The approach of material embodiment in agricultural production systems is important because it determines the convergence of inputs (indirectly, the natural resources) to the field. Additionally, material flow is the basis for both environmental (energy analysis, emergy synthesis, life-cycle analysis and carbon inventories) and economical analyses. Since different materials cannot compose a single index, generally these flows are not shown, making comparisons among approaches difficult. Another aspect that makes comparisons difficult is the definition of the boundary of the studied system. If these boundaries differ, results will also be different, hiding actual distinctions among systems. The present study aims to suggest an arrangement of existing models to determine material flow in agricultural production systems. The following steps were considered: i) the adoption of a diagram language to represent the analyzed system; ii) determination of the material flow for directly applied inputs; iii) determination of the material flow for indirectly applied inputs, which included: determination of the effective field capacity; fuel consumption; machinery depreciation; and labor. Data on fuel consumption were compared with the models presented. The best model applied was a fixed parameter based on engine power (0.163 L kW-1 h-1). The determination of the material flow for maize silage production presented similar results as those obtained in regional databases.
LCA; material embodiment; environmental management; mechanization
