Maximizing yields is opposed to the goal of minimizing the use of inputs. In the context of system rationalization, the addition of non-economic parameters in the decision making and the magnitude of eucalyptus plantation in Sao Paulo State, Brazil led to this study. The objective was to establish the flows and to evaluate the performance of energy transformations on eucalyptus production. The evaluated system presented three alternatives of soil acidity management: lime, ash and sludge application. The applied indicators were energy return on investment, energy intensity and energy balance, which meant, respectively, the return over energy investment, the energy content of biomass and the energy obtained per area. For the basic scenario, lime, E ROI was 58.5 MJ MJ -1 , energy intensity was 124.7 MJ m -3 , and the energy balance was 2120.7 GJ ha -1 . The required energy was larger when ash (5.2%) and sludge (57.2%) were used. The main inputs were, in order, fuel, fertilizers, herbicide and lime. Harvesting was the main operation (56.7%), followed by subsoiling. Fuel in harvesting, fertilizers and lime summed 79.6% of the total energy. The sensitivity of the system showed that the material used to control soil acidity had more effect on the energy demand (up to +57.4%) than the suggested scenarios (-5.3% when the field efficiency was increased).Key words: sustainability, environmental analysis, E ROI , energy balance Desempenho energético de uma produção de eucalipto RESUMO O contexto da racionalização dos sistemas de produção, a inserção de parâmetros não-econômicos na tomada de decisão e a magnitude do cultivo de eucalipto, no Estado de São Paulo, Brasil, nortearam este estudo, cujo objetivo foi estabelecer os fluxos e o desempenho das transformações energéticas de um sistema de produção de eucalipto. O sistema avaliado apresentou três alternativas de manejo de acidez do solo: calcário, cinzas e biossólido. Os indicadores utilizados foram o retorno de energia sobre energia investida, intensidade e balanço energéticos, que representam, respectivamente, a taxa de retorno de energia obtida, a energia contida na biomassa e a energia obtida por área. Para o cenário básico, calcário, o retorno de energia sobre energia investida foi de 58,5 MJ MJ -1 , a intensidade energética da biomassa 124,7 MJ m -3 e o balanço de energia foi 2120,7 GJ ha -1 . A energia demandada foi maior com cinzas (5,2%) e biossólido (57,2%). Os principais insumos foram, em ordem decrescente: combustível, fertilizantes, herbicida e calcário. A colheita é a principal operação (56,7%), seguida da subsolagem. O combustível gasto na colheita mais fertilizantes e calcário correspondem a 79,6% da energia necessária. A sensibilidade do sistema mostrou que o material de controle de acidez do solo causa maiores efeitos na demanda de energia (até +57,4%) que os cenários sugeridos (-5,3% com acréscimo da eficiência de campo).Palavras-chave: sustentabilidade, análises ambientais, balanço de energia

The approach of material embodiment in agricultural production systems is important because it determines the convergence of inputs (indirectly, the natural resources) to the field. Additionally, material flow is the basis for both environmental (energy analysis, emergy synthesis, life-cycle analysis and carbon inventories) and economical analyses. Since different materials cannot compose a single index, generally these flows are not shown, making comparisons among approaches difficult. Another aspect that makes comparisons difficult is the definition of the boundary of the studied system. If these boundaries differ, results will also be different, hiding actual distinctions among systems. The present study aims to suggest an arrangement of existing models to determine material flow in agricultural production systems. The following steps were considered: i) the adoption of a diagram language to represent the analyzed system; ii) determination of the material flow for directly applied inputs; iii) determination of the material flow for indirectly applied inputs, which included: determination of the effective field capacity; fuel consumption; machinery depreciation; and labor. Data on fuel consumption were compared with the models presented. The best model applied was a fixed parameter based on engine power (0.163 L kW -1 h -1 ). The determination of the material flow for maize silage production presented similar results as those obtained in regional databases. Key words: LCA, material embodiment, environmental management, mechanization Determinação de fluxo de materiais por meio do gerenciamento de máquinas agrícolasRESUMO: A abordagem da incorporação material em sistemas agrícolas é importante, pois determina a convergência de insumos (indiretamente, de recursos naturais) no campo. Além disso, os fluxos de materiais são a base para quaisquer análises ambientais (análises de energia, síntese de emergia, ciclo de vida e inventários de carbono) e econômicas. Uma vez que diferentes materiais não podem compor um único índice, geralmente esses fluxos não são mostrados. Isso dificulta comparações entre análises. Outro aspecto que contribui para isso é a definição dos limites dos sistemas estudados. Se eles diferirem os resultados serão diferentes, disfarçando as distinções reais entre eles. O presente estudo visa sugerir um arranjo de modelos existentes para a determinação dos fluxos de energia e materiais em sistemas agrícolas. Os seguintes passos foram considerados: i) a adoção de uma linguagem de diagramação para representar o sistema analisado; ii) a determinação do fluxo de materiais dos insumos diretamente aplicados; iii) a determinação do fluxo de materiais dos insumos indiretamente aplicados, que envolve a capacidade de campo operacional dos sistemas mecanizados, o consumo de combustível, a depreciação de maquinário e a mão-de-obra. Dados de consumo de combustível foram comparados com os modelos apresentados. O melhor modelo aplicado foi o fixado em função da potência do motor (0,163 L kW -1 h -1

Driven by biofuel policies, which aim to reduce greenhouse gas (GHG) emissions and increase domestic energy supply, global production and consumption of bioethanol have doubled between 2007 and 2016, with rapid growth in corn-based bioethanol in the U.S. and sugar cane-based bioethanol in Brazil. Advances in crop yields, energy use efficiency in fertilizer production, biomass-to-ethanol conversion rates, and energy efficiency in ethanol production have improved the energy balance and GHG emission reduction potential of bioethanol. In the current study, digitalcommons.unl.edu

The mechanized harvest of sugar cane (Saccharum officinarum L.) in Brazil is an irreversible trend and it comes with a great concern about the quality of the cane delivered to the industry. A key component to quality is the billet length which affects the processing of raw material, cane deterioration, invisible losses and load density of transport vehicles. Thus, due to the importance of the billet standard in quality and cost of raw material, this study aimed to evaluate if the mechanized harvesting of sugar cane can supply the quality requirements for the crushing process, regarding the billet length. A plot with burnt sugar cane (3.2 ha) and another one with green sugar cane (8.0 ha) were selected to be harvested by two (2) selfpropelled sugar cane harvesters. For each harvested 0.4 ha a sample from each infield wagon was collected. The sample was composed by ten billets. The variability in burnt sugar cane was higher than in green sugar cane, and both harvesters did not present the capacity of keeping the billets with similar lengths when operating either in burnt or green conditions. Key words: mechanization, sugar cane harvester, statistical process control Capacidade do processo de corte de rebolos de cana-de-açúcar colhidos mecanicamente RESUMO: A colheita mecanizada de cana-de-açúcar (Saccharum officinarum L.) no Brasil é uma tendência irreversível e junto a ela vem à preocupação com a qualidade da matéria-prima que chega à indústria. O tamanho de rebolos tem influência nessa qualidade por afetar o processo de deterioração da cana, perdas invisíveis e a densidade de carga no transbordo e transporte. Considerando-se a importância do padrão do rebolo na qualidade e custo da matéria-prima, avaliou-se se a colheita mecanizada de cana-de-açúcar pode atender às exigências de qualidade da moagem no que se refere ao indicador tamanho de rebolo. Para tanto, uma área de cana queimada (3,2 ha) e outra de cana crua (8,0 ha) foram selecionadas. As áreas foram colhidas por duas colhedoras automotrizes. Para cada colhedora e área, uma amostra a cada 0,4 ha colhidos foi coletada, junto ao conjunto de transbordo e cada amostra era composta por dez rebolos. Os resultados foram analisados por meio de gráficos de controle, e a capacidade do processo de corte foi determinada. Houve maior variabilidade na condição de cana queimada em relação à cana crua, e que ambas as colhedoras não têm a capacidade de manter os rebolos em tamanhos semelhantes, quando operando nessas duas condições diferentes. Palavras-chave: mecanização, colheita mecanizada, controle estatístico do processo

The amount of energy required to produce a commodity or to supply a service varies from one production system to another and consequently giving rise to differing levels of environmental efficiency. Moreover, since energy prices have been continuously increasing over time, this energy amount may be a factor that has economic worth. Biomass production has a variety of end-products such as food, energy, and fiber; thus, taking into account the similarity in end-product of different crops (e.g.: sunflower, peanuts, or soybean for oil) it is possible to evaluate which crops require less energy per functional unit, such as starch, oil, and protein.This information can be used in decision-making about policies for food safety or bioenergy. In this study, 23 crops were evaluated allowing for a comparison in terms of energy embodied per functional unit. Crops were grouped as follows: starch, oil, horticultural, perennial and fiber, to provide for a deeper analysis of alternatives for the groups, and subsidize further studies comparing conventional and alternative production systems such as organic or genetically modified organisms, in terms of energy. The best energy balance observed was whole sugarcane (juice, bagasse and straw) with a surplus of 268 GJ ha −1 yr −1; palm shows the highest energy return on investment with a ratio of approximately 30:1. For carbohydrates and protein production, cassava and soybean, respectively, emerged as the crops offering the greatest energy savings in the production of these functional foods.Keywords: EROI, starch, oil, fertilizer, fiber, energy balance requirements by Brazilian agriculture is important to an evaluation of its sustainability. Based on this view, this study aimed to evaluate the energy embodied in 23 crops and assess how much energy is used in their production as well as the energy return, in order to direct subsidies in accordance with an environmental friendly and energy-saving policy that will secure the food supply in Brazil. Materials and MethodsEnergy flows of the following 23 crops were assessed: maize; wheat, cassava, potato, rice, bean, soybean (produced in two Brazilian regions: system 1 in the state of Paraná and system 2 in the state of Mato Grosso), peanut, sunflower, castor bean (comparing two systems, system 1 using low-level technology and system 2 a higher level of machinery and technology; and a third group comprising palm, lettuce, banana, onion, carrot, cucumber, bell pepper, tomato, cotton, eucalyptus, citrus, coffee and sugarcane. For this group, three scenarios of energy output flow (EOF) were developed: the first considering the production of juice only, the second juice plus bagasse, and third juice, bagasse and straw as output.From the utilisation point of view, there are basically two types of material flow: i) inputs applied directly, such as limestone, fertilizers, seeds and other chemicals used that carry with them amounts of energy for the production process and are currently in use in the fields; and ii) inputs applied indirec...

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Cattle is the main protein source in Brazil and cattle production depends on preserving forage in order to decrease the influence of dry periods on grass production. To minimize such problems, some new techniques have been created to increase the yield which also leads to energy demand increase. Energy balance is a vital tool to evaluate the efficiency of energy consumption in production systems. There is no standard methodology established for this determination. It is also difficult to analyze different management options because of the complexity of the production systems and the interactions among variables. Therefore the purpose of this study is to develop a methodology that supports the development of a model, using a spreadsheet, and to use it to analyze the energy balance of production systems. The model was applied to a traditional production system of maize (Zea mays L.) silage and a Bermuda grass (Cynodon spp.) haylage. The gross energy balance presented was 14.1 energy units of output per energy units of input for maize silage and -0.98 for haylage. For the digestible energy balance, the values were 9.1 and -0.99, respectively. The total energy demanded was 74.3% in maize silage fertilizations and 99.7% in haylage irrigation. Yield and dry matter contents were indicated in a sensitivity analysis as the main critical variables for maize, whereas for haylage, it was not possible to indicate any. The best alternative scenarios for improving energy efficiency in maize silage and haylage production were the reductions of fertilizer concentration and irrigation use, respectively. Key words: environmental management, production systems, sustainability, silage, haylage METODOLOGIA E MODELAGEM DO BALANÇO ENERGÉTICO EM FORRAGENS SUPLEMENTARES PARA BOVINOSRESUMO: A pecuária é a principal fonte de proteína no Brasil, e sofre pela estacionalidade das chuvas, necessitando-se da suplementação alimentar. Para amenizar tais problemas surgem técnicas visando o aumento da produtividade, porém demandando mais energia. O balanço energético é uma importante ferramenta para avaliar a eficiência com que um sistema de produção utiliza os insumos, pois relaciona os fluxos de energia de entrada (input) e a energia disponibilizada pelo sistema (output). No entanto, não há uma metodologia padrão para tal análise, e ainda analisar diferentes opções não é uma tarefa fácil, pela complexidade de sistemas agrícolas e pelas interações de suas variáveis. Sendo assim, o presente trabalho objetivou propor uma metodologia de determinação do balanço energético, que desse suporte ao desenvolvimento de um modelo em planilha eletrônica. Este foi utilizado para avaliar dois sistemas: um de produção de silagem de milho (Zea mays L.) e um de silagem emurchecida de Tifton 85 (Cynodon spp.). A silagem de milho apresentou balanços energéticos bruto de 14,08 e a emurchecida -0,98, já para o balanço de energia digestível foram 9,12 e -0,99, respectivamente. As adubações demandaram 73,4% do total de energia na silagem de milho e a irrigação ...

ABSTRACT:As the requirement for agriculture to be environmentally suitable there is a necessity to adopt indicators and methodologies approaching sustainability. In Brazil, biodiesel addition into diesel is mandatory and soybean oil is its main source. The material embodiment determines the convergence of inputs into the crop. Moreover, the material flows are necessary for any environmental analysis. This study evaluated distinct production scenarios, and also conventional versus GMO crops, through the material embodiment and energy analysis. GMO crops demanded less indirectly applied inputs. The energy balance showed linearity with yield, whereas for EROI, the increases in input and yield were not affected.