Energy flows in lowland soybean production system in Brazil/Fluxos de energia em sistema de producao de soja em varzea no Brasil

• Published in: Ciência rural 2016-08, Vol.46 (8), p.1395
• Main Authors: Andrea, Maria Carolina da Silva, Romanelli, Thiago Liborio, Molin, Jose Paulo
• Format: Article
• Language: English
• ISSN: 0103-8478
• DOI: 10.1590/0103-8478cr20151298

Soybean is the main product of Brazilian agribusiness, both production and income. Considering the increase in food and energy demand and the search for more sustainable production systems, this study aimed to analyze inputs and energy use of a possible area of expansion of soybean production: a system under sub irrigation management located in a lowland area of Cerrado biome, northern region of Brazil. Its environmental performance was compared to other Brazilian locations among them traditionally soybean producers. The evaluation and comparison was made through material and energy flow tools in order to determine the inputs embodied per area, as well as energy demand, availability and efficiency in the analyzed production system. Energy demand (IE) and energy availability (OE) of the analyzed production system were 7.6 and 57.1 GJ [ha.sup.-1], respectively. Energy balance (EB) was 49,5 GJ [ha.sup.-1], energy return over investment (EROI) was 7.5 and embodied energy in grains (EE) was 2,2 M J [kg.sup.-1], respectively. Highest energy consumption was due to the use of fertilizers, fuel and herbicide. The system is energy efficient, since it provides more energy than demands, and efficient when compared to usual production systems in other regions, however it is highly dependent on non-renewable energy. Key words: Glycine max (L.) Merr, material flow, energy balance, EROI. A soja e o principal produto do agronegocio Brasileiro, em volume e geracao de renda. Considerando o aumento da demanda por alimentos e energia, bem como a busca por sistemas de producao mais sustentaveis, o presente estudo teve como objetivo analisar o uso de energia oriunda de insumas agricolas em area de possivel expansao de producao de soja: sistema de producao sob subirrigacao em area de varzea no Cerrado, regiao Norte do Brasil. Seu desempenho ambiental foi comparado a outros locais no Brasil, entre os quais regioes tradicionalmente produtores de soja. A avaliacao e comparacao foram feitas por meio do uso de ferramentas de fluxo de materiais e energia, afim de determinar a quantidade de insumas utilizados por area, bem como a demanda, disponibilidade e eficiencia do uso de energia no sistema de producao avaliado. A demanda (IE) e disponibilidade (OE) de energia foram de 7.6 e 57.1 GJ [ha.sup.-1], respectivamente. O balanco energetico (BE), o retorno de energia sobre o investimento (EROI) e a energia incorporada dos graos (EE) foram 49.5 GJ [ha.sup.-1], 7.5 e 2.2 MJ [kg.sup.-1], resp