2016/08/25 by Nesme, Thomas, Nowak, Benjamin, David, Christophe +1
#Agriculture conventionnelle #Azote #Conventional farming #District scale #Nitrogen #Nutrient recycling #Phosphore #Phosphorus #Recyclage #Territoire
paper · doi:10.15454/1.4721176631543018e12
The Ecology principle is at the core of organic farming. Regarding nutrient management, this principle implies that chemical fertiliser should be banned and be replaced by enhanced recycling (within and among farms) and biological nitrogen fixation by legumes. However, based on the survey of 63 organic farms in three French districts, we demonstrated that organic farming can be somehow, indirectly reliant on chemical fertiliser. Such reliance is due to two major factors. First, organic farms import a large share of their nutrients (23% of nitrogen and 73% of phosphorus entering organic farms, mostly as manure) from conventional farms. Second, organic farms can rely on nutrient accumulated in soils prior to the conversion: this legacy effect results in the 70% anthropogenic signature of the P in organic crop and animal products. These results suggest that organic farming development can conflict with the Ecology principle. However, this paper also demonstrates that some solutions exist to limit the indirect reliance on chemical fertilisers. In particular, the diversity of agricultural productions at the district scale is a strong leverage to increase nutrient recycling among organic farms.