Comparison of the environmental performance of light mechanization and animal traction using a modular LCA approach

Animal traction has supported humans in most field operations since the origin of agriculture. With the introduction of mechanization, humans gained access to much more work power at similar management costs and were able to significantly increase the productivity and time efficiency of field operations. This achievement completely changed food production systems for all populations able to access such technology. Nowadays, animal traction is mainly used in the developing countries, in specific contexts such as mountainous areas due to the difficulties in using tractors, and within farm tourism in the developed countries. Although the consumption of non-renewable resources is clearly higher in crop production systems that use mechanized traction, tractor traction may involve low consumption of fuel relative to that needed for feed production for equivalent draught animals. Mechanical traction can also facilitate precision agriculture, which uses less fuel, while animals, as living systems, consume resources even when they are not working. This study compared the environmental performance of animal traction with that of machine traction in two scenarios: (I) A forest harvesting system, using as the functional unit the logging operations needed to obtain 50 t market-ready wood and (II) a seedbed preparation system, using as the functional unit the management of 1000 m 2 of prepared seedbed. Use of animal traction for these two systems was evaluated on the La Masca farm in Roccaverano, Asti, Northern Italy, while use of machine traction was evaluated using field data on two-wheel tractors performing the operations in similar production systems, converted to the specific functional unit. Owing to the differing properties of mechanical and living systems, it was difficult to establish a reliable standard LCA model of the forestry and food production system. In particular, it proved necessary to include the whole life cycle impacts from tractors and animals. Therefore, we applied a modular LCA approach in which all mechanical implements and animals were accounted as independent modules, a complete life cycle impact assessment phase was performed and results were related to the contribution of the module in the main workflow of the scenario. The final results showed better environmental performance of animal traction both per unit weight of market-ready wood and per unit surface area of prepared seedbed.