Present and future environmental impact of poplar cultivation in the Po Valley (Italy) under different crop management systems

摘要

Two commercial and representative plantations of poplar located in the Po Valley (Italy) under very short rotation (VSRC) and short rotation (SRC) regimes dedicated to biomass production for energy purposes have been analysed to identify their environmental effects and to define the best option for a biomass production system. The standard framework of Life Cycle Assessment (LCA) was followed in this study and detailed inventories for both regimes were provided. The environmental profile was analysed in terms of abiotic depletion, acidification, eutrophication, global warming, ozone layer depletion, photochemical oxidants formation, human toxicity and ecotoxicity. In addition, an energy analysis was performed using the cumulative energy demand method. Differences were identified in terms of biomass yield, fertilizers requirement as well as intensive agricultural activities and, according to the results, SRC presents the best environmental profile in seven of the eleven environmental impacts assessed. The key processes in both regimes were: nutrient application and agricultural activities such as mechanical weed control, harvesting and biomass collection due to the energy consumption and derived emissions. Improvement alternatives were proposed based on these results and two sensitivity analyses were carried out based on the use of only cattle manure as nutrient input under a VSRC regime and on the increment of biomass yield in the future (2020 and 2030 seasons) due to better clones but under an SRC regime. As a general conclusion, in a short period of time, poplar plantations dedicated to energy purposes should be driven towards SRC regimes instead of VSRC.