Mixed crop-livestock farm: definitions and research issues. A review

For two decades, mixed crop-livestock farms have once again been attracting worldwide interest, in particular in the northern hemisphere, where mixed crop-livestock farms have been decreasing. As they are considered to be a good way of limiting environmental problems while being productive and economically viable, mixed crop-livestock systems could be a way to tackle environmental challenges linked to specialised agriculture. The definition of mixed crop-livestock farming nevertheless includes many different types of farming around the world. According to the level of interactions between livestock and crops within farm, mixed crop-livestock farms could be more or less able to meet sustainability challenges. The research works reviewed are mostly focused on biophysical flows between crops and livestock within farms. Farmers' decisions and practices are not taken into account in these works. Mixed crop-livestock studies are based mainly on technical or economic arguments, or on contrasted case studies of the southern hemisphere. Systemic approaches are needed to allow a rethink of the way in which mixed crop-livestock farming could contribute to sustainable development. To limit misunderstanding, the definition of mixed crop-livestock systems should better explained in research studies on the topic, in particular the level of integration between crops and livestock considered. Specific political incentives would be needed to develop and maintain mixed crop-livestock systems, especially in the northern hemisphere