Balanços energéticos agropecuários: uma importante ferramenta como indicativo de sustentabilidade de agroecossistemas

In Brazil, little attention has been given to the ways energy flows are distributed in the productive systems. In the agriculture, the main focus was directed to new sources of energy (biomass) or in alternative technology, aiming to a rational use of the fossil and electric energy. However, the modern agriculture has been based on massive machines utilization, with a consequent use of fossil fuel. A hard strangulating factor in the general energy consumption has been the intensive use of fertilizers derived from petroleum in the agricultural ecosystems. The agricultural energy system has been developed based on intensive use of fertilizers derivate from petroleum. Studies considering Energy Balance, aim to determine the weak points of those systems and establish the fundaments for energy saver technologies especially fossil source (fuel, fertilizer, pesticides, energy expended in machines, implements, etc.). In Brazil, the South Region where important programs have been developed for a more sustainable agricultural systems according to energy utilization. Under the perspective of eventual energy crisis in the future, the present work was done to analyze the state of the art of Energy Balance studies in Brazil and in the world, as an instrument of sustainability indication in agricultural systems.