Environmental impacts and energy demand of rapeseed as an energy crop in Chile under different fertilization and tillage practices

The implementation of energy crops in Chile is an option that requires prior environmental studies within the framework of a sustainable national policy of energy security. The aim of this study is to assess the environmental performance of rapeseed crop (Brassica napus L.) in Chile in view of its potential use for the production of biodiesel. Using Life Cycle Assessment (LCA), the study quantifies the energy demand and the environmental impacts associated with the main tillage systems of Chilean rapeseed production on a national level: conventional tillage and zero tillage, and with four mineral fertilisation trials on a local level (combination of N, P and K rates). In the inventory, the agricultural inputs are obtained from national sources; international databases processes are partially adapted to Chilean conditions. For the impact assessment, the CML 2 baseline 2001 method is applied. The results indicate that the two tillage systems present similar energy demand and environmental impacts profile, with the exception of the categories photochemical ozone creation and freshwater aquatic ecotoxicity. In both systems, the use of mineral fertilisers has the greatest energy demand, with a contribution of over 75%, and the greatest environmental impacts. In contrast, fungicides and seeds have a minimum contribution, all together, less than 3%. The results of LCA of fertilisation trials show that higher fertilisation rates require an increase in seed yield to compensate additional impacts and to be environmentally favourable.

► Local data are integrated into international database; making LCA more site-specific.
► Conventional and zero tillage present similar energy demand and environmental impacts.
► Fertilisers cause the highest energy demand and the greatest impacts in both tillages.
► Higher fertilisation rates require a yield increase to compensate additional impacts.