Crop-livestock systems for effective nitrogen utilisation

Agricultural production systems have become significantly more intensive, specialised and concentrated within regions that have themselves become highly specialised. This development was driven by economic considerations at a time when energy prices were low and environmental concerns were ignored. Today, these regions are facing the degradation of their ecosystems, with damage to water and soil quality and a decline in biodiversity. In particular, the decoupling of livestock from land use leads to significant emissions of reactive nitrogen. Mixed crop-livestock systems offer opportunities to increase the efficiency of nitrogen use within agricultural systems by optimising ecological interactions and the recycling of nutrients, and by basing production systems more heavily on the utilisation of renewable resources. This paper examines the potential for developing an innovative crop-livestock-livestock farming system that limits the use of synthetic mineral fertilisers through the widespread use of legumes and the recycling of livestock manure, whilst conserving nitrogen within the systems through the selection of crop rotations that include grassland or other fodder crops. These synergies between animal and crop production should be sought at various organisational levels, ranging from the individual farm, to groups of interacting farms, and at regional or even national level.