Dissertations / Theses: 'Nitrous oxide emissions'

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Rezaei, Rashti Mehran. "Nitrous Oxide Emissions from Vegetable Cropping Systems." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/365552.

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Agricultural manipulation of the soil nitrogen (N) cycle has caused a significant increase in nitrous oxide (N2O) emissions during the past five decades. Nitrous oxide is one of the major greenhouse gases with potent and long-lasting global warming effects [298 times higher than carbon dioxide (CO2) over a time period of 100 years]. The major biogenic processes responsible for N2O production in agricultural soils are identified as nitrification which is the oxidation of ammonium (NH4+) to nitrite (NO2-) and nitrate (NO3-) and denitrification that is the anaerobic reduction of NO2- and NO3- to gaseous nitric oxide (NO), N2O or N2. Although the current concentration of N2O in the atmosphere is relatively lower than other greenhouse gases, it is annually increasing at a rate of 0.25%. Vegetable cropping systems, a major agricultural activity worldwide, generally comprise intensive cultivation and high rates of N application. However, the N recovery from intensively cultivated vegetable fields is reported to be only 20 - 50% of the applied N fertiliser, suggesting large amounts of N loss from these fields. In Australia, horticulture represents less than 1% of land used for agriculture, but accounts for 6-12% of N fertiliser use in agriculture and its contribution to national N2O emissions is significant.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Guilbault, Michael Roland 1967. "Nitrous oxide emissions from desert region soils." Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/291928.

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This study was conducted to determine emission rates of nitrous oxide (N₂O) gas from arid region locations. Fluxes were measured at an effluent-irrigated turfgrass location in Arizona, a Sonoran desert location, and a savannah location in Africa. Fluxes were measured by a closed chamber method at the Arizona locations on a weekly basis during the summer of 1991, and at the African location during two separate three day studies during the summer of 1992. Soils were sampled at each location during each sampling period and analyzed for water content, nitrate, pH, and total organic carbon content. Nitrous oxide fluxes in Arizona averaged approximately 13 and 0.7 kg N₂O-N ha⁻¹ yr⁻¹ for the turfgrass and desert locations respectively. The average fluxes from the African sites were 1.3, 1.6, and 1.3 kg N₂O-N ha⁻¹ yr⁻¹ for a millet field, fallow field, and "tigerbush" plateau, respectively. Diurnal and seasonal variability was observed.

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Freing, Alina [Verfasser]. "Production and emissions of oceanic nitrous oxide / Alina Freing." Kiel : Universitätsbibliothek Kiel, 2009. http://d-nb.info/1019870257/34.

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Boles, Elisabeth L. "Natural variability in eastern tropical Pacific nitrous oxide emissions." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118132.

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Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 45-47).
Nitrous oxide (N2O) is a powerful greenhouse gas and ozone depleting substance, but its natural sources remain poorly constrained. Marine emissions are likely much higher than IPCC estimates predict, due to unusually high emissions from the oxygen minimum zones (OMZs) in the eastern tropical Pacific and Arabian Sea that are not accounted for in assessments. Measurements of atmospheric concentrations from a selection of AGAGE stations around the Pacific Ocean were combined with back-trajectories calculated using the HYSPLIT4 atmospheric model, in order to study the relative importance of OMZs on Pacific N2O emissions. Spatial and temporal variability in nitrous oxide concentrations were analyzed in order to determine potential regions of higher emissions, as well as the impacts of ENSO on biogeochemistry in the OMZs. Air parcels that passed over the oxygen minimum zone in the Eastern Tropical South Pacific were found to have N2O concentrations as much as 0.5 ppb higher than average. Average concentrations over the OMZ were modulated by an additional ~0.2 ppb higher during La Niia events and ~0.2 ppb lower during El Niio periods, a deviation of the same order of magnitude as N2O's seasonal cycle. Comparisons with CFC-12 and SF6 suggested strong influences on nitrous oxide concentrations in the Southern Hemisphere from stratosphere-troposphere exchange, but little influence from inter-hemispheric transport.
by Elisabeth L. Boles.
S.B.

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Miller, Scot M. "Emissions of Nitrous Oxide and Methane in North America." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467371.

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Methane (CH_4) and nitrous oxide (N_2O) are the second- and third-most important long-lived greenhouse gas species after carbon dioxide (CO_2) in terms of radiative forcing. This thesis describes the magnitude, spatial distribution, and seasonality of N_2O and CH_4 sources over North America using atmospheric data. We also investigate the environmental drivers and/or anthropogenic source sectors that can explain these emissions patterns. Overall, this thesis provides information on the magnitude, distribution, and likely drivers of greenhouse gas emissions to aid existing or future climate change mitigation policies in the US and Canada. We estimate anthropogenic N_2O and CH_4 emissions that greatly exceed most existing inventory estimates. Our US budgets for N_2O and CH_4 are approximately 2.8 and 1.5 times higher, respectively, than inventory estimates from the US EPA. Much of the discrepancy in methane appears to stem from oil and natural gas industry and agricultural emissions. In contrast, we estimate natural CH_4 sources that are smaller than most existing process-based biogeochemical models. These estimated fluxes have a spatial distribution centered around the Hudson Bay Lowlands. Most existing models estimate fluxes that are far more spatially distributed across the Canadian shield. These estimates provide negative information on the spatial distribution of fluxes relative to a spatially-constant model. We find that a simple model using only three environmental variables can describe flux patterns (as seen by the atmospheric observations) as well as any process-based estimate.
Earth and Planetary Sciences

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Marsden, Karina A. "Sheep urine patch nitrous oxide emissions : measurement and mitigation." Thesis, Bangor University, 2015. https://research.bangor.ac.uk/portal/en/theses/sheep-urine-patch-nitrous-oxide-emissions-measurement-and-mitigation(74d981af-b04d-47c7-bb17-1c191504fb33).html.

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Demand for livestock products are expected to rise due to increasing global population, urbanisation and affluence. Sustainably managing livestock excreta will be central to achieving an expansion in production whilst minimising environmental damage. The deposition of excreta to soil by livestock accounts for ca. 21% of the UK agricultural N2O emissions. Accurate quantification of N2O and assessments of the efficacy of mitigation technologies are key research areas for progressing toward enhanced sustainability and productivity in grazed grasslands. The overall thesis aims are to enhance understanding of N cycling and losses in sheep urine patches, as ‘hot-spots’ and ‘hot-moments’ for rapid nutrient cycling. Objectives were (i) to determine how sheep urine patch and environmental parameters influence N2O emissions, (ii) to determine the optimal way to accurately measure N2O emissions from sheep urine patches via the static chamber technique, and (iii) to assess the efficacy of synthetic nitrification inhibitors as a mitigation strategy for urine patch N2O emissions. Sheep-grazed grasslands were selected for study, based on the lack of current available evidence for these agroecosystems. N2O emissions were monitored from sheep urine-influenced soil in small incubation vessels, or by the static chamber technique in the field (manual and automated campaigns). The use of 14C-labelled inhibitors were also employed in laboratory studies, to trace the fate of nitrification inhibitors in the plant-soil-microbe system and provide a better understanding of the factors that affect the efficacy of inhibitors to reduce N2O emissions. Urine patch size and N concentration were found to be important parameters influencing emissions of N2O from sheep urine patches. Emissions of N2O were generally lower than the IPCC default of 1% of the N applied in sheep excreta, where peaks in emissions occurred alongside rainfall events. Total extractable N, oxidation reduction potential and soil water-filled pore space were determined to be key drivers of N2O emissions from sheep urine under controlled conditions. The urine patch diffusional area was shown to be important for accurate quantification of N2O emissions when using the chamber technique; the importance of daily sampling of emissions, an assessment of the diurnal nature of N2O emissions and having a high number of replicate chambers to adequately represent the large spatial variability in N2O emissions was also confirmed. The nitrification inhibitors DCD and DMPP had contrasting behaviours in differing soil types. DCD had a greater sorption in comparison to DMPP and microbial uptake and degradation were concluded to be important parameters influencing their effective period in the soil. A graminaceous plant was shown to be able to acquire DCD intact through its roots and translocate the compound to shoots which raises concerns about contamination of food products. A liquid application of DMPP was not effective in reducing cumulative N2O emissions from sheep urine patches in the field. The efficacy of nitrification inhibitors to reduce N2O appears to vary widely, nevertheless they are a mitigation strategy that could be implemented in the short term. Achieving enhanced sustainability and productivity in grazed grasslands is a complex problem, requiring an interdisciplinary approach and the involvement of policy-makers and farmers to resolve. There are several mitigation strategies available or being developed, and some which require more research before being practicable. Advances in technologies to measure and mitigate N2O emissions will greatly enhance our knowledge of N cycling and losses, and the potential to alleviate such losses from the urine patch environment in the near future.

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Bateman, Emma Joanne. "The contribution of nitrification to nitrous oxide emissions from soils." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416462.

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Mazurek, Agnieszka. "Nitrous oxide emissions from deammonification process under different operation conditions." Thesis, KTH, Mark- och vattenteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-180283.

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Wastewater treatment plays significant role in the environmental protection. The process has direct impact on quality of air and water. All treated sewage reaches fresh water reservoirs as well as gasses escaping from the process are emitted to the atmosphere. Main aim of the thesis is to determine N2O emissions from partial nitritation/Anammox (deammonification process) in one-stage system applied in MBBR technology. Whole project was operated successfully on two pilot-scale reactors parallel, fed by the same reject water. Both reactors were filled to capacity of 200 L each, where 40% of the working volume was fulfilled by Kaldnes carriers suspended in liquid by mechanical stirrer. First reactor (R1) presented strategy of intermittent aeration with ratio (R=1/3) and stable DO concentration at amount of 1.5 mg O2/L, whereas second one (R2) operated in constant aeration with variable values of dissolved oxygen which differ in range of 1.0-2.5 mg O2/L. Every week analyses of ammonium and nitrogen forms were carried out in influent and effluent by Hach-Lange cuvettes. Results of measurements showed high NH4+-N removal efficiency of approximately 95% for R1 reactor and 86% for R2. During the process, the continuous measurement of nitrous oxide in gaseous and liquid phase was performed by Teledyne data logger and Unisense microsensor. Measurements during 4 months resulted in assessment of nitrous oxide emission tendency dependent on aeration system. The result from reactor R1 showed that 1.0-2.4% of N-load was emitted as N2O to the atmosphere, and 0.05-0.28% was released as dissolved N2O in outgoing water. Regarding reactor R2 tendency of nitrous oxide production is similar. Estimated emission of N2O in gaseous phase in reactor R2 is 1.4-2.0% of nitrogen load and 0.02-0.39% in liquid phase. All gathered results are shown in the appendix of the paper.

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Limpert, Alexandra D. "Field Emissions of Methane and Nitrous Oxide from California Landfills." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2027.

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Comprehensive and systematic aerial and field investigations were conducted at representative California landfills to quantify emissions of methane and nitrous oxide. Landfills are highly engineered; however, they are one of the largest anthropogenic sources of greenhouse gases, causing human health and safety concerns. Methane (CH4) and nitrous oxide (N2O) are significant greenhouse gases with high global warming potentials that are generated in a landfill environment. For site selection, sites were evaluated based on waste in place, climate zone, faults and oil and gas operations, population density, cover conditions and percentage of cover types, age of waste, waste profile, landfill style and configuration, and disposal of waste tires. Fifteen representative sites were chosen for the aerial portion of testing, and of those fifteen, five sites were selected for extensive ground testing using the static flux chamber method, conducted over a year-long time period. At the five sites for ground testing, between five and seven cover systems were tested at each site during the wet and dry season. Daily, intermediate, and final covers were tested to obtain representative and comparative measurements during the wet and dry season to account for seasonal variation. In addition to the flux chamber testing, geotechnical characterization of cover materials was conducted. CH4 flux values exhibited higher variability in the dry season (102 g/m2/d to -101 g/m2/d) than the wet season (102 g/m2/d to 10-1 g/m2/d). N2O flux values exhibited slightly higher variability in the wet season (10-1 g/m2/d to -10-3 g/m2/d) than the dry season (10-1 g/m2/d to -10-3 g/m2/d). The measured flux value for CH4 was generally greater than the measured flux value for N2O across both seasons. N2O flux values (10-1 g/m2/d to -10-3 g/m2/d) exhibited less variability than CH4 flux values (102 g/m2/d to -10-1 g/m2/d). Relationships were developed between aerial emissions and areal coverage, throughput, waste column height, and waste in place. All correlations were positive. Relationships were also developed between flux values and geotechnical properties of covers, including density and cover thickness. Most geotechnical parameters yielded limited correlation. The surface flux values from the field investigation were scaled up to estimate facility-wide surface emission values. The methane surface emissions ranged from 10-1 to 103 and from 100 to 102 tonnes/year in the wet season and dry season. The nitrous oxide surface emissions ranged -10-2 to 100 and from 10-2 to 10-1 tonnes/year in the wet season and dry season, respectively. Emissions were converted to CO2 equivalent (CO2 E) to allow for comparison between methane and nitrous oxide. The methane surface emissions in CO2 E terms ranged from 101 to 104 tonnes/year in both the wet season and dry season, respectively. The nitrous oxide surface emissions in CO2 E terms ranged from -100 to 102 and from 101 to 102 tonnes/year in the wet season and dry season, respectively. Aerial and ground emissions were compared, with aerial results being higher at all five ground sites. This study provides systematic and comprehensive field emissions testing comparing climate and waste in place, among other parameters, that demonstrate the complicated nature of the landfill environment.

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Sithole, Alec. "Feedbacks of Methane and Nitrous Oxide Emissions from Rice Agriculture." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/43.

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The effect of global warming on methane (CH₄) and nitrous oxide (N₂O) emissions from agriculture was investigated and simulated from a soil warming experiment. Experiments were designed and installed in a temperature controlled greenhouse. The relationships between elevated temperatures and CH₄ and N₂O emissions were determined and calculated as the Q₁₀s of production, emission and oxidation. A study of the populations of methanogens and methanotrophs at a range of soil temperatures was performed based on soil molecular DNA analysis. This study showed that global warming would increase CH₄ emissions from rice agriculture and that the resultant emissions will be potentially large enough to cause changes in the present atmospheric concentrations. This research also showed that this increase was most evident for soil temperatures below 30⁰C, above which emissions decreased with increasing temperature. The seasonal average Q₁₀s of CH₄ emission, production, oxidation, methanogen and methanotroph populations were found to be 1.7, 2.6 and 2.2, 2.6 and 3.8, respectively, over a temperature of 20-32⁰C. Considering that the processes of CH₄ production and emission are similar to those in natural wetlands, which is the largest source of atmospheric CH₄, the contribution of this feedback is likely to cause a significant increase to the present CH₄ atmospheric budget if the current global warming trend persists over the next century. The Q₁₀s of N₂O emissions and production were 0.5-3.3 and 0.4-2.9, respectively. The low Q₁₀ values found for N₂O suggest that although global warming will have a direct impact on the production and emission rates. Nevertheless, the magnitude of the impact of global on both CH₄ and N₂O emissions from agriculture is likely to vary from one region to another due to the spatial variations in agricultural soil temperatures and the likely changes in the global regional distribution of water resources (water tables, rainfall patterns), water management practices and the responses of terrestrial CH₄ and N₂O sources such as natural wetlands and plants.

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Huang, Xiaodong. "Spatiotemporal modelling in estimation of nitrous oxide emissions from soil." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/61191/1/Xiaodong_Huang_Thesis.pdf.

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Nitrous oxide is a major greenhouse gas emission. The aim of this research was to develop and apply statistical models to characterize the complex spatial and temporal variation in nitrous oxide emissions from soils under different land use conditions. This is critical when developing site-specific management plans to reduce nitrous oxide emissions. These studies can improve predictions and increase our understanding of environmental factors that influence nitrous oxide emissions. They also help to identify areas for future research, which can further improve the prediction of nitrous oxide in practice.

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Prieto, Roberto. "The role of earthworms in nitrous oxide emissions from forage agroecosystems." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103783.

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Nitrous oxide (N2O) emission from agricultural soils contributes to the greenhouse effect, depletion of the ozone layer, and acid rain formation. In laboratory studies, soil in contact with earthworms had significantly higher N2O production than soil devoid of earthworm activity. The elevated N2O production occurs via activation or priming of nitrifying and/or denitrifying microorganisms. Yet, field scale experiments have been inconclusive with respect to N2O fluxes attributed to earthworms. The objectives of this thesis were in the field to (1) determine the effect of elevated anecic and endogeic earthworm populations on N2O fluxes from legume and non-legume enclosures, and in the laboratory to (2) qualify the denitrification community and (3) quantify the denitrification rate of earthworm-related structures including the gut, casts, burrows and middens of the anecic Lumbricus terrestris. In the field study, elevated earthworm populations increased N2O fluxes significantly (P<0.05) in legume but not in non-legume enclosures. Anecic species appeared to have a greater effect on N2O fluxes. The linear regression model of the flux data and number of earthworms added was significant (P<0.05); on average earthworms emitted 335 ng N2O m-2 h-1 from the legume enclosures when soil moisture exceeded 60% water-filled pore space. In the laboratory study, a 454 pyrosequencing analysis on the diversity and phylogeny of bacterial nosZ gene fragments (encoding N¬2O reductase) revealed a set of 39 unique OTUs, of which 14 were found only in the earthworm gut. The earthworm gut appears to have a unique set of endemic denitrifying bacteria. An acetylene block assay revealed that the earthworm itself had the greatest denitrification rate of 2.67 g N2O-N g soil-1 h-1, which was significantly (P<0.05) greater than bulk soil and other earthworm structures except fresh casts. Fresh casts had a denitrification rate of 0.94 g N2O-N g soil-1 h-1 which was significantly (P<0.05) greater than the rate of aged cast and bulk soil. The set of unique gut denitrifiers is highly active due to the favourable conditions in the gut, including anoxia and quality substrate. When fresh, anecic earthworm related structures are important "hot spots" favouring the activity of soil denitrifiers. This thesis demonstrates the importance of earthworm-denitrifier interactions for N2O emissions, particularly in legume-based agroecosystems, which should be considered when developing predictive models of greenhouse gas emissions from agricultural soils.
Les émissions d'oxyde nitreux (N2O) provenant de sols agricoles contribuent à l'effet de serre, à la destruction de la couche d'ozone et à la formation de pluies acides. Des études en laboratoire ont démontré que, lorsque le sol est en contact avec des vers de terre, celui-ci présente des niveaux plus élevés de flux de N2O que lorsqu'il n'y a pas de verres de terre présents. Un taux élevé de N2O se produit lorsque les micro-organismes nitrifiants et/ou dénitrifiants sont activés. Pourtant, les études publiées sur les essais aux champs n'ont pas été concluantes quant aux niveaux de N2O attribuables à la présence de vers de terre. Les objectifs de ce mémoire étaient : (1) sur le terrain, de déterminer l'incidence des quantités élevées de vers de terre anéciques et endogés sur les niveaux de flux de N2O dans les chambres avec et sans légumineuses, (2) en laboratoire, de définir les agents bactériologiques dénitrificateurs, et (3) de quantifier le taux de dénitrification des structures associées aux vers de terre, incluant intestins, turriculés, tubes et tertres du ver de terre anécique Lumbricus terrestris. Selon les études effectuées sur le terrain, lorsqu'il y avait une présence accrue de vers de terre, les niveaux de N2O augmentaient de façon importante (P<0,05), mais seulement dans les chambres avec des légumineuses. Les espèces anéciques semblaient avoir un effet plus important sur les émissions de N2O. Le modèle de régression linéaire des données relatives aux niveaux de N2O et à la quantité de vers de terres ajoutés était significative (P<0,05) ; en moyenne, les vers de terre émettaient 335 ng N2O m-2 h-1 lorsque l'humidité du sol dans les chambres avec légumineuses excédait 60% de l'espace poral irrigué. Lors de l'étude en laboratoire, une analyse de 454 pyroséquençage portant sur la diversité et la phylogénie des fragments génétiques de la bactérie nosZ (codification de réductase de N2O) a révélé un ensemble de 39 unités taxonomique opérationel (UTOs) unique, dont 14 identifiées dans les intestins du ver de terre. Les intestins semblent contenir un ensemble unique de bactéries dénitrificatrices endémiques. Une analyse au blocage à l'acétylène a démontré que le ver de terre lui-même présentait le potentiel le plus élevé de dénitrification, soit 2,67 µg N2O-N g sol-1 h-1, valeur nettement supérieure (P<0,05) à celles du sol brut et des autres structures de vers de terre, à l'exception des turriculés frais. Les turriculés frais indiquaient un taux moyen de dénitrification de 0,94 µg N2O-N g sol-1 h-1, donc plus élevé (P<0,05) que le taux de turriculés vieillis et du sol brut. L'ensemble distinct de dénitrificateurs intestinaux est très actif de par leurs conditions favorables dans les intestins, dont l'anoxie et le substrat de qualité. Lorsque les structures de vers de terre anéciques sont fraîches, celles-ci deviennent des endroits propices favorisant la dénitrification du sol. Ce mémoire affirme l'importance de l'interaction entre les verres de terre et les microorganismes dénitrifiants quant aux émissions de N2O, en particulier dans les agroécosystèmes de légumineuses. Ces interactions devraient être prises en compte lors du développement de modèles de prévision des émissions de gaz à effet de serre provenant des sols agricoles.

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Zhu, Yuhao [Verfasser], and Klaus [Akademischer Betreuer] Butterbach-Bahl. "Nitrous oxide emissions from excreta deposited onto tropical pasture in Kenya." Freiburg : Universität, 2020. http://d-nb.info/1216417598/34.

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De, Antoni Migliorati Massimiliano. "Reducing nitrous oxide emissions while supporting subtropical cereal production in Oxisols." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/82496/10/Massimiliano%20Migliorati%20Thesis.pdf.

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This is the first study to investigate alternative fertilisation strategies to increase cereal production while reducing greenhouse gas emissions from the most common soil type in subtropical regions. The results of this research will contribute to define future farming practices to achieve global food security and mitigate climate change. The study established that introducing legumes in cropping systems is the most agronomically viable and environmentally sustainable fertilisation strategy. Importantly, this strategy can be widely adopted in subtropical regions since it is economically accessible, requires little know-how transfer and technology investment, and can be profitable in both low- and high-input cropping systems.

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Sozanska, Malgorzata. "Distribution and amounts of nitrous and nitric oxide emissions from British soils." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/27447.

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This study establishes an empirical predictive model of N₂O and NO emissions for Great Britain based on multivariate regression analysis of field measurement data from several studies in European countries and the USA for which the results have been published in the last 18 years. The significance of studying the emissions of these gases is due to the role of N₂O as a greenhouse effect gas and NO participation in reactions with ozone. Soils are known to be an important source of N₂O and also contribute significant amounts of NO into the atmosphere. Knowledge of N₂O and NO emissions from soils at a national scale is important due to the signed international agreements which oblige Great Britain to produce inventories of greenhouse effect gases and monitor the emissions of NOx gases. The field studies observed the relationships between the emissions and their controlling factors and on the basis of those relationships, national modelling approaches to predicting the amounts of emissions have been defined. Due to the highly variable nature of emissions, more than one empirical model was developed for each of the gases. The relationships defined in the analysis were later applied to estimate N₂O and NO emissions from British soils with an application of input parameter data of the established controlling factors in the framework of ArcInfo GRID. Data of N fertiliser input, soil moisture and temperature were not readily available and therefore had to be estimated with existing data. Soil moisture was predicted with the SPACTeach model based on the monthly precipitation sums obtained from the Climate LINK data set. This data source also provided monthly air temperature data used to model soil temperature with the theory of heat flux. N input was estimated as a sum of mineral and organic N fertiliser inputs from agriculture and atmospheric N deposition.

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Mulligan, Declan Thomas. "Regional modelling of nitrous oxide emissions from fertilised agricultural soils within Europe." Thesis, Bangor University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433691.

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Zawawi, Norliyana Binti Haji Zin. "Nitrous oxide emissions from oil palm planted on peat soils in Malyasia." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=239395.

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Nguyen, Phi Hung. "Feasible solutions to manage emissions of nitrous oxide in vegetable crops and orchards in Australia and Vietnam." Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/21454.

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Crop production is a significant contributor to greenhouse gas emissions because cropping inputs and cultivation lead to the formation of nitrous oxide (N2O) in soils. This research measured the baseline N2O emissions from apple, cherry, processing tomato and babyleaf spinach production in Australia and assessed the impacts of crop management practices on these emissions. Nitrous oxide emissions were measured using static chambers, and the impact of management practices including crop residue mulches, cover crops, composts and irrigation management on emissions was assessed; and, the data compared to estimated emissions calculated using the Intergovernmental Panel on Climate Change (IPCC) and the Cool Farm Tool (CFT) models. In Vietnam N2O emissions were measured in preliminary studies on vegetables crops, and the effectiveness of technical extension guidelines to mitigate N2O emissions were analysed. Average N2O emissions from fruit orchards and vegetable crops in Australia were low (less than 10 g N2O-N ha-1 day-1), while the emissions for choy sum, mustard and cabbage crops in Vietnam were higher, ranging from 12 g to 40 g N2O-N ha-1 day-1. Compost and lucerne straw additions increased N2O emissions in orchards while wheat straw mulch or bare soils did not. Sub-surface drip irrigation, legumes and ryegrass cover crops and low nitrogen fertiliser inputs were identified as potential strategies for mitigating N2O emissions in baby leaf spinach and processing tomatoes. The CFT and IPCC default values tended to overestimate measured N2O emissions. Technical guidelines for vegetable production in Vietnam focus on economic benefits rather than managing greenhouse gas emissions. Avoiding overuse of urea, using NPK, organic, slow-release urea fertilisers, and establishing permanent beds with small tractors were identified and ways to reduce GHG emissions in Vietnam.

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Webb, J. "Nitrous oxide and methane emissions from agriculture and approaches to mitigate greenhouse gas emissions from livestock production." Thesis, University of Wolverhampton, 2017. http://hdl.handle.net/2436/621013.

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This thesis links papers reporting field measurements, modelling studies and reviews of greenhouse gas (GHG) emissions and their abatement from agriculture, in particular from livestock production. The aims of the work were to: quantify GHG emissions from litter-based farmyard manures; evaluate means by which GHG emissions from agricultural production may be abated; assess synergies and conflicts between the abatement of other N pollutants on emissions of nitrous oxide (N2O); analyse two records of soil temperature from 1976-2010 from Wolverhampton (UK) and Vienna (Austria). Agricultural emissions of GHGs are not readily abated by ‘end of pipe’ technologies. Large decreases in agricultural GHG emissions may require changes in the production and consumption of food that could have unwelcome impacts on both consumers and producers. However, identifying and prioritizing both modes and locations of production, together with utilizing inputs, such as N fertilizer and livestock feeds, more efficiently can reduce GHG emissions while maintaining outputs. For example, GHG emissions from livestock production may be lessened by increasing the longevity of dairy cows, thereby decreasing the proportion of unproductive replacement animals in the dairy herd. Sourcing a larger proportion of calves from the dairy herd would decrease emissions of GHGs from beef production. The distance between the region of food production to that of consumption has relatively little impact on total GHG emissions per tonne of food product. Due to greater productivity or lesser energy inputs, importing some foods produced in other parts of the world may decrease GHG emissions per tonne compared with UK production, despite the additional emissions arising from long-distance transport. Manure application techniques to abate ammonia (NH3) emissions do not axiomatically increase emissions of N2O and may decrease them. Soil temperature measurements from 1976 to 2010 were consistent with the warming trends reported over the last 40 years.

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20

Gunnarsdotter, Beck-Friis Barbro. "Emissions of ammonia, nitrous oxide and methane during composting of organic household waste /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-5793-9.pdf.

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21

Bernard, Marie-Eve. "Nitrous oxide emissions and denitrification potential of fertilized grassland soils in Western Norway." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104860.

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In Norway, 65% of agricultural soils are under grassland that receives high N inputs from manure and mineral fertilizers each year and are expected to be an important source of N₂O from denitrification. The objectives of this thesis were to quantify the N₂O emissions, denitrification potential and N₂O:(N₂+N₂O) ratio of grassland soils from Western Norway and to relate these measures of N₂O production to soil physico-chemical properties and climate. During a two-year field experiment, there was relatively little N₂O emitted (fluxes did not exceed 200 μg N₂O-N m-2 h-1) from grassland receiving manure and mineral fertilizers. The N₂O fluxes were positively correlated (p < 0.001) with soil mineral N (r= 0.29) and air temperature (r= 0.31) in both years, but negatively correlated with WFPS (r= -0.44) in 2009 only. Cumulative N₂O losses were from 1.5 to 2.1 kg N₂O-N ha-1 in 2009 and 0.2 to 0.7 kg N₂O-N ha-1 in 2010. Year-to-year variation in N₂O loss was attributed to the N fertilizer regime prior to 2009 and higher N mineralization rates in 2009 than in 2010. Dry matter yield and the cumulative N₂O losses were negatively correlated in 2009 and positively correlated in 2010, probably due to differences in climatic conditions and grassland productivity. Laboratory incubations with soil from eight grasslands gave N₂O:(N₂+N₂O) ratios from 0.14 to 0.74, which were negatively correlated (p< 0.05) with soil organic C (Corg) and soil pH. Higher N₂O:(N₂+N₂O) ratios from soils washed with a 5mM KNO₃ solution imply that N₂O production by denitrifiers was limited by NO₃ availability. Denitrification potential was from 0.42 to 9.38 μg N₂O-N gdwsoil-1 h-1, with the lowest value in the forest soil, intermediate values in the mineral soils and the highest value in the peat soil. The denitrification potential was correlated with soil Corg (r= 0.95, p < 0.01) and soil pH (r=0.46, p < 0.05). We propose that grassland soil be limed more frequently to increase soil pH and therefore reduce the N₂O emissions associated with low soil pH. Furthermore, the low NO₃ availability in Norwegian grasslands due to the efficient N use by plants indicates that these agroecosystems should have low N₂O emissions.
En Norvège, 65% des terres agricoles sont cultivées en fourrage et reçoivent de grandes quantités d'engrais organique et minéral, représentant donc des sources potentielles de N₂O par la dénitrification. Les objectifs de ce mémoire étaient de quantifier les émissions de N₂O, le potentiel de dénitrification et le ratio N₂O:(N₂+N₂O) de sols de prairies agricoles de l'ouest de la Norvège et de relier ces mesures de production de N₂O aux propriétés physiques et chimiques du sol et aux variations climatiques. Lors des deux années de l'expérience au champ, il y a eu relativement peu de N₂O émis (les flux n'ont jamais excédé 200 μg N₂O-N m-2 h-1) par la prairie ayant reçu du lisier et des engrais minéraux. Les flux de N₂O étaient positivement corrélés (p < 0.001) avec l'azote minéral du sol (r= 0.29) et la température de l'air (r= 0.31) durant les deux années, mais négativement corrélés avec le contenu du sol en eau (r= -0.44) en 2009. Les pertes cumulatives de N₂O ont varié de 1,5 à 2,1 kg N₂O-N ha-1 en 2009 et de 0,2 à 0,7 kg N₂O-N ha-1 en 2010. La variation inter-annuelle est attribuée à un effet résiduel de la fertilisation avant 2009 et par un taux de minéralisation de l'azote supérieur en 2009 qu'en 2010. Le rendement en matière sèche et les pertes cumulatives en N₂O étaient corrélés négativement en 2009 mais positivement en 2010, probablement dû à des différences climatiques et à la productivité de la prairie. Des expériences d'incubation au laboratoire avec huit sols de prairies ont donné des ratios N₂O:(N₂+N₂O) entre 0.14 et 0.74, et ces ratios étaient négativement corrélés (p< 0.05) avec le contenu du sol en carbone organique et le pH du sol. Le ratio N₂O:(N₂+N₂O) plus élevé dans les sols ayant reçu du KNO₃ (5 mM) indique que la production de N₂O par les dénitrifiants était limité par le NO₃. Le potentiel de dénitrification se situait entre 0,42 μg N₂O-N g sol-1 h-1 et 9,38 μg N₂O-N g sol-1 h-1, avec la plus petite valeur dans le sol forestier, les values intermédiaires dans les sols minéraux et le plus élevé dans le sol organique. Le potentiel de dénitrification était significativement corrélé avec le contenu du sol en carbone organique (r= 0.95, p < 0.01) et le pH du sol (r=0.46, p < 0.05). Nous suggérons que les prairies soient chaulées plus fréquemment pour augmenter le pH du sol afin de réduire les émissions de N₂O dû au faible pH du sol. De plus, la faible disponibilité des NO₃ dans les prairies de l'ouest de la Norvège dû à l'efficacité des plantes à utiliser l'azote indique que ces agro-écosystèmes devraient émettre de petites quantités de N₂O.

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22

Arango, Argoti Miguel Andres. "Nitrous oxide emissions: measurements in corn and simulations at field and regional scale." Diss., Kansas State University, 2013. http://hdl.handle.net/2097/16680.

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Doctor of Philosophy
Department of Agronomy
Charles W. Rice
Nitrogen is critical for plant growth and is a major cost of inputs in production agriculture. Too much nitrogen (N) is also an environmental concern. Agricultural soils account for 85% of anthropogenic N₂O which is a major greenhouse gas. Management strategies for N fertilization and tillage are necessary for enhancing N use efficiency and reducing negative impacts of N to the environment. The different management practices induce changes in substrate availability for microbial activity that may result in increasing or reducing net N₂O emitted from soils. The objectives of this research were to (1) integrate results from field studies to evaluate the effect of different management strategies on N₂O emissions using a meta-analysis, (2) quantify N₂O-N emissions under no-tillage (NT) and tilled (T) agricultural systems and the effect of different N source and placements, (3) perform sensitivity analysis, calibration and validation of the Denitrification Decomposition (DNDC) model for N₂O emissions, and (4) analyze future scenarios of precipitation and temperature to evaluate the potential effects of climate change on N₂O emissions from agro-ecosystems in Kansas. Based on the meta-analysis there was no significant effect of broadcast and banded N placement. Synthetic N fertilizer usually had higher N₂O emission than organic N fertilizer. Crops with high N inputs as well as clay soils had higher N₂O fluxes. No-till and conventional till did not have significant differences regarding N₂O emissions. In the field study, N₂O-N emissions were not significantly different between tillage systems and N source. The banded N application generally had higher emissions than broadcasted N. Slow release N fertilizer as well as split N applications reduced N₂O flux without affecting yield. Simulations of N₂O emissions were more sensitive to changes in soil parameters such as pH, soil organic carbon (SOC), field capacity (FIELD) and bulk density (BD), with pH and SOC as the most sensitive parameters. The N₂O simulations performed using Denitrification Decomposition model on till (Urea) had higher model efficiency followed by no-till (compost), no-till (urea) and till (compost). At the regional level, changes in climate (precipitation and temperature) increased N₂O emission from agricultural soils in Kansas. The conversion from T to NT reduced N₂O emissions in crops under present conditions as well as under future climatic conditions.

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23

Harty, Mary. "Evaluation of fertiliser formulations on grassland N use efficiency and nitrous oxide emissions." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.706688.

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Obligations to reduce greenhouse gas emissions (GHG) in agriculture (30% below 1990 levels by 2030) have seen renewed interest in switching from ammonium nitrate (AN) based to urea based fertilisers as a mitigation strategy for GHG emissions. The performance of a comprehensive range of urea based formulations was compared to Calcium AN in a two-year study over three sites across the island of Ireland. The performance criteria were nitrous oxide (N2O) emissions, ammonia (NH3) emissions, grassland yield and N uptake encompassing a range of soils and climatic conditions. The results of the main field experiments showed that all urea formulations reduced N2O emissions relative to CAN in all site-years with larger reductions under the heavier and wetter soil conditions. The inclusion of the urease inhibitor NBPT also reduced NH3 emissions relative to urea and maintained yield and N uptake relative to CAN in all six site-years. In contrast, the nitrification inhibitor dicyandiamide (DCD) showed inconsistent effects on NH3 emissions compared to urea and reduced yield and N uptake relative to CAN in three and four of six site-years respectively. The most climate favourable option was urea incorporating NBPT, however as it is more expensive than urea, a tax on urea or financial incentive to use NBPT will be required to ensure farmers select the stabilised urea incorporating NBPT over urea. In addition, the assessment of N2O emissions from the same fertilisers also contributes to a more detailed accurate national inventory of mineral fertiliser N2O emissions. The tier 1 reporting of emission factors (EF) under the Intergovernmental Panel on Climate Change (IPCC) requirements uses a default EF for N2O from soils of 1% of the N applied, irrespective of its form even though N2O emissions tend to be higher from nitrate-containing fertilisers compared to urea. This research generated tier 2 emission factors for mineral N fertiliser by formulation and soil type.

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24

Beck-Friis, Barbro Gunnarsdotter. "Emissions of ammonia, nitrous oxide and methane during composting of organic household waste /." Uppsala, Sweden : Swedish University of Agricultural Sciences, 2001. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=009767821&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.

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Thesis (Ph. D.)--Sverges lantbruksuniversitet, 2001.
Thesis statement in Swedish and English abstract inserted. Based on 5 previously prepared or published papers reprinted here. Includes bibliographical references.

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25

Myrgiotis, Vasileios. "Simulating soil N2O emissions in arable Eastern Scotland." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31325.

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Nitrous oxide (N2O) is a powerful greenhouse gas and a major contributor to ozone layer depletion. The application of nitrogenous fertilisers to agricultural soils is a major source of N2O on a global scale. Arable soils receive significant rates of synthetic nitrogen (N) and thus have a considerable N2O footprint. The reduction of the N2O footprint of agricultural systems is a key target for those countries that seek to reduce their contribution to climate change and achieve a more sustainable agriculture. These twin targets are part of Scotland's agro-environmental policy. Because soil N2O emissions vary significantly both temporally and spatially, measuring N2O emissions across wide agricultural areas is impractical. However, the quantification of the N2O footprint of important agricultural regions is very valuable to scientists, farmers and policymakers alike. In this context, agro-ecosystem biogeochemistry models are scientific tools, which are developed using in-depth knowledge on the underlying processes, and are used to quantify N2O emissions across spatial and temporal scales. In Scotland, arable agriculture is concentrated at the Eastern part of the country where wheat, barley and oilseed rape are the most widely cultivated crops. The main aim of this study was to quantify the amount of N2O that is emitted from arable soils due to the cultivation of these three crops in Eastern Scotland by using the Landscape-DNDC model. Landscape-DNDC is a mechanistic biogeochemistry model that describes the flows of energy, water and nutrients in agricultural ecosystems. As part of the study, the parametric sensitivities of key model outputs have been quantified using well-established sensitivity analysis methods, which were tailored in order to consider the particularities of N cycling in arable soils. Driven by the fact that the existence of spatiotemporal uncertainties around field-measured soil N2O data complicates the evaluation of model performance, a novel model evaluation algorithm has been developed and was used to assess the model's predictive accuracy. By combining the knowledge of the model's parametric sensitivity with the abilities of the evaluation algorithm, nine key parameters of Landscape-DNDC were calibrated to UK edaphoclimatic conditions (using the Metropolis-Hastings Bayesian calibration algorithm). Model calibration led to improved prediction of field-measured soil N2O emissions at a set of sites. The model was then coupled to geographically explicit data on climate, soil N2O and crop management and used to simulate N2O emissions from the arable soils of Eastern Scotland. The results show that, on average, 0.59 % of the applied fertiliser N (kg N ha-1) was lost to the atmosphere as N2O. This factor is much lower than the generic N2O emission factor (EF) of 1% and closer to the UK cropland-specific N2O EF (i.e. 0.79%). The predicted annual N2O was the combined result of different drivers (i.e. fertiliser rate, soil and climate variables) but the geographic distribution of the estimated N2O EFs revealed some hotspots of high N2O EF (larger than 1%). Interestingly, these hotspots were caused by the cultivation of winter oilseed rape on soils with high bulk density and clay content. The comparison of the simulated yields per hectare with respective measured data and of the simulated nitrate (NO-3 ) leaching and crop N uptake factors with respective literature-based values showed that the prediction of soil N2O was not made at the expense of realistic prediction of other important aspects of agro-ecosystem biogeochemistry. Also, the study found that the simulated N2O is almost twice as sensitive to soil input uncertainty as the simulated NO-3 is, while, crop N uptake is rather insensitive to this source of uncertainty. Finally, the study shows that the uncertainty around the nine calibrated model parameters affects the prediction of NO-3 leaching strongly but its role in regards to the simulation of N2O emissions is small.

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Khan, Shabana. "Factors affecting nitric oxide and nitrous oxide emissions from grazed pasture urine patches under New Zealand conditions." Lincoln University, 2009. http://hdl.handle.net/10182/1570.

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New Zealand is dominated by its agricultural industry with one of the most intensive farming practices being that of intensive dairying. New Zealand currently has approximately 5.3 million dairy cows that excrete up to 2.2 L of urine, per urination event, up to 12 times per day. This equates to 5.1 x10¹⁰ L per year or enough urine to fill over 1.2 million milk tankers. This sheer volume of urine and its associated N content has implications for the cycling of N within the pasture soils utilised, and New Zealand’s greenhouse gas budget due to the emission of N₂O from urine affected areas. The emission of nitric oxide (NO) from agricultural systems is also receiving increasing attention due to concerns about alterations in the balance of atmospheric trace gases and sinks. Worldwide there is a dearth of information with respect to the emissions of NO from urine-N deposition onto soils with only two in situ studies and no studies on the effects of soil pH, environmental variables or urine-N rate on NO fluxes. This present study has provided some fundamental information on the factors and processes affecting the emission of NO from bovine urine applied to pasture soils. Five experiments were performed in total; three laboratory experiments and two field experiments. The first laboratory experiment (chapter 4) examined the effect of the initial soil pH on NOx emissions from urine-N applied at 500 kg N ha⁻¹. Soil was treated to alter the initial soil pH over the range of 4.4 to 7.6. Initial soil pH affected rates of nitrification which in turn affected the decline in soil pH. Emissions of NO increased with increasing soil pH. However, a strong positive linear relationship was established between the NO-N flux, expressed as a percentage of the net NH4⁺-N depletion rate, and the level of soil acidity. The NO-N fluxes were higher under the more acidic soil conditions where N turnover was lower. The fluxes of N₂O did not follow the same pattern and were attributed to biological mechanisms. In experiment two (chapter 5) the objectives were to concurrently examine the effects of varying the soil temperature and the water-filled pore space (WFPS) on NOx emissions from urine-N. In this experiment increasing the soil temperature enhanced both the rate of nitrification and the rate of decrease in soil pH. The relationship between the net NO-N flux, expressed as a percentage of the net NH4⁺-N depletion rate, and the level of soil acidity was again demonstrated at the warmest soil temperature (22°C) where soil acidification had progressed sufficiently to enable abiotic NO formation. The NO-N fluxes increased with decreasing soil moisture and increasing soil acidity indicating abiotic factors were responsible for NO production. The Q10 response of the NO flux between 5 to 15°C decreased from 4.3 to 1.5 as WFPS increased from 11% to 87% respectively. Fluxes of N₂O increased with increasing WFPS and temperature indicating that denitrification was the dominant process. Results from experiments 2 and 3 indicated that the rate of nitrification had a direct bearing on the ensuing soil acidity and that it was this in conjunction with the available inorganic-N pools that affected NOx production. Therefore the third experiment examined the effect of urine-N rate on NOx emissions, with urine-N rate varied over 5 levels from 0 to 1000 kg N ha⁻¹, the highest rate being that found under maximal urine-N inputs to pasture. Rates of nitrification were diminished at the highest rates of urine-N applied and decreases in soil acidity were not as rapid due to this. Again significant but separate linear relationships were developed, for each urine-N rate used, between the NO-N flux, expressed as a percentage of the net NH4⁺-N depletion rate, and the level of soil acidity. The slope of these relationships increased with increasing urine-N rate. The NO-N flux, expressed as a percentage of the net NH4⁺-N depletion rate, versus soil acidity was higher under 1000 kg N ha⁻¹, despite the lower soil acidity in this treatment. This indicated that the enhanced inorganic-N pool was also playing a role in increasing the NO flux. The N₂O fluxes were of limited duration in this experiment possibly due to conditions being disadvantageous for denitrification. In the field experiments two urine-N rates were examined under both summer and winter conditions at two urine-N rates. The emission factors after 71 days for NO-N in the summer were 0.15 and 0.20% of the urine-N applied for the 500 and 1000 kg N ha⁻¹ rates respectively while the respective N₂O-N fluxes were 0.14 and 0.16%. Under winter conditions the emission factors after 42 days for NO-N were <0.001% of the urine-N applied regardless of urine-N rate while the N₂O-N fluxes were 0.05 and 0.09% for the 500 and 1000 kg N ha⁻¹ urine-N rates respectively. The relationships and predictors of NO-N flux determined in the laboratory studies did not serve as strong indicators of the NO-N flux under summer conditions. Low emissions from urine-N over winter were due to the low soil temperatures and high WFPS. These studies have demonstrated that soil chemical and environmental variables influence the production of NOx and N₂O emissions from urine-N applied to soil and that seasonal effects have a significant impact on the relative amounts of NO-N and N₂O-N emitted from urine patches. Suggestions for future work are also made.

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Marinheiro, Joana Filipa Jorge. "Quantification of greenhouse gas emissions from the biodegradation of garden waste." Master's thesis, ISA, 2019. http://hdl.handle.net/10400.5/19478.

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Mestrado em Engenharia do Ambiente - Instituto Superior de Agronomia
The primary aim of this study was to quantify garden waste potential for GHG emissions (with focus on CH4 and N2O); and to identify relationships between these GHG emissions and meteorological variables in different climates. The study was carried out in two countries with contrasting climates and soil structures: Portugal with a Mediterranean climate and Scotland with a hyperoceanic climate. A closed static chamber methodology was used for measure N2O and CH4 gaseous flux in three types of treatments installed in containers kept outdoors: S with soil; S+GW with soil and garden waste layered on top; and GW with only garden waste. The range of N2O fluxes varied on a log-normal scale, ranging from slightly negative values to very high values (3 orders of magnitude). With the exception of the “control” S treatments (maximum flux of 0.54 N2O nmolm-2s-1 at both sites). The percentage of the emitted CO2 equivalent (CO2eq) from the original C content applied to the treatments as garden waste indicates the overall impact on emissions of the composting process. Based on CO2eq global warming potential (GWP) multipliers stated by the IPCC (2014) (25 for CH4 and 298 for N2O), Portugal emitted 28.47% from the treatment S+GW and 11.26% from GW, while the majority of the C remained on soils (>70%). Scotland’s treatment S+GW had a lower CO2eq emission of 11.99%, with 58.47% emitted from the GW treatment. These results show that the overall impact on GWP of composting varies dramatically depending on management, and that CO2 is being converted into considerably high quantities of longer lived GHGs like CH4 and N2O. Cumulative CH4 flux measurements showed sequestration in Portugal and emissions in Scotland, the effects were more pronounced in treatment S for both sites (-210.85 and 209.0519 mgCH4m-2d-1, respectively). The garden waste diminished the emissions for Scotland and hindered the sequestration for Portugal. The contribution of weather conditions from each site was significant and very different relatively to the behaviour of each GHG. Portugal had constant moderate/high temperatures with peaks of rain which stimulated the GHG; Scotland on the other hand had constant rain with low temperatures with occasional rises which was the controlling factor stimulating the GHG
N/A

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28

Millar, Neville. "The effect of improved fallow residue quality on nitrous oxide emissions from tropical soils." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268667.

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29

McClellan, Michael James. "Estimating regional nitrous oxide emissions using isotopic ratio observations and a Bayesian inverse framework." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119986.

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Thesis: Ph. D. in Atmospheric Science, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 141-148).
Atmospheric nitrous oxide (N₂O) significantly impacts Earth's climate due to its dual role as an inert potent greenhouse gas in the troposphere and as a reactive source of ozone-destroying nitrogen oxides in the stratosphere. Global atmospheric concentrations of N₂O, produced by natural and anthropogenic processes, continue to rise due to increases in emissions linked to human activity. The understanding of the impact of this gas is incomplete as there remain significant uncertainties in its global budget. The experiment described in this thesis, in which a global chemical transport model (MOZART-4), a fine-scale regional Lagrangian model (NAME), and new high-frequency atmospheric observations are combined, shows that uncertainty in N₂O emissions estimates can be reduced in areas with continuous monitoring of N₂O mole fraction and site-specific isotopic ratios. Due to unique heavy-atom (15N and 18O) isotopic substitutions made by different N₂O sources, the measurement of N₂O isotopic ratios in ambient air can help identify the distribution and magnitude of distinct sources. The new Stheno-TILDAS continuous wave laser spectroscopy instrument developed at MIT, recently installed at the Mace Head Atmospheric Research Station in western Ireland, can produce high-frequency timelines of atmospheric N₂O isotopic ratios that can be compared to contemporaneous trends in correlative trace gas mole fractions and NAME-based statistical distributions of the origin of air sampled at the station. This combination leads to apportionment of the relative contribution from five major N₂O sectors in the European region (agriculture, oceans, natural soils, industry, and biomass burning) plus well-mixed air transported from long distances to the atmospheric N₂O measured at Mace Head. Bayesian inverse modeling methods that compare N₂O mole fraction and isotopic ratio observations at Mace Head and at Diibendorf, Switzerland to simulated conditions produced using NAME and MOZART-4 lead to an optimized set of source-specific N₂O emissions estimates in the NAME Europe domain. Notably, this inverse modeling experiment leads to a significant decrease in uncertainty in summertime emissions for the four largest sectors in Europe, and shows that industrial and agricultural N₂O emissions in Europe are underestimated in inventories such as EDGAR v4.3.2. This experiment sets up future work that will be able to help constrain global estimates of N₂O emissions once additional isotopic observations are made in other global locations and integrated into the NAME-MOZART inverse modeling framework described in this thesis.
by Michael James McClellan.
Ph. D. in Atmospheric Science

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30

Fries, Anastasia E. "Biogenic Methane and Nitrous Oxide Emissions from the Wastewater Collection System in Cincinnati, Ohio." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1495801077083016.

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31

Scott, Drew Austin. "ENVIRONMENTAL HETEROGENEITY EFFECTS ON DIVERSITY AND NITROUS OXIDE EMISSIONS FROM SOIL IN RESTORED PRAIRIE." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/dissertations/1683.

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Ecological theory predicts that high environmental heterogeneity causes high biodiversity. Theory further predicts that more biodiversity results in greater ecosystem functioning. These theoretical predictions were evaluated in three studies using grassland restorations from agriculture.

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32

Case, Sean Daniel Charles. "Biochar amendment and greenhouse gas emissions from agricultural soils." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8049.

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The aim of this study was to investigate the effects of biochar amendment on soil greenhouse gas (GHG) emissions and to elucidate the mechanisms behind these effects. I investigated the suppression of soil carbon dioxide (CO2) and nitrous oxide (N2O) emissions in a bioenergy and arable crop soil, at a range of temperatures and with or without wetting/drying cycles. More detailed investigation on the underlying mechanisms focused on soil N2O emissions. I tested how biochar altered soil physico-chemical properties and the subsequent effects on soil N2O emissions. In addition, 15N pool dilution techniques were used to investigate the effect of biochar on soil N transformations. Biochar amendment significantly suppressed soil GHG emissions for two years within a bioenergy soil in the field and for several months in an arable soil. I hypothesised that soil CO2 emissions were suppressed under field conditions by a combination of mechanisms: biochar induced immobilisation of soil inorganic-N (BII), increased C-use efficiency, reduced C-mineralising enzyme activity and adsorption of CO2 to the biochar surface. Soil CO2 emissions were increased for two days following wetting soil due to the remobilisation of biochar-derived labile C within the soil. Soil N2O emissions were suppressed in laboratory incubations within several months of biochar addition due to increased soil aeration, BII or increased soil pH that reduced the soil N2O: N2 ratio; effects that varied depending on soil inorganic-N concentration and moisture content. These results are significant as they consistently demonstrate that fresh hardwood biochar has the potential to reduce soil GHG emissions over a period of up to two years in bioenergy crop soil, while simultaneously sequestering C within the soil. They also contribute greatly to understanding of the mechanisms underlying the effect of biochar addition on soil N transformations and N2O emissions within bioenergy and arable soils. This study supports the hypothesis that if scaled up, biochar amendment to soil may contribute to significant reductions in global GHG emissions, contributing to climate change mitigation. Further studies are needed to ensure that these conclusions can be extrapolated over the longer term to other field sites, using other types of biochar.

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33

Bertram, Janet. "Effects of cow urine and its constituents on soil microbial populations and nitrous oxide emissions." Diss., Lincoln University, 2009. http://hdl.handle.net/10182/1334.

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New Zealand’s 5.3 million strong dairy herd returns approximately 106 million litres of urine to pasture soils daily. The urea in that urine is rapidly hydrolysed to ammonium (NH₄⁺), which is then nitrified, with denitrification of nitrate (NO₃⁻) ensuing. Nitrous oxide (N₂O), a potent greenhouse gas (GHG), is produced via nitrification and denitrification, which are enzyme-catalysed processes mediated by soil microbes. Thus microbes are linked intrinsically to urine patch chemistry. However, few previous studies have investigated microbial dynamics in urine patches. Therefore the objective of these four experiments was to investigate the effects on soil microbial communities of cow urine deposition. Methods used included phospholipid fatty acid (PLFA) analyses of microbial community structure and microbial stress, dehydrogenase activity (DHA) assays measuring microbial activity, and headspace gas sampling of N₂O, ammonia (NH₃) and carbon dioxide (CO₂) fluxes. Experiment 1, a laboratory study, examined the influence of soil moisture and urinary salt content on the microbial community. Both urine application and high soil moisture increased microbial stress, as evidenced by significant changes in PLFA trans/cis and iso/anteiso ratios. Total PLFAs and DHA showed a short-term (< 1 week) stimulatory effect on microbes after urine application. Mean cumulative N₂O-N fluxes were 2.75% and 0.05% of the nitrogen (N) applied, from the wet (70% WFPS) and dry (35% WFPS) soils, respectively. Experiment 2, a field trial, investigated nutrient dynamics and microbial stress with plants present. Concentrations of the micronutrients, copper, iron and molybdenum, increased up to 20-fold after urine application, while soil phosphorus (P) concentrations decreased from 0.87 mg kg ⁻¹ to 0.48 mg kg⁻¹. Plant P was also lower in urine patches, but total PLFAs were higher, suggesting that microbes had utilised the available nutrients. Microbial stress again resulted from urine application but, in contrast to experiment 1, the fungal biomass recovered after its initial inhibition. Studies published during the course of this thesis reported that hippuric acid (HA) and its hydrolysis product benzoic acid (BA) significantly reduced N₂O-N emissions from synthetic cow urine, thus experiment 3 investigated this effect using real cow urine. Cumulative N₂O-N fluxes were 16.8, 5.9 and 4.7% of N applied for urine (U) alone, U+HA and U+BA, respectively. Since NH₃-N volatilisation remained unchanged, net gaseous N emissions were reduced. Trends in total PLFAs and microbial stress were comparable to experiment 1 results. Experiment 4 studied HA effects at different temperatures and found no inhibition of N₂O-N fluxes from HA-amended urine. However, mean cumulative N₂O-N fluxes were reduced from 7.6% of N applied at 15–20°C to 0.2% at 5–10°C. Total cumulative N emissions (N₂O-N + NH₃-N) were highest at 20°C (17.5% of N applied) and lowest at 10°C (9.8% of N applied). Microbial activity, measured as potential DHA, increased with increasing temperature. This work has clearly shown that the stimulation and inhibition of the soil microbial community by urine application are closely linked to soil chemistry and have significant impacts not only on soil nutrient dynamics but also on N₂O-N emissions and their possible mitigation.

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Weber, Marie Aimee. "N2O emissions from wheat agro-ecosystems under elevated atmospheric CO2." Thesis, The University of Arizona, 1997. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0146_sip1_w.pdf&type=application/pdf.

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Raucci, Guilherme Silva. "Greenhouse gas assessment of Brazilian soybean production and postharvest nitrous oxide emissions from crop residues decomposition." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/64/64135/tde-30032015-151057/.

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Brazil is one of the world\'s largest producers and exporters of soybeans. The oil and meal obtained from grains are important components of biodiesel and animal feed chains. In recent years, international standards and certifications were developed to promote sustainability in the agricultural supply chain. In this context, greenhouse gases (GHG) emissions in the products life cycle has been the main point of interest to the scientific community and consumers. Few studies have evaluated the GHG emissions in soybean cultivation with specific data for the Brazilian reality. The aim of this study was to evaluate the main sources of GHG in soybean production in the State of Mato Grosso, Brazil. We evaluated 55 farms in the crop years of 2007/08, 2008/09 and 2009/10, accounting for 180,000 hectares of soybean cultivation area and totaling 114 individual situations. The results indicated that the largest source of GHG in the soybean production is the decomposition of crop residues (36%), followed by fuel use (19%), fertilizer application (16%), liming (13%), pesticides (7%), seeds (8%) and electricity consumed at the farms (<1%). The average GHG emissions considering the three crop years were 0.186 kg of CO2eq kg-1 of soybean produced. Based on these results, field experiments were conducted to quantify N2O emissions from the decomposition of soybean crop residues in different climatic regions and harvest periods in Brazil. Our results show that, in field conditions, the contribution of N2O emissions from senesced and desiccated residues that remain on field after soybean harvest are unlikely to represent a significant source of N2O loss above normal background soil emissions. These results were also supported by the laboratory incubation experiment, indicating that the IPCC methodology for estimating N2O emissions from soybean crop residues may provide overestimations for the Brazilian conditions. The results of this study provide relevant and specific information to producers, industry and scientific community regarding the environmental impacts associated with soybean production in Brazil
O Brasil é um dos maiores produtores e exportadores mundiais de soja. O óleo e farelo obtidos dos grãos são componentes importantes das cadeias do biodiesel e ração animal. Nos últimos anos, normas e certificações internacionais foram desenvolvidas para promover a sustentabilidade na cadeia de produção agrícola. Nesse contexto, as emissões de gases de efeito estufa (GEE) no ciclo de vida dos produtos tem sido o principal ponto de interesse para a comunidade científica e consumidores. Poucos estudos avaliaram as emissões de GEE no cultivo da soja com dados específicos para a realidade brasileira. O objetivo deste estudo foi determinar as principais fontes de GEE na produção de soja em Mato Grosso, principal estado produtor brasileiro. Foram coletados dados de 55 fazendas nos anos-safra de 2007/08, 2008/09 e 2009/10, totalizando 114 avaliações. Os resultados indicaram que a maior fonte de GEE na produção de soja é a decomposição de resíduos culturais (36%), seguido pelo uso de combustível (19%), aplicação de fertilizantes (16%), calagem (13%), pesticidas (7%), sementes (8%) e eletricidade consumida nas fazendas (<1%). A emissão média considerando os três anos-safra avaliados foi 0,186 kg de CO2eq kg-1 de soja produzido. Com base nesses resultados, foram desenvolvidos experimentos em campo para quantificação das emissões de N2O proveniente da decomposição dos resíduos culturais da soja em diferentes regiões climáticas e períodos de colheita no Brasil. Adicionalmente, foram realizadas incubações em laboratório com materiais de soja em diferentes estágios de desenvolvimento. Os resultados indicaram que resíduos culturais de soja que permanecem no campo após a colheita não representam uma fonte significativa de N2O. Os resultados obtidos neste estudo fornecem informações relevantes para produtores, indústria e comunidade científica quanto aos impactos ambientais associados à cultura da soja no Brasil

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Lynch, Kirsty. "Methane and nitrous oxide emissions from pen surfaces in a commercial beef feedlot in South Africa." Diss., University of Pretoria, 2019. http://hdl.handle.net/2263/77839.

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The aim of the study was to determine methane (CH4) and nitrous oxide (N2O) emissions from beef feedlot pen surfaces, as influenced by diet and seasons, and from back grounding operations as well as manure management systems across different seasons at a commercial beef feedlot in Mpumalanga, South Africa. The closed static chamber method was used for measuring CH4 and N2O emissions from the feedlot. Feedlot surface parameters such as temperature, pH, moisture, ash, nitrogen (N), neutral detergent fibre (NDF) and acid detergent fibre (ADF) concentrations all observed differences (P<0.05) in set seasons between treatments. Methane and N2O emissions from feedlot pen surfaces were influenced by different feedlot diets fed. Within the feedlot, the grower diet observed the highest overall CH4 and N2O emissions over the measured seasons, whilst the starter treatments observed the lowest CH4 and N2O emissions over the measured seasons. The seasons that experienced, on average, higher CH4 and N2O emissions were the dry and hot season and the wet and hot season, which indicated that temperature and moisture had an effect on CH4 and N2O emissions from manure and feedlot surfaces. Methane and N2O emissions from the manure management practices were affected by season, with the wet and hot season having the highest CH4 emission for both the effluent dam and manure piles, which indicated that available substrate, through rainfall wash off into the dam, and adequate moisture, though rainfall, in the piles allowed favourable conditions for CH4 production to occur. The N2O emissions from the effluent dam were lowest in the wet and hot season and highest in the dry and cold season, whilst for the manure piles it was lowest in the dry and cold season and highest in the wet and hot season. Manure characteristics differed between seasons as a result of different feedlot diets, including rangeland grass and supplement fed. This could have affected the rate of CH4 and N2O emissions from the manure as a result. The gas emissions observed did show a trend between diets fed within the feedlot, with the manure management areas (pile and effluent dams) recording the highest CH4 emissions over each of the measured seasons. The CH4 emissions between seasons within the feedlot and manure management practices, observed significant differences for certain treatments and seasons, as well as certain manure characteristics which observed significant differences. The N2O emissions observed showed no set trend between areas measured on the feedlot. The varying values, and negative values obtained may indicate a general uptake of N by soil or microorganisms (Chantigny et al., 2007; Li et al., 2011). Chadwick et al. (2011) described how farm management decisions interact with environmental controls, such as temperature and water availability to influence key microbial processes, which ultimately affects the magnitude of emissions from each stage of the manure management continuum. In this trial, environmental conditions could have influenced the manure composition at different sites within the feedlot across the different seasons. Although the CH4 and N2O emissions from a commercial beef cattle feedlot in the present trial did differ between seasons, only the grower treatment observed significant differences for CH4 emissions from feedlot pens surfaces. Rangeland observed significant differences between the dry and cold season and dry and hot season as compared to the wet and hot season for both CH4 and N2O emissions. This was different for the manure piles, N2O emissions, which observed no differences (p>0.05) between seasons, and the effluent dam, CH4 emissions, which observed a significant difference between the wet and hot season as compared to the dry and hot season and dry and cold season. The piles CH4 emissions observed a difference between the dry and hot season as compared to both the dry and cold season and wet and hot season. Within the present trial the highest emissions within the feedlot pens were recorded during the dry and hot season for the grower treatment and the dry and cold season for CH4 and N2O respectively. The highest recorded emissions for CH4 in the management systems were in the hot and wet season for both the effluent dam and manure pile system. The highest N2O emissions were observed during the dry and cold and wet and hot seasons for effluent dams and manure piles respectively. The results of the present trial suggests that the difference between the seasons, and manure composition, based on diet fed, impacted on the feedlot pen surface parameters, and ultimate CH4 and N2O production from beef cattle manure.
Dissertation (MSc (Agric))--University of Pretoria, 2019.
Animal and Wildlife Sciences
MSc (Agric)
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Majeed, Muhammad Zeeshan. "Emissions of nitrous oxide by tropical soil macrofauna : impact of feeding guilds and licrobial communities involved." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20073/document.

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Les sols représentent environ 63% des émissions de N2O et à eux seuls les sols tropicaux représentent 23% de ce budget soit une contribution bien plus élevé que les sols tempérés. Ces sols sont connus pour abriter une grande biodiversité d'invertébrés dominés par quatre types i.e. termites, vers de terre, fourmis et larves de scarabaeid. Ces groupes macrofaunal sont considérés comme des ingénieurs des sols via notamment leurs actions de régulation de la disponibilité des ressources chimiques, tels que l'azote minéral pour les micro-organismes. Cette régulation est due à leurs capacités de digestion spécifiques de la matière organique ainsi que la création et/ou la modification des habitats des sols. Cette étude est basée sur l'hypothèse suivante (i) l'environnement digestif et les structures biogéniques de ces ingénieurs du sol sont considérées comme des « hot spot » d' émissions de N2O (ii) les taux d'émission de N2O varient en fonction de leurs régimes alimentaires, cette macrofaune ingérant des substrats avec différents C:N (iii) le taux d'émission de N2O de chaque invertébré est corrélé à la densité des communautés bactériennes digestives impliquées dans l'émission de N2O (bactéries nitrifiantes et dénitrifiantes) et à leur teneur en azote minéral dans leur tube digestif. Pour évaluer ces différentes hypothèses, des mesures des taux d'émission de N2O ont été effectuées in vitro en aérobiose pour la macrofaune (30 espèces différentes en provenance d'Afrique, d'Amérique du Sud et d'Europe) et leurs matériels biogéniques associées (nids, turricules). L'abondance des gènes fonctionnelles des bactéries nitrifiantes (AOA et AOB) et dénitrifiantes (nirK, nirS, nosZ) ont été quantifiés par PCR quantitative. Les termites humivores et champignonnistes ainsi que les larves de scarabaeid émettent des quantités significatives de N2O alors que les fourmis n'en émettent pas. Quand aux termites xylophages et litièrivore, ils absorbent le N2O. Les structures biogéniques des vers de terre (turricules) et des fourmis (nid) émettent des quantités importantes de N2O ce qui n'est pas le cas des nids de termites. La faune du sol et leurs structures biogéniques associées, sont donc, dans la majorité des cas étudiés, un lieu d'émission de N2O, confirmant ainsi notre première hypothèse. Ce travail a également démontré qu'il y a avait une étroite corrélation entre régime alimentaire et intensité de l'émission de N2O au sein de chaque type de macrofaune étudié. En revanche, l'abondance des gènes des communautés digestive nitrifiantes et dénitrifiantes et le contenu en N minéral au sein du tube digestif ne semblent pas être des proxies pertinents des émissions de N2O. A partir de ces mesures, des calculs ont été effectuées pour déterminer l'importance de ces émissions à l'échelle des écosystèmes tropicaux étudiés (forêt et savane). Ces calculs suggèrent que la macrofaune du sol dans ces écosystèmes pourrait contribuer entre 0,1 à 11,7% et 0,1 à 8,8% du budget total des émissions de N2O, respectivement. Les résultats de ces travaux devraient contribuer à une meilleure prise en compte de la composante biotique dans la modélisation des émissions de gaz à effet de serre provenant des sols en milieu tropical
Soils account for about 63% of N2O emissions. Tropical soils are estimated to emit 23% of global N2O emission budget which is much higher than temperate soil N2O emissions. These soils also harbor a huge biodiversity of invertebrates dominated by four types of macrofauna i.e. termites, earthworms, ants and scarabaeid grubs. These macrofaunal groups are considered as soil engineers because they regulate the availability of chemical resources, like mineral nitrogen, for the microorganisms via their specific digestion capabilities and/or by creating and modifying soil habitats. This study is based on the following hypothesis (i) the gut environment or biogenic structures of these soil engineers are considered as hotspots of N2O emission (ii) the N2O emission rates will vary according to their feeding behavior as these macrofauna thrive on diverse substrates with different C:N ratio (iii) the rate of N2O emission in each soil fauna will also depend on the gut density of the bacterial communities involved in the N2O emission (nitrifiers and denitrifiers) and on the mineral nitrogen content within the gut. To assess these different hypotheses in-vitro short-term N2O emission rates were assessed for either live macrofauna (30 species collected from Africa, South America and Europe) or their biogenic materials or both under aerobic incubations. Genes abundance of nitrifiers (AOA and AOB) and denitrifiers (nirK, nirS, nosZ) were quantified by real time quantitative PCR. Soil-feeders and fungus-growing termites and scarabaeid grubs emitted in-vivo N2O while ants did not. Surprisingly, wood- and grass-feeding termites revealed an uptake of N2O. Biogenic structures of earthworms and ants emitted substantial amount of N2O while those of termites did not. The emission difference between macrofauna or their biogenic materials and their control materials was significant for most of the macrofaunal groups studied confirming our first hypothesis. We also confirmed that the feeding behavior (total N content and C:N ratio of food material) is the main factor explaining the observed N2O emission pattern of each macrofaunal group investigated whereas genes abundances, particularly of denitrifiers and gut N mineral content did not appear to be relevant proxies of the N2O emissions rates. A back-on-the-envelope data upscaling suggests that soil macrofauna could contribute from 0.1–11.7% and 0.1–8.8% of the total soil N2O emissions, respectively, for the tropical rainforest and dry savanna ecosystems. This work should contribute to a better estimation of the soil biotic compartment in the different models of greenhouse gas emissions from tropical soils

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Capiral, Mary Joy Josephine M. "Measurements of ammonia and nitrous oxide emissions from potato fields in Central Washington using differential optical absorption spectroscopy (DOAS), tracer dispersion, and static chamber methods." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Thesis/Spring2009/m_capiral_042309.pdf.

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Thesis (M.S. in environmental engineering)--Washington State University, May 2009.
Title from PDF title page (viewed on May 21, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 87-91).

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39

Huynh, Tan Loi. "Greenhouse gas emissions from blackwater septic systems in Hanoi，Vietnam." Kyoto University, 2020. http://hdl.handle.net/2433/259036.

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40

Bicalho, Elton da Silva. "Soil greenhouse gas emissions and their relations to soil attributes in a sugarcane area /." Jaboticabal, 2016. http://hdl.handle.net/11449/135903.

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Orientador: Newton La Scala Júnior
Abstract: The production of the main soil greenhouse gases (GHG: CO2, CH4 and N2O) is influenced by agricultural practices that causes changes in soil phys¬ical, chemical and biological attributes, directly affecting their emission to the atmos¬phere. The aim of this study was to investigate the infield soil CO2 emissions (FCO2) and the soil CO2, CH4 and N2O production potentials (PCO2, PCH4 and PN2O, respec¬tively) in laboratory conditions, and their relationship to soil attributes in a mechanically harvested sugarcane area. The experimental area consisted of a 50 × 50-m radially symmetrical grid containing 133 points spaced at minimum distances of 0.5 m in the center of the sample grid. It was carried out eight evaluations of FCO2, soil temperature and soil moisture over a period of 19 days. Soil physical and chemical attributes were determined by sampling at a depth of 0-10 cm. The quantification of PCO2, PCH4 and PN2O consisted of laboratory incubation and determination of gas concentration by gas chromatography. FCO2 presented an infield average emission value of 1.19 µmol CO2 m−2 s−1, while GHG production in laboratory was 2.34 µg C-CO2 g−1 d−1 and 0.20 ng N-N2O g−1 d−1 for PCO2 and PN2O, respectively. No significant production or oxidation was observed for CH4. The factor analysis showed the formation of two independent processes that explained almost 72% of the total variance observed in the data. The first process was related to the transport of FCO2 and its relation to soil p... (Complete abstract click electronic access below)
Resumo: A produção dos principais gases de efeito estufa (GEE: CO2, CH4 e N2O) é influenciada por práticas agrícolas que causam alterações nos atributos físi¬cos, químicos e biológicos do solo, afetando diretamente sua emissão para a atmos¬fera. O objetivo deste estudo foi investigar a emissão de CO2 do solo (FCO2) em con¬dições de campo e a produção potencial de CO2, CH4 e N2O do solo (PCO2, PCH4 e PN2O, respectivamente) em condições de laboratório, além de suas relações com os atributos do solo em uma área de cana-de-açúcar colhida mecanicamente. A área experimental constituiu-se de um gradeado simétrico radialmente de 50 × 50 m con-tendo 133 pontos espaçados em distâncias mínimas de 0,5 m no centro da malha amostral. Foram conduzidas oito avaliações para FCO2, temperatura e umidade do solo durante um período de 19 dias. Os atributos físicos e químicos do solo foram determinados por meio de amostragem na profundidade de 0-10 cm. A quantificação de PCO2, PCH4 e PN2O consistiu de incubação em laboratório e determinação da con¬centração dos gases por meio de cromatografia gasosa. FCO2 apresentou um valor de emissão média de 1,19 µmol CO2 m−2 s−1, enquanto a produção de GEE em laborató¬rio foi de 2,34 µg C-CO2 g−1 d−1 e 0,20 ng N-N2O g−1 d−1 respectivamente para PCO2 e PN2O. Não foi observada produção ou oxidação significativa de CH4. A análise de fatores mostrou a formação de dois processos independentes que explicaram quase 72% da variância total observada nos dados. O primeiro proce... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor

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41

Lemke, Reynald L. "Quantification and simulation of nitrous oxide emissions from agroecosystems in the Boreal and Parkland regions of Alberta." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq21590.pdf.

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42

Lin, Mei. "Effects of temperature, readily available organic C and nitrate on soil nitrous oxide emissions, a laboratory study." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24415.pdf.

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43

Kesenheimer, Katharina Anne [Verfasser], and Torsten [Akademischer Betreuer] Müller. "Nitrous oxide emissions and mitigation strategies in winter oilseed rape cultivation / Katharina Anne Kesenheimer ; Betreuer: Torsten Müller." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2019. http://d-nb.info/1200466837/34.

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44

Braun, Ross Charles. "Environmental and management impacts in turfgrass systems: nitrous oxide emissions, carbon sequestration, and drought and traffic stress." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/36215.

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Doctor of Philosophy
Department of Horticulture and Natural Resources
Dale J. Bremer
Turfgrasses sequester and emit carbon dioxide, and emit nitrous oxide (N₂O) when fertilized with nitrogen and irrigated. Future water availability is a serious issue and drought restrictions may be imposed on turf managers while turf areas are subjected to traffic stress. My objectives in Chapter 2 were to: 1) quantify the magnitude and patterns of N₂O emissions and carbon (C) sequestration in zoysiagrass (Zoysia japonica Steud.); and 2) determine how irrigation (66% and 33% reference evapotranspiration [ET₀] replacement) and fertilization (polymer-coated urea, urea, and unfertilized) management may reduce N₂O emissions and enhance carbon sequestration. My objectives in Chapters 3 and 4 were to evaluate above- and below-ground responses of cool-season (C3) [Kentucky bluegrass (Poa pratensis L.) and perennial ryegrass (Lolium perenne L.)] and warm-season (C4) grasses {buffalograss [Buchloe dactyloides (Nutt.) Engelm] and zoysiagrass] at golf course-related mowing heights [1.6-cm (fairway) and 6.4-cm (rough)], with and without traffic during a simulated drought and subsequent recovery period (without traffic). In Chapter 2, N₂O emissions increased by 6.3% with more irrigation during summers and increased from 4.06 kg ha⁻¹ in unfertilized turf to 4.50, and 5.62 kg ha⁻¹ in polymer-coated urea and urea treated turf, respectively, during the 2-year study. There was no difference in C sequestration rates between a high vs. low input management schedule. The C sequestration rate was 0.952 Mg C ha⁻¹ yr⁻¹ for zoysiagrass when averaged across management schedules and depths. The use of a controlled-release fertilizer such as PCU compared to the use of a quick-release fertilizer and/or lower irrigation will reduce N₂O emissions in turfgrass. In Chapters 3 and 4, the better drought tolerance of C4 grasses led to more differences between traffic treatments within C4 than C3 grasses, but C4 grasses maintained the highest quality and green cover. Quality at rough- compared to fairway-height was more impacted by traffic. Decreasing soil moisture due to drought led to a minimal impact from traffic on soil bulk density, soil penetration resistance (SPR), and root measurements. During drought, SPR at deeper soil depths and fairway plots increased and exceeded the critical value of 2.0 MPa. Both C4 grasses and perennial ryegrass had larger root diameters, which may have led to better soil compaction resistance. Traffic during drought will have a negative and accelerated impacts above-ground, but minimal impact below-ground, which will vary with turf species and mowing height.

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Araújo, Júnior José Moacir de Carvalho. "Nitrous oxide emissions and metal biogeochemistry in coastal wetland soils in response to bioturbation by Ucides cordatus." reponame:Repositório Institucional da UFC, 2016. http://www.repositorio.ufc.br/handle/riufc/21598.

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ARAUJO JUNIOR, José Moacir de Carvalho. Nitrous oxide emissions and metal biogeochemistry in coastal wetland soils in response to bioturbation by Ucides cordatus. 2016. 96 f. Tese (Doutorado em Ecologia e Recursos Naturais)-Universidade Federal do Ceará, Fortaleza, 2016
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Coastal wetlands, among them the mangroves, are ecosystems with high biodiversity. In these environments, the crabs stand out both for its large number of species as by its economic and ecological importance, mainly due to the dens formation process (bioturbation. In this work, the effects of bioturbation by Ucides cordatus crabs from the Jaguaribe River mangrove (Ceará, Brazil) were analyzed under the concentrations of the different biogeochemical forms of the iron, zinc and manganese metals in the nearby soil and in the tissues of these animals, besides the variations in the (N2O) in areas with and without these crustaceans, comparing the values found between the rainy and dry periods. Soil samples were collected at low tide period in the demarcated two collection areas, one with and one without crabs. Measurements of bioecological parameters of crabs, soil physical and chemical parameters and concentrations of the metals associated with the different soil fractions (exchangeable, carbonate, ferridrite, lepidocrocite, goethite and pyrite) and Ucides cordatus crab Determination of the N2O flow. The results clearly showed a significantly greater variation of bioturbation activity in the dry period, with consequent increase in oxidation and acidification of the soil in the areas with crab. The more oxidized forms of the metals were predominantly larger in the area with crab burrows in relation to the control area, while those of pyrite were smaller. However, the emission of nitrous oxide fluxes was higher in the control area in both climatic periods, which indicates that the bioturbation activity of the crab promotes reduction of the emissions of this gas. The results allowed us to understand the role of bioturbation in GHG emissions and dynamics of biogeochemical processes in coastal wetlands soils, and identify possible seasonal variations in these values and the determination of GHG emissions and contamination of soil and crabs in these areas by trace metals, to improve environmental monitoring.
As zonas úmidas costeiras, dentre elas os manguezais, são ecossistemas com elevada biodiversidade. Nesses ambientes, os caranguejos destacam-se tanto por seu grande número de espécies quanto por sua importância econômica e ecológica e econômica, principalmente devido ao processo de formação de tocas (bioturbação). Neste trabalho foram analisados os efeitos da bioturbação realizada por caranguejos Ucides cordatus de manguezais do Rio Jaguaribe (Ceará, Brasil) sob as concentrações das diferentes formas biogeoquímicas dos metais ferro, zinco e mangânes no solo próximo e no tecido desses animais, além das variações no fluxo de óxido nitroso (N2O) em áreas com e sem esses crustáceos, comparando os valores encontrados entre os períodos chuvoso e seco. Os solos foram coletados no período de maré baixa em duas 2 áreas de coleta, uma com caranguejos e outra sem. Foram realizadas medições de parâmetros bioecológicos dos caranguejos, de parâmetros físico-químicos do solo e as concentrações dos metais associados às diferentes frações do solo (trocável, carbonato, ferridrita, lepidocrocita, goethita e pirita) e nos tecidos do caranguejo Ucides cordatus, além da determinação do fluxo de N2O. Os resultados demonstraram claramente uma variação significativamente maior de atividade bioturbadora no período seco, com consequente aumento na oxidação e acidificção do solo nas áreas com caranguejo. As formas mais oxidadas dos metais foram predominantemente maiores na área com tocas de caranguejos em relação a área control, enquanto as de pirita foram menores. Entretanto, a emissão de fluxos de óxido nitroso foi maior na área controle em ambos os períodos climáticos estudados, o que indica que a atividade bioturbadora do caranguejo promove redução das emissçoes desse gás. Os resultados obtidos permitiram compreender o papel da bioturbação na emissão de GEE e na dinâmica dos processos biogeoquímicos nos solos de zonas úmidas costeiras, além de identificar possíveis variações sazonais nesses valores e a determinação das emissões de GEE e da contaminação dos solos e caranguejos dessas áreas por metais traços, de forma a melhorar o monitoramento ambiental.

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46

Hernandez, Maria Elizabeth. "The effect of hydrologic pulses on nitrogen biogeochemistry in created riparian wetlands in midwestern USA." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1154448558.

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47

Liu, Yuexin. "Modeling the emissions of nitrous oxide (N₂O) and methane (CH₄) from the terrestrial biosphere to the atmosphere." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/59869.

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Muller, Jesse Michael. "Improving fertiliser nitrogen recovery and mitigating nitrous oxide emissions from intensive vegetable cropping systems in South East Queensland." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/132721/1/Jesse_Muller_Thesis.pdf.

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This thesis is a study into the efficacy of cropping methods Australian vegetable growers can adopt to increase nitrogen fertiliser efficiency, reduce nitrogen fertiliser application rates and reduce nitrous oxide emissions. The experiment, conducted in the Lockyer Valley (South East Queensland, Australia) investigated the utilization of the DMPP and Piadin nitrification inhibitors to achieve these research objectives. Outcomes from this research will help growers to reduce nitrogen fertiliser application rates and reduce greenhouse gas emissions without reducing yields.

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Winning, Nicola Jane. "Greenhouse gas emissions from Scottish arable agriculture and the potential for biochar to be used as an agricultural greenhouse gas mitigation option." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10052.

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Nitrous oxide (N2O) is a powerful greenhouse gas (GHG) which has a global warming potential 296 times greater than that of carbon dioxide (CO2). Agriculture is a major source of N2O and in the UK approximately 71 % of N2O emissions are produced by agricultural soils, mainly as a result of the application of nitrogenous fertilisers. Despite previous research into agricultural N2O emissions which has demonstrated that N2O emissions have high spatial and temporal variability, there is still a lack of knowledge surrounding the factors that influence the magnitude of emissions from agricultural soils. Agricultural N2O emissions for the UK’s annual GHG inventory are currently estimated using a 1.25 % emission factor (EF) (to be decreased to 1 % in 2015) which assumes that 1.25 % of applied nitrogen (N) fertiliser is emitted as N2O. The EF does not take into account influencing factors such as location or fertiliser type. Mitigation of N2O emissions is vital if future climate change is to be prevented, yet this must also be combined with the need to intensify agricultural production to feed the increasing global population. Biochar which is a carbon rich material produced during the pyrolysis of biomass has been identified as a potentially useful soil amendment with the ability to mitigate N2O emissions. However, most previous research has focused on laboratory scale experiments and there is a need to investigate the use of biochar in a field environment. Other N2O mitigation options such as nitrification inhibitors, or altering fertiliser management practices, require testing under different conditions to assess their suitability for use. This thesis aims to investigate a). The factors affecting N2O emissions from synthetically and organically fertilised arable soils, and b). To explore the potential of various N2O mitigation options for arable systems, including biochar. This thesis firstly investigates N2O emissions from synthetically fertilised arable soil. Varying application rates of ammonium nitrate fertiliser were applied to a Scottish arable soil during a year long field experiment and the effects of mitigation options such as a nitrification inhibitor (DCD) were assessed. N2O emissions were shown to be significantly affected by soil water filled pore space and the 1.25 % EF was demonstrated to be generally greater than those calculated in this experiment. The use of DCD significantly decreased N2O emissions and crop yields. A second year long field experiment was carried out to investigate N2O and NH3 emissions from an organically fertilised arable soil and to explore the effect of the timing, form and method of organic fertiliser application on emissions and EFs. Slurry, poultry litter, layer manure and farmyard manure were applied in the autumn and the spring. Cumulative N2O emissions were generally greater from the autumn applications and NH3 emissions were greater from the spring applications, due to wetter soil conditions and incorporation of fertiliser during the autumn. The type of fertiliser applied affected the magnitude of emissions with the greatest cumulative N2O and NH3 emissions from the layer manure. The method of fertiliser application had no effect on emissions. The following experiment investigated the ability of different biochars to retain N from a solution and the effect of biochar particle size on retention. A batch sorption experiment was used to test the affinity and capacity of six biochars for ammonium (NH4+) and nitrate (NO3-) from different concentrations of NH4NO3 solution. All of the biochars studied demonstrated the ability to retain NH4+ and NO3- from solution although greater NH4+ retention was observed. Differences in biochar affinity for N could be explained by pyrolysis temperature, but there was no effect of particle size or pH. Oil seed rape straw biochar was demonstrated to have the greatest NH4+ and NO3- retention capacity and as such was chosen for use in the next experiment. This work investigated the potential for oil seed rape straw biochar to decrease emissions of N2O, CH4 and CO2 from stored slurry and whether any GHG mitigation effects would continue following application of the slurry to arable soil. The effect on emissions of amending the biochar and slurry mixture with DCD after application to the soil was also explored. There was no significant effect of the biochar on GHG emissions from the stored slurry although the slurry initially acted as a sink for N2O and CO2. There were no significant differences between emissions from any treatments following application to the soil. The overall results of these studies indicate that N2O emissions are highly dependent on weather conditions, and hence location, in addition to fertiliser type and application timing. It was concluded that the use of a standard 1.25 % EF for synthetic and organic N fertiliser applications for the whole of the UK is inappropriate. Mitigation options such as the use of DCD, altering fertiliser application season or fertiliser type have been shown to possess the potential to mitigate N2O emissions but tradeoffs between N2O and NH3 emissions, and impacts on crop yields must be considered. Biochar was demonstrated to retain NH4+ and NO3- ions and this property may account for biochar’s N2O mitigation capabilities as observed by previous researchers. However, if N retention is taking place, the N appears to still be available for production of N2O and crop uptake.

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Khan, Amer Ijaz. "Nitrous oxide emissions, nutrient dynamics and nitrifier communities following fertilization of western hemlock, lodgepole pine and Douglas-fir forests." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/24250.

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I explored effects of fertilization on soil N₂O fluxes and underlying soil nutrients using short-term (up to 7 mo.) simulated operational fertilization with urea-nitrogen or nitrogen, phosphorus, potassium, and micronutrients (a N + micronutrients mix) in lodgepole pine, western hemlock, and Douglas-fir forests in British Columbia. The effect on the structure of ammonia- oxidizing bacterial (AOB) communities in the three forest ecosystems was also studied using polymerase chain reaction coupled with denaturing gradient gel electrophoresis (PCR-DGGE). Urea appeared to be rapidly mineralized to ammonium, and nitrification (relative to controls) was only observed in the lodgepole pine site and represented only 0.5% of added nitrogen. Across all sites and treatments, soils were as likely to consume as emit nitrous oxide, and among treatment replicates, rates were never significantly different from zero, with the exception of one efflux of 1.5 μg m-² hr-¹ on the warmest day in the study. I conclude from this pilot study that in acidic, unpolluted (with regard to nitrogen deposition) upland conifer forest soils in western Canada fertilized once or infrequently with urea or ammonium or a combination of nutrients, soil greenhouse-gas flux dynamics are generally not altered over the short-term, with soils remaining neutral with regards to flux of nitrous oxide.

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Dissertations / Theses on the topic 'Nitrous oxide emissions'

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