Importance of agricultural transport in the biogeochemical cycle of nitrogen in France: insight into territorial production specialization

The French agriculture, agronomically and economically very efficient, is responsible for significant nitrogen losses to the hydrosystems and the atmosphere, causing severe environmental damages. Based on the analysis of the SitraM database on commodity transport between French administrative departments and with foreign countries, a budget of agricultural goods has been established, in terms of imbedded protein-N fluxes, for seven groups of agricultural commodities. The 95 French departments were grouped into 33 agricultural territories defined according to their geographical proximity and the similarity of their production system. The results show the magnitude of commercial mobility of agricultural goods. Trade exchanges between territories and with foreign countries in 2006 amount to 1.6 fold the national production. Overall, France appears as net exporter of proteins with foreign countries, importing 284 ktonN/yr of feed and exporting 390 ktonN/yr mostly as cereals. The analysis reveals the extreme specialisation of many territories into either cash crop or livestock farming, and allows distinguishing five major territorial ensembles on the basis of the magnitude and destination of their food and feed exchanges. Controlling the nitrogen cycle and its perturbations by agriculture requires taking into account trade fluxes of agricultural commodities.