Recoupling of crop and livestock production: a prerequisite to close biogeochemical cycles?

Overview & Synopsis

Specialisation of farms and spatial segregation between crop and livestock production systems have hampered the proper recycling of nutrients. As a result, N and P budgets are often in excess in intensive livestock regions, whereas intensive arable regions rely on mineral fertilisers. Despite progress in adjusting mineral supply to animal needs in feed rations, nutrient use efficiency by animals remains low, between 10 and 60% depending on the animal species and livestock system. Conversely, the efficiency of use of N and P supplied by animal manure by plants is close to that observed for soluble mineral fertilizers since the methods and schedules of intake allow a supply of nutrients synchronous with plant needs. Therefore, an overall high efficiency of the system requires a recoupling of crop and livestock production systems. Innovative technical or organisational levers, at several organisation levels, may help reaching this recoupling.