Reconnecting crop farming and cattle breeding for a reduction of nitrogen losses in an instensive agricultural watershed

Abstract : Industrial agriculture and the use of nitogen fertilisers have led to the massive introduction of reactive nitrogen into the biosphere, which subsequently cascades through a number of environmental compartments (Galloway et al 2003 ; Sutton et al 2011). Nitrate contamination of ground- and surface water as well as atmospheric pollution are among the major threats. To overcome this problem a drastic change must be initiated now in agriculture. Several experimental studies have been carried out to implement a modeling approach able to simulate the current situation. Our objectives here are to explore scenarios to reduce nitrogen losses including one dealing with reconnection of crop production and cattle breeding, as was the rule in this area previously. Centered on a small watershed level, our analysis aims to extrapolate the result at the scale of the entire Seine basin (80000 km2) or at a pluriregional scales.