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

Since the Industrial Revolution, human beings have emitted huge amounts of greenhouse gases for economic growth, and greenhouse gases may influence climate. To slow down climate change, everyone has to take action. Recently, the carbon footprint (CF) labeling on products offers consumers an opportunity to do so in daily shopping. However, so far a CF label reveals only the amount of CO2 emitted during the product's life cycle, but not the product's relative CO2 emission level (i.e., whether the product emitted more or less CO2 than similar products). This study thus hypothesized that the mere presentation of a CF label would not affect consumers' buying intent. To test this and other related hypotheses, this study ran an experiment with 3 independent variables. The variables are amount of CO2 emitted (400gm or 750gm), CO2-saving signal (given or not given) and price (20 NTD or 30 NTD) of the product, which was a tetra-packed tea. In the CO2-saving signal given condition, the experimenter told the participants either that a green CF label denoted low CO2 emissions (in the 400gm condition) or that a green CF label denoted high CO2 emissions (in the 750gm condition). The label shown, in fact, was always green. In the CO2-saving signal not given condition, the experimenter did not explain the meaning of the label color.A convenient sample of 240 adults joined the experiment. They were randomly assigned to the experiment conditions. Each participant saw a picture of a tetra-packed tea with a CF label and listed price. Results showed that when CO2-saving signal was given, the low-CO2-high-price tea could induce higher buying intent than the high-CO2-low-price tea. When CO2-saving signal was not given, the two conditions did not differ in buying intent. Furthermore, participants' environmental attitude¡Xas measured a scale adapted from Dunlap and van Liere's (1978) New Environmental Paradigm Scale¡Xdid not qualify the above results. These findings suggest that CF label can neither help nor encourage people to choose low-CO2 products, unless it is complemented with a clear CO2-saving signal.

Atmospheric concentrations of greenhouse gas emissions are now higher than ever before, with severe implications for both humans and ecosystems around the world. To mitigate climate change, large and sustained reductions of greenhouse gas emissions are required. The management of lawns entail frequent maintenance activities, such as mowing, irrigation and fertilisation, which require energy and cause greenhouse gas emissions. Lawns cover a significant part of urban areas worldwide, with functions such as air quality improvement, flood mitigation and the potential to sequester carbon and consequently reduce carbon dioxide (CO2) from the atmosphere. The existing knowledge about the environmental impact from lawn management is limited and more research is needed to determine related climate effects. The objective of the study was to evaluate energy use and carbon footprint from urban lawn systems with different intensities through a life cycle perspective. The lawns included in the study consisted of utility lawns and meadow lawns, with management under responsibility of Uppsala municipality, and the two golf courses Upsala GK and Sigtuna GK, divided into the lawn types greens, tees, fairways and roughs. The energy use and carbon footprint was determined by an inventory of the existing lawn management practices through interviews with greenkeepers at the golf courses, stakeholder at Uppsala municipality and lawn caretakers. Additional information for the inventory was received from literature and databases. Based on the inventory, calculations of the energy use and carbon footprint throughout the life cycle was made. The results showed that greens had the largest carbon footprint and energy use per hectare followed by tees, fairways, roughs, utility lawns and meadow lawns. The energy use was the highest for the golf courses, with 16.5 GJ ha-1 year-1 for Upsala GK and 13.0 GJ ha-1 year-1 for Sigtuna GK. Lower energy use was determined for the utility lawns and meadow lawns, where 3.0 and 0.5 GJ ha-1 year-1 were required for the lawn management, respectively. The carbon footprint of the golf courses was 1.33 Mg CO2- equivalents (CO2e) ha-1year-1 for Upsala GK and 0.94 Mg CO2e ha-1 year-1 for Sigtuna GK, which was larger compared to the utility lawns of 0.2 Mg CO2e ha-1 year-1 and meadow lawns of 0.03 Mg CO2e ha-1 year-1. Mowing, irrigation and manufacturing of fertiliser were the management activities consuming most energy. The activities with largest carbon footprint were mowing, manufacturing of fertiliser and soil emissions from application of fertilisers. This study was a part of a multidisciplinary research programme, where the results will be used to determine the net emission balance when the carbon sequestration potential of the lawns has been concluded. Suggested improvements at the golf courses were to reduce the applied amounts of nitrogen fertiliser and improve the documentation of used resources. Increasing the usage of hybrid and electrical mowers was recommended for both the municipality as well as the golf courses to reduce the energy use and the carbon footprint. / Halterna av växthusgaser i atmosfären är högre än någonsin, vilket medför stora konsekvenser för både människor och ekosystem runt om i världen. För att motverka klimatförändringar måste åtgärder för att minska växthusgaserna i atmosfären genomföras. Gräsytor kräver kontinuerlig skötsel, såsom klippning, bevattning och gödsling, vilket är energikrävande och ger upphov till utsläpp av växthusgaser. En stor del av världens städer består av gräsytor som bidrar med positiva effekter till samhället genom att bland annat förbättra luftkvaliteten, dämpa översvämningar och lagra in kol i marken och på så sätt reducera atmosfärens koldioxidhalt. Den nuvarande kunskapen om miljöpåverkan från gräsyteskötsel är bristfällig och fler studier behövs för att bestämma ytornas klimatpåverkan. Syftet med studien var att bestämma energianvändning och klimatavtryck ur ett livscykelperspektiv för gräsytor med varierande skötselintensitet. De valda ytorna var bruksgräsmattor och slåttermarker som sköts av Uppsala kommun samt de två golfklubbarna Upsala GK och Sigtuna GK, vars ytor delades upp i green, tee, fairway och ruff. Energianvändningen och klimatavtrycket bestämdes genom en inventering av nuvarande skötselåtgärder. Detta gjordes genom intervjuer med greenkeepers på golfklubbarna, ansvariga på Uppsala kommun samt ansvariga för gräsyteskötsel på entreprenadföretag upphandlade av kommunen. Dessutom inhämtades information från litteraturen och databaser. Baserat på inventeringen utfördes beräkningar på energianvändning och klimatavtryck ur ett livscykelperspektiv. Resultatet visade att greener hade den högsta energianvändningen och det största klimatavtrycket, som i fallande storleksordning följdes av tee, fairway, ruff, bruksgräsmattor och slåttermarker. Greenerna bidrog med 20 % av golfbanornas totala klimatavtryck, trots att de bara utgör 3 % av golfbanans totala area. Den totala energianvändningen var störst för golfbanorna, med 16.5 GJ ha-1 år-1 för Upsala GK och 13.0 GJ ha-1 år-1 för Sigtuna GK. Den lägsta energianvändningen resulterade från bruksgräsmattor och slåttermarker där 3.0 och 0.5 GJ ha-1 år-1 krävdes för respektive gräsyta. Även för klimatavtrycket så var det större för golfbanorna med 1.33 Mg CO2- ekvivalenter (CO2e) ha-1 år-1 för Upsala GK och 0.94 Mg CO2e ha-1 år-1 för Sigtuna GK, jämfört med bruksgräsmattorna vars klimatavtryck var 0.2 Mg CO2e ha-1 år-1 och slåttermarkerna med 0.03 Mg CO2e ha-1 år-1. Klippning, bevattning och produktion av gödningsmedel var de skötselåtgärder som hade högst energiförbrukning. De skötselåtgärder med det största klimatavtrycket var klippning, produktion av gödningsmedel samt de emissioner som uppstod till följd av gödslingen. Detta projekt var en del av ett multidisciplinärt forskningsprogram där resultaten kommer att användas för att bestämma nettoutsläppsbalanser för gräsytorna när potentialen att lagra kol i marken har bestämts. Förslagna åtgärder för golfbanorna var att reducera gödselgivorna av kväve och öka dokumentationen av använda resurser. Det rekommenderades att öka användandet av hybrider och elektriska maskiner både inom kommunens gräsyteskötsel och på golfbanorna.

Paid working patterns are currently regulated by governments around the world for a range of social and economic reasons: to increase labour supply and skills; to provide a strong tax base to support an ageing population; to help people reconcile work and family life over increasingly diversified life courses; and to be in line with the general principle of the activating, employment led welfare state. Environmental considerations rarely feature in the design or evaluation of working time policy. Nevertheless, various authors working on policies for sustainable development argue that reductions in average paid working time could lead to environmental benefits: as people work less, they in turn earn less, and so consume less, resulting in lower environmental impacts from lower levels of production of products. This thesis takes this argument as its starting point, and synthesises these distinct perspectives on working time and its regulation to address two key questions: what level of environmental benefits could arise from such reductions in paid working time?; and what are the implications for the design of working time policy? The research addresses these questions, taking the case of greenhouse gas emissions, and the UK and the Netherlands in the early 2000s as case studies. Using household expenditure survey data and data on product emissions intensities, the relationship between paid working time and emissions is analysed at both the household and national levels. At the household level, statistically and substantively significant correlations are found between higher levels of paid work and higher levels of consumption and so greenhouse gas emissions. The effects on emissions of hypothetical changes in the working patterns of the national populations are then modelled. The research estimates that meeting current national objectives to increase labour market participation rates would increase national greenhouse gas emissions by 0.6-0.7%, a cost that might be considered acceptable if it also achieves its aims of reducing income poverty, benefit dependency, and social exclusion. Meanwhile, widespread reductions in average working hours and increased use of career breaks, with corresponding reductions in income, would reduce national emissions. The scenarios modelled (a 20% reduction in the working hours of full time workers, and increasing use of 3 month career breaks) lead to reductions of 3-4.5% in national emissions, with the corresponding increases in “leisure” time, reductions in income inequality, and reduced gender imbalances in the distribution of paid work potentially also improving wellbeing, social cohesion, and gender equality in work and care. The results indicate that environmental factors warrant consideration in the design and evaluation of working time policy, and that challenging but achievable levels of working time reduction could contribute a small but significant share to meeting greenhouse gas emissions targets. Policy instruments would need to address a range of values, attitudes and norms around employment and consumption, as well as employer and situational factors, if substantial working time reduction were to be achieved. Reconciling diverse environmental, social and economic goals also requires careful policy design, particularly for certain demographic groups such as the low income, who would need financial and other support to turn rights to reduce working time into functional freedoms that they could utilise.

This thesis examines the economic and environmental impacts that precision agriculture technologies (PATs) can have on the carbon footprint of a grain farm. An analysis is offered using two manuscripts. The first examines the impacts of three PATs and compares the findings to a conventional farming method. It was found that all three PATs investigated showed a potential Pareto improvement over conventional farming. The second manuscript expanded the model used previously to in order to develop a process to construct a carbon efficient frontier (CEF). The model employed examined uniform and variable rate technologies. In addition to the CEF, a marginal abatement cost curve was constructed. Using these curves in a complementary fashion, more accurate information on the adaptive behavior of farmer technology adoption can be gleaned. the information gleaned for the two manuscripts can give both producers and policy makers the analytical tools needed to make more information decisions with regard to economic and environmental feasibility of PATs.

abstract: The construction industry is becoming more aware of its impact on the environment. It has become more sensitive to how it operates and how it can reduce the carbon footprint of the construction process. This research identifies the source of and quantities of the carbon emissions created by an operating modular home fabrication plant in producing, transporting and installing modular structures. This study demonstrates how to measure the carbon footprint created in the production of a modular home. It quantifies and reports the results on a home, on a single module and on a per square foot basis. The primary conclusions of this study are: a) electricity was found to be the largest energy source used in this fabrication process; b) the modular fabrication process consumes a significant amount of electrical energy per month; c) production volume has a bearing on the carbon footprint of each home since the carbon footprint for each period is allocated to every home produced in that period; and d) transportation of fabricated modules and set-up add to the carbon footprint. Further, a carbon calculator was produced and is included with the study. The tool calculates the impact of energy consumption on the carbon footprint of a modular factory or a modular home. It may be expanded to other process driven fabrication entities. This research is valuable to developers and builders who wish to measure the carbon impact of a modular new home delivery system. The study also provides a methodology for modular home fabricators to measure the carbon footprint of their factories and factory production. / Dissertation/Thesis / Ph.D. Construction 2010

abstract: Consumer goods supply chains have gradually incorporated lean manufacturing principles to identify and reduce non-value-added activities. Companies implementing lean practices have experienced improvements in cost, quality, and demand responsiveness. However certain elements of these practices, especially those related to transportation and distribution may have detrimental impact on the environment. This study asks: What impact do current best practices in lean logistics and retailing have on environmental performance? The research hypothesis of this dissertation establishes that lean distribution of durable and consumable goods can result in an increased amount of carbon dioxide emissions, leading to climate change and natural resource depletion impacts, while lean retailing operations can reduce carbon emissions. Distribution and retailing phases of the life cycle are characterized in a two-echelon supply chain discrete-event simulation modeled after current operations from leading organizations based in the U.S. Southwest. By conducting an overview of critical sustainability issues and their relationship with consumer products, it is possible to address the environmental implications of lean logistics and retailing operations. Provided the waste reduction nature from lean manufacturing, four lean best practices are examined in detail in order to formulate specific research propositions. These propositions are integrated into an experimental design linking annual carbon dioxide equivalent emissions to: (1) shipment frequency between supply chain partners, (2) proximity between decoupling point of products and final customers, (3) inventory turns at the warehousing level, and (4) degree of supplier integration. All propositions are tested through the use of the simulation model. Results confirmed the four research propositions. Furthermore, they suggest synergy between product shipment frequency among supply chain partners and product management due to lean retailing practices. In addition, the study confirms prior research speculations about the potential carbon intensity from transportation operations subject to lean principles. / Dissertation/Thesis / Ph.D. Sustainability 2011

Doctor of Philosophy / Department of Biological & Agricultural Engineering / Zifei Liu / The Unmix and Positive Matrix Factorization (PMF) models for source apportionment were applied to evaluate prescribed burning impacts on air quality, identify model advantages, and establish a relationship between visibility and PM₂.₅ sources. Speciated PM₂.₅ data were from the Flint Hills (FH) rural and the Kansas City (KC) urban sites. At the FH site, the Unmix model identified five sources: nitrate/agricultural, sulfate/industrial, crustal/soil, smoke, and secondary organic aerosol (SOA); while the PMF model identified the copper source in addition. The smoke source from PMF result includes both primary and secondary aerosols from prescribed burning when the smoke source in Unmix result only includes primary burning aerosols. The secondary smoke aerosols at the FH site were combined with secondary aerosols from other origins and formed the SOA source in Unmix result. Comparative analysis of the modeling results estimated the SOA to be 2.3 to 2.7 times of the primary aerosols in burning season. At the KC site, both receptor models derived seven-source solutions: nitrate/agricultural, sulfate/industrial, crustal/soil, smoke, traffic/SOA, heavy-duty diesel vehicle (HDDV), and calcium. The smoke source at the KC site carries an exceedingly organic carbon to elemental carbon (OC/EC) ratio, which is more than five times higher than in FH smoke source. The PMF results at KC site tend to classify more SOA from nitrate/agricultural and sulfate/industrial sources into traffic/SOA source. In the burning season, the smoke source from both sites showed a relatively high correlation when KC is under west and southwest wind, suggesting that part of the smoke originated PM₂.₅ at the urban site could be from the upwind burning activities. The Tobit modeling recognized the nitrate/agricultural as the leading visibility degradation impact factor at both sites. The latter chapter conducted a review of life cycle assessment (LCA) on carbon footprint (CF) of beef production. The objectives were to evaluate CF range in raising systems from different countries, identify the leading CF contributor and dominant source of uncertainty, and summarize LCA inventory defined in cattle production systems. Most existing beef LCA studies followed a “cradle to farm gate” approach. The CF in 3-phase systems ranged from 16 to 29.5 kg CO2e kg⁻¹ carcass weight. The 2-phase raising system reported a slightly lower CF than the 3-phase system (18.9 to 26.9 kg CO2e kg⁻¹ carcass weight), but no significant differences were observed. The grass-fed system in the US has the highest CF, but the CF of grass-fed systems in the European Union (EU) is 40% less than them in the US. This is because more than half of cattle farms in EU produce both beef and milk, and the CF burden was partaken by the dairy production. Cow-calf phase contributed the most CF in 3-phase raising system, while enteric fermentation was the major contributor. Feed production contributed the most in the feedlot phase if forages were applied rather than concentrates. The leading uncertainty sources reported was land use change and disparate dressing percentage. To improve the LCA accuracy, more research is needed in collecting reliable LCA inventory data such as raising period and feed intake efficiency.

Climate change may have detrimental effects on agriculture productivity (Challinor et al., 2009). At the same time, agriculture also plays a role in contributing to the causes of global warming (IPCC, 2009). The present research examined current agro-management practices of select agriculture management practices and products with a threefold objective, namely i) to understand the possible impact of climate change on crop yields, ii) to examine the carbon sequestration potential of select agricultural crops and management practices, and iii) to conduct a thorough life cycle assessment to estimate the carbon footprint of select agriculture crops and management practices, so as to help policy makers, planners and business managers in devising appropriate mitigation and adaptation policy frameworks and make sensible management decisions in the context of climate change. The research was conducted in a series of three studies. The first study investigated future corn and soybean yields in the Raccoon watershed in the US Corn Belt using projected climate data. This study used the Environment Policy Integrated Climate (EPIC) model to estimate the impact of climate change for 2015-2099 with data downscaled from eight atmosphere-ocean general circulation models (AOGCMs) with three emissions pathways reflecting low, medium and high greenhouse gas scenarios. Soil properties were gathered from the Soil Survey Geographic Database and data on crop rotation was derived from CropScape, a geospatial cropland data layer product of the US National Agricultural Statistics Service. Our findings show that 5-year averages of both corn and soybean yields for 2095-2099 depicted by all eight AOGCMs under low and medium carbon scenarios will increase in comparison to the 5-year average yields for 2015-2019. However, under the high carbon scenario, 5-year averages of both corn and soybean yields for 2095-2099 will decline in comparison to the 5-year average yields for 2015-2019 pointing to the effects of climate change. The study also examined the possible impact of carbon fertilization on yields. The results show that carbon fertilization of soybean, a C3 plant, may contribute to an increase in yield of 3% to 22% while its contribution to the growth of corn, a C4 plant, will be much lower. The second study focused on land-based carbon sequestration possibilities. Land-based carbon sequestration constitutes a major low cost and immediately viable option in climate change mitigation. Using downscaled data from eight atmosphere-ocean general circulation models for a simulation period between 2015 and 2099, the study examined the carbon sequestration potential of alternative agricultural land uses in an intensively farmed Corn Belt watershed and the impact of climate change on crop yields including impact on switchgrass. The results of the study show that switching from conventional tillage and continuous corn to no-till corn-soybean can sequester the equivalent of 192.1 MtCO2 eq of soil organic carbon per hectare with a sequestration rate of 2.26 MtCO2 eq ha-1 yr-1. The results also indicate that switchgrass can sequester the equivalent of 310.7 MtCO2 eq of soil organic carbon per hectare with a sequestration rate of 3.65 MtCO2 eq ha-1 yr-1. The findings of this research suggest that climate change does not have a significant effect on switchgrass yields, unlike on corn and soybean yields, possibly due to the carbon fertilization effect. As mentioned, agriculture can contribute to climate change mitigation efforts by providing low–land-based options through changes in agricultural management practices. A thorough life cycle assessment is necessary to compare various opportunities provided by a variety of agricultural approaches. The last study is a cradle-to-farm gate life cycle assessment of the contributions of select agricultural practices to mitigate global warming. The study focused on land-based practices including crop rotations instead of just individual crops. In the assessment, the study also included examinations of below-the-ground soil to determine the organic carbon sequestration potential of such practices, which most of the time is ignored in life cycle assessments due to lack of data. Specifically, the study examined three farming practices in the intensively farmed Raccoon watershed: continuous corn rotation with conventional tillage, corn-soybean rotation with no-till, and switchgrass. The assessment was conducted based on land units (hectares), instead of utilizing the usual practice of reporting life cycle assessment in product units, such as kilograms. The results of the life cycle assessment reveal that among the three agricultural practices, switchgrass has the lowest carbon footprint overall, and continuous corn rotation has the highest. Switching from continuous corn to switchgrass would reduce the overall greenhouse gases the most, by 6.30 Mg CO2eq/ha/yr, or by 62% compared to the emissions generated by the continuous corn rotation. Similarly, planting switchgrass instead of a corn-soybean rotation would reduce the overall emissions of greenhouse gases by 1.84 Mg CO2eq/ha/yr, or by 32% compared to the corn-soybean rotation. Finally, switching from continuous corn to the corn-soybean rotation would reduce overall greenhouse gases emissions by 4.46 Mg CO2eq/ha/yr or by 44% of the emissions generated by continuous corn. These findings can inform policy discussions on the potential of agriculture’s role in climate change mitigation.

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