Machinery management as an environmental tool - material embodiment in agriculture
Keywords:sustainability, material flows, life cycle assessment, energy flows, mechanization, Brazil
The material embodiment in agricultural production systems is important because it determines the convergence of inputs (indirectly, the natural resources) into the crop. Besides this, the material flows are the basis for any environmental (energy analysis, emergy evaluation, life-cycle analysis and carbon inventories) and economical analyses. Since different materials cannot compose a single index, generally these flows are not shown and this fact makes comparisons difficult to be done. Another aspect that makes comparisons more difficult is the establishment of the studied system's boundary. If they differ, results will be different, disguising actual distinctions among systems. This study aimed to apply a methodology in order to determine material flows in agricultural production systems. A secondary goal is to show that machinery management can propitiate less material convergence into the crop. A diagram language to represent the analyzed system was adopted in order to establish the systems' limit. The determination of the material flows of indirectly applied inputs (fuel consumption; the machinery depreciation; and labor) included the determination of the effective field capacity, since the latter aggregates efficiency and is able to make data related to time to be related to area. Data of fuel consumption were compared with the models presented (the most accurate for the surveyed system was presented by Molin and Milan, 2002). The material embodiment of a maize silage production system was determined and compared with regional data, presenting similar data. For this system and a haylage (Tifton 85) production system the embodiment was calculated for different aspects (area, yield and qualitative aspects) in order to show the importance of establishing the limit of study and indicators. A comparison approaching the efficiency was also done, the variables considered were farm size, machinery use and labor requirement, efficiency increased more than the area increase.