (that is, nitrification and denitrification). Soil amended with biochar (charcoal created by pyrolysis of biomass) has been demonstrated to increase crop yield, improve soil quality and affect greenhouse gas emissions, for example, reduce N2O emissions. Despite several studies on variations in the general microbial community structure due to soil biochar amendment, hitherto the specific role of the nitrogen cycling microbial community in mitigating soil N2O emissions has not been subject of systematic investigation. We performed a microcosm study with a water-saturated soil amended with different amounts (0%, 2% and 10% (w/w)) of high-temperature biochar. By quantifying the abundance and activity of functional marker genes of microbial nitrogen fixation (nifH), nitrification (amoA) and denitrification (nirK, nirS and nosZ) using quantitative PCR we found that biochar addition enhanced microbial nitrous oxide reduction and increased the abundance of microorganisms capable of N2-fixation. Soil biochar amendment increased the relative gene and transcript copy numbers of the nosZ-encoded bacterial N2O reductase, suggesting a mechanistic link to the observed reduction in N2O emissions. Our findings contribute to a better understanding of the impact of biochar on the nitrogen cycling microbial community and the consequences of soil biochar amendment for microbial nitrogen transformation processes and N2O emissions from soil.

  10. 40 CFR Table Aa-1 to Subpart Aa of... - Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O AA Table AA-1 to Subpart AA of Part 98 Protection of Environment... Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O Wood furnish Biomass-based emissions...

  11. 40 CFR Table Aa-1 to Subpart Aa of... - Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O AA Table AA-1 to Subpart AA of Part 98 Protection of Environment... Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O Wood furnish Biomass-based emissions...

  12. 40 CFR Table Aa-1 to Subpart Aa of... - Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O AA Table AA-1 to Subpart AA of Part 98 Protection of Environment... Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O Wood furnish Biomass-based emissions...

  13. 40 CFR Table Aa-1 to Subpart Aa of... - Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Kraft Pulping Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O AA Table AA-1 to Subpart AA of Part 98 Protection of Environment... Liquor Emissions Factors for Biomass-Based CO2, CH4, and N2O Wood furnish Biomass-based emissions...

  14. Nitrogen loss from high N-input vegetable fields: a) Direct N2O emissions b) Spatiotemporal variability of N species (N2O, NH4+, NO3-) in soils

    NASA Astrophysics Data System (ADS)

    Palmer, I.; Pfab, H.; Ruser, R.; Fiedler, S.

    2009-04-01

    Nitrous oxide (N2O) is a greenhouse gas contributing to stratospheric ozone depletion. Soils are considered to be the major (70%) source for atmospheric N2O. Agriculture in general accounts for about 85% of the anthropogenic N2O emissions. Whereas 80% of these, are emitted from ag-riculturally used soils. Such estimations of N2O fluxes are associated with a high degree of uncertainties. Uncertainty of source strength estimates mainly results from local scale variability of known and unknown sources. It is not known how much uncertainty is due to unmeasured sources. For example, considerations of N2O fluxes from soils used for intensive vegetable production within inventories are still missing. We speculate that these types of arable soils act as ‚hot spots' for N2O. Given conditions (1) high N-input due to fertilization in concert with (2) easily mineralizable harvest residues should pro-mote disproportional high reaction rates in N-cycling and enhance N2O production as a by-product of nitrification and denitrification. Our investigation focused on the influence of: (1) N-input level (Ammonium Sulfate Nitrate (ASN)) below and above common N doses used for "good agricultural practice". (2) Application of modified fertilizers including nitrification inhibitor DMPP (Dimethylpyrazolphosphate, ENTEC®) and depot fertilization (pseudo-CULTAN) in comparison to non-fertilized control and common ASN application. (3) Effects of plant residues on N-cycling and (4) the deduction of mitigation strategies to reduce the potential N-loss from theses sites. The study was carried out during summer and autumn 2008 on a field cropped with cauliflower, located at the "Heidfeldhof" (South-West Germany; MAT 10.5°C, MAP 660 mm). Three different N-species (N2O; within gaseous soil phase, ammonium (NH4+) and nitrate (NO3-) extracted from bulk soil) were measured weekly in three different soil depths (0-25 cm; 25-50 cm and 50-75 cm) in a fully randomized field design. At same depths water

  15. Stimulation of N2 O emission by manure application to agricultural soils may largely offset carbon benefits: a global meta-analysis.

    PubMed

    Zhou, Minghua; Zhu, Bo; Wang, Shijie; Zhu, Xinyu; Vereecken, Harry; Brüggemann, Nicolas

    2017-01-31

    Animal manure application as organic fertilizer does not only sustain agricultural productivity and increase soil organic carbon (SOC) stocks, but also affects soil nitrogen cycling and nitrous oxide (N2 O) emissions. However, given that the sign and magnitude of manure effects on soil N2 O emissions is uncertain, the net climatic impact of manure application in arable land is unknown. Here, we performed a global meta-analysis using field experimental data published in peer-reviewed journals prior to December 2015. In this meta-analysis we quantified the responses of N2 O emissions to manure application relative to synthetic N fertilizer application from individual studies and analyzed manure characteristics, experimental duration, climate and soil properties as explanatory factors. Manure application significantly increased N2 O emissions by an average 32.7% (95% confidence interval: 5.1-58.2%) compared to application of synthetic N fertilizer alone. The significant stimulation of N2 O emissions occurred following cattle and poultry manure applications, subsurface manure application and raw manure application. Furthermore, the significant stimulatory effects on N2 O emissions were also observed for warm temperate climate, acid soils (pH < 6.5) and soil texture classes of sandy loam and clay loam. Average direct N2 O emission factors (EFs) of 1.87% and 0.24% were estimated for upland soils and rice paddy soils receiving manure application, respectively. Although manure application increased SOC stocks, our study suggested that the benefit of increasing SOC stocks as GHG sinks could be largely offset by stimulation of soil N2 O emissions and aggravated by CH4 emissions if, particularly for rice paddy soils, the stimulation of CH4 emissions by manure application was taken into account. This article is protected by copyright. All rights reserved.

  16. Ecological Controls on N2O Emission in Surface Litter and Near-surface Soil of a Managed Grassland: Modelling and Measurements

    NASA Astrophysics Data System (ADS)

    Grant, Robert; Neftel, Albrecht; Calanca, Pierluigi

    2016-04-01

    Large variability in N2O emissions from managed grasslands may occur because most emissions originate in surface litter or near-surface soil where variability in soil water content (q) and temperature (Ts) is greatest. To determine whether temporal variability in q and Ts of surface litter and near-surface soil could explain that in N2O emissions, a simulation experiment was conducted with ecosys, a comprehensive mathematical model of terrestrial ecosystems in which processes governing N2O emissions were represented at high temporal and spatial resolution. Model performance was verified by comparing N2O emissions, CO2 and energy exchange, and q and Ts modelled by ecosys with those measured by automated chambers, eddy covariance (EC) and soil sensors at an hourly time-scale during several emission events from 2004 to 2009 in an intensively managed pasture at Oensingen, Switzerland. Both modelled and measured events were induced by precipitation following harvesting and subsequent fertilizing or manuring. These events were brief (2 - 5 days) with maximum N2O effluxes that varied from < 1 mg N m-2 h-1 in early spring and autumn to > 3 mg N m-2 h-1 in summer. Only very small emissions were modelled or measured outside these events. In the model, emissions were generated almost entirely in surface litter or near-surface (0 - 2 cm) soil, at rates driven by N availability with fertilization vs. N uptake with grassland regrowth, and by O2 limitation from wetting relative to O2 demand from respiration. In the model, NOx availability relative to O2 limitation governed both the reduction of more oxidized electron acceptors to N2O and the reduction of N2O to N2, so that the magnitude of N2O emissions was not simply related to surface and near-surface q and Ts. Modelled N2O emissions were found to be sensitive to defoliation intensity and timing (relative to that of fertilization) which controlled plant N uptake and soil q and Ts prior to and during emission events. In a model

  17. N2O, NO, N2, and CO2 emissions from tropical savanna and grassland of Northern Australia: an incubation experiment with intact soil cores

    NASA Astrophysics Data System (ADS)

    Werner, C.; Reiser, K.; Dannenmann, M.; Hutley, L. B.; Jacobeit, J.; Butterbach-Bahl, K.

    2014-06-01

    Strong seasonal variability of hygric and thermal soil conditions are a defining environmental feature in Northern Australia. However, how such changes affect the soil-atmosphere exchange of nitrous oxide (N2O), nitric oxide (NO) and dinitrogen (N2) is still not well explored. By incubating intact soil cores from four sites (3 savanna, 1 pasture) under controlled soil temperatures (ST) and soil moisture (SM) we investigated the release of the trace gas fluxes of N2O, NO and carbon dioxide (CO2). Furthermore, the release of N2 due to denitrification was measured using the helium gas flow soil core technique. Under dry pre-incubation conditions NO and N2O emission were very low (<7.0 ± 5.0 μg NO-N m-2 h-1; <0.0 ± 1.4 μg N2O-N m-2 h-1) or in case of N2O, even a net soil uptake was observed. Substantial NO (max: 306.5 μg N m-2 h-1) and relatively small N2O pulse emissions (max: 5.8 ± 5.0 μg N m-2 h-1) were recorded following soil wetting, but these pulses were short-lived, lasting only up to 3 days. The total atmospheric loss of nitrogen was dominated by N2 emissions (82.4-99.3% of total N lost), although NO emissions contributed almost 43.2% at 50% SM and 30 °C ST. N2O emissions were systematically higher for 3 of 12 sample locations, which indicates substantial spatial variability at site level, but on average soils acted as weak N2O sources or even sinks. Emissions were controlled by SM and ST for N2O and CO2, ST and pH for NO, and SM and pH for N2.

  18. Seasonal CH4 and N2O emissions and plant growth characteristics of several cultivars in direct seeded rice systems

    NASA Astrophysics Data System (ADS)

    Simmonds, M.; Anders, M. M.; Adviento-Borbe, M. A.; Van Kessel, C.; McClung, A.; Linquist, B.

    2014-12-01

    Understanding cultivar effects on field greenhouse gas (GHG) emissions in rice (Oryza sativa L.) systems is needed to improve the accuracy of predictive models used for estimating GHG emissions, and to determine to what extent choice of cultivar may have on GHG mitigation. We compared CH4 and N2O emissions, global warming potential (GWP = N2O + CH4), yield-scaled GWP (GWPY = GWP Mg-1 grain), and plant growth characteristics of 8 cultivars within 4 study sites in California and Arkansas. Seasonal CH4 emissions differed between cultivars by a factor of 2.1 and 1.3 at one California and one Arkansas site, respectively. Nitrous oxide emissions were negligible, comprised <10% of GWP, and were not different among cultivars. When sites and cultivars were pooled, and data were normalized to site averages, there was a positive correlation (r = 0.33) between root biomass at heading and seasonal CH4 emissions, but no correlation with shoot biomass at heading, or grain or straw biomass at maturity. Although differences in GWP and GWPY were observed, the consistency of some of the trends was variable across sites, indicating the importance of the genotype x environment interaction. While no high-yielding and low CH4-emitting cultivars were identified at the California sites, among the Southern varieties tested at the Arkansas site, the lowest emitting cultivar had the highest yield. This highlights the potential for breeding high-yielding varieties with low GWP, the ideal scenario to achieve low GWPY due to simultaneously mitigating GHG emissions and improving global food security.

  19. Combined use of nitrification inhibitor and struvite crystallization to reduce the NH3 and N2O emissions during composting.

    PubMed

    Jiang, Tao; Ma, Xuguang; Tang, Qiong; Yang, Juan; Li, Guoxue; Schuchardt, Frank

    2016-10-01

    Struvite crystallization (SCP) is combined with a nitrification inhibitor (dicyandiamide, DCD) to mitigate the NH3 and N2O emission during composting. The MgO and H3PO4 were added at a rate of 15% (mole/mole) of initial nitrogen, and the DCD was added at rates of 0%, 2.5%, 5.0%, 7.5% and 10% (w/w) of initial nitrogen respectively. Results showed that the combination use of SCP and DCD was phytotoxin free. The SCP could significantly reduce NH3 losses by 45-53%, but not the DCD. The DCD significantly inhibits nitrification when the content was higher than 50mgkg(-1), and that could reduce the N2O emission by 76.1-77.6%. The DCD degraded fast during the thermophilic phase, as the nitrification will be inhibited by the high temperature and high free ammonia content in this stage, the DCD was suggested to be applied in the maturing periods by 2.5% of initial nitrogen.

  20. Study of the characteristics of CH4 and N2O emission and methods of controlling their emission in the soil-trench wastewater treatment process.

    PubMed

    Kong, Hai Nan; Kimochi, Yuzuru; Mizuochi, Motoyuki; Inamori, Ryuhei; Inamori, Yuhei

    2002-05-06

    In recent years, worldwide concern over global warming has been expressed. It has been reported that domestic wastewater and its treatment processes are sources of CH4 and N2O, designated as greenhouse gases, the reduction of which was noted to be extremely important at the Third Conference of the Framework Convention on Climate Change (Conference Of the Parties; COP3). Here we report a study of a field that has been unexplored until now: analytical evaluation of the properties of the emission of CH4 and N2O and methods of restricting their emission in soil-trench wastewater treatment processes, the use of which is spreading, mainly in developing nations. The results have provided the following information. A field fact-finding survey has confirmed that soil trenches emit 9.3-13.9 g CH4 m(-3) and 8.2-12.2 gN2O m(-3) in Japan, and 3.0-4.5 g CH4 m(-3) and 3.3-5.0 g N2O m(-3) in China. The emission properties widely vary according to the structure of the treatment system. The conversion ratio for nitrogen in the wastewater influent to N2O by a soil trench is between 2 and a maximum of 8%, and ranges from a few- to several 10-fold as much as that with the activated sludge method, suggesting that this can be a large source of N2O emission. It has also clearly been shown that the aerobic-anaerobic state inside the treatment system is closely related to its CH4 and N2O emission characteristics. By performing ventilation to maintain the oxidation-reduction potential (ORP) near the trench at an aerobic condition of +200 mV or more, the quantities of CH4 and N2O emitted can be reduced by as much as 50% from the levels without this ventilation, and that this can make a large contribution.

  1. Simulating N2O emissions from irrigated cotton wheat rotations in Australia using DAYCENT: Mitigation options by optimized fertilizer and irrigation management

    NASA Astrophysics Data System (ADS)

    Scheer, Clemens; DelGrosso, Stephen; Parton, William; Rowlings, David; Grace, Peter

    2014-05-01

    Irrigation and fertilization do not only stimulate plant growth, but also accelerate microbial C- and N-turnover in the soil and thus can lead to enhanced emissions of nitrous oxide (N2O) from soils. In Australia there are more than 2 million hectares of agricultural land under irrigation and research has now focused on a combination of nitrogen fertilizer and irrigation management to maintain crop yields, maximize nitrogen use efficiency and reduce N2O emissions. Process-based models are now being used to estimate N2O emissions and assess mitigation options of N2O fluxes by improving management at field, regional and national scales. To insure that model predictions are reliable it is important to rigorously test the model so that uncertainty bounds for N2O emissions can be reduced and the impacts of different management practices on emissions can be better quantified. We used high temporal frequency dataset of N2O emissions to validate the performance of the agroecosystem model DayCent to simulate daily N2O emissions from sub-tropical vertisols under different irrigation intensities. Furthermore, we evaluated potential N2O mitigation strategies in irrigated cotton-wheat rotations in Australia by simulating different fertilizer and irrigation management scenarios over a climatically variable 25 year time span. DayCent accurately predicted soil moisture dynamics and the timing and magnitude of high fluxes associated with fertilizer additions and irrigation events. At the daily scale we found a good correlation of predicted vs. measured N2O fluxes (r2 = 0.52), confirming that DayCent can be used to test agricultural practices for mitigating N2O emission from irrigated cropping systems. The simulations of different fertilization and irrigation practices in cotton-wheat rotations over a 25 year time frame clearly showed that there is scope for reducing N2O emissions by modified fertilizer and irrigation management. For wheat and for cotton the model predicted that a

  2. Responses of direct N2O emissions from agricultural mineral soils on natural conditions and management - a multi site analysis across Europe

    NASA Astrophysics Data System (ADS)

    Dechow, R.; Freibauer, A.

    2012-04-01

    Widely used approaches that relate direct N2O emissions to inputs of reactive N using globally estimated emission factors are believed to be highly uncertain and regionally biased because they do not account for effects of natural conditions on microbial mediated processes responsible for N2O production/consumption and N2O transport processes in soils. At the other side the development of process based approaches is suffering from the fact that sufficient data to feed and train these models is available for a limited number of sites only challenging the spatial representativeness of these approaches. Inventories and mitigation assessment deserve simple applicable tools with restricted data needs that describe major mechanisms or dependencies. Last decades efforts in measuring direct annual and seasonal N2O emissions on plot scale built up data sets covering wide ranges of environmental conditions and management options. Statistical and hybrid approaches (fuzzy inference scheme) were used to infer responses of direct annual and seasonal N2O emissions on natural and anthropogenic drivers from multi-site measurements. The underlying idea of inference schemes is to split the multidimensional response surface by rules into situations (sub domains) that produce a uniform N2O response. Factors lowering the unexplained variability of seasonal and annual N2O emissions were determined by a forward selection algorithm. Simulated annealing was used to train models. For modeling of seasonal N2O emissions the input of the fuzzy inference scheme was generated by simple process based approaches (WFPS, soil temperature, available N). Nitrous oxide emissions of cropland soils and grassland soils exhibited distinct emission patterns. On cropland soils significant amounts of N2O emit during autumn to spring and freeze thaw induced emission peaks highly impact the annual N2O budget. The strength of emission peaks throughout the year is driven by available N, SOC and WFPS. From this it

  3. Broadcast urea reduces N2O emissions but increases NO emissions compared with conventional and shallow-applied anhydrous ammonia in a coarse-textured soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantifying nitrous oxide (N2O) and nitric oxide (NO) fluxes from corn (Zea Mays L.) production fields under contrasting fertilizer regimes is essential for identifying ways of mitigating agricultural greenhouse gas (GHG) emissions. Despite the importance of anhydrous ammonia (AA) and urea as N fert...

  4. Inverse modelling of European CH4 and N2O emissions 2006-2012 using different inverse models and improved atmospheric observations

    NASA Astrophysics Data System (ADS)

    Bergamaschi, Peter; Karstens, Ute; Koffi, Ernest; Saunois, Marielle; Arnold, Timothy; Manning, Alistair; Tsuruta, Aki; Berchet, Antoine; Vermeulen, Alex; Janssens-Maenhout, Greet; Hammer, Samuel; Levin, Ingeborg; Schmidt, Martina

    2016-04-01

    We present top-down estimates of European CH4 and N2O emissions for 2006-2012, based on the new quality controlled and harmonized data set from 18 European atmospheric monitoring stations generated within the European FP7 project InGOS ("Integrated non-CO2 Greenhouse gas Observing System"). We applied an ensemble of 7 different inverse models for CH4 (and 4 for N2O), and performed four different inversion experiments, investigating the impact of different sets of stations and the use of 'a priori' information on emissions. The inverse models infer total CH4 emissions of 28.4 ± 6.4 (2σ) Tg CH4 yr-1 for the EU-28 for 2006-2012 from the 4 inversion experiments. For comparison, total anthropogenic CH4 emissions reported to UNFCCC ('bottom-up', based on statistical data and emissions factors) amount to only 19.0 - 20.9 Tg CH4 yr-1 for the same period. A potential explanation for the discrepancy between the 'bottom-up' and 'top-down' estimates could be the contribution of natural sources, such as peatlands, wetlands, and wet soils, which might have been underestimated in previous analyses. The hypothesis of significant natural emissions is supported by the finding that the inversions yield significant seasonal cycles of derived CH4 emissions with maximum in summer, while anthropogenic CH4 emissions are assumed to have much lower seasonal variability. Furthermore we investigate potential biases of the flux inversions by comparing model simulations with regular aircraft profiles at 4 European sites and the 'Infrastructure for Measurement of the European Carbon Cycle (IMECC)' aircraft campaign. For N2O, for which uncertainties of bottom-up inventories are very large - typically on the order of 100% for the total N2O emissions per country (mainly due to N2O emissions from agricultural soils) - our results demonstrate that atmospheric measurements and inverse modelling can significantly reduce the uncertainties. Despite the large uncertainties in the bottom-up inventories

  5. Effects of nitrogen application rate and a nitrification inhibitor dicyandiamide on ammonia oxidizers and N2O emissions in a grazed pasture soil.

    PubMed

    Dai, Yu; Di, Hong J; Cameron, Keith C; He, Ji-Zheng

    2013-11-01

    Ammonia oxidizers, including ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA) are important drivers of a key step of the nitrogen cycle - nitrification, which affects the production of the potent greenhouse gas, nitrous oxide (N2O). A field experiment was conducted to determine the effect of nitrogen application rates and the nitrification inhibitor dicyandiamide (DCD) on the abundance of AOB and AOA and on N2O emissions in a grazed pasture soil. Nitrogen (N) was applied at four different rates, with urea applied at 50 and 100 kg N ha(-1) and animal urine at 300 and 600 kg N ha(-1). DCD was applied to some of the N treatments at 10 kg ha(-1). The results showed that the AOB amoA gene copy numbers were greater than those of AOA. The highest ratio of the AOB to AOA amoA gene copy numbers was 106.6 which occurred in the urine-N 600 treatment. The AOB amoA gene copy numbers increased with increasing nitrogen application rates. DCD had a significant impact in reducing the AOB amoA gene copy numbers especially in the high nitrogen application rates. N2O emissions increased with the N application rates. DCD had the most significant effect in reducing the daily and total N2O emissions in the highest nitrogen application rate. The greatest reduction of total N2O emissions by DCD was 69% in the urine-N 600 treatment. The reduction in the N2O emission factor by DCD ranged from 58% to 83%. The N2O flux and NO3(-)-N concentrations were significantly correlated to the growth of AOB, rather than AOA. This study confirms the importance of AOB in nitrification and the effect of DCD in inhibiting AOB growth and in decreasing N2O emissions in grazed pasture soils under field conditions.

  6. N2O EMISSIONS FROM STREAMS IN THE NEUSE RIVER WATERSHED, NORTH CAROLINA

    EPA Science Inventory

    The paper presents N2O emission data from 11 sites in the Neuse River watershed. Emissions were measured using a static surface enclosure technique deployed on eight sites on the main river channel and three tributary sites. Ancillary data collected included dissolved ...

  7. Phosphorus removal and greenhouse gas N2O emission in a lime-induced aerobic sludge granule process.

    PubMed

    Wu, X L; Guan, Y T; Zhang, X; Huang, X; Qian, Y

    2002-06-01

    Aerobic sludge granulation was achieved in an activated sludge process continuously fed with lime (Ca2+ 100 mg l(-1) influent) every other day. Eighteen days after lime addition, activated sludge granules with the size of 0.5-2.2 mm were formed, which occupied 10-25% of total sludge volume. Sludge volume index (SVI) was reduced to an average of 50 ml g(-1), which increased average sludge concentration to 3.6-5.0 g VSS l(-1), 1.6-2.1 times of that of control. Greenhouse gas N2O emission was also significantly reduced: N2O concentration from the lime-addition reactor was 5-15 ppmv, 47-61% of that of control, Effluent PO4-P concentration was generally lower than 1 mg l(-1) when average influent PO4-P concentration was 6.07-6.37 mg l(-1). Total phosphorus (TP) and total nitrogen (TN) removal efficiencies were around 89.6% and 14.5-16.1%, over 3.5 and 1 times higher than those of control, respectively. COD removal rate in the lime-addition reactor was 2.05-2.48 kg COD m(-3) d(-1), higher than 1.34-1.61 kg COD m(-3) d(-1) in the control.

  8. Ecological controls on N2O emission in surface litter and near-surface soil of a managed grassland: modelling and measurements

    NASA Astrophysics Data System (ADS)

    Grant, Robert F.; Neftel, Albrecht; Calanca, Pierluigi

    2016-06-01

    Large variability in N2O emissions from managed grasslands may occur because most emissions originate in surface litter or near-surface soil where variability in soil water content (θ) and temperature (Ts) is greatest. To determine whether temporal variability in θ and Ts of surface litter and near-surface soil could explain this in N2O emissions, a simulation experiment was conducted with ecosys, a comprehensive mathematical model of terrestrial ecosystems in which processes governing N2O emissions were represented at high temporal and spatial resolution. Model performance was verified by comparing N2O emissions, CO2 and energy exchange, and θ and Ts modelled by ecosys with those measured by automated chambers, eddy covariance (EC) and soil sensors on an hourly timescale during several emission events from 2004 to 2009 in an intensively managed pasture at Oensingen, Switzerland. Both modelled and measured events were induced by precipitation following harvesting and subsequent fertilizing or manuring. These events were brief (2-5 days) with maximum N2O effluxes that varied from < 1 mgNm-2h-1 in early spring and autumn to > 3 mgNm-2h-1 in summer. Only very small emissions were modelled or measured outside these events. In the model, emissions were generated almost entirely in surface litter or near-surface (0-2 cm) soil, at rates driven by N availability with fertilization vs. N uptake with grassland regrowth and by O2 supply controlled by litter and soil wetting relative to O2 demand from microbial respiration. In the model, NOx availability relative to O2 limitation governed both the reduction of more oxidized electron acceptors to N2O and the reduction of N2O to N2, so that the magnitude of N2O

  9. Role of surface and subsurface processes in scaling N2O emissions along riverine networks.

    PubMed

    Marzadri, Alessandra; Dee, Martha M; Tonina, Daniele; Bellin, Alberto; Tank, Jennifer L

    2017-04-11

    Riverine environments, such as streams and rivers, have been reported as sources of the potent greenhouse gas nitrous oxide ([Formula: see text]) to the atmosphere mainly via microbially mediated denitrification. Our limited understanding of the relative roles of the near-surface streambed sediment (hyporheic zone), benthic, and water column zones in controlling [Formula: see text] production precludes predictions of [Formula: see text] emissions along riverine networks. Here, we analyze [Formula: see text] emissions from streams and rivers worldwide of different sizes, morphology, land cover, biomes, and climatic conditions. We show that the primary source of [Formula: see text] emissions varies with stream and river size and shifts from the hyporheic-benthic zone in headwater streams to the benthic-water column zone in rivers. This analysis reveals that [Formula: see text] production is bounded between two [Formula: see text] emission potentials: the upper [Formula: see text] emission potential results from production within the benthic-hyporheic zone, and the lower [Formula: see text] emission potential reflects the production within the benthic-water column zone. By understanding the scaling nature of [Formula: see text] production along riverine networks, our framework facilitates predictions of riverine [Formula: see text] emissions globally using widely accessible chemical and hydromorphological datasets and thus, quantifies the effect of human activity and natural processes on [Formula: see text] production.

  10. Soil Emissions of N2O and NO in Agricultural Production Systems in the Upper Midwest U.S.: Management Controls and Measurement Issues (Invited)

    NASA Astrophysics Data System (ADS)

    Venterea, R. T.; Baker, J. M.

    2009-12-01

    Cropped fields in the upper Midwest have the potential to emit relatively large quantities of N2O and NO resulting from soil transformation of N fertilizers applied to crops such as corn and potatoes. The mitigation of N2O emissions may be an effective strategy for offsetting greenhouse gas emissions. While the rate of N fertilizer application exerts some control over N trace gas emission rates, a variety of other management practices and environmental factors interact to regulate these emissions. Observation-based studies are essential for improving models, developing accurate inventories, and documenting offsets. Since 2003, we have been examining the effects of management factors including: tillage, crop rotation, irrigation, and fertilizer chemical form and application method on N2O and NO emissions from corn and potato production systems using chamber-based measurement techniques. A summary of our findings will be presented, including: Application of anhydrous ammonia resulted in twice the N2O emissions compared to urea fertilizer, and twice the NO emissions compared to liquid urea ammonium nitrate (UAN) fertilizer. Growing corn continuously compared to in rotation with soybeans did not alter the amount of N2O emitted during the corn growing season. Reduced tillage (RT), often promoted as a means of reducing carbon losses to the atmosphere, also altered soil N2O emissions. However, the impact of RT on N2O emissions was found to vary, in both magnitude and direction, as a function of N fertilizer management. In addition to these studies, our efforts to overcome some of the inherent limitations of chamber-based flux measurement techniques will be discussed.

  11. Soil N2O and NO emissions from land use and land-use change in the tropics and subtropics: a meta-analysis

    NASA Astrophysics Data System (ADS)

    van Lent, J.; Hergoualc'h, K.; Verchot, L. V.

    2015-08-01

    Deforestation and forest degradation in the tropics may substantially alter soil N-oxide emissions. It is particularly relevant to accurately quantify those changes to properly account for them in a REDD+ climate change mitigation scheme that provides financial incentives to reduce the emissions. With this study we provide updated land use (LU)-based emission rates (103 studies, 387 N2O and 111 NO case studies), determine the trend and magnitude of flux changes with land-use change (LUC) using a meta-analysis approach (43 studies, 132 N2O and 37 NO cases) and evaluate biophysical drivers of N2O and NO emissions and emission changes for the tropics. The average N2O and NO emissions in intact upland tropical forest amounted to 2.0 ± 0.2 (n = 88) and 1.7 ± 0.5 (n = 36) kg N ha-1 yr-1, respectively. In agricultural soils annual N2O emissions were exponentially related to N fertilization rates and average water-filled pore space (WFPS) whereas in non-agricultural sites a Gaussian response to WFPS fit better the observed NO and N2O emissions. The sum of soil N2O and NO fluxes and the ratio of N2O to NO increased exponentially and significantly with increasing nitrogen availability (expressed as NO3-/[NO3-+NH4+]) and WFPS, respectively; following the conceptual Hole-In-the-Pipe model. Nitrous and nitric oxide fluxes did not overall increase significantly as a result of LUC (Hedges's d of 0.11 ± 0.11 and 0.16 ± 0.19, respectively), however individual LUC trajectories or practices did. Nitrous oxide fluxes increased significantly after intact upland forest conversion to croplands (Hedges's d = 0.78 ± 0.24) and NO increased significantly following the conversion of low forest cover (secondary forest younger than 30 years, woodlands, shrublands) (Hedges's d of 0.44 ± 0.13). Forest conversion to fertilized systems significantly and highly raised both N2O and NO emission rates (Hedges's d of 1.03 ± 0.23 and 0.52 ± 0.09, respectively). Changes in nitrogen availability

  12. Reviews and syntheses: Soil N2O and NO emissions from land use and land-use change in the tropics and subtropics: a meta-analysis

    NASA Astrophysics Data System (ADS)

    van Lent, J.; Hergoualc'h, K.; Verchot, L. V.

    2015-12-01

    Deforestation and forest degradation in the tropics may substantially alter soil N-oxide emissions. It is particularly relevant to accurately quantify those changes to properly account for them in a REDD+ climate change mitigation scheme that provides financial incentives to reduce the emissions. With this study we provide updated land use (LU)-based emission rates (104 studies, 392 N2O and 111 NO case studies), we determine the trend and magnitude of flux changes with land-use change (LUC) using a meta-analysis approach (44 studies, 135 N2O and 37 NO cases) and evaluate biophysical drivers of N2O and NO emissions and emission changes for the tropics. The average N2O and NO emissions in intact upland tropical forest amounted to 2.0 ± 0.2 (n = 90) and 1.7 ± 0.5 (n = 36) kg N ha-1 yr-1, respectively. In agricultural soils annual N2O emissions were exponentially related to N fertilization rates and average water-filled pore space (WFPS) whereas in non-agricultural sites a Gaussian response to WFPS fit better with the observed NO and N2O emissions. The sum of soil N2O and NO fluxes and the ratio of N2O to NO increased exponentially and significantly with increasing nitrogen availability (expressed as NO3- / [NO3-+NH4+]) and WFPS, respectively; following the conceptual Hole-In-the-Pipe model. Nitrous and nitric oxide fluxes did not increase significantly overall as a result of LUC (Hedges's d of 0.11 ± 0.11 and 0.16 ± 0.19, respectively), however individual LUC trajectories or practices did. Nitrous oxide fluxes increased significantly after intact upland forest conversion to croplands (Hedges's d = 0.78 ± 0.24) and NO increased significantly following the conversion of low forest cover (secondary forest younger than 30 years, woodlands, shrublands) (Hedges's d of 0.44 ± 0.13). Forest conversion to fertilized systems significantly and highly raised both N2O and NO emission rates (Hedges's d of 1.03 ± 0.23 and 0.52 ± 0.09, respectively). Changes in nitrogen

  13. Simulated nitrogen deposition reduces CH4 uptake and increases N2O emission from a subtropical plantation forest soil in southern China.

    PubMed

    Wang, Yongsheng; Cheng, Shulan; Fang, Huajun; Yu, Guirui; Xu, Minjie; Dang, Xusheng; Li, Linsen; Wang, Lei

    2014-01-01

    To date, few studies are conducted to quantify the effects of reduced ammonium (NH4+) and oxidized nitrate (NO3-) on soil CH4 uptake and N2O emission in the subtropical forests. In this study, NH4Cl and NaNO3 fertilizers were applied at three rates: 0, 40 and 120 kg N ha(-1) yr(-1). Soil CH4 and N2O fluxes were determined twice a week using the static chamber technique and gas chromatography. Soil temperature and moisture were simultaneously measured. Soil dissolved N concentration in 0-20 cm depth was measured weekly to examine the regulation to soil CH4 and N2O fluxes. Our results showed that one year of N addition did not affect soil temperature, soil moisture, soil total dissolved N (TDN) and NH4+-N concentrations, but high levels of applied NH4Cl and NaNO3 fertilizers significantly increased soil NO3(-)-N concentration by 124% and 157%, respectively. Nitrogen addition tended to inhibit soil CH4 uptake, but significantly promoted soil N2O emission by 403% to 762%. Furthermore, NH4+-N fertilizer application had a stronger inhibition to soil CH4 uptake and a stronger promotion to soil N2O emission than NO3(-)-N application. Also, both soil CH4 and N2O fluxes were driven by soil temperature and moisture, but soil inorganic N availability was a key integrator of soil CH4 uptake and N2O emission. These results suggest that the subtropical plantation soil sensitively responses to atmospheric N deposition, and inorganic N rather than organic N is the regulator to soil CH4 uptake and N2O emission.

  14. Simulated Nitrogen Deposition Reduces CH4 Uptake and Increases N2O Emission from a Subtropical Plantation Forest Soil in Southern China

    PubMed Central

    Wang, Yongsheng; Cheng, Shulan; Fang, Huajun; Yu, Guirui; Xu, Minjie; Dang, Xusheng; Li, Linsen; Wang, Lei

    2014-01-01

    To date, few studies are conducted to quantify the effects of reduced ammonium (NH4+) and oxidized nitrate (NO3−) on soil CH4 uptake and N2O emission in the subtropical forests. In this study, NH4Cl and NaNO3 fertilizers were applied at three rates: 0, 40 and 120 kg N ha−1 yr−1. Soil CH4 and N2O fluxes were determined twice a week using the static chamber technique and gas chromatography. Soil temperature and moisture were simultaneously measured. Soil dissolved N concentration in 0–20 cm depth was measured weekly to examine the regulation to soil CH4 and N2O fluxes. Our results showed that one year of N addition did not affect soil temperature, soil moisture, soil total dissolved N (TDN) and NH4+-N concentrations, but high levels of applied NH4Cl and NaNO3 fertilizers significantly increased soil NO3−-N concentration by 124% and 157%, respectively. Nitrogen addition tended to inhibit soil CH4 uptake, but significantly promoted soil N2O emission by 403% to 762%. Furthermore, NH4+-N fertilizer application had a stronger inhibition to soil CH4 uptake and a stronger promotion to soil N2O emission than NO3−-N application. Also, both soil CH4 and N2O fluxes were driven by soil temperature and moisture, but soil inorganic N availability was a key integrator of soil CH4 uptake and N2O emission. These results suggest that the subtropical plantation soil sensitively responses to atmospheric N deposition, and inorganic N rather than organic N is the regulator to soil CH4 uptake and N2O emission. PMID:24714387

  15. N2O emissions from a one stage partial nitrification/anammox process in moving bed biofilm reactors.

    PubMed

    Yang, Jingjing; Trela, Jozef; Plaza, Elzbieta; Tjus, Kåre

    2013-01-01

    Nitrous oxide (N2O) emissions from wastewater treatment are getting increased attention because their global warming potential is around 300 times that of carbon dioxide. The aim of the study was to measure nitrous oxide emissions from one stage partial nitrification/anammox (Anaerobic Ammonium Oxidation) reactors, where nitrogen is removed in a biological way. The first part of the experimental study was focused on the measurements of nitrous oxide emissions from two pilot scale reactors in the long term; one reactor with intermittent aeration at 25 °C and the other reactor with continuous aeration at 22-23 °C. The second part of the experiment was done to evaluate the influence of different nitrogen loads and aeration strategies, described by the ratio between the non-aerated and aerated phase and the dissolved oxygen concentrations, on nitrous oxide emissions from the process. The study showed that 0.4-2% of the nitrogen load was converted into nitrous oxide from two reactors. With higher nitrogen load, the amount of nitrous oxide emission was also higher. A larger fraction of nitrous oxide was emitted to the gas phase while less was emitted with the liquid effluent. It was also found that nitrous oxide emissions were similar under intermittent and continuous aeration.

  16. Characterizing Nitrous Oxide (N2O) Emissions over a Wheat-based Cropping System in the Northwest United States Using the Modified Bowen Ratio Technique and Static Chambers

    NASA Astrophysics Data System (ADS)

    Waldo, Sarah; Kostyanovsky, Kirill; O'Keeffe, Patrick; Pressley, Shelley; Huggins, Dave; Stockle, Claudio; Lamb, Brian

    2015-04-01

    Nitrous oxide (N2O) is a potent greenhouse gas and ozone depleting substance. Agricultural soils are the primary source of N2O, which is created as a by-product of soil microbial processes. The production and emission of N2O is characterized by high spatial and temporal variability, or "hot spots" and "hot moments". These behaviors, along with limitations in instrument sensitivity to N2O, are challenges in characterizing emissions. Many studies have monitored N2O emissions using either static chambers or micrometeorological measurements or the two methods together. The two techniques are complementary: chamber methods have a lower detection limit and are more reliable as their operation does not depend on atmospheric conditions, but may not capture spatial variability even with multiple chambers. Tower-based methods are subject to relatively high data loss due to non-ideal conditions and to less sensitive detection limits, but have a larger measurement footprint and can characterize field-scale emissions. This study aims to characterize a long-term, field-scale N2O budget over two winter wheat fields located in the Inland Pacific Northwest of the United States, both in terms of an annual emission budget and in terms of understanding what causes hot moments. We combined continuous measurements of N2O emissions from a system of sixteen automated, static chambers with tower-based measurements of N2O fluxes. We used the modified Bowen ratio (MBR) technique with temperature as a tracer. Preliminary results indicate that freeze-thaw cycles in the winter make up a higher percentage of annual emissions than previously thought. Furthermore, comparison of the chamber results to the tower-based measurements imply that the chambers may be underestimating field-scale N2O fluxes because they are not adequately capturing hot spots of emissions. We are conducting ongoing work on how to integrate the two measurement techniques, as well as how the empirical measurements compare with

  17. BOREAS TGB-5 Biogenic Soil Emissions of NO and N2O

    NASA Technical Reports Server (NTRS)

    Levine, J. S.; Winstead, E. L.; Parsons, D. A. B.; Scholes, M. C.; Cofer, W. R.; Cahoon, D. R.; Sebacher, D. I.; Scholes, R. J.; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB)-5 team made several measurements of trace gas concentrations and fluxes at various NSA sites. This data set contains biogenic soil emissions of nitric oxide and nitrous oxide that were measured over a wide range of spatial and temporal site parameters. Since very little is known about biogenic soil emissions of nitric oxide and nitrous oxide from the boreal forest, the goal of the measurements was to characterize the biogenic soil fluxes of nitric oxide and nitrous oxide from black spruce and jack pine areas in the boreal forest. The diurnal variation and monthly variation of the emissions was examined as well as the impact of wetting through natural or artificial means. Temporally, the data cover mid-August 1993, June to August 1994, and mid-July 1995. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884).

  18. 40 CFR Table Aa-2 to Subpart Aa of... - Kraft Lime Kiln and Calciner Emissions Factors for CH4 and N2O

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Kraft Lime Kiln and Calciner Emissions... Manufacturing Pt. 98, Subpt. AA, Table AA -2 Table AA-2 to Subpart AA of Part 98—Kraft Lime Kiln and Calciner... CH4 N2O Kraft calciners CH4 N2O Residual Oil (any type) 0.0027 0 0.0027 0.0003 Distillate Oil...

  19. Assessing fertilizer N placement on CH4 and N2O emissions in irrigated rice systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improved N fertilizer management practices can increase rice yields and mitigate global warming potential (GWP). While banding N has been shown to have positive effects on yield and nitrogen use efficiency (NUE), there is little information in how it affects greenhouse gas (GHG) emissions from flood...

  20. Influence of Antecedent Soil Moisture Conditions and Substrate Quality on the Magnitude and Timing of N2O Emissions From Riparian Soil

    NASA Astrophysics Data System (ADS)

    Owens, J. L.; Macrae, M. L.; Bourbonniere, R. A.; Petrone, R. M.; Schiff, S. L.

    2009-05-01

    Nitrous oxide (N2O) is a greenhouse gas with a large global warming potential. Consequently there is concern over increased concentrations of atmospheric N2O. Denitrification and nitrification are the primary sources of N2O emissions from agricultural soils and riparian wetlands within these systems. These processes are regulated by soil moisture, oxygen levels in soil pores, soil substrate/nutrient supply (e.g. carbon (C) and nitrogen (N)), pH, and temperature. Soil moisture history may also be a key determinant of N2O flux timing and magnitude through its influence on soil turnover processes and therefore available nutrient pools. However, the linkages between these controls as well as their relative influence on N2O fluxes are poorly understood. This research uses an experimental approach to examine the combined influences of soil moisture and nutrient availability (as affected by soil antecedent moisture history) on N2O fluxes from riparian soil. Soil cores were collected from both an upland (loam soil) location and a lowland (organic soil) location in an agricultural riparian wetland in Southern Ontario for this experiment. In the laboratory, intact soil cores were subject to moisture cycles (wet-dry-wet; dry-wet-dry) over a six-week period to examine how N2O fluxes and soil available nutrient pools changed throughout different types of moisture cycles. Preliminary results indicate that antecedent soil moisture influences the timing and magnitude of N2O flux due to its influence on both soil available nutrient content and likely O2 availability; however, these relationships differ for the two soil types. Larger N2O fluxes were observed from upland soils on a drying trend as opposed to a wetting trend. In contrast, larger N2O fluxes were observed from soils on a wetting trend rather than a drying trend from lowland soil. In addition, the timing of the onset and cessation of N2O fluxes differed both with soil type and the direction of the moisture cycle (i

  1. [Quantifying direct N2O emissions from paddy fields during rice growing season in China: model and input data validation].

    PubMed

    Zou, Jian-Wen; Liu, Shu-Wei; Qin, Yan-Mei; Feng, De-Sheng; Zhu, Hui-Lin; Xu, Yong-Zhong

    2009-04-15

    The models on direct N2O emissions from rice paddies under different water regimes developed by the authors were validated against field measurements in China reported in 2005-2007 and in other regions. In flooding rice paddies (F), N2O emission predicted by the model was consistent with previous reports in other regions. Under the water regime of flooding-midseason drainage-reflooding (F-D-F), the model developed in this study was comparable to that established by using worldwide database. The models also well fitted N2O emissions from rice paddies under the water regime of flooding-midseason drainage-reflooding-moisture but without waterlogging (F-D-F-M) in China. Consistency of rice production data derived from the database of this study with those reported in previous studies suggests that the model input data of rice production had high reliability. The input data showed that water management and nitrogen input regimes have greatly changed in rice paddies since the 1950s. During the 1950s-1970s, about 20%-25% of the rice paddy was continuous water logging, and 75%-80% under the water regime of F-D-F. Since the 1980s, about 12%-16%, 77% and 7%-12% of paddy fields were under the water regimes of F, F-D-F and F-D-F-M, respectively. Total N input during the rice growing season averaged 87.49 kg x hm(-2) in the 1950s and 224.64 kg x hm(-2) in the 1990s. Chemical N input during the rice growing season has increased from 37.4 kg x hm(-2) in the 1950s to 198.8 kg x hm(-2) in the 1990s, accounting for 43% and 88% of the seasonal total N inputs, respectively. Manure N input was applied at stable rate, ranging from 45.2 kg x hm(-2) to 48.2 kg x hm(-2) during the 1950s-1970s, but thereafter it decreased over time. The contribution of manure N to total N inputs has decreased from 52% in the 1950s to 9% in the 1990s. Crop residue N retained during the rice growing season has increased from 4.9 kg x hm(-2) in the 1950s to 6.3 kg x hm(-2) in the 1980s. A high spatial

  2. [Effects of different fertilization measures on N2O emission in oil sunflower field in irrigation area of upper Yellow River].

    PubMed

    Chen, Zhe; Chen, Yuan-yuan; Gao, Ji; Liu, Ru-liang; Yang, Zheng-li; Zhang, Ai-ping

    2015-01-01

    Agricultural soil has become the largest anthropogenic source of atmospheric nitrous oxide (N20). To estimate the impacts of long-term combined application of organic and inorganic fertilizers on N20 emission in a typical winter wheat-oil sunflower cropping system in the Ningxia irrigation area, we measured N20 fluxes using the static opaque chamber-gas chromatograph method and monitored the seasonal dynamics of related factors. Our results showed that nitrogen addition in the previous crop field significantly stimulated N2O emissions during the following oil-sunflower cultivation, and the mean fluxes of N300-OM, N240-OM1/2, N300 and N240 were (34.16 ± 9.72), (39.69 ±10.70), (27.75 ±9.57) and (26.30 ± 8.52) µg . m-2 . h-1, respectively, which were 4.09, 4.75, 3.32 and 3.15 times of the control groups. The total cumulative N2O emissions of fertilizer treatments in growing season was as high as 796.7 to 1242.5 g . hm-2, which was 2.99 to 4.67 times of the control groups. During the growing season, the rates of N2O emission in each month organic and inorganic fertlizers combined treatments were similar at high levels. N2O emission in chemical fertilizer treatments gradually decreased, and the main period of N2O emission occurred at the beginning of growing season. Taking July for example, N2O emission accounted for 41.3% to 41. 8% of total cumulative amount. The amounts of N20 emission under organic and inorganic fertilizers combined treatments were significantly higher than under chemical fertilizer treatments. The N2O emissions were not significantly different between conventional and optimized applications of nitrogen fertilizer under the same fertilizing method, either between N300-OM and N240-OM1/2, or between N300 and N240. On account of the drought, N2O emission in each treatment was mainly affected by soil moisture. N2O emission had a significant positive correlation with soil ammonium nitrogen content under combined applications of organic and inorganic

  3. Insights into the effect of soil pH on N(2)O and N(2) emissions and denitrifier community size and activity.

    PubMed

    Cuhel, Jirí; Simek, Miloslav; Laughlin, Ronnie J; Bru, David; Chèneby, Dominique; Watson, Catherine J; Philippot, Laurent

    2010-03-01

    The objective of this study was to investigate how changes in soil pH affect the N(2)O and N(2) emissions, denitrification activity, and size of a denitrifier community. We established a field experiment, situated in a grassland area, which consisted of three treatments which were repeatedly amended with a KOH solution (alkaline soil), an H(2)SO(4) solution (acidic soil), or water (natural pH soil) over 10 months. At the site, we determined field N(2)O and N(2) emissions using the (15)N gas flux method and collected soil samples for the measurement of potential denitrification activity and quantification of the size of the denitrifying community by quantitative PCR of the narG, napA, nirS, nirK, and nosZ denitrification genes. Overall, our results indicate that soil pH is of importance in determining the nature of denitrification end products. Thus, we found that the N(2)O/(N(2)O + N(2)) ratio increased with decreasing pH due to changes in the total denitrification activity, while no changes in N(2)O production were observed. Denitrification activity and N(2)O emissions measured under laboratory conditions were correlated with N fluxes in situ and therefore reflected treatment differences in the field. The size of the denitrifying community was uncoupled from in situ N fluxes, but potential denitrification was correlated with the count of NirS denitrifiers. Significant relationships were observed between nirS, napA, and narG gene copy numbers and the N(2)O/(N(2)O + N(2)) ratio, which are difficult to explain. However, this highlights the need for further studies combining analysis of denitrifier ecology and quantification of denitrification end products for a comprehensive understanding of the regulation of N fluxes by denitrification.

  4. Effects of dicyandiamide and acetylene on N2O emissions and ammonia oxidizers in a fluvo-aquic soil applied with urea.

    PubMed

    Wang, Qing; Zhang, Li-Mei; Shen, Ju-Pei; Du, Shuai; Han, Li-Li; He, Ji-Zheng

    2016-11-01

    Ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) are crucial for N2O emission as they carry out the key step of nitrification. Dicyandiamide (DCD) and acetylene (C2H2) are typical nitrification inhibitors (NIs), while the comparative effects of these NIs on N2O production and ammonia oxidizers' (AOB and AOA) growth are unclear. Four treatments including a control, urea, urea + DCD, and urea + C2H2 were set up to investigate their effect of inhibiting soil nitrification, nitrification-related N2O emission as well as the growth of ammonia oxidizers with a fluvo-aquic soil using microcosms for 28 days. N2O emission and net nitrification rate increased after the application of urea, but were significantly restrained in urea + NI treatments, while C2H2 was more effective in reducing N2O emission and nitrification rate than DCD. The abundance of AOB, which was significantly correlated with N2O emission and net nitrification rate, was more inhibited by C2H2 than DCD. Furthermore, the application of urea in all the soils had little impact on the AOA community, while obvious shifts of AOB community structure were found compared with the control. All AOB sequences fell within Nitrosospira cluster 3, and the AOA community was clustered to group 1.1b. Collectively, it indicated that application of urea combined with NIs (DCD or C2H2) could potentially alter N2O emission, mainly through regulating the growth of AOB but not AOA in this fluvo-aquic soil.

  5. Seasonal Dynamics of N2O and CO2 Emissions from a Corn Production System measured with the Eddy covariance and Chamber techniques

    NASA Astrophysics Data System (ADS)

    Iwuozo, S. A.; Hui, D.; Dennis, S.

    2013-12-01

    Agricultural Practices play a major role in the global fluxes of the greenhouse gases carbon dioxide, nitrous oxide, and methane. The use of fertilizer in Corn production has generated concerns about its contribution to global climate change. Thus, farmers and others concerned have become interested in more efficient fertilization management practice and reduced greenhouse gas emissions. To understand best management practices, in the 2012 and 2013 corn growing seasons, field experiments was conducted at Tennessee State University Agricultural Research and Demonstration Center in Nashville, TN. The study examines the seasonal variations of (N2O) and (CO2) emissions from soil as a function of six treatment that include inorganic nitrogen fertilizer, chicken litter and biochar application. The combinations were: regular URAN 32-0-0 liquid fertilizer (2 times) no till, regular URAN 32-0-0 liquid fertilizer (2 times) conventional till, multiple URAN applications (4 times) no till, Denitrification inhibitor with regular URAN application in no till, chicken litter with regular URAN application no till and URAN application with biochar in no tilled plots. Each treatment was replicated 6 times. N2O and CO2 emissions were measured using a closed chamber method after rainfall event(s), fertilizer applications or every two weeks whichever was shorter. Corresponding soil NH4+-N and NO3--N, soil temperature and moisture were also measured during gas sampling. Plant physiological and growth parameters were measured as appropriate and meteorological records were kept. N2O flux was also continuously measured in a commercial corn field using the eddy covariance (EC) technique fitted with a fast response N2O analyzer to check the N2O emissions at the large scale and compare it to the chamber method. Results obtained with the EC technique were comparable with the chamber methods. Preliminary data indicate that N2O and CO2 fluxes were significantly influenced by the agricultural

  6. The influence of straw returning on N2O emissions from a maize-wheat field in the North China Plain.

    PubMed

    Zhou, Yizhen; Zhang, Yuanyuan; Tian, Di; Mu, Yujing

    2017-01-30

    Crop straw returning has become a prevailing cultivation practice in the vast area of the North China Plain (NCP), while few investigations about its influence on nitrous oxide (N2O) emission have been conducted. In this study, N2O emissions from an agricultural field in the NCP with and without straw returning were comparably investigated by using static chambers in two consecutive maize-wheat growing seasons from June 2010 to June 2012. Compared with the NP treatment (compound nitrogen fertilizer only), the cumulative N2O emission from the SP treatment (compound nitrogen fertilizer plus straw) increased about 150% during the maize season in 2010, but decreased by about 35% during the maize season in 2011. The inconsistent influence of straw returning on N2O emission from the maize field was ascribed to the evidently different soil moisture between the two years, which was further confirmed by laboratory simulation experiments. About 40% reduction of N2O emission from the SP treatment during the two winter wheat seasons, which was mainly attributed to anoxic condition induced by rotting the maize straw.

  7. Cost-effectiveness analysis of farmers' rice straw management practices considering CH4 and N2O emissions.

    PubMed

    Launio, Cheryll C; Asis, Constancio A; Manalili, Rowena G; Javier, Evelyn F

    2016-12-01

    This study assessed the environmental consequences of burning and other rice straw management practices in terms of non-CO2 greenhouse gas (GHG) emissions, and evaluated the cost-effectiveness of selected rice straw management alternatives. On a per-hectare basis and considering a time horizon of five years, incorporating stubble more than 30 days before crop establishment, and incorporating composted rice straw in the field yielded the lowest cumulative CH4 and N2O emissions. Considering the associated costs and secondary benefits, the most cost-effective option for farmers is to incorporate stubble and straw in the soil more than 30 days before crop establishment. Rapid straw composting and incorporation of rice straw compost entails much higher additional cost but it also significantly mitigates GHG emission, hence it is the next most cost-effective option. Incorporating rice stubble and straw less than a month before crop establishment and removing rice straw for use as animal feed, on the other hand, appear to result in a net increase in ton CO2-eq given the assumed time horizon. The results underscore the impacts on the environment of small changes in straw management practices entailing minimal costs. Cost-effectiveness analysis considering rice straw for power generation and bio ethanol production is recommended. Further study on water management and tillage practice as mitigation options is recommended for a broader perspective useful for farmers, policy-makers, and other rice stakeholders.

  8. Effect of mowing on N2O and CH4 fluxes emissions from the meadow-steppe grasslands of Inner Mongolia

    NASA Astrophysics Data System (ADS)

    Lu, Zedong; Du, Rui; Du, Pengrui; Li, Ziming; Liang, Zongmin; Wang, Yaling; Qin, Saisai; Zhong, Lei

    2015-09-01

    To assess the impacts of mowing on N2O and CH4 fluxes emissions from the meadow-steppe grasslands of Inner Mongolia, China, two regimes were investigated: unmown since 2005 (UM), and mown once every three years since 2009 (M3). On-site measurements were conducted continuously during a year-round period (August 2011 to August 2012). During the observation period, three diurnal cycles were also measured. In addition, a targeted laboratory experiment was conducted to make up for the few measurements in winter. A large pulse of N2O emissions related to freeze-thaw cycles was observed at M3 during the spring thaw. Results showed that the meadow-steppes played a role as a sink for CH4 and a source for N2O. Significantly lower mean CH4 uptake at UM (40.3 μg C·m-2·h-1) as compared to M3 (70.5 μg C ·m-2·h-1) ( p<0.01), and significantly higher mean N2O efflux at UM (6.3 μgN·m-2·h-1) as compared to M3 (4.3 μg N·m-2·h-1) ( p<0.05) were found. The laboratory experiment results revealed that mowing changed the soil conditions that favor the activity of denitrifiers during thawing periods. The CH4 and N2O fluxes were significantly correlated with soil temperature ( p<0.05). Mowing affected CH4 uptake and N2O emission mainly through its effect on vegetation types and some soil properties, such as soil inorganic N content, soil temperature, and soil moisture content, while soil inorganic N and moisture were not leading factors. Our results also suggested that mowing could mitigate the potential global warming in terms of CH4 uptake and N2O emissions.

  9. High-Resolution Denitrification Kinetics in Pasture Soils Link N2O Emissions to pH, and Denitrification to C Mineralization

    PubMed Central

    Samad, Md Sainur; Bakken, Lars R.; Nadeem, Shahid; Clough, Timothy J.; de Klein, Cecile A. M.; Richards, Karl G.; Lanigan, Gary J.; Morales, Sergio E.

    2016-01-01

    Denitrification in pasture soils is mediated by microbial and physicochemical processes leading to nitrogen loss through the emission of N2O and N2. It is known that N2O reduction to N2 is impaired by low soil pH yet controversy remains as inconsistent use of soil pH measurement methods by researchers, and differences in analytical methods between studies, undermine direct comparison of results. In addition, the link between denitrification and N2O emissions in response to carbon (C) mineralization and pH in different pasture soils is still not well described. We hypothesized that potential denitrification rate and aerobic respiration rate would be positively associated with soils. This relationship was predicted to be more robust when a high resolution analysis is performed as opposed to a single time point comparison. We tested this by characterizing 13 different temperate pasture soils from northern and southern hemispheres sites (Ireland and New Zealand) using a fully automated-high-resolution GC detection system that allowed us to detect a wide range of gas emissions simultaneously. We also compared the impact of using different extractants for determining pH on our conclusions. In all pH measurements, soil pH was strongly and negatively associated with both N2O production index (IN2O) and N2O/(N2O+N2) product ratio. Furthermore, emission kinetics across all soils revealed that the denitrification rates under anoxic conditions (NO+N2O+N2 μmol N/h/vial) were significantly associated with C mineralization (CO2 μmol/h/vial) measured both under oxic (r2 = 0.62, p = 0.0015) and anoxic (r2 = 0.89, p<0.0001) conditions. PMID:26990862

  10. Two years monitoring of soil N_{2}O emissions on durum wheat in a Mediterranean area: the effect of tillage intensity and N-fertilizer rate.

    NASA Astrophysics Data System (ADS)

    Volpi, Iride; Bosco, Simona; Triana, Federico; Di Nasso, Nicoletta Nassi o.; Laville, Patricia; Virgili, Giorgio; Bonari, Enrico

    2016-04-01

    Evaluating the magnitude and the key factors affecting N2O emissions from agriculture has a scientific and practical relevance, in fact emissions from agricultural and natural soils account for 56-70% of all global N2O sources (Syakila and Kroeze, 2011). Moreover, the necessity to increase the food production rate minimizing greenhouse gas emissions require a deeper understanding of the effect of the agricultural practices on direct soil emissions. Therefore, the aim of this work is to assess the effect of tillage intensity and nitrogen rate on soil N2O emissions on durum wheat. A two years monitoring campaign was carried out using a high-sensibility transportable instrument developed within the LIFE+ "Improved flux Prototypes for N2O emission from Agriculture" IPNOA project (Bosco et al., 2015; Laville et al., 2015). The project aims at improving the measurement technique of N2O flux directly in field using the flow-through non-steady state chamber technique. The monitoring campaign on durum wheat lasted for two growing seasons and two fallow periods (2013-14 and 2014-15). Treatment on the main plot was tillage intensity with two levels, ploughing and minimum tillage, and three different nitrogen rates were distributed to the subplots (N0: 0 kg ha-1, N1: 110 kg ha-1, N2: 170 kg ha-1). Ancillary measurements concerned meteorological data, soil temperature and moisture, NO3-, NH4+ soil concentration. Main results of the two years highlighted N rate as the main driver for both N2O daily flux and cumulative emissions during the growing season, while in the fallow period treatments did not affect the emission magnitude. Tillage intensity was not a key factor for N2O emissions. N2O emissions were significantly different in the two years. In particular, cumulative emissions of 2013-14 were about five times higher than in 2014-15, respectively on average 2885±260 g N-N2O ha-1 and 534±53 g N-N2O ha-1 for a similar monitoring period of about 300 days. Differences could be

  11. [Effects of dicyandiamide combined with nitrogen fertilizer on N2O emission and economic benefit in winter wheat and summer maize rotation system].

    PubMed

    Wang, Yan-qun; Li, Ying-chun; Peng, Zheng-ping; Wang, Chao-dong; Liu, Ya-nan

    2015-07-01

    Aiming at the problems of excessive and unreasonable fertilizer application, lower nitrogen use efficiency, increasing N2O emission from soil and fertilizer in current intensified agricultural productions, a field experiment was conducted to study the effects of dicyandiamide (DCD) combined with nitrogen fertilizer application at different levels, i.e., 150, 225, 300 kg . hm-2, on N20 emission and relevant economic benefit in a typical winter wheat-summer maize rotation system in North China Plain. The results showed that DCD application decreased N2O emission fluxes and cumulative emissions by 25.6%-32.1% and 23.1%-31.1% in the year-round. There was a significant positive exponential correlation between N2O flux and soil surface temperature or soil moisture content. The effect of soil moisture on N2O emission was stronger in wheat season than in maize season, while the effect of temperature on N2O emission was on the contrary. The yields of winter wheat and summer maize with DCD addition were increased by 16.7%-24.6% and 29.8%-34.5%, respectively, and the average economic income of two seasons was increased by 7973.2 yuan . hm-2. Therefore, appropriate rate of N fertilizer combined with DCD could not only increase crop yield and economic income, but also reduce N2O emission. Considering environmental and economic benefit under this experimental condition, DCD combined with nitrogen of moderate level (total N amount 225 kg . hm-2) was a good nitrogen management mode in North China.

  12. CH4 and N2O emissions from China's beef feedlots with ad libitum and restricted feeding in fall and spring seasons.

    PubMed

    Lin, Zhi; Liao, Wenhua; Yang, Yuanyuan; Gao, Zhiling; Ma, Wenqi; Wang, Dianwu; Cao, Yufeng; Li, Jianguo; Cai, Zhenjiang

    2015-04-01

    Accurately quantifying methane (CH4) and nitrous oxide (N2O) emissions from beef operations in China is necessary to evaluate the contribution of beef cattle to greenhouse gas budgets at the national and global level. Methane and N2O emissions from two intensive beef feedlots in the North China Plain, one with a restricted feeding strategy and high manure collection frequency and the other with an ad libitum feeding strategy and low manure collection frequency, were quantified in the fall and spring seasons using an inverse dispersion technique. The diel pattern of CH4 from the beef feedlot with an ad libitum feed strategy (single peak during a day) differed from that under a restricted feeding condition (multiple peaks during a day), but little difference in the diel pattern of N2O emissions between two feeding strategies was observed. The two-season average CH4 emission rates of the two intensive feedlots were 230 and 198gCH4animal(-1)d(-1) and accounted for 6.7% and 6.8% of the gross energy intake, respectively, indicating little impact of the feeding strategy and manure collection frequency on the CH4 conversion factor at the feedlot level. However, the average N2O emission rates (21.2g N2Oanimal(-1)d(-1)) and conversion factor (8.5%) of the feedlot with low manure collection frequency were approximately 131% and 174% greater, respectively, than the feedlot under high frequency conditions, which had a N2O emission rate and conversion factor of 9.2g N2Oanimal(-1)d(-1) and 3.1%, respectively, indicating that increasing manure collection frequency played an important role in reducing N2O emissions from beef feedlots. In addition, comparison indicated that China's beef and dairy cattle in feedlots appeared to have similar CH4 conversion factors.

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

    PubMed Central

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

    2013-01-01

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

  14. 40 CFR Table Jj-7 to Subpart Jj of... - Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N)

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Nitrous Oxide Emission Factors (kg N2O-N/kg Kjdl N) JJ Table JJ-7 to Subpart JJ of Part 98 Protection of Environment ENVIRONMENTAL... Pt. 98, Subpt. JJ, Table JJ-7 Table JJ-7 to Subpart JJ of Part 98—Nitrous Oxide Emission Factors...

  15. Alternate wetting and drying of rice reduced CH4 emissions but triggered N2O peaks in a clayey soil of central Italy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reducing CH4 and N2O emissions from rice cropping systems while sustaining production levels with less water requires a better understanding of the key processes involved. Alternate wetting and drying (AWD) irrigation is one promising practice that has been shown to reduce CH4 emissions. However, li...

  16. The influence of microbial-based inoculants on N2O emissions from soil planted to corn under greenhouse conditions with different nitrogen fertilizer regimens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrous oxide (N2O) emissions are increasing at an unprecedented rate due to increased nitrogen (N) fertilizers use. Thus, new innovative management tools are needed to reduce emissions. One potential approach is the use of microbial inoculants in agricultural production. In a previous incubation st...

  17. Pig slurry acidification and separation techniques affect soil N and C turnover and N2O emissions from solid, liquid and biochar fractions.

    PubMed

    Gómez-Muñoz, B; Case, S D C; Jensen, L S

    2016-03-01

    The combined effects of pig slurry acidification, subsequent separation techniques and biochar production from the solid fraction on N mineralisation and N2O and CO2 emissions in soil were investigated in an incubation experiment. Acidification of pig slurry increased N availability from the separated solid fractions in soil, but did not affect N2O and CO2 emissions. However acidification reduced soil N and C turnover from the liquid fraction. The use of more advanced separation techniques (flocculation and drainage > decanting centrifuge > screw press) increased N mineralisation from acidified solid fractions, but also increased N2O and CO2 emissions in soil amended with the liquid fraction. Finally, the biochar production from the solid fraction of pig slurry resulted in a very recalcitrant material, which reduced N and C mineralisation in soil compared to the raw solid fractions.

  18. A modeling study on mitigation of N2O emissions and NO3 leaching at different agricultural sites across Europe using LandscapeDNDC.

    PubMed

    Molina-Herrera, Saúl; Haas, Edwin; Klatt, Steffen; Kraus, David; Augustin, Jürgen; Magliulo, Vincenzo; Tallec, Tiphaine; Ceschia, Eric; Ammann, Christof; Loubet, Benjamin; Skiba, Ute; Jones, Stephanie; Brümmer, Christian; Butterbach-Bahl, Klaus; Kiese, Ralf

    2016-05-15

    The identification of site-specific agricultural management practices in order to maximize yield while minimizing environmental nitrogen losses remains in the center of environmental pollution research. Here, we used the biogeochemical model LandscapeDNDC to explore different agricultural practices with regard to their potential to reduce soil N2O emissions and NO3 leaching while maintaining yields. In a first step, the model was tested against observations of N2O emissions, NO3 leaching, soil micrometeorology as well as crop growth for eight European cropland and grassland sites. Across sites, LandscapeDNDC predicts very well mean N2O emissions (r(2)=0.99) and simulates the magnitude and general temporal dynamics of soil inorganic nitrogen pools. For the assessment of site-specific mitigation potentials of environmental nitrogen losses a Monte Carlo optimization technique considering different agricultural management options (i.e., timing of planting, harvest and fertilization, amount of applied fertilizer as well as residue management) was used. The identified optimized field management practices reduce N2O emissions and NO3 leaching from croplands on average by 21% and 31%, respectively. Likewise, average reductions of 55% for N2O emissions and 16% for NO3 leaching are estimated for grasslands. For mitigating environmental loss - while maintaining yield levels - it was most important to reduce fertilizer application rates by in average 10%. Our analyses indicate that yield scaled N2O emissions and NO3 leaching indicate possible improvements of nitrogen use efficiencies in European farming systems. Moreover, the applied optimization approach can be used also in a prognostic way to predict optimal timings and fertilization options (rates and splitting) upon accurate weather forecasts combined with the knowledge of modeled soil nutrient availability and plant nitrogen demand.

  19. N2O and CH4 emissions from a fallow-wheat rotation with low N input in conservation and conventional tillage under a Mediterranean agroecosystem.

    PubMed

    Tellez-Rio, Angela; García-Marco, Sonia; Navas, Mariela; López-Solanilla, Emilia; Tenorio, Jose Luis; Vallejo, Antonio

    2015-03-01

    Conservation agriculture that includes no tillage (NT) or minimum tillage (MT) and crop rotation is an effective practice to increase soil organic matter in Mediterranean semiarid agrosystems. But the impact of these agricultural practices on greenhouse gases (GHGs), such as nitrous oxide (N2O) and methane (CH4), is variable depending mainly on soil structure and short/long-term tillage. The main objective of this study was to assess the long-term effect of three tillage systems (NT, MT and conventional tillage (CT)) and land-covers (fallow/wheat) on the emissions of N2O and CH4 in a low N input agricultural system during one year. This was achieved by measuring crop yields, soil mineral N and dissolved organic C contents, and fluxes of N2O and CH4. Total cumulative N2O emissions were not significantly different (P>0.05) among the tillage systems or between fallow and wheat. The only difference was produced in spring, when N2O emissions were significantly higher (P<0.05) in fallow than in wheat subplots, and NT reduced N2O emissions (P<0.05) compared with MT and CT. Taking into account the water filled pore space (WFPS), both nitrification and denitrification could have occurred during the experimental period. Denitrification capacity in March was similar in all tillage systems, in spite of the higher DOC content maintained in the topsoil of NT. This could be due to the similar denitrifier densities, targeted by nirK copy numbers at that time. Cumulative CH4 fluxes resulted in small net uptake for all treatments, and no significant differences were found among tillage systems or between fallow and wheat land-covers. These results suggest that under a coarse-textured soil in low N agricultural systems, the impact of tillage on GHG is very low and that the fallow cycle within a crop rotation is not a useful strategy to reduce GHG emissions.

  20. The influence of microbial-based inoculants on N2O emissions from soil planted with corn (Zea mays L.) under greenhouse conditions with different nitrogen fertilizer regimens.

    PubMed

    Calvo, Pamela; Watts, Dexter B; Kloepper, Joseph W; Torbert, H Allen

    2016-12-01

    Nitrous oxide (N2O) emissions are increasing at an unprecedented rate owing to the increased use of nitrogen (N) fertilizers. Thus, new innovative management tools are needed to reduce emissions. One potential approach is the use of microbial inoculants in agricultural production. In a previous incubation study, we observed reductions in N2O emissions when microbial-based inoculants were added to soil (no plants present) with N fertilizers under laboratory incubations. This present study evaluated the effects of microbial-based inoculants on N2O and carbon dioxide (CO2) emissions when applied to soil planted with corn (Zea mays L.) under controlled greenhouse conditions. Inoculant treatments consisted of (i) SoilBuilder (SB), (ii) a metabolite extract of SoilBuilder (SBF), and (iii) a mixture of 4 strains of plant-growth-promoting Bacillus spp. (BM). Experiments included an unfertilized control and 3 N fertilizers: urea, urea - ammonium nitrate with 32% N (UAN-32), and calcium - ammonium nitrate with 17% N (CAN-17). Cumulative N2O fluxes from pots 41 days after planting showed significant reductions in N2O of 15% (SB), 41% (BM), and 28% (SBF) with CAN-17 fertilizer. When UAN-32 was used, reductions of 34% (SB), 35% (SBF), and 49% (BM) were obtained. However, no reductions in N2O emissions occurred with urea. Microbial-based inoculants did not affect total CO2 emissions from any of the fertilized treatments or the unfertilized control. N uptake was increased by an average of 56% with microbial inoculants compared with the control (nonmicrobial-based treatments). Significant increases in plant height, SPAD chlorophyll readings, and fresh and dry shoot mass were also observed when the microbial-based treatments were applied (with and without N). Overall, results demonstrate that microbial inoculants can reduce N2O emissions following fertilizer application depending on the N fertilizer type used and can enhance N uptake and plant growth. Future studies are planned to

  1. Dicyandiamide and 3,4-dimethyl pyrazole phosphate decrease N2O emissions from grassland but dicyandiamide produces deleterious effects in clover.

    PubMed

    Macadam, Xana Melissa Belastegui; del Prado, Agustin; Merino, Pilar; Estavillo, José María; Pinto, Miriam; González-Murua, Carmen

    2003-12-01

    The application of nitrogen fertilisers leads to different ecological problems such as nitrate leaching and the release of nitrogenous gases. N2O is a gas involved in global warming, therefore, agricultural soils can be regarded as a source of global warming. Soil N2O production comes from both the nitrification and denitrification processes. From an ecological viewpoint, using nitrification inhibitors with ammonium based fertilisers may be a potential management strategy to lower the fluxes of N2O, thus decreasing its undesirable effect. In this study, the nitrification inhibitors (NIs) dicyandiamide (DCD) and 3,4-dimethyl pyrazole phosphate (DMPP) have been evaluated as management tools to mitigate N2O emissions from mineral fertilisation and slurry application in grassland systems (experiments 1 and 2), and to assess the phytotoxic effect of these inhibitors per se on clover (experiment 3). Both nitrification inhibitors acted in maintaining soil nitrogen (N) in ammonium form, decreasing cumulative N2O emissions. DCD, but not DMPP, produced phytotoxic effects and yield reduction in white clover. A nutrient imbalance, which led to a senescence process visually observed as chlorosis and necrosis at the border of the leaves, was noted.

  2. Response of CH4 and N2O emissions and wheat yields to tillage method changes in the North China plain.

    PubMed

    Tian, Shenzhong; Ning, Tangyuan; Zhao, Hongxiang; Wang, Bingwen; Li, Na; Han, Huifang; Li, Zengjia; Chi, Shuyun

    2012-01-01

    The objective of this study was to quantify soil methane (CH(4)) and nitrous oxide (N(2)O) emissions when converting from minimum and no-tillage systems to subsoiling (tilled soil to a depth of 40 cm to 45 cm) in the North China Plain. The relationships between CH(4) and N(2)O flux and soil temperature, moisture, NH(4) (+)-N, organic carbon (SOC) and pH were investigated over 18 months using a split-plot design. The soil absorption of CH(4) appeared to increase after conversion from no-tillage (NT) to subsoiling (NTS), from harrow tillage (HT) to subsoiling (HTS) and from rotary tillage (RT) to subsoiling (RTS). N(2)O emissions also increased after conversion. Furthermore, after conversion to subsoiling, the combined global warming potential (GWP) of CH(4) and N(2)O increased by approximately 0.05 kg CO(2) ha(-1) for HTS, 0.02 kg CO(2) ha(-1) for RTS and 0.23 kg CO(2) ha(-1) for NTS. Soil temperature, moisture, SOC, NH(4) (+)-N and pH also changed after conversion to subsoiling. These changes were correlated with CH(4) uptake and N(2)O emissions. However, there was no significant correlation between N(2)O emissions and soil temperature in this study. The grain yields of wheat improved after conversion to subsoiling. Under HTS, RTS and NTS, the average grain yield was elevated by approximately 42.5%, 27.8% and 60.3% respectively. Our findings indicate that RTS and HTS would be ideal rotation tillage systems to balance GWP decreases and grain yield improvements in the North China Plain region.

  3. Straw return reduces yield-scaled N2O plus NO emissions from annual winter wheat-based cropping systems in the North China Plain.

    PubMed

    Yao, Zhisheng; Yan, Guangxuan; Zheng, Xunhua; Wang, Rui; Liu, Chunyan; Butterbach-Bahl, Klaus

    2017-07-15

    Straw return in combination with synthetic N fertilizer is considered to be beneficial to soil fertility and crop yield. Such practice, however, can considerably modify soil microbial activity and relative C and N availability, both of which are known to regulate soil nitrous oxide (N2O) and nitric oxide (NO) emissions. Minimizing these emissions per unit of crop yield is a prerequisite to minimize the environmental footprint of agricultural production and thus, a policy objective. In our study, we quantified N2O and NO emissions and determined fertilizer-N use efficiencies (NUE) and crop yields of two double-cropping (summer maize/Welsh onion-winter wheat) systems with and without straw incorporation in the North China Plain. Relative to the fertilized treatment without straw amendments, straw incorporation showed a significant inhibitory effect on annual N2O emissions from the maize-wheat system (-31%), but no significant effect was observed for the Welsh onion-wheat system. However, straw return significantly reduced annual NO emissions by >30% for both systems. Meanwhile, straw return in both systems significantly increased the NUE and crop yields by 34-47% and 7-16%, respectively, as compared to the treatment without straw additions. Across the double-cropping systems, annual direct emission factors of N2O, NO and N2O+NO were 0.37-0.57%, 0.08-0.78% and 0.57-1.36%, respectively. Furthermore, a negative relationship between direct emission factors of N2O+NO and crop NUE was observed, highlighting the importance of optimizing NUE for reducing environmental risks of a cropping system. When expressing emissions on a yield basis, straw return significantly reduced annual yield-scaled N2O+NO emissions by 15-42% for both systems. Overall, our results show that the combined application of crop straw and synthetic N fertilizer is a promising N management strategy for maximizing crop yields while mitigating N-trace gas emissions.

  4. Application of herbicides is likely to reduce greenhouse gas (N2O and CH4) emissions from rice-wheat cropping systems

    NASA Astrophysics Data System (ADS)

    Jiang, Jingyan; Chen, Linmei; Sun, Qing; Sang, Mengmeng; Huang, Yao

    2015-04-01

    Herbicides have been widely used to control weeds in croplands; however, their effects on greenhouse gas emissions remain unclear. The effects of three wheat herbicides (acetochlor, AC; tribenuron-methyl, TBM; fenoxaprop-p-ethyl, FE) and two rice herbicides (butachlor, BC; bensulfuron-methyl, BSM) on N2O and CH4 emissions were investigated in this study. In the wheat growing season, applications of AC and FE + TBM significantly reduced N2O emissions by 31% compared with no herbicide use (p = 0.001). In the rice growing season, the application of BC significantly reduced CH4 emissions by 58% (p = 0.022), and BSM significantly reduced N2O emissions by 27% (p = 0.040); however, no significant difference among treatments with regard to the aggregate emissions of N2O and CH4 in the CO2 equivalent for the 100-year horizon was observed (p > 0.05). Relative to control plots, which were not treated with herbicides, the combined application of the herbicides FE and TBM in the wheat season led to a significant decrease in greenhouse gas intensity (GHGI) by ∼41% (p = 0.002), and the application of BC together with BSM reduced GHGI by 22% in the rice season, although this reduction was not statistically significant (p = 0.158). Further investigation suggested that the inhibitory effect of herbicides on N2O emissions in the wheat field could be ascribed to low soil ammonium nitrogen and less abundance of denitrifying bacteria. The inhibitory effects of separate applications of BC on CH4 emissions in rice fields, in contrast, were linked to high soil nitrate nitrogen and urease activity.

  5. Effects of nitrogen conversion and environmental factors on landfill CH4 oxidation and N2O emissions in aged refuse.

    PubMed

    Zhang, Houhu; Zhao, Keqiang; Yan, Xiaofei; Sun, Qinfang; Li, Yi; Zhang, Yi; Zun, Zhao; Ke, Fan

    2013-09-15

    We determined the effects of nitrification capacity and environmental factors on landfill methane oxidation potential (MOP) using an aged refuse in laboratory batch assays and compared it with two different types of soils. The nitrogen conversion in the three experimental materials after 120 h incubation yielded first-order reaction kinetics at an initial concentration of 200 mg kg(-1) NH4(+)-N. The net nitrification rate for the aged refuse was 1.50 (p < 0.05) and 2.08 (p < 0.05) times that of the clay soil and the sandy soil, respectively. The net NO3(-)-N generation rate by the aged refuse was 1.93 (p < 0.05) and 2.57 (p < 0.05) times that of the clay soil and the sandy soil, respectively. When facilitated by ammonia-oxidizing bacteria during CH4 co-oxidation, the average value of the MOP in the aged refuse at a temperature range of 4-45 °C was 2.34 (p < 0.01) and 4.71 (p < 0.05) times greater than that of the clay soil and the sandy soil, respectively. When the moisture content ranged from 8 to 32% by mass, the average values for the MOP in the aged refuse were 2.08 (p < 0.01) and 3.15 (p < 0.01) times greater than that of the clay soil and the sandy soil, respectively. The N2O fluxes in the aged refuse at 32% moisture content were 5.33 (p < 0.05) and 12.00 (p < 0.05) times more than in the clay and the sandy soil, respectively. The increase in N2O emissions from a municipal solid waste landfill can be neglected after applying an aged refuse bio-cover because of the much higher MOP in the aged refuse. The calculated maximum MOP value in the aged refuse was 12.45 μmol g(-1) d.w. h(-1), which was much higher than the documented data.

  6. EMISSIONS AND COST ESTIMATES FOR GLOBALLY SIGNIFICANT ANTHROPOGENIC COMBUSTION SOURCES OF NOX, N2O, CH4, CO AND CO2

    EPA Science Inventory

    The report discusses the development of emission factors for CO2, CO, CH4, NOx, and N2O for about 80 globally significant combustion sources in seven source categories: utility, industrial, fuel production, transportation, residential, commercial, and kilns/ovens/dryers. ecause o...

  7. Application of microbial-based inoculants for reducing N2O emissions from soil under two different ammonium nitrate-based fertilizers.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Considerable effort is being made among the scientific community to identify mechanisms to reduce nitrous oxide (N2O) emissions from agriculture soils. Thus, the objective of this study was to test the hypothesis that microbial-based inoculants known to promote root growth and nutrient uptake will r...

  8. Mitigating effects of ex situ application of rice straw on CH4 and N2O emissions from paddy-upland coexisting system.

    PubMed

    Wang, Wei; Wu, Xiaohong; Chen, Anlei; Xie, Xiaoli; Wang, Yunqiu; Yin, Chunmei

    2016-11-21

    The in situ application of rice straw enhances CH4 emissions by a large margin. The ex situ application of rice straw in uplands, however, may mitigate total global warming potential (GWP) of CH4 and N2O emissions from paddy-upland coexisting systems. To evaluate the efficiency of this practice, two field trials were conducted in rice-rice-fallow and maize-rape cropping systems, respectively. Year-round measurements of CH4 and N2O emissions were conducted to evaluate the system-scaled GWP. The results showed that CH4 accounted for more than 98% of GWP in paddy. Straw removal from paddy decreased 44.7% (302.1 kg ha(-1) yr(-1)) of CH4 emissions and 51.2% (0.31 kg ha(-1) yr(-1)) of N2O emissions, thus decreased 44.8% (7693 kg CO2-eqv ha(-1) yr(-1)) of annual GWP. N2O accounted for almost 100% of GWP in upland. Straw application in upland had insignificant effects on CH4 and N2O emissions, which increased GWP only by 91 kg CO2-eqv ha(-1) yr(-1). So, the transfer of straw from paddy to upland could decrease GWP by 7602 kg CO2-eqv ha(-1) yr(-1). Moreover, straw retention during late rice season contributed to 88.2% of annual GWP increment. It is recommended to transfer early rice straw to upland considering GWP mitigation, nutrient recycling and labor cost.

  9. Mitigating effects of ex situ application of rice straw on CH4 and N2O emissions from paddy-upland coexisting system

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Wu, Xiaohong; Chen, Anlei; Xie, Xiaoli; Wang, Yunqiu; Yin, Chunmei

    2016-11-01

    The in situ application of rice straw enhances CH4 emissions by a large margin. The ex situ application of rice straw in uplands, however, may mitigate total global warming potential (GWP) of CH4 and N2O emissions from paddy-upland coexisting systems. To evaluate the efficiency of this practice, two field trials were conducted in rice-rice-fallow and maize-rape cropping systems, respectively. Year-round measurements of CH4 and N2O emissions were conducted to evaluate the system-scaled GWP. The results showed that CH4 accounted for more than 98% of GWP in paddy. Straw removal from paddy decreased 44.7% (302.1 kg ha‑1 yr‑1) of CH4 emissions and 51.2% (0.31 kg ha‑1 yr‑1) of N2O emissions, thus decreased 44.8% (7693 kg CO2-eqv ha‑1 yr‑1) of annual GWP. N2O accounted for almost 100% of GWP in upland. Straw application in upland had insignificant effects on CH4 and N2O emissions, which increased GWP only by 91 kg CO2-eqv ha‑1 yr‑1. So, the transfer of straw from paddy to upland could decrease GWP by 7602 kg CO2-eqv ha‑1 yr‑1. Moreover, straw retention during late rice season contributed to 88.2% of annual GWP increment. It is recommended to transfer early rice straw to upland considering GWP mitigation, nutrient recycling and labor cost.

  10. Mitigating effects of ex situ application of rice straw on CH4 and N2O emissions from paddy-upland coexisting system

    PubMed Central

    Wang, Wei; Wu, Xiaohong; Chen, Anlei; Xie, Xiaoli; Wang, Yunqiu; Yin, Chunmei

    2016-01-01

    The in situ application of rice straw enhances CH4 emissions by a large margin. The ex situ application of rice straw in uplands, however, may mitigate total global warming potential (GWP) of CH4 and N2O emissions from paddy-upland coexisting systems. To evaluate the efficiency of this practice, two field trials were conducted in rice-rice-fallow and maize-rape cropping systems, respectively. Year-round measurements of CH4 and N2O emissions were conducted to evaluate the system-scaled GWP. The results showed that CH4 accounted for more than 98% of GWP in paddy. Straw removal from paddy decreased 44.7% (302.1 kg ha−1 yr−1) of CH4 emissions and 51.2% (0.31 kg ha−1 yr−1) of N2O emissions, thus decreased 44.8% (7693 kg CO2-eqv ha−1 yr−1) of annual GWP. N2O accounted for almost 100% of GWP in upland. Straw application in upland had insignificant effects on CH4 and N2O emissions, which increased GWP only by 91 kg CO2-eqv ha−1 yr−1. So, the transfer of straw from paddy to upland could decrease GWP by 7602 kg CO2-eqv ha−1 yr−1. Moreover, straw retention during late rice season contributed to 88.2% of annual GWP increment. It is recommended to transfer early rice straw to upland considering GWP mitigation, nutrient recycling and labor cost. PMID:27869209

  11. Greenhouse gas (CO2, CH4, N2O) emissions from soils following afforestation in central China

    NASA Astrophysics Data System (ADS)

    Dou, Xiaolin; Zhou, Wei; Zhang, Quanfa; Cheng, Xiaoli

    2016-02-01

    The effects of afforestation are of great importance for terrestrial carbon sequestration. However, the consequences of afforestation for greenhouse gas (GHG, CO2, CH4 and N2O) fluxes remain poorly quantified. We investigate the temporal variations in CO2, CH4 and N2O fluxes in afforested soils (implementing woodland and shrubland) and the adjacent uncultivated area in the Danjiangkou Reservoir area of central China. We examined the effects of soil factors [e.g. soil temperature, soil moisture, soil pH, soil organic carbon (SOC), soil organic nitrogen (SON)], litter exclusion and vegetation types on GHG fluxes. Our results revealed that afforestation lead to a higher average CO2 flux from soils by 63.96% and a higher N2O flux by 54.53% in the observed year. The peak CO2 and CH4 fluxes from afforested soils occurred in summer, while the peak N2O flux occurred in winter. Afforestation also enhanced CH4 flux from soil with the largest increase by 247.94% in woodland and by 188.18% in shrubland in spring compared with the open area. On average, surface litter exclusion reduced soil CO2 fluxes by 18.84% and N2O fluxes by 27.93% in the woodland. The surface litter exclusion did not significantly affect CH4 flux from the afforested soils. The CO2, CH4 and N2O fluxes from soils were strongly influenced by soil temperature, moisture and SOC content across seasons. The N2O flux was also strongly affected by SON content in our experimental field. Our results suggested that afforestation enhanced GHG fluxes from soils; however, the magnitude of the GHG fluxes should also be considered from various environmental conditions and vegetation types.

  12. Estimation and mitigation of N2O emission and nitrate leaching from intensive crop cultivation in the Haean catchment, South Korea.

    PubMed

    Kim, Youngsun; Seo, Youngho; Kraus, David; Klatt, Steffen; Haas, Edwin; Tenhunen, John; Kiese, Ralf

    2015-10-01

    Considering intensive agricultural management practices and environmental conditions, the LandscapeDNDC model was applied for simulation of yields, N2O emission and nitrate leaching from major upland crops and temperate deciduous forest of the Haean catchment, South Korea. Fertilization rates were high (up to 314 kg N ha(-1) year(-1)) and resulted in simulated direct N2O emissions from potato, radish, soybean and cabbage fields of 1.9 and 2.1 kg N ha(-1) year(-1) in 2009 and 2010, respectively. Nitrate leaching was identified as the dominant pathway of N losses in the Haean catchment with mean annual rates of 112.2 and 125.4 kg N ha(-1) year(-1), causing threats to water quality and leading to substantial indirect N2O emissions of 0.84 and 0.94 kg N ha(-1) year(-1) in 2009 and 2010 as estimates by applying the IPCC EF5. Simulated N2O emissions from temperate deciduous forest were low (approx. 0.50 kg N ha(-1) year(-1)) and predicted nitrate leaching rates were even negligible (≤0.01 kg N ha(-1) year(-1)). On catchment scale more than 50% of the total N2O emissions and up to 75% of nitrate leaching originated from fertilized upland fields, only covering 24% of the catchment area. Taking into account area coverage of simulated upland crops and other land uses these numbers agree well with nitrate loads calculated from discharge and concentration measurements at the catchment outlet. The change of current agricultural management practices showed a high potential of reducing N2O emission and nitrate leaching while maintaining current crop yields. Reducing (39%) and splitting N fertilizer application into 3 times was most effective and lead to about 54% and 77% reducing of N2O emission and nitrate leaching from the Haean catchment, the latter potentially contributing to improved water quality in the Soyang River Dam, which is the major source of drinking water for metropolitan residents.

  13. N2O and CH4 emissions from a Chinese wheat-rice cropping system under different tillage practices during the wheat-growing season

    NASA Astrophysics Data System (ADS)

    Zhang, Y.

    2015-12-01

    The annual wheat (Triticum aestivum L.)-rice (Oryza sativa L.) cropping system is the most important cereal production system in the Yangtze River Valley of China, in which various tillage systems are currently implemented during the wheat-growing season. The emissions of nitrous oxide (N2O) and methane (CH4) from the different tillage systems in this system remain unclear. We conducted a 3-year field experiment in a wheat-rice cropping system in a silt clay loam soil to investigate the effects of the type of tillage employed during the wheat-growing season (no-tillage (NT), reduced tillage (RT) or conventional tillage (CT)) on the emissions of N2O and CH4 using the static chamber method over three annual rotation cycles from the 2008 wheat season to the 2011 rice season. The results revealed that the adoption of an NT system during the wheat-growing season significantly increased CH4 emissions during both the wheat-growing season and the following rice-growing season. Over the three annual rotation cycles studied, the annual N2O emissions from the NT (2.24 kg N2O-N ha-1) and CT (2.01 kg N2O-N ha-1) treatments were similar to each other and significantly higher than those from the RT treatment (1.73 kg N2O-N ha-1); the annual CH4 emissions were significantly higher from the NT (100.1 kg CH4-C ha-1) than the CT (83.7 kg CH4-C ha-1) and RT (73.9 kg CH4-C ha-1) systems. The overall results regarding the net global warming potential associated with annual N2O and CH4 emissions indicate that the conversion of conventional tillage to no-tillage systems during the wheat-growing season would intensify the radiative forcing in wheat-rice cropping systems in China.

  14. The combined effects of nitrification inhibitor and biochar incorporation on yield-scaled N2O emissions from an intensively managed vegetable field in southeastern China

    NASA Astrophysics Data System (ADS)

    Li, B.; Fan, C. H.; Xiong, Z. Q.; Li, Q. L.; Zhang, M.

    2015-03-01

    An experiment was conducted to study the influences of nitrification inhibitor (NI) and biochar incorporation on yield-scaled N2O using the static chamber method and gas chromatography in an intensively managed vegetable field with seven consecutive vegetable crops from 2012 to 2014 in southeastern China. With an equal annual nitrogen (N) application rate (1217 kg N ha-1 yr-1), six treatments under three biochar amendment rates - namely, 0 t ha-1 (C0), 20 t ha-1 (C1) and 40 t ha-1 (C2) - with compound fertilizer (CF) or urea mixed with NI of nitrapyrin as chlorinated pyridine (CP) were studied in these field experiments. The results showed that, although there was no significant influence on soil organic carbon (SOC) content or total nitrogen (TN), nitrapyrin could result in a significant increase in soil pH during the experimental period. Nitrapyrin significantly decreased cumulative N2O emissions by 15.9-32.1% while increasing vegetable yield by 9.8-41.9%. Thus, it also decreased yield-scaled N2O emissions significantly. In addition to the differential responses of the soil pH, biochar amendment significantly increased SOC and TN. Compared with the treatments without biochar addition, the cumulative N2O emissions showed no significant difference in the CF or the CP group treatments but increased slightly (not significantly) by 7.9-18.3% in the CP group treatments. Vegetable yield was enhanced by 7.1-49.5% in the CF group treatments compared with the treatments without biochar amendment, while there was no significant difference in the CP group treatments, and the yield-scaled N2O emissions were thus decreased significantly. Furthermore, treatments involving with nitrapyrin and biochar incorporation slightly increased yield-scaled N2O emissions by 9.4%, on average, compared with CP-C0. Therefore, the application of nitrapyrin could serve as an appropriate practice for increasing vegetable yield and mitigating N2O emissions in intensively managed vegetable fields

  15. The combined effects of nitrification inhibitor and biochar incorporation on yield-scaled N2O emissions from an intensively managed vegetable field in southeastern China

    NASA Astrophysics Data System (ADS)

    Li, B.; Fan, C. H.; Xiong, Z. Q.; Li, Q. L.; Zhang, M.

    2014-10-01

    The influences of nitrification inhibitor (NI) and biochar incorporation on yield-scaled N2O in a vegetable field were studied using the static chamber method and gas chromatography. An experiment was conducted in an intensively managed vegetable field with 7 consecutive vegetable crops in 2012-2014 in southeastern China. With equal annual amounts of N (1217.3 kg N ha-1 yr-1), 6 treatments under 3 biochar amendment rates, namely, 0 t ha-1 (C0), 20 t ha-1 (C1), and 40 t ha-1 (C2), with compound fertilizer (CF) or urea mixed with chlorinated pyridine (CP) as NI, were studied in these field experiments. The results showed that although no significant influence on soil organic carbon (SOC) content or total nitrogen (TN), CP could result in a significant increase in soil pH during the experimental period. CP significantly decreased cumulative N2O emissions by 15.9-32.1% while increasing vegetable yield by 9.8-41.9%. Thus, it also decreased yield-scaled N2O emissions significantly. In addition to the differential responses of the soil pH, biochar amendment significantly increased SOC and TN. Additionally, compared with the treatments without biochar addition, cumulative N2O emissions showed no significant difference in the CF or the CP group treatments but increased slightly (but not significantly) by 7.9-18.3% in the CP group treatments. Vegetable yield was enhanced by 7.1-49.5% compared with the treatments without biochar amendment, and the yield-scaled N2O emissions were thus decreased significantly. Furthermore, treatments applied with CP and biochar incorporation slightly increased yield-scaled N2O emissions by 9.4%, on average, compared with CP-C0. Therefore, the incorporation of CP could serve as an appropriate practice for increasing vegetable yield and mitigating N2O emissions in intensively managed vegetable fields and should be further examined in various agroecosystems.

  16. Measurement of N2, N2O, NO, and CO2 emissions from soil with the gas-flow-soil-core technique.

    PubMed

    Wang, Rui; Willibald, Georg; Feng, Qi; Zheng, Xunhua; Liao, Tingting; Brüggemann, Nicolas; Butterbach-Bahl, Klaus

    2011-07-15

    Here we describe a newly designed system with three stand-alone working incubation vessels for simultaneous measurements of N(2), N(2)O, NO, and CO(2) emissions from soil. Due to the use of a new micro thermal conductivity detector and the redesign of vessels and gas sampling a so-far unmatched sensitivity (0.23 μg N(2)-N h(-1) kg(-1) ds or 8.1 μg N(2)-N m(-2) h(-1)) for detecting N(2) gas emissions and repeatability of experiments could be achieved. We further tested different incubation methods to improve the quantification of N(2) emission via denitrification following the initialization of soil anaerobiosis. The best results with regard to the establishment of a full N balance (i.e., the changes in mineral N content being offset by simultaneous emission of N gases) were obtained when the anaerobic soil incubation at 25 °C was preceded by soil gas exchange under aerobic conditions at a lower incubation temperature. The ratios of N and C gas emission changed very dynamically following the initialization of anaerobiosis. For soil NO(3)(-) contents of 50 mg N kg(-1) dry soil (ds) and dissolved organic carbon (DOC) concentrations of approximately 300 mg C kg(-1) ds, the cumulative emissions of N(2), N(2)O, and NO were 24.3 ± 0.1, 12.6 ± 0.4, and 10.1 ± 0.3 mg N kg(-1) ds, respectively. Thus, N gas emissions accounted (on average) for 46.2% (N(2)), 24.0% (N(2)O), and 19.2% (NO) of the observed changes in soil NO(3)(-). The maximum N(2) emission reached 1200 μg N h(-1) kg(-1) ds, whereas the peak emissions of N(2)O and NO were lower by a factor of 2-3. The overall N(2):N(2)O and NO:N(2)O molar ratios were 1.6-10.0 and 1.6-2.3, respectively. The measurement system provides a reliable tool for studying denitrification in soil because it offers insights into the dynamics and magnitude of gaseous N emissions due to denitrification under various incubation conditions.

  17. Impact of two different types of grassland-to-cropland-conversion on dynamics of soil organic matter mineralization and N2O emission

    NASA Astrophysics Data System (ADS)

    Roth, G.; Flessa, H.; Helfrich, M.; Well, R.

    2012-04-01

    Conversion of grassland to arable land often causes a decrease of soil organic matter stocks and it increases nitrate leaching and the emission of the greenhouse gases CO2 and N2O. Conversion methods which minimize the mechanical impact on the surface soil may reduce mineralization rates and greenhouse gas emissions. We determined the effect of two different types of grassland to maize conversion (a) plowing of the sward followed by seeding of maize and (b) chemical killing of the sward by glyphosate followed by direct seed of maize) on the mineralization of grassland derived organic matter, the release of nitrate and the emission of N2O. The field experiment was carried out at the research station Kleve which is located in North Rhine-Westphalia, Germany. A four times replicated plot experiment with the following treatments was set up in April 2010: (i) mechanical conversion of grassland to maize (ii) chemical conversion grassland to maize and (iii) continuous grassland as reference. Nitrogen fertilization was 137 kg N ha-1 for maize and 250 kg N ha-1 for grassland. Soil respiration and emission of N2O were measured weekly for one year using manual closed chambers and gas chromatography. Emission of CO2 from mineralization of grassland-derived organic matter was determined from the δ13C signature of soil respiration. Soil respiration was mainly fueled by mineralization of grassland-derived organic carbon. There was no effect of the type of grassland conversion on total mineralization of organic matter originating from grassland. Both grassland to maize conversion treatments exhibited very high soil nitrate concentrations one year after grassland conversion (about 250 kg NO3-N in 0 - 90 cm). Total N2O emission decreased in the order chemical conversion of grassland (25.5) > mechanical conversion of grassland (20.1) > permanent grassland (10.8). Emissions were highest after harvest of maize when soil moisture increased. The results show that both types of grassland

  18. [Characteristics of N2, N2O, NO, CO2 and CH4 Emissions in Anaerobic Condition from Sandy Loam Paddy Soil].

    PubMed

    Cao, Na; Wang, Rui; Liao, Ting-ting; Chen, Nuo; Zheng, Xun-hua; Yao, Zhi-sheng; Zhang, Hai; Butterbach-Bahl, Klaus

    2015-09-01

    Understanding the characteristics of the production of nitrogen gases (N2, N2O and NO), CO2 and CH4 in anaerobic paddy soils is not only a prerequisite for an improved mechanistic understanding of key microbial processes involved in the production of atmospheric greenhouse gases (GHG), but might also provide the basis for designing greenhouse gas mitigation strategies. Moreover, quantifying the composition fractions of denitrification gaseous products is of key importance for improving parameterization schemes of microbial processes in process-oriented models which are increasingly used for assessing soil GHG emissions at site and national scales. In our experiments we investigated two sandy loam soils from two paddy fields. The initial concentrations of soil nitrate and dissolved organic carbon (DOC) were set at approximately 50 mg.kg-1 and mg.kg-1, respectively, by adding a mixture solution of KNO3 and glucose. The emissions of N2, N2O NO, CO2 and CH4, as well as concentrations of carbon and nitrogen substrates for each soil sample were measured simultaneously, using a gas-flow-soil-core technique and a paralleling substrate monitoring system. The results showed that the accumulative emissions of N2, N2O and NO of the two soil samples for the entire incubation period were 6 - 8, 20, and 15 - 18 mg.kg-1, respectively. By measuring the cumulative emissions of denitrification gases (N, = N2 + N2O + NO) we were able to explain 95% to 98% of observed changes in s1ifr nilrate concentrations. The mass fractions of N2, N2O and NO emissions to Nt were approximately 15% -19%, 47% -49%, and 34% -36%, respectively. Thus, in our experiments N2O and NO were the main products of denitrification for the entire incubation period. However, as the temporal courses of hourly or daily production of the denitrification gases showed, NO production dominated and peaked firstly, and then N2O, before finally N2 became the dominant product. Our results show the high temporal dynamic of

  19. Drainage and tillage practices in the winter fallow season mitigate CH4 and N2O emissions from a double-rice field in China

    NASA Astrophysics Data System (ADS)

    Zhang, Guangbin; Yu, Haiyang; Fan, Xianfang; Yang, Yuting; Ma, Jing; Xu, Hua

    2016-09-01

    Traditional land management (no tillage, no drainage, NTND) during the winter fallow season results in substantial CH4 and N2O emissions from double-rice fields in China. A field experiment was conducted to investigate the effects of drainage and tillage during the winter fallow season on CH4 and N2O emissions and to develop mitigation options. The experiment had four treatments: NTND, NTD (drainage but no tillage), TND (tillage but no drainage), and TD (both drainage and tillage). The study was conducted from 2010 to 2014 in a Chinese double-rice field. During winter, total precipitation and mean daily temperature significantly affected CH4 emission. Compared to NTND, drainage and tillage decreased annual CH4 emissions in early- and late-rice seasons by 54 and 33 kg CH4 ha-1 yr-1, respectively. Drainage and tillage increased N2O emissions in the winter fallow season but reduced it in early- and late-rice seasons, resulting in no annual change in N2O emission. Global warming potentials of CH4 and N2O emissions were decreased by 1.49 and 0.92 t CO2 eq. ha-1 yr-1, respectively, and were reduced more by combining drainage with tillage, providing a mitigation potential of 1.96 t CO2 eq. ha-1 yr-1. A low total C content and high C / N ratio in rice residues showed that tillage in the winter fallow season reduced CH4 and N2O emissions in both early- and late-rice seasons. Drainage and tillage significantly decreased the abundance of methanogens in paddy soil, and this may explain the decrease of CH4 emissions. Greenhouse gas intensity was significantly decreased by drainage and tillage separately, and the reduction was greater by combining drainage with tillage, resulting in a reduction of 0.17 t CO2 eq. t-1. The results indicate that drainage combined with tillage during the winter fallow season is an effective strategy for mitigating greenhouse gas releases from double-rice fields.

  20. Microbial N Transformations and N2O Emission after Simulated Grassland Cultivation: Effects of the Nitrification Inhibitor 3,4-Dimethylpyrazole Phosphate (DMPP).

    PubMed

    Duan, Yun-Feng; Kong, Xian-Wang; Schramm, Andreas; Labouriau, Rodrigo; Eriksen, Jørgen; Petersen, Søren O

    2017-01-01

    Grassland cultivation can mobilize large pools of N in the soil, with the potential for N leaching and N2O emissions. Spraying with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) before cultivation was simulated by use of soil columns in which the residue distribution corresponded to plowing or rotovation to study the effects of soil-residue contact on N transformations. DMPP was sprayed on aboveground parts of ryegrass and white clover plants before incorporation. During a 42-day incubation, soil mineral N dynamics, potential ammonia oxidation (PAO), denitrifying enzyme activity (DEA), nitrifier and denitrifier populations, and N2O emissions were investigated. The soil NO3(-) pool was enriched with (15)N to trace sources of N2O. Ammonium was rapidly released from decomposing residues, and PAO was stimulated in soil near residues. DMPP effectively reduced NH4(+) transformation irrespective of residue distribution. Ammonia-oxidizing archaea (AOA) and bacteria (AOB) were both present, but only the AOB amoA transcript abundance correlated with PAO. DMPP inhibited the transcription of AOB amoA genes. Denitrifier genes and transcripts (nirK, nirS, and clades I and II of nosZ) were recovered, and a correlation was found between nirS mRNA and DEA. DMPP showed no adverse effects on the abundance or activity of denitrifiers. The (15)N enrichment of N2O showed that denitrification was responsible for 80 to 90% of emissions. With support from a control experiment without NO3(-) amendment, it was concluded that DMPP will generally reduce the potential for leaching of residue-derived N, whereas the effect of DMPP on N2O emissions will be significant only when soil NO3(-) availability is limiting.

  1. Effects of nitrogen on the ecosystem respiration, CH4 and N2O emissions to the atmosphere from the freshwater marshes in northeast China

    NASA Astrophysics Data System (ADS)

    Zhang, Lihua; Song, Changchun; Zheng, Xunhua; Wang, Dexuan; Wang, Yiyong

    2007-04-01

    Freshwater marshes could be a source of greenhouse gases emission because they contain large amounts of soil carbon and nitrogen. These emissions are strongly influenced by exogenous nitrogen. We investigate the effects of exogenous nitrogen on ecosystem respiration (CO2), CH4 and N2O emissions from freshwater marshes in situ in the Sanjiang Plain Northeast of China during the growing seasons of 2004 and 2005, using a field fertilizer experiment and the static opaque chamber/GC techniques. The results show that there were no significant differences in patterns of seasonal variations of CO2 and CH4 among the fertilizer and non-fertilizer treatments, but the seasonal patterns of N2O emission were significantly influenced by the exogenous nitrogen. Seasonal averages of the CO2 flux from non-fertilizer and fertilizer were 987.74 and 1,344.35 mg m -2 h -1, respectively, in 2004, and 898.59 and 2,154.17 mg m -2 h -1, respectively, in 2005. And the CH4 from the control and fertilizer treatments were 6.05 and 13.56 mg m -2 h -1 and 0.72 and 1.88 mg m -2 h -1, respectively, in 2004 and 2005. The difference of N2O flux between the fertilizer and non-fertilizer treatments is also significant either in 2004 and 2005. On the time scale of 20-, 100-, and 500-year periods, the integrated global warming potential (GWP) of CO2 +CH4 +N2O released during the two growing seasons for the treatment of fertilizer was 97, 94 and 89%, respectively, higher than that for the control, which suggested that the nitrogen fertilizer can enhance the GWP of the CH4 and N2O either in long time or short time scale.

  2. Historical and future land use effects on N2O and NO emissions using an ensemble modeling approach: Costa Rica's Caribbean lowlands as an example

    USGS Publications Warehouse

    Reiners, William A.; Liu, S.; Gerow, K.G.; Keller, M.; Schimel, D.S.

    2002-01-01

    [1] The humid tropical zone is a major source area for N2O and NO emissions to the atmosphere. Local emission rates vary widely with local conditions, particularly land use practices which swiftly change with expanding settlement and changing market conditions. The combination of wide variation in emission rates and rapidly changing land use make regional estimation and future prediction of biogenic trace gas emission particularly difficult. This study estimates contemporary, historical, and future N2O and NO emissions from 0.5 million ha of northeastern Costa Rica, a well-documented region in the wet tropics undergoing rapid agricultural development. Estimates were derived by linking spatially distributed environmental data with an ecosystem simulation model in an ensemble estimation approach that incorporates the variance and covariance of spatially distributed driving variables. Results include measures of variance for regional emissions. The formation and aging of pastures from forest provided most of the past temporal change in N2O and NO flux in this region; future changes will be controlled by the degree of nitrogen fertilizer application and extent of intensively managed croplands.

  3. Influence of bulking agents on CH4, N2O, and NH3 emissions during rapid composting of pig manure from the Chinese Ganqinfen system*

    PubMed Central

    Sun, Xiang-ping; Lu, Peng; Jiang, Tao; Schuchardt, Frank; Li, Guo-xue

    2014-01-01

    Mismanagement of the composting process can result in emissions of CH4, N2O, and NH3, which have caused severe environmental problems. This study was aimed at determining whether CH4, N2O, and NH3 emissions from composting are affected by bulking agents during rapid composting of pig manure from the Chinese Ganqinfen system. Three bulking agents, corn stalks, spent mushroom compost, and sawdust, were used in composting with pig manure in 60 L reactors with forced aeration for more than a month. Gas emissions were measured continuously, and detailed gas emission patterns were obtained. Concentrations of NH3 and N2O from the composting pig manure mixed with corn stalks or sawdust were higher than those from the spent mushroom compost treatment, especially the sawdust treatment, which had the highest total nitrogen loss among the three runs. Most of the nitrogen was lost in the form of NH3, which accounts for 11.16% to 35.69% of the initial nitrogen. One-way analysis of variance for NH3 emission showed no significant differences between the corn stalk and sawdust treatments, but a significant difference was noted between the spent mushroom compost and sawdust treatments. The introduction of sawdust reduced CH4 emission more than the corn stalks and spent mushroom compost. However, there were no significant differences among the three runs for total carbon loss. All treatments were matured after 30 d. PMID:24711356

  4. Effect of biochar addition on short-term N2O and CO2 emissions during repeated drying and wetting of an anthropogenic alluvial soil.

    PubMed

    Yang, Fang; Lee, Xinqing; Theng, Benny K G; Wang, Bing; Cheng, Jianzhong; Wang, Qian

    2016-06-07

    Agricultural soils are an important source of greenhouse gases (GHG). Biochar application to such soils has the potential of mitigating global anthropogenic GHG emissions. Under irrigation, the topsoils in arid regions experience repeated drying and wetting during the crop growing season. Biochar incorporation into these soils would change the soil microbial environment and hence affect GHG emissions. Little information, however, is available regarding the effect of biochar addition on carbon dioxide (CO2) and nitrous oxide (N2O) emissions from agricultural soils undergoing repeated drying and wetting. Here, we report the results of a 49-day aerobic incubation experiment, incorporating biochar into an anthropogenic alluvial soil in an arid region of Xinjiang Province, China, and measuring CO2 and N2O emissions. Under both drying-wetting and constantly moist conditions, biochar amendment significantly increased cumulative CO2 emission. At the same time, there was a significant reduction (up to ~20 %) in cumulative N2O emission, indicating that the addition of biochar to irrigated agricultural soils may effectively slow down global warming in arid regions of China.

  5. Annual emissions of CH4 and N2O, and ecosystem respiration, from eight organic soils in Western Denmark managed by agriculture

    NASA Astrophysics Data System (ADS)

    Petersen, S. O.; Hoffmann, C. C.; Schäfer, C.-M.; Blicher-Mathiesen, G.; Elsgaard, L.; Kristensen, K.; Larsen, S. E.; Torp, S. B.; Greve, M. H.

    2012-01-01

    The use of organic soils by agriculture involves drainage and tillage, and the resulting increase in C and N turnover can significantly affect their greenhouse gas balance. This study estimated annual fluxes of CH4 and N2O, and ecosystem respiration (Reco), from eight organic soils managed by agriculture. The sites were located in three regions representing different landscape types and climatic conditions, and three land use categories were covered (arable crops, AR, grass in rotation, RG, and permanent grass, PG). The normal management at each site was followed, except that no N inputs occurred during the monitoring period from August 2008 to October 2009. The stratified sampling strategy further included six sampling points in three blocks at each site. Environmental variables (precipitation, PAR, air and soil temperature, soil moisture, groundwater level) were monitored continuously and during sampling campaigns, where also groundwater samples were taken for analysis. Gaseous fluxes were monitored on a three-weekly basis, giving 51, 49 and 38 field campaigns for land use categories AR, PG and RG, respectively. Climatic conditions in each region during monitoring were representative as compared to 20-yr averages. Peat layers were shallow, typically 0.5 to 1 m, and with a pH of 4 to 5. At six sites annual emissions of N2O were in the range 3 to 24 kg N2O-N ha-1, but at two arable sites (spring barley, potato) net emissions of 38 and 61 kg N2O-N ha-1 were recorded. The two high-emitting sites were characterized by fluctuating groundwater, low soil pH and elevated groundwater SO42- concentrations. Annual fluxes of CH4 were generally small, as expected, ranging from 2 to 4 kg CH4 ha-1. However, two permanent grasslands had tussocks of Juncus effusus L. (soft rush) in sampling points that were consistent sources of CH4 throughout the year. Emission factors for organic soils in rotation and with permanent grass, respectively, were estimated to be 0.011 and 0.47 g m-2

  6. Annual emissions of CH4 and N2O, and ecosystem respiration, from eight organic soils in Western Denmark managed by agriculture

    NASA Astrophysics Data System (ADS)

    Petersen, S. O.; Hoffmann, C. C.; Schäfer, C.-M.; Blicher-Mathiesen, G.; Elsgaard, L.; Kristensen, K.; Larsen, S. E.; Torp, S. B.; Greve, M. H.

    2011-10-01

    The use of organic soils by agriculture involves drainage and tillage, and the resulting increase in C and N turnover can significantly affect their greenhouse gas balance. This study estimated annual fluxes of CH4 and N2O, and ecosystem respiration (Reco), from eight organic soils managed by agriculture. The sites were located in three regions representing different landscape types and climatic conditions, and three land use categories (arable crops, AR, grass in rotation, RG, and permanent grass, PG) were covered. The normal management at each site was followed, except that no N inputs occurred during the monitoring period from August 2008 to October 2009. The stratified sampling strategy further included six sampling points in three blocks at each site. Environmental variables (precipitation, PAR, air and soil temperature, soil moisture, groundwater level) were monitored continuously and during sampling campaigns, where also groundwater samples were taken for analysis. Gaseous fluxes were monitored on a three-weekly basis, giving 51, 49 and 38 field campaigns for land use categories AR, PG and RG, respectively. Climatic conditions in each region during monitoring were representative based on 20-yr averages. Peat layers were shallow, typically 0.5 to 1 m, and with a pH of 4-5. At six sites annual emissions of N2O were in the range 3 to 24 kg N2O-N ha-1, but at two arable sites (spring barley, potato) net emissions of 38 and 61 kg N2O-N ha-1 were recorded. Both were characterized by fluctuating groundwater with elevated SO42- concentrations. Annual fluxes of CH4 were generally small, as expected, ranging from -2 to 4 kg CH4 ha-1. However, two permanent grasslands had tussocks of Juncus effusus (soft rush) in sampling points that were consistent sources of CH4 throughout the year. Emission factors for organic soils in rotation and permanent grass, respectively, were estimated to be 0.011 and 0.47 g m-2 for CH4, and 2.5 and 0.5 g m-2 for N2O. This first

  7. The impact of corn stover removal on N2O emission and soil respiration: An investigation with automated chambers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn stover removal, whether for silage, bedding, or bioenergy production, could have a variety of environmental consequences through its effect on soil processes, particularly N2O production and soil respiration. Because these effects may be episodic in nature, weekly snapshots with static chambers...

  8. Soil and fertilizer type effects on short-term N2 and N2O emissions: Results of a helium-oxygen incubation study

    NASA Astrophysics Data System (ADS)

    Hagemann, Ulrike; Andres, Monique; Augustin, Jürgen

    2015-04-01

    Emitted N gas species from agricultural fields are highly relevant in terms of environmental and climate protection and mainly result from numerous simultaneously occurring production and consumption processes, which are influenced by a range of proximal (e.g. nutrient and oxygen availability) and distal factors (e.g. soil conditions, climate and management). Fertilization generally influences the rate of denitrification through increased C and N availability in the soil. But, compared to unfermented organic fertilizers, this effect is more pronounced for fermented residues (FR) due to higher concentrations of NH4+, Nt and labile organic C. Thus, FR likely serve as an additional energy source for denitrifying bacteria, potentially resulting in temporally increased denitrification rates. However, field studies of simultaneous N2 and N2O emissions following fertilization with FR are still lacking, but are required to improve our understanding of the combined effects of relevant factors on the resulting N2 : N2O ratios. We will present results of an incubation experiment conducted to quantify the effects of i) 2 N fertilizer types (fermentation residue, FR and granular calcium ammonium nitrate, CAN) and ii) 5 soil types (ranging from slightly loamy sand to very clayey silt) on short-term emissions of N2 and N2O as well as N2 : N2O ratios. Immediately after fertilizer application and incorporation in spring 2012, five intact soil cores per treatment were randomly taken from each of 5 study sites in Germany. Simultaneous measurements of N2O and N2 fluxes were conducted in special gas-tight incubation vessels inside a climate box at 10°C using the helium-oxygen incubation method of Butterbach-Bahl et al. (2002), classified as a flow-through steady-state system according to Livingston and Hutchinson (1995). Across all sites, FR samples showed both significantly higher absolute and relative (to fertilizer N input) N2O efflux and significantly higher average absolute and

  9. N2O FIELD STUDY

    EPA Science Inventory

    The report gives results of measurements of nitrous oxide (N2O) emissions from coal-fired utility boilers at three electric power generating stations. Six units were tested, two at each site, including sizes ranging from 165 to 700 MW. Several manufacturers and boiler firing type...

  10. Short-term emissions of CO2 and N2O in response to periodic flood irrigation with waste water in the Mezquital Valley of Mexico

    NASA Astrophysics Data System (ADS)

    González-Méndez, B.; Webster, R.; Fiedler, S.; Loza-Reyes, E.; Hernández, J. M.; Ruíz-Suárez, L. G.; Siebe, C.

    2015-01-01

    Irrigation with waste water adds labile carbon and nitrogen compounds to the soil, and when applied by flooding it rapidly changes the soil's atmosphere and redox potential. In the Mezquital Valley more than 90 000 ha is irrigated with waste water from Mexico City, and enhanced emissions of CO2 and N2O follow each flooding. We measured the emissions of these two gases from a field irrigated periodically with waste water and under three crops, namely alfalfa, rye-grass and maize, using static chambers for 21 months. We also measured emissions from a field growing rain-fed maize before and shortly after two rain events. The data from repeated measurements from the same chambers are correlated in time, and so we modelled the ante-dependence and fitted the models by residual maximum likelihood (REML). The emissions of both CO2 and N2O increased rapidly in response to flood irrigation with peaks up to 448 mg C m-2 hour-1 for CO2 and 2.98 mg N m-2 hour-1 for N2O under maize. Emissions peaked in particular irrigation events either as the infiltrating water replaced the gas from air-filled pores or several days after irrigation as excess nitrogen and fresh sources of carbon were mineralized. Processes operating during the few days during and immediately after irrigation seem to determine the dynamics of gaseous production in this agricultural ecosystem.

  11. A comparison of CH4, N2O and CO2 emissions from three different cover types in a municipal solid waste landfill.

    PubMed

    Wang, Xiaojun; Jia, Mingsheng; Lin, Xiangyu; Xu, Ying; Ye, Xin; Kao, Chih Ming; Chen, Shaohua

    2017-04-01

    High-density polyethylene (HDPE) membranes are commonly used as a cover component in sanitary landfills, although only limited evaluations of its effect on greenhouse gas (GHG) emissions have been completed. In this study, field GHG emission were investigated at the Dongbu landfill, using three different cover systems: HDPE covering; no covering, on the working face; and a novel material-Oreezyme Waste Cover (OWC) material as a trial material. Results showed that the HDPE membrane achieved a high CH4 retention, 99.8% (CH4 mean flux of 12 mg C m(-2) h(-1)) compared with the air-permeable OWC surface (CH4 mean flux of 5933 mg C m(-2) h(-1)) of the same landfill age. Fresh waste at the working face emitted a large fraction of N2O, with average fluxes of 10 mg N m(-2) h(-2), while N2O emissions were small at both the HDPE and the OWC sections. At the OWC section, CH4 emissions were elevated under high air temperatures but decreased as landfill age increased. N2O emissions from the working face had a significant negative correlation with air temperature, with peak values in winter. A massive presence of CO2 was observed at both the working face and the OWC sections. Most importantly, the annual GHG emissions were 4.9 Gg yr(-1) in CO2 equivalents for the landfill site, of which the OWC-covered section contributed the most CH4 (41.9%), while the working face contributed the most N2O (97.2%). HDPE membrane is therefore, a recommended cover material for GHG control.

  12. Long-term elevation of temperature affects organic N turnover and associated N2O emissions in a permanent grassland soil

    NASA Astrophysics Data System (ADS)

    Jansen-Willems, Anne B.; Lanigan, Gary J.; Clough, Timothy J.; Andresen, Louise C.; Müller, Christoph

    2016-11-01

    Over the last century an increase in mean soil surface temperature has been observed, and it is predicted to increase further in the future. In order to evaluate the legacy effects of increased temperature on both nitrogen (N) transformation rates in the soil and nitrous oxide (N2O) emissions, an incubation experiment and modelling approaches were combined. Based on previous observations that gross N transformations in soils are affected by long-term elevated-temperature treatments we hypothesized that any associated effects on gaseous N emissions (e.g. N2O) can be confirmed by a change in the relative emission rates from various pathways. Soils were taken from a long-term in situ warming experiment on temperate permanent grassland. In this experiment the soil temperature was elevated by 0 (control), 1, 2 or 3 °C (four replicates per treatment) using IR (infrared) lamps over a period of 6 years. The soil was subsequently incubated under common conditions (20 °C and 50 % humidity) and labelled as NO315NH4 Gly, 15NO3NH4 Gly or NO3NH4 15N-Gly. Soil extractions and N2O emissions were analysed using a 15N tracing model and source-partitioning model. Both total inorganic N (NO3- + NH4+) and NO3- contents were higher in soil subjected to the +2 and +3 °C temperature elevations (pre- and post-incubation). Analyses of N transformations using a 15N tracing model showed that, following incubation, gross organic (but not inorganic) N transformation rates decreased in response to the prior soil warming treatment. This was also reflected in reduced N2O emissions associated with organic N oxidation and denitrification. Furthermore, a newly developed source-partitioning model showed the importance of oxidation of organic N as a source of N2O. In conclusion, long-term soil warming can cause a legacy effect which diminishes organic N turnover and the release of N2O from organic N and denitrification.

  13. Disaggregated N2O emission factors in China based on cropping parameters create a robust approach to the IPCC Tier 2 methodology.

    PubMed

    Shepherd, Anita; Yan, Xiaoyuan; Nayak, Dali; Newbold, Jamie; Moran, Dominic; Dhanoa, Mewa Singh; Goulding, Keith; Smith, Pete; Cardenas, Laura M

    2015-12-01

    China accounts for a third of global nitrogen fertilizer consumption. Under an International Panel on Climate Change (IPCC) Tier 2 assessment, emission factors (EFs) are developed for the major crop types using country-specific data. IPCC advises a separate calculation for the direct nitrous oxide (N2O) emissions of rice cultivation from that of cropland and the consideration of the water regime used for irrigation. In this paper we combine these requirements in two independent analyses, using different data quality acceptance thresholds, to determine the influential parameters on emissions with which to disaggregate and create N2O EFs. Across China, the N2O EF for lowland horticulture was slightly higher (between 0.74% and 1.26% of fertilizer applied) than that for upland crops (values ranging between 0.40% and 1.54%), and significantly higher than for rice (values ranging between 0.29% and 0.66% on temporarily drained soils, and between 0.15% and 0.37% on un-drained soils). Higher EFs for rice were associated with longer periods of drained soil and the use of compound fertilizer; lower emissions were associated with the use of urea or acid soils. Higher EFs for upland crops were associated with clay soil, compound fertilizer or maize crops; lower EFs were associated with sandy soil and the use of urea. Variation in emissions for lowland vegetable crops was closely associated with crop type. The two independent analyses in this study produced consistent disaggregated N2O EFs for rice and mixed crops, showing that the use of influential cropping parameters can produce robust EFs for China.

  14. A novel 15N tracer approach for the quantification of N2 and N2O emissions from soil incubations in a completely automated laboratory set up

    NASA Astrophysics Data System (ADS)

    Scheer, Clemens; Dannenmann, Michael; Meier, Rudolf

    2015-04-01

    The microbial mediated production of nitrous oxide (N2O) and its reduction to dinitrogen (N2) via denitrification represents a loss of nitrogen (N) from fertilised agro-ecosystems to the atmosphere. Although denitrification has received great interest by biogeochemists in the last decades, the magnitude of N2lossesand related N2:N2O ratios from soils still are largely unknown due to methodical constraints. We present a novel 15N tracer approach, based on a previous developed tracer method to study denitrification in pure bacterial cultures which was modified for the use on soil incubations in a completely automated laboratory set up. The method uses a background air in the incubation vessels that is replaced with a helium-oxygen gas mixture with a 50-fold reduced N2 background (2 % v/v). This method allows for a direct and sensitive quantification of the N2 and N2O emissions from the soil with isotope-ratio mass spectrometry after 15N labelling of denitrification N substrates and minimises the sensitivity to the intrusion of atmospheric N2 at the same time. The incubation set up was used to determine the influence of different soil moisture levels on N2 and N2O emissions from a sub-tropical pasture soil in Queensland/Australia. The soil was labelled with an equivalent of 50 μg-N per gram dry soil by broadcast application of KNO3solution (4 at.% 15N) and incubated for 3 days at 80% and 100% water filled pore space (WFPS), respectively. The headspace of the incubation vessel was sampled automatically over 12hrs each day and 3 samples (0, 6, and 12 hrs after incubation start) of headspace gas analysed for N2 and N2O with an isotope-ratio mass spectrometer (DELTA V Plus, Thermo Fisher Scientific, Bremen, Germany(. In addition, the soil was analysed for 15N NO3- and NH4+ using the 15N diffusion method, which enabled us to obtain a complete N balance. The method proved to be highly sensitive for N2 and N2O emissions detecting N2O emissions ranging from 20 to 627 μN kg

  15. Emission of CO2 and N2O from soil cultivated with common bean (Phaseolus vulgaris L.) fertilized with different N sources.

    PubMed

    Fernández-Luqueño, F; Reyes-Varela, V; Martínez-Suárez, C; Reynoso-Keller, R E; Méndez-Bautista, J; Ruiz-Romero, E; López-Valdez, F; Luna-Guido, M L; Dendooven, L

    2009-07-01

    Addition of different forms of nitrogen fertilizer to cultivated soil is known to affect carbon dioxide (CO(2)) and nitrous oxide (N(2)O) emissions. In this study, the effect of urea, wastewater sludge and vermicompost on emissions of CO(2) and N(2)O in soil cultivated with bean was investigated. Beans were cultivated in the greenhouse in three consecutive experiments, fertilized with or without wastewater sludge at two application rates (33 and 55 Mg fresh wastewater sludge ha(-1), i.e. 48 and 80 kg N ha(-1) considering a N mineralization rate of 40%), vermicompost derived from the wastewater sludge (212 Mg ha(-1), i.e. 80 kg N ha(-1)) or urea (170 kg ha(-1), i.e. 80 kg N ha(-1)), while pH, electrolytic conductivity (EC), inorganic nitrogen and CO(2) and N(2)O emissions were monitored. Vermicompost added to soil increased EC at onset of the experiment, but thereafter values were similar to the other treatments. Most of the NO(3)(-) was taken up by the plants, although some was leached from the upper to the lower soil layer. CO(2) emission was 375 C kg ha(-1) y(-1) in the unamended soil, 340 kg C ha(-1) y(-1) in the urea-amended soil and 839 kg ha(-1) y(-1) in the vermicompost-amended soil. N(2)O emission was 2.92 kg N ha(-1) y(-1) in soil amended with 55 Mg wastewater sludge ha(-1), but only 0.03 kg N ha(-1) y(-1) in the unamended soil. The emission of CO(2) was affected by the phenological stage of the plant while organic fertilizer increased the CO(2) and N(2)O emission, and the yield per plant. Environmental and economic implications must to be considered to decide how many, how often and what kind of organic fertilizer could be used to increase yields, while limiting soil deterioration and greenhouse gas emissions.

  16. CH4 and N2O dynamics in the boreal forest-mire ecotone

    NASA Astrophysics Data System (ADS)

    Tupek, B.; Minkkinen, K.; Pumpanen, J.; Vesala, T.; Nikinmaa, E.

    2014-06-01

    In spite of advances in greenhouse gas research, the spatio-temporal CH4 and N2O dynamics of boreal landscape remain challenging, e.g. we need clarification of whether the forest-mire transitions are occasional hotspots of landscape CH4 and N2O emissions during exceptionally high and low ground water level events. In our study, we tested the differences and drivers of CH4 and N2O dynamics of forest/mire types in field conditions along the soil moisture gradient of the forest-mire ecotone. Soils changed from podzols to histosols and ground water rose downslope from the depth of 10 m in upland sites to 0.1 m in mires. Yearly meteorological conditions changed from being exceptionally wet to typical and exceptionally dry for the local climate. The median fluxes measured with a static chamber technique varied from -51 to 586 μg m-2 h-1 for CH4 and from 0 to 6 μg m-2 h-1 for N2O between forest/mire types throughout the entire wet-dry period. In spite of the highly dynamic soil water fluctuations in carbon rich soils in forest-mire transitions, there were no large peak emissions in CH4 and N2O fluxes and the flux rates changed minimally between years. Methane oxidations were significantly lower in poorly drained transitions than in the well-drained uplands. Water saturated mires showed large CH4 emissions, which were reduced entirely during the exceptional summer drought period. Near zero N2O fluxes did not differ significantly between the forest/mire types probably due to their low nitrification potential. When up scaling boreal landscapes, pristine forest-mire transitions should be categorized as CH4 oxidation types and background N2O emission types instead of CH4 and N2O emission hotspots.

  17. 40 CFR Table I-8 to Subpart I of... - Default Emission Factors (1-UN2O j) for N2O Utilization (UN2O j)

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Default Emission Factors (1-UN2O j) for N2O Utilization (UN2O j) I Table I-8 to Subpart I of Part 98 Protection of Environment... Electronics Manufacturing Pt. 98, Subpt. I, Table I-8 Table I-8 to Subpart I of Part 98—Default...

  18. 40 CFR Table I-8 to Subpart I of... - Default Emission Factors (1-UN2O,j) for N2O Utilization (UN2O,j)

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Default Emission Factors (1-UN2O,j) for N2O Utilization (UN2O,j) I Table I-8 to Subpart I of Part 98 Protection of Environment... Electronics Manufacturing Pt. 98, Subpt. I, Table I-8 Table I-8 to Subpart I of Part 98— Default...

  19. N use efficiencies and N2O emissions in two contrasting, biochar amended soils under winter wheat—cover crop—sorghum rotation

    NASA Astrophysics Data System (ADS)

    Hüppi, Roman; Neftel, Albrecht; Lehmann, Moritz F.; Krauss, Maike; Six, Johan; Leifeld, Jens

    2016-08-01

    Biochar, a carbon-rich, porous pyrolysis product of organic residues, is evaluated as an option to tackle major problems of the global food system. Applied to soil, biochar can sequester carbon and have beneficial effects on nitrogen (N) cycling, thereby enhancing crop yields and reducing nitrous oxide (N2O) emissions. There is little understanding of the underlying mechanisms, but many experiments indicated increased yields and manifold changes in N transformation, suggesting an increase in N use efficiency. Biochar’s effects can be positive in extensively managed tropical agriculture, however less is known about its use in temperate soils with intensive fertilisation. We tested the effect of slow pyrolysis wood chip biochar on N use efficiency, crop yields and N2O emissions in a lysimeter system with two soil types (sandy loamy Cambisol and silty loamy Luvisol) in a winter wheat—cover crop—sorghum rotation. 15N-labelled ammonium nitrate fertiliser (170 kg N ha-1 in 3 doses, 10% 15N) was applied to the first crop to monitor its fate in three ecosystem components (plants, soil, leachate). Green rye was sown as cover crop to keep the first year’s fertiliser N for the second year’s sorghum crop (fertilised with 110 kg N ha-1 in two doses and natural abundance 15N). We observed no effects of biochar on N fertiliser use efficiency, yield or N uptake for any crop. Biochar reduced leaching by 43 ± 19% but only towards the end of the experiment with leaching losses being generally low. For both soils N2O emissions were reduced by 15 ± 4% with biochar compared to the control treatments. Our results indicate that application of the chosen biochar induces environmental benefits in terms of N2O emission and N leaching but does not substantially affect the overall N cycle and hence crop performance in the analyzed temperate crop rotation.

  20. [N2O and CH4 emission from Japan rice fields under different long-term fertilization patterns and its environmental impact].

    PubMed

    Luo, Liang-guo; Kondo, Motohiko; Itoh, Sumio

    2010-12-01

    This study intended to investigate the greenhouse gases emission from Japan single cropping paddy fields after 75-year continuous application of ammonium sulfate, composted rice straw with soybean cake, and fresh clover, as well as the environmental impact of the emission. During this long period, field management remained constant in terms of rice cultivation density, irrigation, and equivalent net N fertilization. No significant differences were observed in N2O emission among the fertilization treatments, but the CH4 emission differed significantly between organic amendment and ammonium sulfate application, indicating that long-term organic fertilization didn' t increase N2O emission but promoted CH4 emission. The cumulative global warming potential (GWP) of the CH4 and NO2O from the paddy ecosystem was the greatest (310.7 g CO2e x m(-2)) under fresh clover application, followed by composted rice straw plus soybean cake addition (151 g CO2e x m(-2)), and the least (60.6 g CO2e x m(-2)) under ammonium sulfate application. This study showed that for paddy system, it was CH4 instead of N2O the major factor affecting global warming, and thereby, to control and reduce the CH4 emission from paddy system would be the core in mitigating greenhouse gases emission from paddy field. Long-term consecutive application of composted rice straw plus soybean cake could increase soil organic matter, improve soil fertility, promote rice high-yielding, and as well, mitigate CH4 emission, being the recommendable paddy rice production mode in practice.

  1. A review of nitrogen enrichment effects on three biogenic GHGs: the CO2 sink may be largely offset by stimulated N2O and CH4 emission.

    PubMed

    Liu, Lingli; Greaver, Tara L

    2009-10-01

    Anthropogenic nitrogen (N) enrichment of ecosystems, mainly from fuel combustion and fertilizer application, alters biogeochemical cycling of ecosystems in a way that leads to altered flux of biogenic greenhouse gases (GHGs). Our meta-analysis of 313 observations across 109 studies evaluated the effect of N addition on the flux of three major GHGs: CO(2), CH(4) and N(2)O. The objective was to quantitatively synthesize data from agricultural and non-agricultural terrestrial ecosystems across the globe and examine whether factors, such as ecosystem type, N addition level and chemical form of N addition influence the direction and magnitude of GHG fluxes. Results indicate that N addition increased ecosystem carbon content of forests by 6%, marginally increased soil organic carbon of agricultural systems by 2%, but had no significant effect on net ecosystem CO(2) exchange for non-forest natural ecosystems. Across all ecosystems, N addition increased CH(4) emission by 97%, reduced CH(4) uptake by 38% and increased N(2)O emission by 216%. The net effect of N on the global GHG budget is calculated and this topic is reviewed. Most often N addition is considered to increase forest C sequestration without consideration of N stimulation of GHG production in other ecosystems. However, our study indicated that although N addition increased the global terrestrial C sink, the CO(2) reduction could be largely offset (53-76%) by N stimulation of global CH(4) and N(2)O emission from multiple ecosystems.

  2. CH4 and N2O dynamics in the boreal forest-mire ecotone

    NASA Astrophysics Data System (ADS)

    Tupek, B.; Minkkinen, K.; Pumpanen, J.; Vesala, T.; Nikinmaa, E.

    2015-01-01

    In spite of advances in greenhouse gas research, the spatiotemporal CH4 and N2O dynamics of boreal landscapes remain challenging, e.g., we need clarification of whether forest-mire transitions are occasional hotspots of landscape CH4 and N2O emissions during exceptionally high and low ground water level events. In our study, we tested the differences and drivers of CH4 and N2O dynamics of forest/mire types in field conditions along the soil moisture gradient of the forest-mire ecotone. Soils changed from Podzols to Histosols and ground water rose downslope from a depth of 10 m in upland sites to 0.1 m in mires. Yearly meteorological conditions changed from being exceptionally wet to typical and exceptionally dry for the local climate. The median fluxes measured with a static chamber technique varied from -51 to 586 μg m-2 h-1 for CH4 and from 0 to 6 μg m-2 h-1 for N2O between forest and mire types throughout the entire wet-dry period. In spite of the highly dynamic soil water fluctuations in carbon rich soils in forest-mire transitions, there were no large peak emissions in CH4 and N2O fluxes and the flux rates changed minimally between years. Methane uptake was significantly lower in poorly drained transitions than in the well-drained uplands. Water-saturated mires showed large CH4 emissions, which were reduced entirely during the exceptional summer drought period. Near-zero N2O fluxes did not differ significantly between the forest and mire types probably due to their low nitrification potential. When upscaling boreal landscapes, pristine forest-mire transitions should be regarded as CH4 sinks and minor N2O sources instead of CH4 and N2O emission hotspots.

  3. Sub-arctic Wetland Greenhouse Gases (CO2, CH4 & N2O) Emissions are Driven by Interactions of Environmental Controls and Herbivore Grazers

    NASA Astrophysics Data System (ADS)

    Kelsey, K.; Leffler, A. J.; Beard, K. H.; Choi, R. T.; Welker, J. M.

    2015-12-01

    Climate change is increasing temperatures, altering precipitation regimes and causing earlier growing seasons, particularly at northern latitudes. Such changes in local environmental conditions have the potential to affect biogeochemical cycling including the exchange of greenhouses gases between the atmosphere and the terrestrial biosphere. In addition to the effects of these environmental controls, animals such as migratory geese also influence biogeochemical cycles through grazing, trampling and delivering nutrient-rich fecal matter. In this work we aimed to quantify how local environmental conditions and the presence of grazing interact as drivers of emissions of three key greenhouse gases, CO2, CH4 and N2O, in coastal wetlands of the Yukon Kuskokwim Delta. We explored the magnitude of emissions across gradients of soil temperature and water table depth, and across vegetation types related to the presence of grazing, ranging from no vegetation through grazed and ungrazed vegetation. We also investigated emissions from grazed areas using experimental manipulations of the timing of grazing and advancement of the growing season. We found that local environmental conditions and use by grazers exert interacting controls on emissions of CO2, CH4 and N2O. Emissions of CO2 and CH4 were positively related to soil temperature and CH4 emissions were inversely related to water table depth, but the relationship varied by vegetation type. Net emissions of CO2 were greatest in ungrazed vegetation types (6.62 umols CO2 m-2 sec-1; p=0.0007) whereas CH4 emissions were greatest in the grazed vegetation (122.56 nmols CH4 m-2 sec-1; p=0.037). Flux of N2O was less than 1 nmol N2O m-2 sec-1 across all landscape positions under typical grazing and temperature conditions, but emissions were stimulated to over 10 nmols m-2 sec-1 when grazing occurred early relative to a typical season. Our results indicate that environmental conditions and the presence of migratory herbivores are both

  4. North American terrestrial CO2 uptake largely offset by CH4 and N2O emissions: toward a full accounting of the greenhouse gas budget

    DOE PAGES

    Tian, Hanqin; Chen, Guangsheng; Lu, Chaoqun; ...

    2014-03-14

    The terrestrial ecosystems of North America have been identified as a sink of atmospheric CO2 though there is no consensus on the magnitude. However, the emissions of non-CO2 greenhouse gases (CH4 and N2O) may offset or even overturn the climate cooling effect induced by the CO2 sink. Using a coupled biogeochemical model, in this study, we have estimated the combined global warming potentials (GWP) of CO2, CH4 and N2O fluxes in North American terrestrial ecosystems and quantified the relative contributions of environmental factors to the GWP changes during 1979–2010. The uncertainty range for contemporary global warming potential has been quantifiedmore » by synthesizing the existing estimates from inventory, forward modeling, and inverse modeling approaches. Our “best estimate” of net GWP for CO2, CH4 and N2O fluxes was₋0.50 ± 0.27 Pg CO2 eq/year (1 Pg=1015 g) in North American terrestrial ecosystems during 2001–2010. The emissions of CH4 and N2O from terrestrial ecosystems had offset about two thirds (73% ± 14%) of the land CO2 sink in the North American continent, showing large differences across the three countries, with offset ratios of 57% ± 8% in US, 83% ± 17 % in Canada and 329% ± 119 % in Mexico. Climate change and elevated tropospheric ozone concentration have contributed the most to GWP increase, while elevated atmospheric CO2 concentration have contributed the most to GWP reduction. Extreme drought events over certain periods could result in a positive GWP. By integrating the existing estimates, we have found a wide range of uncertainty for the combined GWP. In conclusion, from both climate change science and policy perspectives, it is necessary to integrate ground and satellite observations with models for a more accurate accounting of these three greenhouse gases in North America.« less

  5. Sectoral CO 2, CH 4, N 2O and SO 2 emissions from fossil fuel consumption in Nagpur City of Central India

    NASA Astrophysics Data System (ADS)

    Majumdar, Deepanjan; Gajghate, D. G.

    2011-08-01

    Emission inventory of CO 2, CH 4, N 2O and SO 2 has been prepared for Nagpur city in Central India for the year 2004. Data on fossil fuel (coal, light diesel oil, high speed diesel, petrol/gasoline, low sulphur heavy stock, furnace oil and kerosene) consumption in thermal power, industrial, transport and domestic sectors were collected. Thermal power sector had the maximum coal consumption followed by the industrial and domestic sectors, whereas kerosene, liquefied petroleum gas (LPG), diesel and gasoline were used only in any single sector. Total annual CO 2, CH 4, N 2O and SO 2 emissions from these fuels in Nagpur city for the year 2004 was found to be 14792418 MT (14.8 Tg), 4649 (4.6 Tg), 1529 (1.5 Tg) and 69093 (6.9 Tg), respectively, in which thermal power and domestic sector had the maximum share. Coal was found to be the major contributor to Green House Gas (GHG) and SO 2 emissions in all the sectors barring transport and domestic sectors. Carbon dioxide was the predominant GHG emitted by the selected sectors in terms of absolute emissions and also global warming contribution (GWC), though the share in the latter was lesser in magnitude due to higher global warming potential (GWP) of CH 4 and N 2O than CO 2. Thermal power sector had a share of 51% in total CO 2 emissions from all the sectors, followed by domestic, industrial and transport sectors having 27, 12 and 10% contributions, respectively. Share of thermal power sector in total SO 2 emissions was 61%, followed by 24% from industrial, 10% from domestic and 5% from transport sector.

  6. Simulating CH4 and N2O emissions from direct-seeded rice systems using the DeNitrification DeComposition (DNDC) model

    NASA Astrophysics Data System (ADS)

    Simmonds, M.; Li, C.; Lee, J.; Six, J.; Van Kessel, C.; Linquist, B.

    2015-12-01

    Process-based modeling of CH4 and N2O emissions from rice fields is a practical tool for conducting greenhouse gas inventories and estimating mitigation potentials of alternative practices at the scales of management and policy-making. However, few studies have evaluated site-level model performance in side-by-side field trials of various management practices during both the growing season and fallow periods. We empirically evaluated the DeNitrification-DeComposition (DNDC) model for estimating CH4 and N2O fluxes in California rice systems under varying management (N fertilizer application rate, type of seeding system, fallow period straw and water management), soil environments, and weather conditions. Five and nine site-year combinations were used for calibration and validation, respectively. The model was parameterized for two cultivars, M206 and Koshihikari, and able to simulate 30% and 78% of the measured variation in yields, respectively. A major strength of DNDC was in estimating general site-level seasonal CH4 emissions (R2 = 0.85). However, a major limitation was in simulating finer resolution of differences in CH4 emissions (or lack thereof) among side-by-side management treatments (range of 0.2-465% relative absolute deviation). Additionally, DNDC did not satisfactorily simulate fallow period CH4 emissions, or seasonal and fallow period N2O emissions across all sites with the exception of a few cases. Specifically, simulated CH4 emissions were oversensitive to fertilizer N rates, but lacked sensitivity to the type of seeding system and prior fallow period straw management. Additionally, N2O emissions were oversensitive to fertilizer N rates and field drainage. Sensitivity analysis showed that CH4 emissions were highly sensitive to changes in the root to total plant biomass ratio. Overall, uncertainty in model predictions was attributed to uncertainty in both the input parameters due to in-field spatiotemporal variability of soil properties, and in the

  7. Effects of N loading rate on CH4 and N2O emissions during cultivation and fallow periods from forage rice fields fertilized with liquid cattle waste.

    PubMed

    Riya, S; Zhou, S; Kobara, Y; Sagehashi, M; Terada, A; Hosomi, M

    2015-09-15

    The use of liquid cattle waste (LCW) as a fertilizer for forage rice is important for material recycling because it can promote biomass production, and reduce the use of chemical fertilizer. Meanwhile, increase in emission of greenhouse gases (GHGs), especially CH4 and N2O would be concerned. We conducted a field study to determine the optimum loading rate of LCW as N to promote forage rice growth with lower GHG emissions. The LCW was applied to forage rice fields, N100, N250, N500, and N750, at four different N loading rates of 107, 258, 522, and 786 kg N ha(-1), respectively, including 50 kg N ha(-1) of basal chemical fertilizer. The above-ground biomass yields increased 14.6-18.5 t ha(-1) with increases in N loading rates. During the cultivation period, both the CH4 and N2O fluxes increased with increases in LCW loading rates. In the treatments of N100, N250, N500, and N750, the cumulative CH4 emissions during the entire period, including cultivation and fallow period were 29.6, 18.1, 54.4, and 67.5 kg C ha(-1), respectively, whereas those of N2O were -0.15, -0.02, 1.49, and 5.82 kg N ha(-1), respectively. Considering the greenhouse gas emissions and above-ground biomass, the yield-scaled CO2-equivalents (CO2-eqs) were 66.3, 35.9, 161, and 272 kg CO2 t(-1) for N100, N250, N500, and N750, respectively. These results suggest that N250 is the most appropriate LCW loading rate for promoting forage rice production with lower GHG emissions.

  8. Changes in CO2, N2O and NO Emissions in Response to Conventional Tillage and No-tillage Management Practices in the State of Rondonia, Brazil

    NASA Astrophysics Data System (ADS)

    Passianoto, C. C.; Ahrens, T. D.; Feigl, B. J.; Steudler, P. A.; Do Carmo, J. B.; Melillo, J. M.

    2002-12-01

    Land management in the Brazilian State of Rondonia is undergoing a new phase at the start of 21st century. In the 1970s and afterwards, vast tracts of tropical forest were cleared and planted to pasture for cattle grazing. With decades of use, the productivity of these pastures has declined. Now, in an effort to restore productivity, new land management regimes are being implemented that involve either tillage or no-tillage options combined with various combinations of fertilizer application, herbicide use and the planting of a cash crop prior to the planting of forage grasses. We are studying a subset of these restoration practices in a large-scale (>3 ha), replicated field experiment in an area of degraded pasture at Fazenda Nova Vida, a 22,000 ha cattle ranch in central Rondonia. Here we report on the emissions of carbon dioxide (CO2), nitrous oxide (N2O) and nitric oxide (NO) from the initial phases (first six months) of three of the treatments. The treatments are - 1) control; 2) conventional tillage followed by planting of forage grass (Brachiaria brizantha) and fertilizer additions; 3) no-tillage/herbicide treatment followed by two plantings, the first being a cash crop of rice followed by forage grass. In treatment 3, the rice was fertilized. Relative to the control, tillage increased CO2 emission by 37% over the first two months, while the no-tillage/herbicide regime decreased CO2 emissions by 7% over the same period. The cumulative N2O emissions over the first two months from the tillage regime (0.94 kg N ha-1) were much higher than the N2O releases from either the no-tillage/herbicide regime (0.64 kg N ha-1) or the control treatment (0.04 kg N ha-1). The highest levels of N2O fluxes from both management regimes were observed following nitrogen fertilizations. The cumulative NO releases over the first two months were largest in the tillage treatment (0.98 kg N ha-1), intermediate in the no-tillage treatment (0.72 kg N ha-1), and smallest in the control

  9. [Observation for CH4 and N2O emissions under different rates of nitrogen and phosphate fertilization in double rice fields].

    PubMed

    Shi, Sheng-Wei; Li, Yu-E; Wan, Yun-Fan; Qin, Xiao-Bo; Gao, Qing-Zhu

    2011-07-01

    Two non-CO2 greenhouse gas emissions (methane and nitrous oxide) and related environmental factors were measured within rice growing season under five treatments including non-fertilization (CK), balanced fertilization (BF), decreased nitrogen and phosphate 1 (DNP1), decreased nitrogen and phosphate 2 (DNP2) and increased nitrogen and phosphate 1 (INP) in double rice fields of red clay soil in 2009, using the method of static chamber-gas chromatograph techniques. The results showed that the average CH4 emission fluxes for treatments of BF, DNP1, DNP2 and INP were 4.57, 5.42, 4.70 and 4.65 mg x (m2 x h)(-1) during early rice growing period, which increased by 39%, 49%, 41% and 40% compared with non-fertilizer treatment, respectively. The average CH4 emission fluxes in late rice growing season was higher than preseason's. Compared to CK, CH4 emission increased by 11%, 1%, 26% and - 4% in treatments of BF, DNP1, DNP2 and INP within late rice growing season. Applying nitrogen and phosphate enhanced CH4 emission in turning green period for early and late rice. No significant difference was observed between the CH4 emissions of five treatments during early and late rice growing season (p > 0.05). N2O emission was very little during mid-seasonal drainage period. In contrast, N2O emission peaks were observed in period of alternation of wetting and drying after mid-seasonal drainage in this experiment. N2O emission was, on average, equivalent to 0.18% of the nitrogen applied in double rice growing season. Statistically, air temperature, soil Eh and soil moisture (water-filled pore space, WFPS) at 0-10cm depth significantly affected the fluctuations of the seasonal CH4 flux, but no significant correlationship has been found between N2O flux and related environmental factors. CH4 was the dominated greenhouse gas in double rice fields which contributed approximately 90% for the integrated global warming potential of CH4 and N2O released during the rice growing season

  10. Automated online measurement of N2, N2O, NO, CO2, and CH4 emissions based on a gas-flow-soil-core technique.

    PubMed

    Liao, Tingting; Wang, Rui; Zheng, Xunhua; Sun, Yang; Butterbach-Bahl, Klaus; Chen, Nuo

    2013-11-01

    The gas-flow-soil-core (GFSC) technique allows to directly measure emission rates of denitrification gases of incubated soil cores. However, the technique was still suffering some drawbacks such as inadequate accuracy due to asynchronous detection of dinitrogen (N2) and other gases and low measurement frequency. Furthermore, its application was limited due to intensive manual operation. To overcome these drawbacks, we updated the GFSC system as described by Wang et al. (2011) by (a) using both a chemiluminescent detector and a gas chromatograph detector to measure nitric oxide (NO), (b) synchronizing the measurements of N2, NO, nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4), and (c) fully automating the sampling/analysis of all the gases. These technical modifications significantly reduced labor demands by at least a factor of two, increased the measurement frequency from 3 to 6 times per day and resulted in remarkable improvements in measurement accuracy (with detection limits of 0.5, 0.01, 0.05, 2.3 and 0.2μgN or Ch(-1)kg(-1)ds, or 17, 0.3, 1.8, 82, and 6μgN or Cm(-2)h(-1), for N2, N2O, NO, CO2, and CH4, respectively). In some circumstances, the modified system measured significantly more N2 and CO2 and less N2O and NO because of the enhanced measurement frequency. The modified system distinguished the differences in emissions of the denitrification gases and CO2 due to a 20% change in initial carbon supplies. It also remarkably recovered approximately 90% of consumed nitrate during incubation. These performances validate the technical improvement, and indicate that the improved GFSC system may provide a powerful research tool for obtaining deeper insights into the processes of soil carbon and nitrogen transformation during denitrification.

  11. Changes in Soil Moisture, Microbial Biomass, Mineralization and Nitrification Explain Increases in N2O Emissions from a Spring Barley Crop Under Combined Reduced Tillage and Cover Crop Management

    NASA Astrophysics Data System (ADS)

    Rueangritsarakul, K.; Jones, M.; Roth, B.; Abdalla, M.; Williams, M.

    2012-04-01

    This study investigated the effect of conventional tillage (CT), combined reduced tillage-cover crop (RT-CC), and reduced N application on crop yield and N2O emissions from spring barley. Reduced tillage plots were established for seven years, the final four incorporating a mustard cover crop. Higher N2O fluxes were from fertilized, RT-CC plots due to higher WFPS, soil nitrate, and soil carbon. Fluxes during the non-growing season were variable and the main source of cumulative emissions. Emission factors were in the range of IPCC default values. Low N fertilization reduced cumulative emissions, however during the wetter growing season this reduction was smaller than the reduction in barley production particular in the conventional tillage plots. Adopting RT-CC management for cereal crops may be problematic in reducing GHG emissions due to high N2O fluxes. Reducing N fertilizer in order to reduce N2O emissions is not feasible due to high inter-annual variation in crop yield. N2O flux in all plots was positively correlated with microbial biomass carbon, net nitrification and mineralization determined in the field. Increased emissions of N2O in the RT-CC plots are accounted for by increases in organic carbon in the soil and increases in mineralization.

  12. Pathways of N removal and N2O emission from a one-stage autotrophic N removal process under anaerobic conditions

    NASA Astrophysics Data System (ADS)

    Li, Kai; Fang, Fang; Wang, Han; Wang, Chao; Chen, Youpeng; Guo, Jinsong; Wang, Xixi; Jiang, Fuyang

    2017-02-01

    To investigate the pathways of nitrogen (N) removal and N2O emission in a one-stage autotrophic N removal process during the non-aeration phase, biofilm from an intermittent aeration sequencing batch biofilm reactor (SBBR) and organic carbon-free synthetic wastewater were applied to two groups of lab-scale batch experiments in anaerobic conditions using a 15N isotopic tracer and specific inhibitors, respectively. Then, the microbial composition of the biofilm was analysed using high-throughput sequencing. The results of the 15N isotopic experiments showed that anaerobic ammonium oxidation (Anammox) was the main pathway of N transformation under anaerobic conditions and was responsible for 83–92% of N2 production within 24 h. Furthermore, experiments using specific inhibitors revealed that when nitrite was the main N source under anaerobic conditions, N2O emissions from heterotrophic denitrification (HD) and ammonia-oxidizing bacteria (AOB) denitrification were 64% and 36%, respectively. Finally, analysing the microbial composition demonstrated that Proteobacteria, Planctomycetes, and Nitrospirae were the dominant microbes, corresponding to 21%, 13%, and 7% of the microbial community, respectively, and were probably responsible for HD, Anammox, and AOB denitrification, respectively.

  13. Pathways of N removal and N2O emission from a one-stage autotrophic N removal process under anaerobic conditions

    PubMed Central

    Li, Kai; Fang, Fang; Wang, Han; Wang, Chao; Chen, Youpeng; Guo, Jinsong; Wang, Xixi; Jiang, Fuyang

    2017-01-01

    To investigate the pathways of nitrogen (N) removal and N2O emission in a one-stage autotrophic N removal process during the non-aeration phase, biofilm from an intermittent aeration sequencing batch biofilm reactor (SBBR) and organic carbon-free synthetic wastewater were applied to two groups of lab-scale batch experiments in anaerobic conditions using a 15N isotopic tracer and specific inhibitors, respectively. Then, the microbial composition of the biofilm was analysed using high-throughput sequencing. The results of the 15N isotopic experiments showed that anaerobic ammonium oxidation (Anammox) was the main pathway of N transformation under anaerobic conditions and was responsible for 83–92% of N2 production within 24 h. Furthermore, experiments using specific inhibitors revealed that when nitrite was the main N source under anaerobic conditions, N2O emissions from heterotrophic denitrification (HD) and ammonia-oxidizing bacteria (AOB) denitrification were 64% and 36%, respectively. Finally, analysing the microbial composition demonstrated that Proteobacteria, Planctomycetes, and Nitrospirae were the dominant microbes, corresponding to 21%, 13%, and 7% of the microbial community, respectively, and were probably responsible for HD, Anammox, and AOB denitrification, respectively. PMID:28205581

  14. North American terrestrial CO2 uptake largely offset by CH4 and N2O emissions: toward a full accounting of the greenhouse gas budget.

    PubMed

    Tian, Hanqin; Chen, Guangsheng; Lu, Chaoqun; Xu, Xiaofeng; Hayes, Daniel J; Ren, Wei; Pan, Shufen; Huntzinger, Deborah N; Wofsy, Steven C

    The terrestrial ecosystems of North America have been identified as a sink of atmospheric CO2 though there is no consensus on the magnitude. However, the emissions of non-CO2 greenhouse gases (CH4 and N2O) may offset or even overturn the climate cooling effect induced by the CO2 sink. Using a coupled biogeochemical model, in this study, we have estimated the combined global warming potentials (GWP) of CO2, CH4 and N2O fluxes in North American terrestrial ecosystems and quantified the relative contributions of environmental factors to the GWP changes during 1979-2010. The uncertainty range for contemporary global warming potential has been quantified by synthesizing the existing estimates from inventory, forward modeling, and inverse modeling approaches. Our "best estimate" of net GWP for CO2, CH4 and N2O fluxes was -0.50 ± 0.27 Pg CO2 eq/year (1 Pg = 10(15) g) in North American terrestrial ecosystems during 2001-2010. The emissions of CH4 and N2O from terrestrial ecosystems had offset about two thirds (73 %±14 %) of the land CO2 sink in the North American continent, showing large differences across the three countries, with offset ratios of 57 % ± 8 % in US, 83 % ± 17 % in Canada and 329 % ± 119 % in Mexico. Climate change and elevated tropospheric ozone concentration have contributed the most to GWP increase, while elevated atmospheric CO2 concentration have contributed the most to GWP reduction. Extreme drought events over certain periods could result in a positive GWP. By integrating the existing estimates, we have found a wide range of uncertainty for the combined GWP. From both climate change science and policy perspectives, it is necessary to integrate ground and satellite observations with models for a more accurate accounting of these three greenhouse gases in North America.

  15. Direct emissions of N2O, CO 2, and CH 4 from A/A/O bioreactor systems: impact of influent C/N ratio.

    PubMed

    Ren, Yangang; Wang, Jinhe; Xu, Li; Liu, Cui; Zong, Ruiqiang; Yu, Jianlin; Liang, Shuang

    2015-06-01

    Direct emissions of N2O, CO2, and CH4, three important greenhouse gases (GHGs), from biological sewage treatment process have attracted increasing attention worldwide, due to the increasing concern about climate change. Despite the tremendous efforts devoted to understanding GHG emission from biological sewage treatment process, the impact of influent C/N ratios, in terms of chemical oxygen demand (COD)/total nitrogen (TN), on an anaerobic/anoxic/oxic (A/A/O) bioreactor system has not been investigated. In this work, the direct GHG emission from A/A/O bioreactor systems fed with actual sewage was analyzed under different influent C/N ratios over a 6-month period. The results showed that the variation in influent carbon (160 to 500 mg/L) and nitrogen load (35 to 95 mg/L) dramatically influenced pollutant removal efficiency and GHG production from this process. In the A/A/O bioreactor systems, the GHG production increased from 26-39 to 112-173 g CO2-equivalent as influent C/N ratios decreased from 10.3/10.7 to 3.5/3.8. Taking consideration of pollutant removal efficiency and direct biogenic GHG (N2O, CO2, and CH4) production, the optimum influent C/N ratio was determined to be 7.1/7.5, at which a relatively high pollutant removal efficiency and meanwhile a low level of GHG production (30.4 g CO2-equivalent) can be achieved. Besides, mechanical aeration turned out to be the most significant factor influencing GHG emission from the A/A/O bioreactor systems.

  16. N2O emission from urine in the soil in the beef production in Southeast Brazil: soil moisture content and temperature effects

    NASA Astrophysics Data System (ADS)

    Simões Barneze, Arlete; Mancebo Mazzetto, Andre; Fernandes Zani, Caio; Siqueira Neto, Marcos; Clemente Cerri, Carlos

    2014-05-01

    Pasture expansion in Brazil has shown an increase in 4.5% per year, and a total cattle herd of about 200 millions in 2010. Associated to animal husbandry there are emissions of N2O (nitrous oxide) and other gases to the atmosphere. The liquid manure contributes to emitte 5% of the total N2O emissions. The urea content of cattle urine will readily hydrolyze to form ammonium after deposition to the soil. Nitrous oxide may then be emitted through the microbiological processes of nitrification and denitrification. Important factors can influence on these processes and consequently in nitrous oxide emissions, as soil water content and temperature (Bolan et al., 2004; Luo et al., 2008). The main goal of this research was to determine the soil water content and temperature influence on N2O emissions from urine depositions on the soil. In order to achieve the objective, soil incubation experiment was conducted in laboratory conditions at three levels of water-filled pore space (40%, 60% and 80% WFPS) and two temperatures (25ºC and 35ºC) with and without urine, with five replicates each. The soil used in this study was collected from the 0-10 cm layer of a grassland field in Southeast of Brazil and classified as Nitisols. For each measurement, the Kilner jar was hermetically sealed by replacing the lid and a first gas sample was immediately taken (time-zero, t0 sample) using a syringe and stored in a pre-evacuated gas vial. After 30 minutes the headspace of each jar was sampled again (time-thirty, t_30 sample). The lids were then removed and kept off until the next sampling day. Nitrous oxide concentrations in the sampled air were measured using a SRI Gas Chromatograph (Model 8610C). Gas fluxes were calculated by fitting linear regressions through the data collected at t0 and t_30 and were corrected for temperature and amount of soil incubated. Gas measurements were carried out up to 55 days. To determine the statistical significance, Tukey tests were carried out at 0

  17. Effects of warming and drought on potential N2O emissions and denitrifying bacteria abundance in grasslands with different land-use.

    PubMed

    Keil, Daniel; Niklaus, Pascal A; von Riedmatten, Lars R; Boeddinghaus, Runa S; Dormann, Carsten F; Scherer-Lorenzen, Michael; Kandeler, Ellen; Marhan, Sven

    2015-07-01

    Increased warming in spring and prolonged summer drought may alter soil microbial denitrification. We measured potential denitrification activity and denitrifier marker gene abundances (nirK, nirS, nosZ) in grasslands soils in three geographic regions characterized by site-specific land-use indices (LUI) after warming in spring, at an intermediate sampling and after summer drought. Potential denitrification was significantly increased by warming, but did not persist over the intermediate sampling. At the intermediate sampling, the relevance of grassland land-use intensity was reflected by increased potential N2O production at sites with higher LUI. Abundances of total bacteria did not respond to experimental warming or drought treatments, displaying resilience to minor and short-term effects of climate change. In contrast, nirS- and nirK-type denitrifiers were more influenced by drought in combination with LUI and pH, while the nosZ abundance responded to the summer drought manipulation. Land-use was a strong driver for potential denitrification as grasslands with higher LUI also had greater potentials for N2O emissions. We conclude that both warming and drought affected the denitrifying communities and the potential denitrification in grassland soils. However, these effects are overruled by regional and site-specific differences in soil chemical and physical properties which are also related to grassland land-use intensity.

  18. Seasonal and diurnal variability of N2O emissions from a full-scale municipal wastewater treatment plant.

    PubMed

    Daelman, Matthijs R J; van Voorthuizen, Ellen M; van Dongen, Udo G J M; Volcke, Eveline I P; van Loosdrecht, Mark C M

    2015-12-01

    During nitrogen removal in conventional activated sludge processes, nitrous oxide can be emitted. With a global warming potential of 298 CO2-equivalents it is an important greenhouse gas that affects the sustainability of wastewater treatment. The present study reports nitrous oxide emission data from a 16 month monitoring campaign on a full-scale municipal wastewater treatment. The emission demonstrated a pronounced diurnal and seasonal variability. This variability was compared with the variability of a number of process variables that are commonly available on a municipal wastewater treatment plant. On a seasonal timescale, the occurrence of peaks in the nitrite concentration correlated strongly with the emission. The diurnal trend of the emission coincided with the diurnal trend of the nitrite and nitrate concentrations in the tank, suggesting that suboptimal oxygen concentrations may induce the production of nitrous oxide during both nitrification and denitrification. This study documents an unprecedented dataset that could serve as a reference for further research.

  19. The contribution of hydroxylamine content to spatial variability of N2O formation in soil of a Norway spruce forest

    NASA Astrophysics Data System (ADS)

    Liu, Shurong; Herbst, Michael; Bol, Roland; Gottselig, Nina; Pütz, Thomas; Weymann, Daniel; Wiekenkamp, Inge; Vereecken, Harry; Brüggemann, Nicolas

    2016-04-01

    Hydroxylamine (NH2OH), a reactive intermediate of several microbial nitrogen turnover processes, is a potential precursor of nitrous oxide (N2O) formation in the soil. However, the contribution of soil NH2OH to soil N2O emission rates in natural ecosystems is unclear. Here, we determined the spatial variability of NH2OH content and potential N2O emission rates of organic (Oh) and mineral (Ah) soil layers of a Norway spruce forest, using a recently developed analytical method for the determination of soil NH2OH content, combined with a geostatistical Kriging approach. Potential soil N2O emission rates were determined by laboratory incubations under oxic conditions, followed by gas chromatographic analysis and complemented by ancillary measurements of soil characteristics. Stepwise multiple regressions demonstrated that the potential N2O emission rates, NH2OH and nitrate (NO3-) content were spatially highly correlated, with hotspots for all three parameters observed in the headwater of a small creek flowing through the sampling area. In contrast, soil ammonium (NH4+) was only weakly correlated with potential N2O emission rates, and was excluded from the multiple regression models. While soil NH2OH content explained the potential soil N2O emission rates best for both layers, also NO3- and Mn content turned out to be significant parameters explaining N2O formation in both soil layers. The Kriging approach was improved markedly by the addition of the co-variable information of soil NH2OH and NO3- content. The results indicate that determination of soil NH2OH content could provide crucial information for the prediction of the spatial variability of soil N2O emissions.

  20. Developing a regional scale approach for modelling the impacts of fertiliser regime on N2O emissions in Ireland

    NASA Astrophysics Data System (ADS)

    Zimmermann, Jesko; Jones, Michael

    2016-04-01

    Agriculture can be significant contributor to greenhouse gas emissions, this is especially prevalent in Ireland where the agricultural sector accounts for a third of total emissions. The high emissions are linked to both the importance of agriculture in the Irish economy and the focus on dairy and beef production. In order to reduce emissions three main categories are explored: (1) reduction of methane emissions from cattle, (2) reduction of nitrous oxide emissions from fertilisation, and (3) fostering the carbon sequestration potential of soils. The presented research focuses on the latter two categories, especially changes in fertiliser amount and composition. Soil properties and climate conditions measured at the four experimental sites (two silage and two spring barley) were used to parameterise four biogeochemical models (DayCent, ECOSSE, DNDC 9.4, and DNDC 9.5). All sites had a range of different fertiliser regimes applied. This included changes in amount (0 to 500 kg N/ha on grassland and 0 to 200 kg N/ha on arable fields), fertiliser type (calcium ammonium nitrate and urea), and added inhibitors (the nitrification inhibitor DCD, and the urease inhibitor Agrotain). Overall, 20 different treatments were applied to the grassland sites, and 17 to the arable sites. Nitrous oxide emissions, measured in 2013 and 2014 at all sites using closed chambers, were made available to validate model results for these emissions. To assess model performance for the daily measurements, the Root Mean Square Error (RMSE) was compared to the measured 95% confidence interval of the measured data (RMSE95). Bias was tested comparing the relative error (RE) the 95 % confidence interval of the relative error (RE95). Preliminary results show mixed model performance, depending on the model, site, and the fertiliser regime. However, with the exception of urea fertilisation and added inhibitors, all scenarios were reproduced by at least one model with no statistically significant total

  1. CO2 and N2O emissions in a soil chronosequence at a glacier retreat zone in Maritime Antarctica

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polar regions represents a large carbon (C) sequestration reservoir in the world. Studies of alterations in C cycle are extremely important to identify changes due to climate change, especially among polar environments. The objectives of this study were to examine (i) patterns of soil CO2-C emission...