Nitrogen fractions in a Luvisol under agroforestry and conventional systems in the semi-arid zone of Ceará, Brazil

Os sistemas agroflorestais têm sido amplamente promovidos como sistemas de produção agrícola sustentáveis, principalmente para regiões subdesenvolvidas, onde o uso de insumos externos é inviável. Este trabalho objetivou avaliar o impacto de quatro sistemas agroflorestais e um sistema convencional sobre os teores de N total, mineral e em diferentes frações orgânicas, após cinco anos de uso de um Luvissolo na região semi-árida cearense, em experimento instalado na Embrapa Caprinos, em Sobral (CE). Os sistemas testados foram: agrossilvipastoril (AGP); silvipastoril (SILV); tradicional cultivado em 1998 e 1999 (TR98); tradicional cultivado em 2002 (TR02); cultivo convencional (CC); e uma área de Caatinga (CA). Nas amostras de solo, avaliaram-se os teores de N total, N-NH4+, N-NO3-, N microbiano, N da matéria orgânica leve (livre e oclusa) e o N das substâncias húmicas. Os resultados indicaram que todos os tratamentos condicionaram elevados teores de N-NO3-, representando entre 10,3 e 23,5 % dos teores de N total. O sistema CC reduziu os teores de N total e das frações das substâncias húmicas em 38 e 44 %, respectivamente, na camada superficial do solo. Dentre os sistemas agroflorestais, os sistemas AGP e TR98 causaram redução significativa dos teores de N total, N da matéria orgânica leve (livre e oclusa) e N das substâncias húmicas. O tratamento SILV preservou e, em alguns casos, aumentou os teores de N do solo e, portanto, constituiu um sistema que pode ser recomendado como uma alternativa sustentável de manejo do solo para o semi-árido cearense.The agroforestry systems have been widely promoted as one sustainable agricultural system, mainly for developing areas, where the external use of resources are not feasible. The aim of this study was to evaluate the impact of one conventional and four agroforestry systems on the contents of total soil nitrogen, mineral nitrogen and different organic nitrogen fractions after five years of experimental cultivation on a Luvisol (Alfisol). The study area was in the semi-arid zone at the National Caprine Research Center (CNPC) of Embrapa, Ceará, Brazil. The following treatments were tested: agrosilvopasture (AGP), silvopasture (SILV), traditional agroforestry in 1998 and 1999 (TR98), traditional agroforestry in 2002 (TR02), conventional cropping (CC), and seasonally dry native vegetation ("Caatinga") (CA). Total-N, N-NH4+, N-NO3-, microbial-N, light organic matter N (free and occluded) and N in the humic substances were evaluated. Results indicated high nitrate-N (NO3-) content in all treatments, accounting for 10.3 to 23.5 % of the total N. The CC treatment reduced the total N and N in humic substances by 38 and 44 %, respectively. The AGP and TR98 agroforestry treatments significantly reduced N in the light organic matter and in humic substances. On the other hand, the SILV system preserved, and in some cases, improved the concentration of the soil. This system can therefore be recommended as a sustainable alternative for soil management in the semi-arid region of Ceará state.CAPES - Programa de Cooperação Acadêmic

Impacts of extreme climate events on Brazilian agricultural production

Brazilian agricultural production stands out in world food security, accounting for a large part of the food produced worldwide. However, occurrence of extreme climate events is a challenge for the sector across the country. Thus, this study aims to assess extreme climate events impacts on Brazilian agricultural production. The loss index was calculated using crop data made available by the IBGE from 2005 to 2017, while data on the occurrence of extreme climate events (2002-2017) was obtained from literature. Data related to PROAGRO (2010-2018) and the Crop Assurance Program (2002-2016) were obtained from reports made available by the relevant agencies. Results showed high drought-induced production losses, mainly maize and beans produced in the Caatinga biome, and soybean and wheat in the Southeastern and Southern regions of the country. Hail and frost events also caused reductions in soybean and rice production in the Southeastern and Southern regions. Those impacts on the Brazilian agricultural production, in different regions, might have serious consequences on the availability and access of food to the population in the country.Brazilian agricultural production stands out in world food security, accounting for a large part of the food produced worldwide. However, occurrence of extreme climate events is a challenge for the sector across the country. Thus, this study aims to assess extreme climate events impacts on Brazilian agricultural production. The loss index was calculated using crop data made available by the IBGE from 2005 to 2017, while data on the occurrence of extreme climate events (2002-2017) was obtained from literature. Data related to PROAGRO (2010-2018) and the Crop Assurance Program (2002-2016) were obtained from reports made available by the relevant agencies. Results showed high drought-induced production losses, mainly maize and beans produced in the Caatinga biome, and soybean and wheat in the Southeastern and Southern regions of the country. Hail and frost events also caused reductions in soybean and rice production in the Southeastern and Southern regions. Those impacts on the Brazilian agricultural production, in different regions, might have serious consequences on the availability and access of food to the population in the country

The Nexus+ approach applied to studies of Impacts, vulnerability and adaptation to climate change in Brazil

This paper aims to present the methodology developed within the Impacts, Vulnerability and Adaptation (IVA) to climate change component of the Fourth National Communication (4CN) of Brazil. The methodological choice of this 4CN involves the application of the nexus+ integrated approach, based on studies of impacts and vulnerabilities for water, energy, food and socio-environmental securities, in the different in the territories of Brazilian biomes, coastal areas and cities. For each of these securities it were identified the observed impacts; analysis of risk conditions; definition and assessments of integrated analysis of key impacts at territorial level; inventory, selection and analysis of adaption options in the context of Nexus+, identifying synergies and trade-offs. This process made possible an integrated assessment among the conditioning risk factors, impacts and interactions among proposed adaptation options.This paper aims to present the methodology developed within the Impacts, Vulnerability and Adaptation (IVA) to climate change component of the Fourth National Communication (4CN) of Brazil. The methodological choice of this 4CN involves the application of the nexus+ integrated approach, based on studies of impacts and vulnerabilities for water, energy, food and socio-environmental securities, in the different in the territories of Brazilian biomes, coastal areas and cities. For each of these securities it were identified the observed impacts; analysis of risk conditions; definition and assessments of integrated analysis of key impacts at territorial level; inventory, selection and analysis of adaption options in the context of Nexus+, identifying synergies and trade-offs. This process made possible an integrated assessment among the conditioning risk factors, impacts and interactions among proposed adaptation options

Estimates of soil carbon emissions due to land-use changes in Rondônia and Mato Grosso states, Brazil

As emissões globais de gases do efeito estufa (GEE) devido a ações do ser humano tem levado a um aumento na temperatura média da superfície terrestre de 0,55oC, e mudanças climáticas como aumento de eventos climáticos extremos, elevação dos níveis dos oceanos, e mudanças nos regimes pluviométricos são alguns exemplos das possíveis implicações deste aquecimento. O carbono orgânico do solo (COS) é o principal reservatório terrestre de C, contendo mais que o dobro do C da atmosfera, portanto, dependendo do manejo os solos podem se transformar em importantes fontes ou drenos de C atmosférico, influenciando significativamente os efeitos do aquecimento global. O objetivo desta pesquisa foi estimar as mudanças nos estoques do COS devido às mudanças no uso da terra e sistemas de manejo nos estados de Rondônia e Mato Grosso entre 1970 e 1985 e 1985 a 2002 utilizando dados específicos da região; e realizar a análise de incerteza destas estimativas mediante o método de Monte Carlo. Para alcançar o objetivo principal, a presente pesquisa foi composta das seguintes etapas: i) cálculo dos estoques do COS sob vegetação nativa (carbono de referência); ii) obtenção dos dados (áreas) das principais categorias de uso da terra nos estados de Rondônia e Mato Grosso para os anos de 1970, 1985 e 2002, a partir da combinação de técnicas de sensoriamento remoto, dados dos censos agropecuários, e informações de especialistas do setor agropecuário; iii) desenvolvimento dos fatores de emissão específicos para os principais sistemas de manejo da região de estudo utilizando um modelo linear misto; iv) e a etapa final que consistiu em combinar as etapas anteriores para se estimar as mudanças nos estoques de COS, e realizar a análise das incertezas associadas. Sucintamente, foram derivados fatores de emissão para as pastagens degradadas (0,91 ± 0,14), típicas em Latossolos (0,99 ± 0,08), típicas nos demais tipos de solos (1,24 ± 0,07), e pastagens melhoradas em Latossolos (1,19 ± 0,07), todos os fatores representam a comparação entre as pastagens manejadas e a vegetação nativa. Nos sistemas agrícolas foi possível derivar fatores de emissão para sistemas de plantio direto (PD) em áreas de Cerrado (1,08 ± 0,06), PD em áreas de floresta Amazônica e Cerradão (1,01 ± 0,17), cultivo convencional (CC) (0,94 ± 0,04) e culturas perenes (0,98 ± 0,14), sendo que o fator para o CC foi comparado aos dados de PD, enquanto que os demais fatores foram obtidos a partir da comparação com os estoques sob vegetações nativas. Quanto às emissões de COS, foi encontrado que usando o método de Monte Carlo com 20000 simulações no período de 1970 a 1985, os solos minerais apresentaram uma perda de C com fluxos anuais de 4,28 e 1,14 Tg C ano-1, para Mato Grosso e Rondônia, respectivamente, e com 95% de intervalo de confiança as incertezas foram de ± 41,5 e 21,9%, respectivamente. No segundo período, as emissões foram de 2,86 e 0,91 Tg C ano-1, com incertezas de ± 40,1 e 33,8%, respectivamente, para Mato Grosso e Rondônia. Quanto às fontes de incerteza, o carbono de referência, a opinião dos especialistas sobre as condições das pastagens e os fatores de emissão para pastagens típicas e degradadas foram às variáveis responsáveis por mais de 90% das incertezas das estimativas das emissões de C do solo.Global emissions of greenhouse gases (GHG) due to human beings actions have led to an increase in average temperature of the earth of 0,55oC, and climate changes such as increases of the extreme weather events, sea level rise and precipitation changes are some examples of the possible implications of this global warming. Soil organic carbon (SOC) is the largest terrestrial organic carbon pool, containing more than the double of the atmospheric C; therefore, depending on the management the soils can became a source or a sink for the atmospheric C, influencing the effects of global warming. The objective of this research was to estimate the changes in SOC stocks due to the land-use and management systems in the states of Rondônia and Mato Grosso from 1970 to 1985 and from 1985 to 2002 using regional specific data, and perform the uncertainty analysis of these estimates through the Monte Carlo method. To achieve the main objective, this research was composed by the following steps: i) the estimate of the SOC stocks under native vegetation (reference carbon), ii) obtain data (areas) of the main land-use categories in the states of Rondônia and Mato Grosso for the years 1970, 1985 and 2002, from a combination of remote sensing, agricultural census data, and information from experts of the agricultural sector, iii) to derive the emission factors specific to the major management systems in the region of study using a linear-mixed model; iv) the final step was to combine the above steps to estimate the changes in SOC stocks, and carry out the uncertainty analysis associated with them. Briefly, emission factors were derived to the degraded grasslands (0.91 ± 0.14), typical in Oxisols (0.99 ± 0.08), typical in other soil types (1.24 ± 0.07), and improved grasslands in Oxisols (1.19 ± 0.07), all factors represent the comparison between managed pastures and native vegetation. In agricultural systems could be derived emission factors for no tillage (NT) systems in the Cerrado areas (1.08 ± 0.06), NT in Amazon Forest and Cerradão areas (1.01 ± 0.17), conventional tillage (CT) (0.94 ± 0.04), and perennial crops (0.98 ± 0.14). However, the CT factor was obtained from the comparison with NT data, while the other factors were compared to SOC stocks under the native vegetation. Using the Monte Carlo approach with 20000 simulations it was estimated the changes in the SOC stocks and the uncertainties associated to them. In the period from 1970 to 1985, mineral soils had a loss of C with annual fluxes of 4.28 and 1.14 Tg C yr-1, in Mato Grosso and Rondônia, respectively, and with a 95% confidence interval the uncertainties were of ± 41.5 and 21.9% respectively. In the second period, emissions were of 2.86 and 0.91 Tg C yr-1, with uncertainty of ± 40.1 and 33.8%, respectively, in Mato Grosso and Rondônia. In terms of the sources of uncertainty, the reference carbon, the experts opinions about the grasslands, and the emission factors for typical and degraded grassland were the variables responsible for more than 90% of the uncertainties in the SOC emissions estimates

Geração de energia elétrica e viabilidade técnico-econômica de um biodigestor no setor hospitalar

A construção de hospitais se transformou e evoluiu sensivelmente nas últimas décadas, sendo visto como um processo industrializado, com aumento em escala, o que gera grandes quantidades de resíduos, causando grandes problemas ambientais. Dentro deste contexto, faz-se necessária uma nova disposição para os resíduos produzidos (biomassa) e sua reutilização. Seguindo técnicas apropriadas, surge como opção o uso do biodigestor, o qual permite que os resíduos hospitalares sejam tratados podendo gerar energia elétrica e/ou gás natural através do biogás e, ainda, possibilitam o emprego do efluente residual como fertilizante de solo. O presente estudo teve como objetivo avaliar o potencial de geração de energia e a viabilidade técnica-econômica da adoção de um biodigestor no Hospital Geral do Estado de Alagoas (HGE). Para tal realizou-se um levantamento da biomassa residual produzida no HGE, do consumo, dos custos e da oscilação da potência elétrica e utilizou-se equações de predição para a obtenção dos valores de produção energética, a viabilidade econômica e ambiental. Os resultados obtidos mostraram que o hospital gera 20.914,40 Kg/ano-1 de resíduos alimentares, com o potencial de geração de 840 m3/ano-1 de biogás, uma produção de energia elétrica de 5.352 kWh/ano-1. Isso resulta em um custo do equipamento que foi de R$80.598,00. Do ponto de vista econômico, a adoção do biodigestor no HGE não se mostrou viável, visto que a energia elétrica gerada por este sistema apresentaria o custo de R$/KWh 1,45, enquanto que o valor pago a Eletrobrás é de R$/KWh 0,24

Organic carbon pools in a Luvisol under agroforestry and conventional farming systems in the semi-arid region of Ceará, Brazil

Many environmental benefits have been attributed to agroforestry systems in various ecosystems around the world. However, there is a limited amount of information to evaluate this agricultural system in the semi-arid region, specifically in the region of Ceará, Brazil. The objective of this work was to evaluate five agricultural (four agroforestry and one conventional) systems in order to test the hypothesis that the agroforestry systems promote an increase in the soil organic carbon stocks and organic carbon pools, thus improving soil quality. The following treatments were tested: agrosilvopasture (AGP), silvopasture (SILV), traditional agroforestry (TRAG), intensive cropping (IC), and native forest (NF). The soil samples were collected at four depths: 0–6, 6–12, 12–20 and 20–40 cm. Total soil organic carbon stocks and the organic carbon pools (microbial biomass-C, mineralizable-C, oxidizable-C, free, occluded light fraction organic matter, and C in the humic substances) were analyzed. After 5 years of experimental cultivation, the soil under the SILV system presented the best results for the attributes studied, preserving, and in some cases, improving these attributes, when compared to the other conditions. The traditional agroforestry system (TRAG) reduced total organic carbon stocks and, consequently, C in some organic matter compartments, indicating that the fallow period was not sufficient to maintain soil quality. The AGP and IC systems presented significant losses in some of the soil organic matter (SOM) pools, suggesting that the soil environment had been degraded. The most labile SOM components were considered sensitive indicators of change in the soil quality. The silvopasture system can, therefore, be recommended as an alternative soil management strategy for food production and for the maintenance of soil quality and agricultural sustainability in the semiarid region of Ceará state

Reducing Amazon Deforestation through Agricultural Intensification in the Cerrado for Advancing Food Security and Mitigating Climate Change

Important among global issues is the trilemma of abrupt climate change, food insecurity, and environmental degradation. Despite the increasing use of fossil fuel, about one third of global C emissions come from tropical deforestation and indiscriminate use of agricultural practices. Global food insecurity, affecting one in seven persons, aggravates environmental degradation. The importance of judicious land use and soil sustainability in addressing the trilemma cannot be overemphasized. While intensifying agronomic production on existing land, it is also essential to identify suitable eco-regions for bringing new land under production. Based on 35-years of data from Brazil, we report that C emissions from agroecosystems are 4 to 5.5 times greater by bringing new land under production in Amazon than in the Cerrado for pastures and cropland production, respectively. The data presented indicate that agricultural intensification is feasible in the Cerrado, and the forest in Rondônia and Mato Grosso states must be protected and restored for nature conservancy. Now is the time to think beyond COP 21—Paris 2015 and take concrete actions to address these issues of global significance

Nexus clima, recursos hídricos, agricultura e energia na bacia estendida do rio São Francisco

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