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Mathematical modeling in animal agriculture can be applied at various levels including at the tissue, organ, animal, farm, regional and global levels. The purposes of this research were i) to evaluate models used to estimate volatile fatty acid (VFA) and methane (CH4) production and assess their impact on regional enteric CH4 inventory, and ii) to develop a process-based, whole-farm model to estimate net farm GHG emissions. In the first study, four VFA stoichiometric models were evaluated for their prediction accuracy of rumen VFA and enteric CH4 production. Comparison of measured and model predicted values demonstrated that predictive capacity of the VFA models varied with respect to the type of VFA in rumen fluid which impacted estimated enteric CH4 production. Moving to a larger scale assessment, we examined the enteric CH4 inventory from Manitoba beef cattle (from 1990 to 2008) using two mechanistic rumen models that incorporate VFA stoichiometric models: COWPOLL and MOLLY, and two empirical models: Intergovernmental Panel on Climate Change (IPCC) Tier 2 and a nonlinear equation (Ellis). The estimated absolute enteric CH4 production varied among models (7 to 63%) indicating that estimates of GHG inventory depend on model selection. This is an important consideration if the values are to be used for management and/or policy-related decisions. Development of models at the individual farm component level (animal, soil, crop) does not accurately reflect net GHG emissions generated from the whole production system. We developed a process-based, whole-farm model (Integrated Components Model, ICM), using the existing farm component models COWPOLL, manure-DNDC and some aspects of IPCC to integrate farm components and their associated GHG emissions. Estimates of total farm GHG emissions and their relative contribution using the ICM were comparable to estimates using two other whole-farm models (Integrated Farm System Model and Holos model). Variation was observed among models both in estimating whole-farm GHG emissions and the relative contribution of the different sources in the production system. Overall, whole-farm models are required to explore management options that will mitigate GHG emissions and promote best management practices. However, for full assessment of the production system, other benefits of the system (e.g., carbon sequestration, ecosystem services), which are not part of current whole-farm models, must be considered.

The increased use of synthetic nitrogen fertilizers since the early 1900s has resulted in greater food production but also problems with nitrogen pollution in freshwaters. Nitrate (NO3-) is a common pollutant in rivers and groundwater in agricultural watersheds; the drinking water limit in Canada is 10 mg N/L. Microbial processing of NO3- and ammonium (NH4+) can produce nitrous oxide (N2O), a potent greenhouse gas responsible for about 5% of the greenhouse effect. Rivers provide a complex environment, where a variety of redox conditions, available substrates and microbial populations can co-exist on small spatial and temporal scales. Therefore, many questions remain about N cycling in river environments. N2O is produced during anoxic microbial NO3- or NO2- reduction to N2 (denitrification) and oxic microbial NH4+ oxidation to NO3- (nitrification). A significant portion (~25%) of global anthropogenic N2O is produced in rivers and estuaries, but mechanisms are not clear and predictability is poor. The United Nations Intergovernmental Panel on Climate Change (IPCC) provides default equations for calculating N2O emission estimates, in which annual NO3- loading to rivers is positively linearly related to N2O emissions. However, it is unclear how sound these linear relationships are and if measured N2O emissions are similar to IPCC estimates. The Grand River watershed is the largest in southern Ontario. Nutrient discharge to the Grand River is high due to extensive agriculture and high urban populations. The river often has a hypoxic water column due to high community respiration in summer. However, although nitrogen pollution is significant, N cycling is not well understood in the river. This thesis shows that NO3- and NH4+ do not typically change on the diel scale, with the exception of two sites downstream of wastewater treatment plants (WWTPs). However, N2O concentration changes dramatically. N2O concentrations are higher at night and lower during the day for most sites, but are reversed at very low-nutrient sites. N2O is therefore a sensitive indicator of changes in N cycling that may not be evident from NO3- and NH4+ concentrations or stable isotope ratios. Additionally, this work shows the importance of having a sampling design that captures diel variability in N2O. Previous work in rivers and streams worldwide focused on the appropriate N2O:NO3- ratio used to predict N2O emissions. In contrast, this thesis shows that there is a significant but very weak relationship between instantaneous N2O emissions and NO3- concentrations. However, there is a much stronger negative exponential relationship between DO and N2O. Annual N2O emissions tripled between 2006 and 2007 but NO3- masses in the river were only 10% higher, likely because river levels were lower and anoxia more prevalent in 2007. This research suggests that the IPCC needs a new conceptual model for N2O-NO3- relationships in rivers. N2O is produced in rivers, partially due to microbial processing of NO3- and NH4+ from WWTP effluent. However, WWTP effluent may also include dissolved N2O and CH4 but this previously had not been directly quantified. It was also unclear if stable isotopic ratios of NH4+, NO3-, N2O and CH4 in WWTP effluent were distinct from river sources and could be used for effluent tracing. N2O emissions from three WWTPs in the Grand River Watershed were measured over 24 hours in summer and winter. N2O emissions were similar to direct emissions from WWTPs but CH4 emissions were about an order of magnitude lower than direct WWTP emissions. This is a previously-ignored source of N2O and CH4 to the atmosphere. While stable isotopic ranges of NO3- and NH4+ were not always distinct from river sources, ??15N-N2O, ??18O-N2O and ??13C-CH4 were distinct, making them potentially useful tracers of WWTP effluent in rivers. N2O isotopic signatures may help determine production and removal processes in rivers, but isotopic effects of the major production pathway, denitrification, have not been characterized for river sediments. This was addressed by preparing anoxic laboratory incubations of river sediment from two sites (non-urban and urban) in the Grand River and measuring stable isotopic effects of N2O production via denitrification. Stable isotopic fractionations were similar to published values but, surprisingly, strongly negatively correlated to production rate, even though NO3- substrate was plentiful. This novel finding suggests that N2O reduction resulting in isotopic effects is more prevalent in high-substrate systems than previously thought, and that N2O reduction may be inhibited by high NO3- or NO2- or by lags in N2O reductase activity in high N2O-production incubations. This could explain why N2O emissions from the Grand River are lower than predicted by IPCC equations, which assume that N2O:(N2O+N2) ratios produced by denitrification are constant. Concern about NO3- export to freshwater lakes and to oceans is growing, but the role of large, eutrophic rivers in removing watershed NO3- loading via denitrification and biotic assimilation is not clear. To understand how much NO3- the Grand River receives, and how much it removes annually, a NO3- isotope mass balance for the Grand River was created. The river denitrified between 0.5% and 17% of incoming NO3-, less than the 50% suggested by the IPCC. This is surprising, as the river is well mixed, has moderate to high NO3- concentrations, experiences hypoxia (promoting denitrification), and has extensive biomass (biofilm and macrophytes) that assimilate N. However, the river???s short residence time (~3 days not counting reservoirs), organic carbon-poor sediment and mineralization of organic matter could contribute to low denitrification rates. These findings suggest that denitrification rates in rivers worldwide could be lower than previously estimated. Although error was high, most ??15N-NO3- values for losses were in the expected range for denitrification and most ??15N-NO3- values for gains were within ranges from tributaries, WWTP effluent and groundwater measured in the watershed. The model suggests that 68% to 83% of N loads to the watershed are lost before entering the Grand River, and 13% is exported to Lake Erie, leaving 5 to 19% lost in the Grand River from a combination of denitrification, assimilation and storage. These findings suggest that large rivers are much less efficient in denitrification than other locations in watersheds such as small streams, ponds, groundwater and riparian zones. They also indicate that agricultural NO3- loading is much higher than WWTP effluent, suggesting that N management strategies should focus on agricultural runoff and groundwater. Given that N2O:NO3- relationships are weak and non-linear in the Grand River, a new conceptual model for N2O:NO3- relationships is presented. First, the Grand River dataset was supplemented with data from high-oxygen streams in southern Ontario. Regression tree analysis shows a weak relationship between NO3- and N2O in these streams with no other factors (temperature, DO, NH4+, TP, DOC, etc.) improving fit. A conceptual model was then created, which posits that N2O emission variability (between and within sites) increases with NO3- concentration when NO3- concentrations are above the threshold for NO3- limitation. The global dataset does not dispute this model, though a NO3- threshold was not clear. The lack of sites with both high NO3- and high N2O may indicate a paucity of research on eutrophic sites. Alternatively, high NO3- may indicate oxic conditions (i.e. little to no denitrification to remove it) which are incompatible with very high N2O emissions. In this case, the conceptual model can be modified such that N2O variability decreases when NO3- > ~ 4 mg N/L. The work also shows that low DO consistently results in high N2O emissions but high temperatures result in a very large range of N2O emissions. This approach allows N2O emissions, which have very high variability and are difficult to predict, to be constrained to likely ranges.

Mathematical modeling in animal agriculture can be applied at various levels including at the tissue, organ, animal, farm, regional and global levels. The purposes of this research were i) to evaluate models used to estimate volatile fatty acid (VFA) and methane (CH4) production and assess their impact on regional enteric CH4 inventory, and ii) to develop a process-based, whole-farm model to estimate net farm GHG emissions. In the first study, four VFA stoichiometric models were evaluated for their prediction accuracy of rumen VFA and enteric CH4 production. Comparison of measured and model predicted values demonstrated that predictive capacity of the VFA models varied with respect to the type of VFA in rumen fluid which impacted estimated enteric CH4 production. Moving to a larger scale assessment, we examined the enteric CH4 inventory from Manitoba beef cattle (from 1990 to 2008) using two mechanistic rumen models that incorporate VFA stoichiometric models: COWPOLL and MOLLY, and two empirical models: Intergovernmental Panel on Climate Change (IPCC) Tier 2 and a nonlinear equation (Ellis). The estimated absolute enteric CH4 production varied among models (7 to 63%) indicating that estimates of GHG inventory depend on model selection. This is an important consideration if the values are to be used for management and/or policy-related decisions. Development of models at the individual farm component level (animal, soil, crop) does not accurately reflect net GHG emissions generated from the whole production system. We developed a process-based, whole-farm model (Integrated Components Model, ICM), using the existing farm component models COWPOLL, manure-DNDC and some aspects of IPCC to integrate farm components and their associated GHG emissions. Estimates of total farm GHG emissions and their relative contribution using the ICM were comparable to estimates using two other whole-farm models (Integrated Farm System Model and Holos model). Variation was observed among models both in estimating whole-farm GHG emissions and the relative contribution of the different sources in the production system. Overall, whole-farm models are required to explore management options that will mitigate GHG emissions and promote best management practices. However, for full assessment of the production system, other benefits of the system (e.g., carbon sequestration, ecosystem services), which are not part of current whole-farm models, must be considered.

The Stable high rate ammonia removal over nitrite (SHARON) at Nykvarnsverket in Linköping is a relatively new kind of biological treatment. Fluxes of nitrous oxide (N2O) has not been fully mapped at Nykvarnsverket and additional efforts are needed for increased knowledge about possible emissions. The primary goals of the study were to measure and compare fluxes of N2O in the SHARON and to do a general greenhouse gas (GHG) flux comparison to those of the Biological treatment, the Chemical treatment and the Second denitrification at Nykvarnsverket. Secondary goals were to evaluate the use of two gas sensors, a SiC-FET sensor for N2O emissions, a CO2 Engine ELG sensor for carbon dioxide (CO2) emissions and their applicability in a WWTP environment. The measurements of GHG fluxes were performed by measuring the temporal change of GHG concentrations in the headspace of floating flux chambers placed in treatment tanks. The two gas sensors were tested either via tests in lab or via field measurements. The flux chamber method made it possible to estimate the fluxes at three out of four targeted tanks. The total daily GHG flux estimations (mmol m-2 d-1 ) in the SHARON were 6900 CO2, 320 methane (CH4) and 35 N2O. The estimations (mmol m-2 d-1) in the Biological treatment were 22 000 CO2, 120 CH4 and 23 N2O for 75% of the time. The estimations (mmol m-2 d-1) in the Chemical treatment were 110 CO2, 0.073 CH4 and 0.60 N2O. The largest N2O emissions were found to occur during nitrification processes in the SHARON. The fluxes in the SHARON were also the largest compared to those in the Biological treatment and the Chemical treatment, except for the CO2 flux that was larger in the Biological treatment. The CO2 sensor could be used during measurements over shorter time periods were CO2 levels did not exceed 10 000 ppm. Further tests on the SiC-FET sensor are needed to evaluate the sensor for measurements of N2O.

Agricultural land releases large amounts of nitrogen and phosphorus to water bodies which causes eutrophication. Creating wetlands on agricultural land is one way to prevent this major issue. However, constructed wetlands are a large emission source of greenhouse gases. The aim of this study was to quantify the CH4 and N2O emissions in 21 constructed wetlands (CWs) around Mälardalen located in mid-Sweden and 19 CWs in the county of Halland along the south-west coast of Sweden and examine if there was any relation between the emissions and the nutrient status. Furthermore, the emission contributed by CH4 ebullition was evaluated. Synoptic water and gas sampling was done during early and late autumn. Floating chambers were deployed in six wetlands and measured CH4 ebullition over a 24-hour period. The diffusive CH4 emissions varied between 0.10–103 mg m-2 d-1 with a mean value of 13 mg m-2 d-1. The N2O emission varied between -0.086–7.8 mg m-2 d-1 with a mean of 1.4 mg m-2 d-1. Significant negative correlation between N2O emission and C:N ratio and a significant positive correlation between N2O emission and N:P ratio was found. No relation between the CH4 emission and total organic carbon (TOC) was found which other studies have been able to prove. Only a weak relation between the CH4 emission and the C:N ratio was found. The ebullition in the six wetlands varied between 0–62 mg m-2 d-1 and accounted for more than 85% of the total CH4 emission in most of the chambers. No significant difference in ebullition was found within the CWs but between the CWs there were found significant differences. The conclusion of this thesis is that CWs in agricultural areas represent a large source of CH4 and N2O emissions and that nutrient status has a major influence of the N2O emissions. Lastly, ebullition seems to be a major pathway for the CH4 emission. / Jordbruksmark släpper ut stora mängder kväve och fosfor till ytvatten vilket orsakarövergödning. Skapandet av våtmarker på jordbruksmark är ett sätt att förhindra detta problem.Dock är anlagda våtmarker stora utsläppskällor av växthusgaser. Målet för den här studien varatt kvantifiera utsläppen av CH4 och N2O från 21 anlagda våtmarker runt Mälardalen beläget imitten av Sverige och 19 anlagda våtmarker i Hallands län längs Sveriges sydvästra kust.Vidare var syftet att undersöka om det fanns någon relation mellan utsläppen ochnäringsstatusen. Fortsättningsvis, utsläppen av CH4 genom ebullition utvärderades. Synoptiskvatten- och gasprovtagning utfördes under tidig höst och senhöst. Flytande kamrar sattes ut isex våtmarker och mätte CH4 ebullition under en 24-timmars period. Utsläppen av CH4genom diffusion varierade mellan 0.10–103 mg m-2 d-1 med ett medelvärde på 13 mg m-2 d-1.Utsläppen av N2O varierade mellan -0.086–7.8 mg m-2 d-1 med ett medelvärde på 1.4 mg m-2d-1. Signifikant negativ korrelation mellan utsläpp av N2O och C:N-kvoten och en signifikantpositiv korrelation mellan utsläpp av N2O och N:P-kvoten hittades. Ingen relation mellanutsläppen av CH4 och totalt organiskt kol hittades vilket andra studier kunnat påvisa. Endasten svag relation mellan utsläppen av CH4 och C:N-kvoten hittades. Ebullitionen i de sexvåtmarkerna varierade mellan 0–62 mg m-2 d-1 och stod för mer än 85 % av det totala CH4utsläppen i de flesta kamrarna. Inga signifikanta skillnader i ebullition kunde hittas inom deanlagda våtmarkerna men dock mellan våtmarkerna. Slutsatsen av den här studien är attanlagda våtmarker på jordbruksmark representerar en stor källa av CH4 och N2O utsläpp ochatt näringsstatusen i anlagda våtmarker har en stor inverkan på utsläppen av N2O. Slutligen,ebullitionen verkar vara en betydande utsläppsväg för CH4.

Résumé : Les résultats alarmants du Groupe d’Experts Intergouvernemental sur l’Évolution du Climat (GIEC) et la tenue des sommets chaque année sur le réchauffement climatique poussent de nombreux pays à prendre la chose au sérieux (notre-planète.info, 2015). C’est ainsi que le Mali, pays enclavé et importateur net de produits pétroliers, cherche des moyens non seulement pour emboiter le pas à la communauté internationale sur la protection de l’environnement mais aussi à mieux gérer sa politique énergétique. Cette volonté repose sur le développement des biocarburants grâce au jatropha qui se cultive aussi bien sur des sols semi-arides que fertiles. Depuis plusieurs décennies les biocarburants font l’objet de recherches. Certaines études permettent de conclure que leur utilisation réduirait les émissions de GES tandis que d’autres vont plus loin au-delà du cadre écologique et trouvent que c’est une source de rentabilité économique. Pour mieux illustrer ses effets, nous avons utilisé un modèle d’équilibre général calculable dynamique (MEGCD) qui permet de voir les interactions des variables structurelles de l’économie malienne sur une durée de 4 ans. Les résultats montrent qu’une politique protectionniste du secteur des biocarburants jumelée à une politique d’exploitation accrue du jatropha à partir des terres non occupées au Mali, génèrent plus d’activité dans le pays et permet de réduire les importations de carburant. De même, la croissance dans le secteur de l’énergie permet d’augmenter la production en électricité dans le pays. / Abstract : The alarming results of the Intergovernmental Panel on Climate Change (IPCC) and the summits annually on global warming are pushing many countries to take it seriously (notre-planète.info, 2015). In this way Mali, landlocked and importing country of fuel, take measure to join in international community on protection of environment also to manage better his energetic policy. This determination is based on the development of biofuels through jatropha which both grown on semi-arid soils fertile. Many searchers are worked on the advantages and disadvantages to Jatropha compared to diesel and fund that his useful reduced greenhouse gas emission while others go further beyond the ecological environment and find it a source of economic profitability. We use a dynamic calculable general equilibrium model (DCGEM) to illustrate relations between all structural variables of economy Malian on four years. We find that a biofuel protectionist policy combined with an increased operating policy jatropha from idle land in Mali, generate more activity and reduces fuel imports. Similarly, growth in the energy sector can increase electricity production in the country.

The Abstract The main objectives of the presented thesis - The Assessment of Environmental Impacts of Representative Renewable Energy Technologies in the Czech Republic were complex assessment of representative renewable energy technologies within different criterions, assessment of their greenhouse gas mitigation effectiveness and evaluation of usefulness of financial incentives aimed on renewable electricity in the Czech Republic in the period 2005-2010. Thereafter representative technologies were compared with nuclear and best available techniques coal-fired power plants in order to determine the best convenient electricity generating technology. Wind, photovoltaic, small hydro-electricity and geothermal power plants were appraised in particular. The thesis was based on partial analysis and meta-analysis aiming on particular aspects and the entire life cycles of the technologies was taken under consideration. The basic methodology framework of life-cycle assessment, which was useful for a comparison of different electricity-generating technologies, was applied within the thesis. The key input data were gathered via meta-analysis. The database GEMIS 4.81, reports by Energy regulatory office, European statistics office, International energy agency and Czech hydrometeorology institute were used to acquire...

A aplicação de resíduos em solos agrícolas pode alterar significativamente a dinâmica do ciclo dos elementos no solo, conseqüentemente modificando sua fertilidade, a nutrição das plantas e os fluxos de gases do solo para a atmosfera. A possibilidade de produção de biocombustíveis a partir de óleos vegetais e com a atenção especial dada a cultura da mamona faz nesse momento com que o cultivo desta oleaginosa ressurja nacionalmente como cultura de interesse. Além disso, em áreas agrícolas próximas a grandes centros urbanos, a utilização agrícola de resíduos na agricultura é uma prática já empregada, porém ainda, sem o total conhecimento dos processos envolvidos em relação ao comportamento desses materiais no ambiente e seu real comportamento como fonte de nutrientes para as culturas. Em função do exposto, o presente trabalho foi realizado com o objetivo de avaliar os efeitos de três resíduos, contendo diferentes formas de N, na fertilidade do solo e nutrição mineral da mamona cultivada em área de reforma de canavial, bem como também quantificar os fluxos de gases do efeito estufa (CO2, CH4 e N2O) em função da aplicação de doses de um lodo de esgoto ou fertilização mineral no solo, antes do plantio da mamona. Assim, foram conduzidos dois experimentos a campo no ano agrícola de 2004-2005. No primeiro avaliou-se a contribuição de resíduos como fonte de N para a cultura da mamona e foi conduzido sob um Argissolo Vermelho-Amarelo distrófico. A dose de nitrogênio referencial foi de 75 kg ha-1 e as quantidades aplicadas de cada resíduo foram calculadas em função do conteúdo e disponibilidade do N nestes. Os dados obtidos mostram que os resíduos de origem orgânica (lodo de esgoto e Citrofer) constituíram-se numa fonte eficiente de N e para as doses equivalentes ou maiores que a referência, a produtividade da mamona foi igual ou superior a adubação mineral. Com relação a outros componentes de produção, o tamanho do racemo e nº de frutos para os tratamentos que receberam a aplicação de N via resíduos orgânicos ou a adubação mineral, não diferiram estatisticamente, mas foram superiores aos demais. O N foi o nutriente que mais limitou o desenvolvimento e produtividade da mamona. No segundo experimento avaliou-se a emissão dos gases CO2, CH4 e N2O na mesma área onde foi realizado o primeiro experimento, porém, foram avaliados os tratamentos que receberam adubação mineral e lodo de esgoto em três doses. Tanto a adição de lodo de esgoto como a adubação mineral alteraram os fluxos de CO2, N2O e CH4. Quando a quantidade de N aplicada via lodo de esgoto foi igual ao tratamento que recebeu adubação mineral, parece não haver diferenças entre as emissões de CO2 desses tratamentos. Para o N2O, quando se faz a comparação entre os tratamentos que foram concebidos para disponibilizar cerca de 75 kg N ha-1, observa-se que os valores de emissão de N2O na maioria das amostragens foram semelhantes. O tratamento que recebeu o dobro da dose de N via lodo de esgoto apresentou emissões de N2O superiores ao tratamento controle e adubação mineral. Com relação à emissão de metano para a atmosfera, não houve diferenças significativas entre os tratamentos. / The application of residues in agricultural soils can significantly change the dynamic of the element cycles into the soil, changing consequently its fertility, the plant nutrition and the soil gas fluxes to the atmosphere. The possibility of bio-fuel production from vegetable oils and the special care given to the castor bean at this time, make interest to this crop to re-start its cultivation in all country. Beside that, agricultural area near big urban centers, the use of residues in crop production is common and it is already incorporated, but there is still lack of knowledge of the process involved in relation to the behavior of these residues in the environment and as a source of nutrients for the crops. Taken in consideration what was written above, the present work was made aiming to evaluate the effect of three residues having different forms of nitrogen in the soil fertility and mineral nutrition of castor bean cultivated in a reform area of sugar cane, and also to quantify the gas fluxes of greenhouse effect (CO2, CH4 and N2O) in relation to the applied dose of sewage sludge or mineral fertilization of the soil before the castor bean plantation. Two experiments were carried out in the field in the agricultural year of 2004-2005. In the first it was evaluated the residues contribution as nitrogen source to the castor bean crop and it was conducted under one Ultisol (Argisolo Vermelho Amarelo distrófico) soil. The reference dose for nitrogen was 75 Kg ha-1 and the applied quantities of each residue were calculated in function of the content and the availability of N into the residues. The data have shown that the residues of organic origin (sewage sludge and Citrofer) constitute in an efficient source of N and for the equivalent dose or grater than the reference dose, the castor bean productivity was similar or higher than the mineral fertilization. In relation to the other parameters of production, the size of raceme and the number of fruits for the treatments that received N application via organic residues or mineral fertilization, did not differ statistically, but they were higher than the other treatments. The N was the nutrient that limited more the development and the productivity of castor bean. In the second experiment, it was evaluated the CO2, CH4 and N2O gas emission in the same area of the first experiment, but with treatments that received mineral fertilization and sewage sludge in three doses. The sewage sludge and the mineral fertilization changed the gas flow of CO2, CH4 and N2O. When the applied quantity of N via sewage sludge was equal to the mineral fertilization treatment seems that there was no difference between the CO2 emissions. For the N2O, when it was compared the treatments responsible to fulfill about 75 Kg ha-1 of N, it was observed that the values of N2O emission were similar for the great part of samples. The treatment that received the double dose of N via sewage sludge presented N2O emission higher than the control and the mineral fertilization treatments. All the treatments presented no difference for the methane emission to the atmosphere.

A aplicação de resíduos em solos agrícolas pode alterar significativamente a dinâmica do ciclo dos elementos no solo, conseqüentemente modificando sua fertilidade, a nutrição das plantas e os fluxos de gases do solo para a atmosfera. A possibilidade de produção de biocombustíveis a partir de óleos vegetais e com a atenção especial dada a cultura da mamona faz nesse momento com que o cultivo desta oleaginosa ressurja nacionalmente como cultura de interesse. Além disso, em áreas agrícolas próximas a grandes centros urbanos, a utilização agrícola de resíduos na agricultura é uma prática já empregada, porém ainda, sem o total conhecimento dos processos envolvidos em relação ao comportamento desses materiais no ambiente e seu real comportamento como fonte de nutrientes para as culturas. Em função do exposto, o presente trabalho foi realizado com o objetivo de avaliar os efeitos de três resíduos, contendo diferentes formas de N, na fertilidade do solo e nutrição mineral da mamona cultivada em área de reforma de canavial, bem como também quantificar os fluxos de gases do efeito estufa (CO2, CH4 e N2O) em função da aplicação de doses de um lodo de esgoto ou fertilização mineral no solo, antes do plantio da mamona. Assim, foram conduzidos dois experimentos a campo no ano agrícola de 2004-2005. No primeiro avaliou-se a contribuição de resíduos como fonte de N para a cultura da mamona e foi conduzido sob um Argissolo Vermelho-Amarelo distrófico. A dose de nitrogênio referencial foi de 75 kg ha-1 e as quantidades aplicadas de cada resíduo foram calculadas em função do conteúdo e disponibilidade do N nestes. Os dados obtidos mostram que os resíduos de origem orgânica (lodo de esgoto e Citrofer) constituíram-se numa fonte eficiente de N e para as doses equivalentes ou maiores que a referência, a produtividade da mamona foi igual ou superior a adubação mineral. Com relação a outros componentes de produção, o tamanho do racemo e nº de frutos para os tratamentos que receberam a aplicação de N via resíduos orgânicos ou a adubação mineral, não diferiram estatisticamente, mas foram superiores aos demais. O N foi o nutriente que mais limitou o desenvolvimento e produtividade da mamona. No segundo experimento avaliou-se a emissão dos gases CO2, CH4 e N2O na mesma área onde foi realizado o primeiro experimento, porém, foram avaliados os tratamentos que receberam adubação mineral e lodo de esgoto em três doses. Tanto a adição de lodo de esgoto como a adubação mineral alteraram os fluxos de CO2, N2O e CH4. Quando a quantidade de N aplicada via lodo de esgoto foi igual ao tratamento que recebeu adubação mineral, parece não haver diferenças entre as emissões de CO2 desses tratamentos. Para o N2O, quando se faz a comparação entre os tratamentos que foram concebidos para disponibilizar cerca de 75 kg N ha-1, observa-se que os valores de emissão de N2O na maioria das amostragens foram semelhantes. O tratamento que recebeu o dobro da dose de N via lodo de esgoto apresentou emissões de N2O superiores ao tratamento controle e adubação mineral. Com relação à emissão de metano para a atmosfera, não houve diferenças significativas entre os tratamentos. / The application of residues in agricultural soils can significantly change the dynamic of the element cycles into the soil, changing consequently its fertility, the plant nutrition and the soil gas fluxes to the atmosphere. The possibility of bio-fuel production from vegetable oils and the special care given to the castor bean at this time, make interest to this crop to re-start its cultivation in all country. Beside that, agricultural area near big urban centers, the use of residues in crop production is common and it is already incorporated, but there is still lack of knowledge of the process involved in relation to the behavior of these residues in the environment and as a source of nutrients for the crops. Taken in consideration what was written above, the present work was made aiming to evaluate the effect of three residues having different forms of nitrogen in the soil fertility and mineral nutrition of castor bean cultivated in a reform area of sugar cane, and also to quantify the gas fluxes of greenhouse effect (CO2, CH4 and N2O) in relation to the applied dose of sewage sludge or mineral fertilization of the soil before the castor bean plantation. Two experiments were carried out in the field in the agricultural year of 2004-2005. In the first it was evaluated the residues contribution as nitrogen source to the castor bean crop and it was conducted under one Ultisol (Argisolo Vermelho Amarelo distrófico) soil. The reference dose for nitrogen was 75 Kg ha-1 and the applied quantities of each residue were calculated in function of the content and the availability of N into the residues. The data have shown that the residues of organic origin (sewage sludge and Citrofer) constitute in an efficient source of N and for the equivalent dose or grater than the reference dose, the castor bean productivity was similar or higher than the mineral fertilization. In relation to the other parameters of production, the size of raceme and the number of fruits for the treatments that received N application via organic residues or mineral fertilization, did not differ statistically, but they were higher than the other treatments. The N was the nutrient that limited more the development and the productivity of castor bean. In the second experiment, it was evaluated the CO2, CH4 and N2O gas emission in the same area of the first experiment, but with treatments that received mineral fertilization and sewage sludge in three doses. The sewage sludge and the mineral fertilization changed the gas flow of CO2, CH4 and N2O. When the applied quantity of N via sewage sludge was equal to the mineral fertilization treatment seems that there was no difference between the CO2 emissions. For the N2O, when it was compared the treatments responsible to fulfill about 75 Kg ha-1 of N, it was observed that the values of N2O emission were similar for the great part of samples. The treatment that received the double dose of N via sewage sludge presented N2O emission higher than the control and the mineral fertilization treatments. All the treatments presented no difference for the methane emission to the atmosphere.