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, EROI 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).
sustainability; environmental analysis; EROI; energy balance
