Mitigation of greenhouse gas emissions in the French winter oilseed rape in order to produce sustainable biodiesel

The objectives of the study were (1) to evaluate the possibility for the French winter oilseed rape to achieve the 50% greenhouse gas (GHG) saving criteria of the European Directive on the promotion of renewable energy (2009/28/EC), and (2) to investigate mitigation options. The agricultural GHG emissions were calculated with the actual seed yields and cultural operations of more than 5000 winter oilseed rape fields producing seeds collected by 27 grain storage companies (GSC), while the same values of GHG emissions for transport and biodiesel processing were used for all GSC. The study clearly showed that the 50% GHG saving criteria could not be achieved each year, by each of the grain storage company, without improvements of crop management. The possibility to reduce the GHG emissions by improving the efficiency of mineral N fertilization was demonstrated. Improving seed yields without increasing the amount of N application on the fields would also decrease GHG emissions. On the contrary, the application of organic matter appeared to be largely ineffective because of the way N2O emissions were calculated in the study (tier 1 method of International Panel on Climate Change).