Soil organic matter fractions as a short-term indicator of carbon turnover under agricultural systems.

Integrated crop-livestock-forest (ICLF) systems has been considered as an important strategy to enhance C sequestration. However, changes in soil C due to agricultural management practices, in general, are observed in long-term experiments. Our objective was to investigate short-term impacts on soil organic matter under different management systems in the Cerrado/Amazonia region. Treatments corresponded to ICLF, No-tillage, Pasture and Eucalyptus plantation. Soil was sampled in 2014, in the 0-5, 5-10 and 10-30 cm layers for quantification of light- and heavy-fraction C stocks as well as their C isotopic composition (DELTA 13C). After three years established, all evaluated treatments showed similar values of light- and heavy-fraction C stocks to those observed under Native Forest in the 0-30 cm layer. Under Pasture and ILCF treatments, we observed that most of C of the light-fraction was substituted by pasturederived C in the uppermost soil layer (0-5 cm). Despite no differences in heavyand light-fraction C, the application of 13C stable isotope technique seems to be an important tool to evaluate short-term C turnover under agricultural systems

Soil organic matter fractions as a short-term indicator of carbon turnover under agricultural systems.

Integrated crop-livestock-forest (ICLF) systems has been considered as an important strategy to enhance C sequestration. However, changes in soil C due to agricultural management practices, in general, are observed in long-term experiments. Our objective was to investigate short-term impacts on soil organic matter under different management systems in the Cerrado/Amazonia region. Treatments corresponded to ICLF, No-tillage, Pasture and Eucalyptus plantation. Soil was sampled in 2014, in the 0-5, 5-10 and 10-30 cm layers for quantification of light- and heavy-fraction C stocks as well as their C isotopic composition (DELTA 13C). After three years established, all evaluated treatments showed similar values of light- and heavy-fraction C stocks to those observed under Native Forest in the 0-30 cm layer. Under Pasture and ILCF treatments, we observed that most of C of the light-fraction was substituted by pasturederived C in the uppermost soil layer (0-5 cm). Despite no differences in heavyand light-fraction C, the application of 13C stable isotope technique seems to be an important tool to evaluate short-term C turnover under agricultural systems

Emissão de CO2 em culturas de soja e arroz irrigado - Safra 2013/2014 - RS.

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Influence of Hybridization on Mechanical Properties and Water Absorption in Jute and Jute /E-Glass Reinforced Composites

The use of composite materials is increasingly present not only in several industrial areas but also in daily life. With the escalating environmental concern, it is necessary the search for materials that prove to be ecologically sustainable and economically viable. Vegetable fibers have been presenting themselves as an excellent alternative, however, because their disadvantage of having a high moisture absorption capacity, the introduction of synthetic fibers, forming hybrid composites, is a good solution since it combines the characteristics of both types of reinforcements. The present research aims to carry out a comparative study between two types of laminated polymer composites, one reinforced with Jute fibers and the other hybrid, composed of Jute and E-glass fibers. The mechanical performances of the composites submitted to the Uniaxial Tensile, Three-point Flexural and Shear tests were evaluated, as well as fracture analyzes. A comparative study to analyze the influence of hybridization on moisture absorption was carried out. The results showed that the hybridized composite showed an increase in the elastic modulus, as well as in its resistance to flexion and shear, which shows the formation of a more rigid material. Hybridization also changed the moisture content of the composite

Thermal behaviour simulation of the passenger compartment of vehicles

In this work a calculus program developed with the objective of simulating the thermal behaviour in the passenger compartment of vehicles is presented. The model is based on the space-integral energy balance equations for the inside air and for the main vehicle body and surfaces. It can solve two kinds of problems. In the first one, it calculates the heat stress that the air conditioning system must equilibrate in order to satisfy predefined permanent regimen project specifications. In the second one, once imposed a particular air conditioning system and given the ambient conditions, it computes the different temperatures and heat fluxes, either in transient or steady regimens. The validation of this model was done with a railway car, in a summer situation, when it was immobilized and running. The model reproduced well the experimentally determined temperature and heat flux evolutions. However, the numeric simulation showed best agreement with the experimental results when used with the convection heat transfer coefficients, determined experimentally in this work

The actions of the Brazilian agricultural sector in the context of climate change negotiations.

Brazil has always maintained a prominent position in negotiations within the United Nations Framework Convention on Climate Change, playing a major role in setting increasingly ambitious goals and encouraging consensus among Parties. With the purpose of reducing GHG emissions from the agricultural sector and disseminating and financing good agricultural practices, Brazil developed a platform of sustainable technologies and public policies, as the Low Carbon Agriculture Plan (the "ABC Plan"). This article reviews the main milestones of Brazil's role in the international negotiation on climate change, how these factors affected the Brazilian agricultural sector between 2009 and 2018 and the authors' personal view on this context. The objective is to provide an overview of Brazil's actions regarding the agricultural sector which contribute to the voluntary commitment assumed by the Brazilian government at COPs 15 and 21 and to provide a critical analysis of how these actions are being implemented. The main results show that low carbon agriculture has been consolidated as the main Brazilian strategy for sustainable rural development, but it is vital for our country to continue with these actions. O Brasil sempre manteve uma posição de destaque nas negociações da Convenção-Quadro das Nações Unidas sobre Mudança do Clima, desempenhando um papel importante no estabelecimento de metas cada vez mais ambiciosas e no incentivo ao consenso entre as Partes. Com o objetivo de reduzir as emissões de Gases de Efeito Estufa (GEE) do setor agrícola e disseminar e financiar boas práticas agrícolas, o Brasil desenvolveu uma plataforma de tecnologias e políticas públicas sustentáveis, como o Plano de Agricultura de Baixo Carbono (o "Plano ABC"). O presente artigo faz uma revisão dos principais marcos da atuação do Brasil no âmbito da negociação internacional sobre mudança do clima, como esses fatores afetaram o setor agrícola brasileiro, entre 2009 e 2018, e a visão pessoal dos autores sobre esse contexto. O objetivo é fornecer uma visão geral das ações do Brasil em relação ao setor agrícola, que contribuem para o compromisso voluntário assumido pelo governo brasileiro nas COPs 15 e 21 e para fornecer uma análise crítica de como essas ações estão sendo implementadas. Os principais resultados mostram que a agricultura de baixo carbono se consolidou como a principal estratégia brasileira para o desenvolvimento rural sustentável, porém é vital que o país continue com essas ações.Título em português: As ações do setor agropecuário brasileiro no contexto das negociações sobre mudança do clima

Efeito de níveis de sombreamento no conteúdo de clorofila foliar e na área foliar específica de cultivares de bananeira.

A fonte de energia que as plantas verdes utilizam é a energia solar, e as características da folha influenciam muito no aproveitamento da luz, especialmente em condições competitivas. Nos sistemas agroflorestais (SAFs), que é um tipo de policultivo, onde espécies agrícolas e ou animais são exploradas em associação com espécies arbóreas lenhosas, a disponibilidade de radiação solar pode ser limitante para o crescimento de algumas espécies