<p dir="ltr">Excess nitrogen loading to surface waters and groundwater from intensive agriculture threatens human and ecosystem health and economic prosperity within and downstream of the Mississippi River Basin. Restoring wetlands and floodplains reduces nitrogen export, but nitrogen export from the Mississippi River Basin remains elevated. Engineering restored wetlands and floodplains to have higher areal denitrification rates is necessary to advance toward nitrogen reduction goals. Environmental controls of denitrification in restored ecosystems must be further investigated to determine under what conditions denitrification is highest and to link these optimal conditions to restoration approaches. Yet, restoration efforts to reduce nitrogen export may inadvertently increase phosphorus export and greenhouse gas emissions. We evaluated different restoration design approaches and identified environmental controls of denitrification, phosphorus release, and greenhouse gas production to advance knowledge of how floodplain and wetland restorations can be designed and managed to maximize denitrification while also constraining phosphorus release and greenhouse gas production. Comparisons of different restoration design approaches in the Wabash River Basin in Indiana, U.S.A., demonstrated that a hydrologically connected floodplain with row crop agriculture provides limited N treatment. Floodplain restorations that involved structural modifications to enhance hydrologic connectivity supported higher denitrification than restorations that only reestablished native vegetation. Investigations of the plot- and field-scale drivers of denitrification indicated that enhanced hydrologic connectivity and specific native wetland and prairie vegetation types were associated with soil conditions that supported high denitrification potential, mainly sufficient soil moisture and bioavailable organic matter. These same soil conditions were associated with increased risks of phosphorus release and greenhouse gas production. However, artificial flooding experiments showed that preventing prolonged flooding has a strong potential to reduce phosphorus export from floodplains with limited impacts on nitrogen treatment. Microcosm experiments with plant litter and wetland soils indicated that certain wetland vegetation types may reduce greenhouse gas production without sacrificing nitrogen removal capacity based on differences in plant biomass composition.</p>

Currently, the cropping area is around 10 million hectares, in which the sugarcane fields are expanding for marginal regions, mainly where grains and pasture were previously cultivated. From that, the objectives of this study were: to calibrate and evaluate a sugarcane yield model using data from 12 fields conducted under high technology field conditions; to evaluate the performance of a gridded system (NASA/POWER) to increase the spatial density of the weather stations in Brazil, to be employed as input data of crop simulation models; to map, in micro-region scale, the potential (Yp), the best farmer\'s (Ybf) and average actual (Yavg) sugarcane yields in Brazil, in order to determine the sugarcane yield gaps by water deficit (YGWD) and by crop management (YGCM), and to define strategies for a most sustainable sugarcane crop production. The yield model showed a good performance in the yield simulation, during the calibration and validation phases. The estimated yield in the calibration phase was 81.9 Mg ha-1 while the observed one was 82.3 Mg ha-1. In the validation phase, the estimated yield was 82.9 Mg ha-1 and the observed was 86.9 Mg ha-1. These results suggested that this kind of model can be used for yield estimation, mainly for agricultural planning purposes, at regional and national scales. The NASA/POWER weather data showed a reasonable performance when compared to observed data that control Yp (solar radiation and air temperature). On the other hand, although the annual average rainfall were very similar in all locations evaluated, this variable presented unsatisfactory statistical coefficients (R2 = 0.60 and MAPE = 233.4%), being suggested, therefore, to replacement of rainfall data from the gridded system by the ones from local rainfall stations (ANA). In the majority of the locations, the percentage errors of Yp were ±15%, while the attainable yield was overestimated by 14% when estimated without replace the rainfall data by the ANA\'s data. Otherwise, when the rainfall data were modified by the ones from ANA, a better adjustment was obtained, revealing an overestimation of only 5%. Finally, 259 virtual weather stations were generated with NASA/POWER data and rainfall from ANA database to estimate yields. The yield types were spatialized through software ArcGis 9.3&reg; at micro-region level. The yield gaps by water deficit and crop management were determined. It was observed that the sugarcane yield losses in Brazil are mainly caused by water deficit (74% of total yield gap), while 26% was due crop management. These results contribute for a better understanding about the factors that control sugarcane production and, therefore, they can be used to define strategies, such use of drought tolerant cultivars, irrigation, and soil decompaction, to make sugarcane production in Brazil more efficient and sustainable. / Atualmente, a cana de açúcar ocupa uma área de aproximadamente 10 milhões de hectares, revelando um pronunciado avanço dos canaviais para regiões marginais, onde anteriormente predominavam os cultivos de grãos e pastagens. Assim, os objetivos deste estudo foram calibrar e avaliar um modelo de estimativa da produtividade de colmos da cana de açúcar em 12 locais, sob elevado padrão tecnológico e operacional de cultivo; avaliar o desempenho de um sistema de dados meteorológicos em grid (NASA/POWER, 1°x1°) para incrementar a densidade espacial de estações meteorológicas no Brasil para serem empregados em modelos de simulação de culturas; e mapear, a produtividade potencial (Yp), a produtividade obtida pelos produtores com elevado nível tecnológico (Ybf) e a produtividade real média (Yavg) de colmos no Brasil, para, posteriormente, determinar a quebra de produtividade da cana de açúcar decorrente do déficit hídrico (YGWD) e do manejo da cultura (YGCM), a fim de indicar estratégias para um cultivo mais sustentável. O modelo agrometeorológico de estimativa apresentou desempenho satisfatório na simulação das produtividades, tanto na fase de calibração como na validação. A produtividade estimada na calibração foi de 81.9 Mg ha-1 enquanto que a observada foi 82.3 Mg ha-1. Na validação, a produtividade estimada foi 82,9 Mg ha-1 e a observada foi 86,9 Mg ha-1. Esses resultados sugerem a possibilidade do emprego desse modelo para a estimativa da produtividade da cultura da cana-de-açúcar, principalmente em termos de planejamento agrícola em média e grande escalas. O sistema NASA/POWER apresentou desempenho satisfatório em relação às variáveis meteorológicas que controlam a Yp (radiação solar e temperatura do ar). Por outro lado, embora os totais anuais de precipitação tenham sido bastante semelhantes, a precipitação apresentou coeficientes estatísticos apenas razoáveis, principalmente para aplicações em modelos de simulação da produtividade (R2 = 0,60 e MAPE = 233,4%), sendo sugerido, portanto, o uso de dados dessa variável provenientes de estações pluviométricas locais. Na grande maioria dos locais avaliados o erro percentual da produtividade potencial variou entre ±15%, enquanto que a produtividade atingível foi superestimada em 14% quando esta foi estimada com os dados de precipitação do sistema NASA/POWER. Por outro lado, quando os dados de precipitação foram modificados pelos dados de estações pluviométricas da ANA, houve apenas 5% de superestimativa da produtividade. Por fim, foram geradas 259 estações meteorológicas virtuais com os dados do sistema NASA/POWER e a precipitação das estações pluviométricas da ANA. Posteriormente, os yield gaps por efeito do déficit hídrico e do manejo da cultura foram determinados. Os resultados indicaram que o principal fator restritivo da produtividade da cana de açúcar no Brasil é o déficit hídrico (74% do YG total), enquanto que as práticas de manejo da cultura sub-ótimas contribuem com 26% da quebra total. Isso contribuiu para um melhor entendimento dos aspectos que afetam a produção de cana de açúcar em diferentes regiões brasileiras, sendo, portanto, possível se delimitar estratégias, como o uso de cultivares tolerantes à seca, a irrigação e a descompactação dos solos, que tornem a cultura mais resiliente e produção canavieira mais eficiente e sustentável.

Realizar a análise econômica de uma produção agropecuária não é algo trivial, seja pela enorme heterogeneidade entre cada unidade produtiva, seja porque utiliza muitos recursos naturais, alguns de difícil mensuração. Há diversos métodos disponíveis para o cálculo do custo de produção, que é o indicador chave para a análise da viabilidade de um empreendimento. O desafio é permitir que a projeção da atividade no horizonte produtivo seja a mais real e dinâmica possível. A simulação computacional é atualmente uma das mais poderosas ferramentas de análise disponível para o planejamento, projeto e controle de sistemas complexos, e vem sendo cada vez mais utilizada e difundida. Simular compreende a elaboração de um método de experimentação que, através da construção de modelos de um sistema real, procura descrever comportamentos, construir teorias ou hipóteses por meio do observado e predizer comportamentos futuros. O uso de modelos de simulação, que incorporem o risco e a probabilidade dentro produção animal, pode ser uma alternativa tanto técnica - auxiliando na tomada de decisão, gestão e planejamento pecuário, quanto científica - permitindo a avaliação de efeitos de resultados da pesquisa e identificação de limitantes que podem incentivar o desenvolvimento de pesquisas futuras. O modelo de simulação híbrido - baseado em simulação de eventos discretos e baseado em agentes, aqui proposto - visou identificar coeficientes zootécnicos e os critérios de manejo que mais impactam a produção de ovinos de corte. Esse modelo de simulação computacional híbrido possui caráter dinâmico e probabilístico, com eventos marcados no tempo (estação de monta, gestação, parição, desmame, engorda, abate, entre outras) e complexos o suficiente para que seus agentes sofram alterações tanto no tempo quanto em resposta a ocorrência ou não das variáveis ligadas a eles. Os resultados dos experimentos e dos cenários estudados revelaram que dentre os índices zootécnicos das matrizes, a ocorrência de aborto gera maior impacto na taxa de abate e financeiramente na margem líquida operacional. Contudo, analisando as variáveis tanto para matrizes como para cordeiros, a mortalidade neonatal, até os cinco dias de vida dos cordeiros, demonstrou ser o ponto fundamental para a lucratividade da atividade. A estabilização do rebanho foi mais afetada pela presença de matrizes adultas no plantel, que culminaram no aumento no número de cordeiros por matriz. Os resultados da análise dos fluxos de caixa de 30 anos, a uma taxa mínima de atratividade de 6,17% aa, permitiram constatar que iniciar a atividade com número muito reduzido de matrizes é o cenário menos interessantes, com taxa interna de retorno negativa para o período de análise. O estudo do fluxo de caixa permitiu atribuir a 200 matrizes como o tamanho de rebanho inicial mais interessante (TIR = 3,30% aa). Assim, o uso de simuladores híbridos baseados em simulação de eventos discretos e baseados em agentes, para estudos na pecuária nacional, apresentou-se como ferramenta com grande potencial de contribuição, no sentido de permitir conhecer os resultados possíveis das diferentes combinações tecnológicas disponíveis. O modelo ainda permite ser utilizado como ferramenta de estudo e análise para a cadeia produtiva, contribuindo na orientação aos cientistas, auxiliando no direcionamento de seus esforços no desenvolvimento de futuras pesquisas / Conduct an economic analysis of agricultural production is not trivial, either by its enormous heterogeneity between each production unit, or because it uses many natural resources, some of which are difficult to measure. There are several methods available for calculating the cost of production, which is the key indicator for assessing the feasibility of a project. The challenge is to allow the projection of activity in the productive horizon in the most real and dynamic form as possible. The computer simulation is currently one of the most powerful analysis tools available for planning, design and control of complex systems and is being increasingly used and disseminated. Simulate includes the development of a method of testing by building models of a real system, that seeks to describe behaviors, build theories or hypotheses through noted and predicted future behaviors. The use of simulation models that incorporate uncertainty and probability in animal production can be both an alternative technique - assisting in decision-making, management and livestock planning; as scientific - allowing the evaluation of the research results of effects and identification of limiting that may encourage the development of future research. The model of hybrid simulation - based on discrete event simulation and on agent-based, proposed here - aimed to identify factors husbandry and management criteria that most affect the production of meat sheep. The model of hybrid computer simulation have dynamic and probabilistic characteristics, with events scheduled in time (breeding season, pregnancy, parturition, weaning, fattening, slaughter, etc.) and enough complexity that its agents be adversely affected both in time and in response to the occurrence or not of variables linked to them. The results of the experiments and the scenarios studied showed that among the zootechnical indexes of the sheep, the occurrence of abortion generates a greater impact on the slaughter rate and financially in the net operating margin. However, analyzing the variables for both sheep and lambs, neonatal mortality, up to the lambs\' five days of life, proved to be the fundamental point for the profitability of the activity. The stabilization of the herd was more affected by the presence of adult sheep in the herd, which culminated increasing the number of lambs per sheep. The results of the analysis of the 30-year cash flows, at a minimum attractiveness rate of 6.17% per year, showed that starting the activity with a very small number of sheep was the least interesting scenario, with a negative internal rate of return for the analysis period. The study of the cash flow allowed to assign to 200 sheep as the most interesting initial herd size (IRR = 3.30% per year). Thus, the use of hybrid simulators, based on discrete event simulation and agent-based for studies in national livestock, is presented as a tool with great potential to contribute, to allow knowing the possible outcomes of different combinations of available technology. The model also allows to be used as a study tool and assessment of different technological combinations for the production chain, contributing to the guidance of scientists, assisting their efforts in the development of future research

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A avaliação da qualidade dos solos e a redução da Mata Atlântica tem sido alvo de diversas pesquisas no Brasil e no mundo, principalmente quando estes estão atrelados ao recorte espacial de Unidades de Conservação. No entanto, tem sido difícil para os gestores dessas unidades a avaliação dos impactos ambientais gerados ao longo dos anos nas bacias hidrográficas, principalmente pela falta de investimentos. Esta dissertação teve por objetivo geral avaliar o atual estágio de degradação da bacia hidrográfica do Córrego da Caçada pertencente à Área de Proteção Ambiental Federal de Cairuçu, no município de Paraty RJ, analisando quantitativamente e qualitativamente a redução dos fragmentos de Mata Atlântica e estabelecendo relações com a degradação física e química dos solos dentro e fora dos fragmentos florestais. A metodologia utilizada para a redução ou avanço dos fragmentos de Mata Atlântica baseou-se no uso de fotografias aéreas do ano de 1956 e imagens de satélite de 2012, onde possibilitou a avaliação espaço-temporal do uso e cobertura das terras, através da produção de um mapa temático final. Além disso, foram elaborados mapas temáticos de reconhecimento da área de estudo, como o de hipsometria, de declividade, de orientação e forma das encostas, além da geração de perfis topográficos. Para a avaliação da qualidade física, química e biológica dos solos foram determinadas as curvas de distribuição granulométrica, a densidade relativa dos grãos sólidos e a densidade aparente, porosidade total, os limites de liquidez e plasticidade, a estabilidade dos agregados em água, análises morfológicas, a saturação de bases, a capacidade de troca catiônica (CTC), a saturação por alumínio, fósforo, pH e o carbono orgânico. Para tal, foi realizada a abertura de três perfis, sendo um em área de fragmento florestal e dois em áreas de pasto. O resultado das análises permitiu, segundo a Sociedade Brasileira de Ciência do solo, a classificação de dois tipos de solos na bacia, sendo: Cambissolo Háplico Tb Distrófico Típico em área fragmento florestal e em área de pasto, e um Latossolo Amarelo Tb Distrófico Típico em área de pasto. Os resultados de laboratório mostraram que os solos avaliados têm baixa fertilidade e valores variados nos resultados de física do solo. No entanto, além do histórico de uso do solo caracterizado pelas práticas rudimentares do manejo empregado pelos Caiçaras, o clima predominante na região possibilita um regime pluviométrico anual que passa dos 2.000mm de chuva/ano, caracterizando solos muito lixiviados e pobres quimicamente. Portanto, conclui-se que a relação das propriedades físicas e químicas avaliadas junto ao manejo inadequado ao longo dos anos tem apresentado um cenário de grandes dificuldades para a recuperação florestal na bacia hidrográfica do Córrego da Caçada, o que mostra a importância da avaliação dos impactos ambientais não só pelo recorte de bacias hidrográficas, como contextualizar seu posicionamento dentro de Unidades de Conservação, com legislações e objetivos específicos. / Evaluation of soil quality and the reduction of the Atlantic Forest has been the subject of several studies in Brazil and abroad, especially when these are linked to the spatial area of protected areas. However, it has been difficult for managers of these units the assessment of environmental impacts over the years in river basins, mainly by lack of investment. This work had as main objective to assess the current watershed degradation stage Hunt Stream belonging to the Federal Environmental Protection Area Cairuçu in the municipality of Paraty - RJ, analyzing qualitatively and quantitatively the reduction of Atlantic Forest fragments and establishing relationships with physical and chemical degradation of soil in and out of the forest fragments. The methodology used for the reduction or advancement of Atlantic Forest fragments was based on air use of photographs of the 1956 and 2012 satellite images, which enabled the evaluation space-use and coverage of land, by producing a final thematic map. In addition, thematic maps were prepared to recognize the study area, such as hypsometry, slope, orientation and shape of the slopes, as well as generating topographic profiles. For assessing the physical, chemical and biological soil were determined particle size distribution curves, the relative density of the solid grains and bulk density, total porosity, the limits of liquidity and plasticity, the stability of water in aggregate, morphological analysis , base saturation, the cation exchange capacity (CEC), saturation of aluminum, phosphorus, pH and organic carbon. To do this, the opening of three profiles was conducted, one in forest fragment area and two in pasture areas. The results of the analysis allowed, according to the Brazilian Society of Soil Science, the classification of two types of soils in the basin, as follows: Cambisol Tb dystrophic Typical in forest fragment area and pasture area, and an Oxisoil Tb dystrophic Typical in pasture area. The laboratory results showed that reviews have low soil fertility and various amounts of soil in physical results. However, besides the history of land use characterized by rudimentary management practices employed by Caiçaras, the prevailing mood in the region provides an annual rainfall of rain passing 2.000mm / year, featuring very leached soils and poor chemically. Therefore, it is concluded that the relationship of the physical and chemical properties evaluated by the inadequate management over the years has presented a scene of great difficulty for forest restoration in the basin of Stream of Hunt, which shows the importance of impact assessment environment not only for crop watersheds, as contextualize its positioning within protected areas, with legislation and specific objectives.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A avaliação da qualidade dos solos e a redução da Mata Atlântica tem sido alvo de diversas pesquisas no Brasil e no mundo, principalmente quando estes estão atrelados ao recorte espacial de Unidades de Conservação. No entanto, tem sido difícil para os gestores dessas unidades a avaliação dos impactos ambientais gerados ao longo dos anos nas bacias hidrográficas, principalmente pela falta de investimentos. Esta dissertação teve por objetivo geral avaliar o atual estágio de degradação da bacia hidrográfica do Córrego da Caçada pertencente à Área de Proteção Ambiental Federal de Cairuçu, no município de Paraty RJ, analisando quantitativamente e qualitativamente a redução dos fragmentos de Mata Atlântica e estabelecendo relações com a degradação física e química dos solos dentro e fora dos fragmentos florestais. A metodologia utilizada para a redução ou avanço dos fragmentos de Mata Atlântica baseou-se no uso de fotografias aéreas do ano de 1956 e imagens de satélite de 2012, onde possibilitou a avaliação espaço-temporal do uso e cobertura das terras, através da produção de um mapa temático final. Além disso, foram elaborados mapas temáticos de reconhecimento da área de estudo, como o de hipsometria, de declividade, de orientação e forma das encostas, além da geração de perfis topográficos. Para a avaliação da qualidade física, química e biológica dos solos foram determinadas as curvas de distribuição granulométrica, a densidade relativa dos grãos sólidos e a densidade aparente, porosidade total, os limites de liquidez e plasticidade, a estabilidade dos agregados em água, análises morfológicas, a saturação de bases, a capacidade de troca catiônica (CTC), a saturação por alumínio, fósforo, pH e o carbono orgânico. Para tal, foi realizada a abertura de três perfis, sendo um em área de fragmento florestal e dois em áreas de pasto. O resultado das análises permitiu, segundo a Sociedade Brasileira de Ciência do solo, a classificação de dois tipos de solos na bacia, sendo: Cambissolo Háplico Tb Distrófico Típico em área fragmento florestal e em área de pasto, e um Latossolo Amarelo Tb Distrófico Típico em área de pasto. Os resultados de laboratório mostraram que os solos avaliados têm baixa fertilidade e valores variados nos resultados de física do solo. No entanto, além do histórico de uso do solo caracterizado pelas práticas rudimentares do manejo empregado pelos Caiçaras, o clima predominante na região possibilita um regime pluviométrico anual que passa dos 2.000mm de chuva/ano, caracterizando solos muito lixiviados e pobres quimicamente. Portanto, conclui-se que a relação das propriedades físicas e químicas avaliadas junto ao manejo inadequado ao longo dos anos tem apresentado um cenário de grandes dificuldades para a recuperação florestal na bacia hidrográfica do Córrego da Caçada, o que mostra a importância da avaliação dos impactos ambientais não só pelo recorte de bacias hidrográficas, como contextualizar seu posicionamento dentro de Unidades de Conservação, com legislações e objetivos específicos. / Evaluation of soil quality and the reduction of the Atlantic Forest has been the subject of several studies in Brazil and abroad, especially when these are linked to the spatial area of protected areas. However, it has been difficult for managers of these units the assessment of environmental impacts over the years in river basins, mainly by lack of investment. This work had as main objective to assess the current watershed degradation stage Hunt Stream belonging to the Federal Environmental Protection Area Cairuçu in the municipality of Paraty - RJ, analyzing qualitatively and quantitatively the reduction of Atlantic Forest fragments and establishing relationships with physical and chemical degradation of soil in and out of the forest fragments. The methodology used for the reduction or advancement of Atlantic Forest fragments was based on air use of photographs of the 1956 and 2012 satellite images, which enabled the evaluation space-use and coverage of land, by producing a final thematic map. In addition, thematic maps were prepared to recognize the study area, such as hypsometry, slope, orientation and shape of the slopes, as well as generating topographic profiles. For assessing the physical, chemical and biological soil were determined particle size distribution curves, the relative density of the solid grains and bulk density, total porosity, the limits of liquidity and plasticity, the stability of water in aggregate, morphological analysis , base saturation, the cation exchange capacity (CEC), saturation of aluminum, phosphorus, pH and organic carbon. To do this, the opening of three profiles was conducted, one in forest fragment area and two in pasture areas. The results of the analysis allowed, according to the Brazilian Society of Soil Science, the classification of two types of soils in the basin, as follows: Cambisol Tb dystrophic Typical in forest fragment area and pasture area, and an Oxisoil Tb dystrophic Typical in pasture area. The laboratory results showed that reviews have low soil fertility and various amounts of soil in physical results. However, besides the history of land use characterized by rudimentary management practices employed by Caiçaras, the prevailing mood in the region provides an annual rainfall of rain passing 2.000mm / year, featuring very leached soils and poor chemically. Therefore, it is concluded that the relationship of the physical and chemical properties evaluated by the inadequate management over the years has presented a scene of great difficulty for forest restoration in the basin of Stream of Hunt, which shows the importance of impact assessment environment not only for crop watersheds, as contextualize its positioning within protected areas, with legislation and specific objectives.

Currently, the cropping area is around 10 million hectares, in which the sugarcane fields are expanding for marginal regions, mainly where grains and pasture were previously cultivated. From that, the objectives of this study were: to calibrate and evaluate a sugarcane yield model using data from 12 fields conducted under high technology field conditions; to evaluate the performance of a gridded system (NASA/POWER) to increase the spatial density of the weather stations in Brazil, to be employed as input data of crop simulation models; to map, in micro-region scale, the potential (Yp), the best farmer\'s (Ybf) and average actual (Yavg) sugarcane yields in Brazil, in order to determine the sugarcane yield gaps by water deficit (YGWD) and by crop management (YGCM), and to define strategies for a most sustainable sugarcane crop production. The yield model showed a good performance in the yield simulation, during the calibration and validation phases. The estimated yield in the calibration phase was 81.9 Mg ha-1 while the observed one was 82.3 Mg ha-1. In the validation phase, the estimated yield was 82.9 Mg ha-1 and the observed was 86.9 Mg ha-1. These results suggested that this kind of model can be used for yield estimation, mainly for agricultural planning purposes, at regional and national scales. The NASA/POWER weather data showed a reasonable performance when compared to observed data that control Yp (solar radiation and air temperature). On the other hand, although the annual average rainfall were very similar in all locations evaluated, this variable presented unsatisfactory statistical coefficients (R2 = 0.60 and MAPE = 233.4%), being suggested, therefore, to replacement of rainfall data from the gridded system by the ones from local rainfall stations (ANA). In the majority of the locations, the percentage errors of Yp were ±15%, while the attainable yield was overestimated by 14% when estimated without replace the rainfall data by the ANA\'s data. Otherwise, when the rainfall data were modified by the ones from ANA, a better adjustment was obtained, revealing an overestimation of only 5%. Finally, 259 virtual weather stations were generated with NASA/POWER data and rainfall from ANA database to estimate yields. The yield types were spatialized through software ArcGis 9.3&reg; at micro-region level. The yield gaps by water deficit and crop management were determined. It was observed that the sugarcane yield losses in Brazil are mainly caused by water deficit (74% of total yield gap), while 26% was due crop management. These results contribute for a better understanding about the factors that control sugarcane production and, therefore, they can be used to define strategies, such use of drought tolerant cultivars, irrigation, and soil decompaction, to make sugarcane production in Brazil more efficient and sustainable. / Atualmente, a cana de açúcar ocupa uma área de aproximadamente 10 milhões de hectares, revelando um pronunciado avanço dos canaviais para regiões marginais, onde anteriormente predominavam os cultivos de grãos e pastagens. Assim, os objetivos deste estudo foram calibrar e avaliar um modelo de estimativa da produtividade de colmos da cana de açúcar em 12 locais, sob elevado padrão tecnológico e operacional de cultivo; avaliar o desempenho de um sistema de dados meteorológicos em grid (NASA/POWER, 1°x1°) para incrementar a densidade espacial de estações meteorológicas no Brasil para serem empregados em modelos de simulação de culturas; e mapear, a produtividade potencial (Yp), a produtividade obtida pelos produtores com elevado nível tecnológico (Ybf) e a produtividade real média (Yavg) de colmos no Brasil, para, posteriormente, determinar a quebra de produtividade da cana de açúcar decorrente do déficit hídrico (YGWD) e do manejo da cultura (YGCM), a fim de indicar estratégias para um cultivo mais sustentável. O modelo agrometeorológico de estimativa apresentou desempenho satisfatório na simulação das produtividades, tanto na fase de calibração como na validação. A produtividade estimada na calibração foi de 81.9 Mg ha-1 enquanto que a observada foi 82.3 Mg ha-1. Na validação, a produtividade estimada foi 82,9 Mg ha-1 e a observada foi 86,9 Mg ha-1. Esses resultados sugerem a possibilidade do emprego desse modelo para a estimativa da produtividade da cultura da cana-de-açúcar, principalmente em termos de planejamento agrícola em média e grande escalas. O sistema NASA/POWER apresentou desempenho satisfatório em relação às variáveis meteorológicas que controlam a Yp (radiação solar e temperatura do ar). Por outro lado, embora os totais anuais de precipitação tenham sido bastante semelhantes, a precipitação apresentou coeficientes estatísticos apenas razoáveis, principalmente para aplicações em modelos de simulação da produtividade (R2 = 0,60 e MAPE = 233,4%), sendo sugerido, portanto, o uso de dados dessa variável provenientes de estações pluviométricas locais. Na grande maioria dos locais avaliados o erro percentual da produtividade potencial variou entre ±15%, enquanto que a produtividade atingível foi superestimada em 14% quando esta foi estimada com os dados de precipitação do sistema NASA/POWER. Por outro lado, quando os dados de precipitação foram modificados pelos dados de estações pluviométricas da ANA, houve apenas 5% de superestimativa da produtividade. Por fim, foram geradas 259 estações meteorológicas virtuais com os dados do sistema NASA/POWER e a precipitação das estações pluviométricas da ANA. Posteriormente, os yield gaps por efeito do déficit hídrico e do manejo da cultura foram determinados. Os resultados indicaram que o principal fator restritivo da produtividade da cana de açúcar no Brasil é o déficit hídrico (74% do YG total), enquanto que as práticas de manejo da cultura sub-ótimas contribuem com 26% da quebra total. Isso contribuiu para um melhor entendimento dos aspectos que afetam a produção de cana de açúcar em diferentes regiões brasileiras, sendo, portanto, possível se delimitar estratégias, como o uso de cultivares tolerantes à seca, a irrigação e a descompactação dos solos, que tornem a cultura mais resiliente e produção canavieira mais eficiente e sustentável.

Realizar a análise econômica de uma produção agropecuária não é algo trivial, seja pela enorme heterogeneidade entre cada unidade produtiva, seja porque utiliza muitos recursos naturais, alguns de difícil mensuração. Há diversos métodos disponíveis para o cálculo do custo de produção, que é o indicador chave para a análise da viabilidade de um empreendimento. O desafio é permitir que a projeção da atividade no horizonte produtivo seja a mais real e dinâmica possível. A simulação computacional é atualmente uma das mais poderosas ferramentas de análise disponível para o planejamento, projeto e controle de sistemas complexos, e vem sendo cada vez mais utilizada e difundida. Simular compreende a elaboração de um método de experimentação que, através da construção de modelos de um sistema real, procura descrever comportamentos, construir teorias ou hipóteses por meio do observado e predizer comportamentos futuros. O uso de modelos de simulação, que incorporem o risco e a probabilidade dentro produção animal, pode ser uma alternativa tanto técnica - auxiliando na tomada de decisão, gestão e planejamento pecuário, quanto científica - permitindo a avaliação de efeitos de resultados da pesquisa e identificação de limitantes que podem incentivar o desenvolvimento de pesquisas futuras. O modelo de simulação híbrido - baseado em simulação de eventos discretos e baseado em agentes, aqui proposto - visou identificar coeficientes zootécnicos e os critérios de manejo que mais impactam a produção de ovinos de corte. Esse modelo de simulação computacional híbrido possui caráter dinâmico e probabilístico, com eventos marcados no tempo (estação de monta, gestação, parição, desmame, engorda, abate, entre outras) e complexos o suficiente para que seus agentes sofram alterações tanto no tempo quanto em resposta a ocorrência ou não das variáveis ligadas a eles. Os resultados dos experimentos e dos cenários estudados revelaram que dentre os índices zootécnicos das matrizes, a ocorrência de aborto gera maior impacto na taxa de abate e financeiramente na margem líquida operacional. Contudo, analisando as variáveis tanto para matrizes como para cordeiros, a mortalidade neonatal, até os cinco dias de vida dos cordeiros, demonstrou ser o ponto fundamental para a lucratividade da atividade. A estabilização do rebanho foi mais afetada pela presença de matrizes adultas no plantel, que culminaram no aumento no número de cordeiros por matriz. Os resultados da análise dos fluxos de caixa de 30 anos, a uma taxa mínima de atratividade de 6,17% aa, permitiram constatar que iniciar a atividade com número muito reduzido de matrizes é o cenário menos interessantes, com taxa interna de retorno negativa para o período de análise. O estudo do fluxo de caixa permitiu atribuir a 200 matrizes como o tamanho de rebanho inicial mais interessante (TIR = 3,30% aa). Assim, o uso de simuladores híbridos baseados em simulação de eventos discretos e baseados em agentes, para estudos na pecuária nacional, apresentou-se como ferramenta com grande potencial de contribuição, no sentido de permitir conhecer os resultados possíveis das diferentes combinações tecnológicas disponíveis. O modelo ainda permite ser utilizado como ferramenta de estudo e análise para a cadeia produtiva, contribuindo na orientação aos cientistas, auxiliando no direcionamento de seus esforços no desenvolvimento de futuras pesquisas / Conduct an economic analysis of agricultural production is not trivial, either by its enormous heterogeneity between each production unit, or because it uses many natural resources, some of which are difficult to measure. There are several methods available for calculating the cost of production, which is the key indicator for assessing the feasibility of a project. The challenge is to allow the projection of activity in the productive horizon in the most real and dynamic form as possible. The computer simulation is currently one of the most powerful analysis tools available for planning, design and control of complex systems and is being increasingly used and disseminated. Simulate includes the development of a method of testing by building models of a real system, that seeks to describe behaviors, build theories or hypotheses through noted and predicted future behaviors. The use of simulation models that incorporate uncertainty and probability in animal production can be both an alternative technique - assisting in decision-making, management and livestock planning; as scientific - allowing the evaluation of the research results of effects and identification of limiting that may encourage the development of future research. The model of hybrid simulation - based on discrete event simulation and on agent-based, proposed here - aimed to identify factors husbandry and management criteria that most affect the production of meat sheep. The model of hybrid computer simulation have dynamic and probabilistic characteristics, with events scheduled in time (breeding season, pregnancy, parturition, weaning, fattening, slaughter, etc.) and enough complexity that its agents be adversely affected both in time and in response to the occurrence or not of variables linked to them. The results of the experiments and the scenarios studied showed that among the zootechnical indexes of the sheep, the occurrence of abortion generates a greater impact on the slaughter rate and financially in the net operating margin. However, analyzing the variables for both sheep and lambs, neonatal mortality, up to the lambs\' five days of life, proved to be the fundamental point for the profitability of the activity. The stabilization of the herd was more affected by the presence of adult sheep in the herd, which culminated increasing the number of lambs per sheep. The results of the analysis of the 30-year cash flows, at a minimum attractiveness rate of 6.17% per year, showed that starting the activity with a very small number of sheep was the least interesting scenario, with a negative internal rate of return for the analysis period. The study of the cash flow allowed to assign to 200 sheep as the most interesting initial herd size (IRR = 3.30% per year). Thus, the use of hybrid simulators, based on discrete event simulation and agent-based for studies in national livestock, is presented as a tool with great potential to contribute, to allow knowing the possible outcomes of different combinations of available technology. The model also allows to be used as a study tool and assessment of different technological combinations for the production chain, contributing to the guidance of scientists, assisting their efforts in the development of future research

Soil and agricultural management practices (AMP) that are able to provide for an increasing population while meeting environmental existential challenges have gained considerable attention in recent times. Such AMP influence the soil profile and hydrological components for varying depths and patterns, depending on site-specific and environmental conditions. Though it is well known that management-induced changes of soil structure have consequences on soil hydraulic properties (SHP) and water fluxes, their dynamics through a season or on a long-term basis are hardly studied. Typically, an invariant soil pore system is assumed when modeling the transport of water and solutes in the soil system which leads to incorrect predictions of the dynamics of water balance components. Ultimately, this may lead to poor decision making and mismanagement of environmental resources. Hence, the present study quantifies the dynamics of SHP from existing studies and evaluates a model that is able to capture soil pore space dynamics following tillage. The objectives were to (1) investigate the quantitative effects of agricultural practices on soil structure and hydraulic properties and the subsequent response of the water balance components (2) evaluate a pore space evolution model for its capability in predicting the evolution of soil pore size distribution (PSD) for two cases: a) when there is a change in the tillage regime and/or land-use change b) in the months following tillage (3) derive corresponding soil water retention and hydraulic conductivity functions to incorporate them in hydrological models To achieve these objectives, first, a review of contemporary literature was undertaken to analyze the impacts of anthropogenic and environmental influences on SHP. The analysis indicated the relevance of studying temporal alterations of soil structure and SHP. Thereafter, a numerical model was evaluated for its ability to capture the dynamics of soil pore space with respect to time and pore radius using water retention parameter data sets from different parts of the world. The physically based coefficients of the model simulated the processes that were expected to occur after tillage. Furthermore, saturated hydraulic conductivity was obtained from the initial and final pore size distributions. Using the final pore size distribution curve and water retention function, the hydraulic conductivity function was also derived. The resulting water retention and hydraulic conductivity curves can directly be used as input in hydrological modeling studies. The results of the literature review indicate that, generally, soils show an abundance of large pores immediately after tillage. Those pores are not stable with time mainly due to precipitation and biological activity. Saturated hydraulic conductivity decreases in periods of rainfall along with the number of macropores and the overall porosity. Thus, the infiltration rates and capacities also decrease. However, the results of existing studies cannot be generalized owing to discrepancies in the dynamics of SHP, infiltration rates and soil moisture dynamics for soils under similar agricultural management practices. They are attributed mainly to a lack of standardization of research methodology as well as to site-specific conditions. Furthermore, it was also seen that incorporating the temporal dynamics of SHP in hydrological models produce more reliable and accurate modeling outcomes in comparison to studies with constant SHP as model input. The evaluation of the pore evolution model illustrated its suitability in capturing the temporal dynamics of soil pore space in response to tillage and environmental influences. High effective rainfalls and plant growth stages at which measurements were done affected the model performance. The use of sink/source terms and providing new initial conditions after high intensity rainfall events were provided as a means to improve the modeling outcomes. Though the model performed quite well in obtaining the water retention function as well as the saturated hydraulic conductivity and hydraulic conductivity functions, the high spatial variability in the sampling sites hampered with the model output. However, the main limitation lay in the lack of availability of sufficient data sets to calibrate and validate the model and its coefficients as well as for the derivation of SHP from the model. Overall, this study is a forerunner in predicting the temporal dynamics of soil structure and hydraulic properties. The established dynamics in the water retention and hydraulic conductivity functions can be used in hydrological simulations for planning land-use and management measures. The current study also reveals the need for more measurements and data sets that capture the alterations in soil hydraulic properties on a long-term basis.

Des données synchroniques de sols observées pendant 20 à 40 ans dans différentes zones agro-écologiques du Togo ont été utilisées pour analyser l’évolution de la fertilité du sol sous différentes pratiques culturales. Trois modèles de complexité croissante d’évolution du stock de C du sol ont été testés et le plus performant a été couplé au modèle QUEFTS pour apprécier l’effet des pratiques culturales sur l’évolution de cette fertilité. Bien que la fertilisation NPK ait été continuellement appliquée à la dose recommandée par la recherche (RR) ou à cette dose augmentée de 50% (1.5RR), les rendements initiaux de 1,5 à 2 t ha-1 pour le coton et 2 à 3 t ha-1 pour les céréales ont baissé pour ne représenter qu’environ 1 t ha-1 après 20 années de culture. L’alternance de 2 ou 3 années consécutives de jachère à la rotation culturale n’a pas amélioré le rendement des cultures, mais tend à stabiliser la production dans le long terme. Les stocks initiaux de C de 15 à 39 t ha-1 ont fortement baissé durant les premières années et ont atteint un équilibre après seulement 10 à 15 ans de culture. La baisse du stock de C a été peu dépendante de la quantité de C retournant au sol et a été mieux décrite avec le modèle à deux compartiments de C. Le taux de minéralisation de la fraction labile de C varie entre 0,15 et 0,24 et le stock de C stable représente 33-67% du stock initial ; pour une quantité de C ayant résisté à l’hydrolyse acide de 30% du stock initial. Les stocks de N du sol ont fortement baissé et cette baisse a été peu dépendante de la dose de fertilisation minérale. L’apport NPK à 1.5RR pendant 20 ans a contribué significativement à la baisse du pH du sol, puis a accentué de 20 et 40% les baisses respectives des concentrations de Ca et Mg. Nous avons conclu que l’apport de Ca/Mg couplé à celui de NPK à la dose RR serait (plus que le surdosage de P et K) une meilleure option pour gérer la fertilité minérale de ces sols. Le labour minimum, associé aux apports externes de C, devrait permettre de mieux gérer leur fertilité organique. / Using data observed during 20 to 40 years in different agro-ecosystems of Togo, we analyzed soil fertility dynamic under different agricultural management practices. Tree soil C models of varying complexity were tested, and the most accurate in terms of soil C dynamics description in these tropical soils was associated with the QUEFTS model and with nutrient partial balance to analyze the effect of each agricultural management practice. Results indicated that, although fertilizers N, P and K were continuously applied at a recommended rate by the research (RR) or at this rate increased in 50% (1.5RR), initial cotton and cereals yields of 1.5 to 2 t ha˗1 and 2 to 3 t ha˗1, respectively, decreased to around 1 t ha-1 after 20 years of soil cultivation. Alternation of 2 or 3 consecutive years of fallow plot with 3 years cropping did not improved crops yields as compared with continuous cropping system, but tends to stabilize crops production in the long-term. In the upper soil 20 cm, soil C stock of 15 to 39 t ha˗1 after vegetation clearance dropped faster during the first years to reached equilibrium after only 10 to 15 years of soil cultivation. Such a decrease was less depended on soil C input and was accurately descried with a two-pool C model, running on an annual time step basis. Calibrated decomposition rate of labile soil C ranged between 0.15 and 0.24, and stable soil C pool represented 33 to 67% of initial total C; while soil C that was resistant for hydrolyze acid was about 30% of initial total C. Soil N stock was also decreased faster and less associated with a rate of N input to soil. Application of NPK at 1.5RR during 20 years contributed significantly to soil pH decrease and pronounced soil Ca and Mg decreases, which respectively were 20 and 40% more than in plots that were not fertilized. We concluded that, association of Ca/Mg and NPK at a recommended rate would be (more than over-dosage of P and K) a promising option to achieving a sustainable management of mineral fertility of these soils. Minimum tillage, associated with external C input, would be an asset to a sustainable management of organic fertility of these soils.

Agricultural management is essential for achieving optimum crop production and maintaining soil quality. Soil microorganisms are responsible for nutrient cycling and are an important consideration for effective soil management. The overall goal of the present research was to better understand microbial communities in agricultural soils as they relate to soil management practices. For this, we evaluated the differential impact of two contrasting drainage practices on microbial community composition and characterized active denitrifiers from selected agricultural sites. Field drainage is important for crop growth in arable soils. Controlled and uncontrolled tile drainage practices maintain water in the field or fully drain it, respectively. Because soil water content influences nutrient concentration, moisture, and oxygen availability, the effects of these two disparate practices on microbial community composition was compared in paired fields that had diverse land management histories. Libraries of the 16S rRNA gene were generated from DNA from 168 soil samples collected from eight fields during the 2012 growing season. Paired-end sequencing using next-generation sequencing was followed by read assembly and multivariate statistical analyses. Results showed that drainage practice exerted no measureable effect on the bacterial communities. However, bacterial communities were impacted by plant cultivar and applied fertilizer, in addition to sampled soil depth. Indicator species were only recovered for depth; plant cultivar or applied fertilizer type had no strong and specific indicator species. Among indicator species for soil depth (30-90 cm) were Chloroflexi (Anaerolineae), Betaproteobacteria (Janthinobacterium, Herminiimonas, Rhodoferax, Polaromonas), Deltaproteobacteria (Anaeromyxobacter, Geobacter), Alphaproteobacteria (Novosphingobium, Rhodobacter), and Actinobacteria (Promicromonospora). Denitrification in agricultural fields transforms nitrogen applied as fertilizer, reduces crop production, and emits N2O, which is a potent greenhouse gas. Agriculture is the highest anthropogenic source of N2O, which underlines the importance of understanding the microbiology of denitrification for reducing greenhouse gas emissions by altered management practices. Existing denitrifier probes and primers are biased due to their development based mostly on sequence information from cultured denitrifiers. To circumvent this limitation, this study investigated active and uncultivated denitrifiers from two agricultural sites in Ottawa, Ontario. Using DNA stable-isotope probing, we enriched nucleic acids from active soil denitrifiers by exposing intact replicate soil cores to NO3- and 13C6-glucose under anoxic conditions using flow-through reactors, with parallel native substrate controls. Spectrophotometric chemistry assays and gas chromatography confirmed active NO3- depletion and N2O production, respectively. Duplicate flow-through reactors were sacrificed after one and four week incubation periods to assess temporal changes due to food web dynamics. Soil DNA was extracted and processed by density gradient ultracentrifugation, followed by fractionation to separate DNA contributed by active denitrifiers (i.e., “heavy” DNA) from that of the background community (i.e., “light” DNA). Light and heavy DNA samples were analyzed by paired-end sequencing of 16S rRNA genes using next-generation sequencing. Multivariate statistics of assembled 16S rRNA genes confirmed unique taxonomic representation in heavy fractions from flow-through reactors fed 13C6-glucose, which exceeded any site-specific or temporal shifts in putative denitrifiers. Based on high relative abundance in heavy DNA, labelled taxa affiliated with the Betaproteobacteria (71%; Janthinobacterium, Acidovorax, Azoarcus, Dechloromonas), Alphaproteobacteria (8%; Rhizobium), Gammaproteobacteria (4%; Pseudomonas), and Actinobacteria (4%; Streptomycetaceae). Metagenomic DNA from the original soil and recovered heavy fractions were subjected to next-generation sequencing and the results demonstrated enrichment of denitrification genes with taxonomic affiliations to Brucella, Ralstonia, and Chromobacterium in heavy fractions of flow-through reactors fed 13C6-glucose. The vast majority of heavy-DNA-associated nitrite-reductase reads annotated to the copper-containing form (nirK), rather than the heme-containing enzyme (nirS). Analysis of recovered nirK genes demonstrated low sequence identity across common primer-binding sites used for the detection and quantification of soil denitrifiers, indicating that these active denitrifiers would not have been detected in molecular surveys of these same soils.