The aim of this work was to evaluate the energy balance in the alfalfa hay production based on seven years data from an Intensive System of Milk Production, located in the region of Coronel Pacheco/MG Brazil. To create the energy matrix determination, the categories of direct and indirect energy were considered. The energy occurred in the implanting and establishing of the crop were distributed along the years considered as useful life. The direct energy, relative to the inputs, had larger participation than the indirect one, being the percentiles found of 93.05 and 6.95, respectively. The main consumer of indirect energy was the tractor, which turns on all the implements, followed by the irrigation system. The estimated energy efficiency by the process was of 3.19. Most of the direct energy used was derived from fossil resources, in the form of fuel (diesel). The use of organic fertilizer, poultry litter, promoted a relative reduction in the consumption of energy originated from fertilizer derived from fossil resources. With the obtained results, it was concluded that, despite the several sources of energy consumption, the production of alfalfa hay is sustainable and efficient in the energy conversion.
energy efficiency; hay production; sustainability of the agriculture
