Summary
The assessment of energy efficiency (EE) and greenhouse gas (GHG) emissions can highlight the sustainability of agro-systems and decision-making regarding reduction of production costs and environmental pollution. In this context, the objective of this work was to evaluate the EE and GHG emissions (CO2, CH4 e N2O) of a soybean crop under organic cultivation in different regions of Brazil in the agricultural year 2014-2015. For this, 19 soybean areas were evaluated. The inputs and outputs of the agricultural operations and / or inputs used were calculated by multiplying the quantity used by their calorific value or energy coefficient at each stage of production. The energy efficiency was obtained by the ratio between the amount of total output energy and the total energy consumption during the production process. In order to estimate GHG emissions, the principles of the life cycle assessment methodology and recommendations of the Intergovernmental Panel on Climate Change (IPCC) were applied. For each 1.0 MJ of energy consumed in the organic production of soybeans, an average of 7.9 MJ of renewable energy was produced in the form of grains of this crop. The main energy costs of growing these organic crops were with seeds, fuel and with tractors, machines and agricultural implements (TMI). For each 1 kg of organic grain produced from soybeans, 0.19 kg of CO(2)eq are emitted during their production and delivery cycles in the warehouse. The main sources of CO(2)eq emission to the atmosphere were the seeds, fuels and organic fertilizers.