Energy balance and greenhouse gas emissions: agricutural perspectives

According to an official french life cycle study, the energetic balance of biodiesel produced from oil seed crops is about 2.99 for oil seed rape and 3.16 for sunflower. Diesel greenhouse gas emissions are roughly four times as important as biodiesel emissions from oil seed crops. So presently, these two major performances of sustainability result very positive. For oil seed rape, development of acreage on deep soils, decrease of N fertilisation rate, decrease of energetic costs in N fertilisers industry and development of minimum tillage should continue to improve on energetic balance. On the contrary, for sunflower, the present trend is not an improvement of its energetic balance. In order to go more ahead, more abrupt changes are needed: as reduction of N applications for sunflower, and oil seed rape plant breeding in order to increase N content of seeds and decrease N content of its harvest residues.