Long-term management of nutrients in organic farming - priciples and practice

Summary

Organic farming faces a number of challenges as it moves forward. It has become a part of the global agricultural industry and therefore organic products are traded not just between farms and regions but between countries and continents. Inevitably, large amounts of nutrients are exported from farms as part of this process. These farms can only continue to produce acceptable quantities of quality food if these nutrients are replaced. Soil has a finite capacity to supply crop nutrients unless they are replenished. The solution is perhaps easiest for nitrogen where biological fixation by legumes can be harnessed to provide the engine for crop production. For other major and micronutrients more consideration needs to be given to acceptable sources for organic production; in situ mineral weathering from soil parent materials will only rarely meet crop demand. In addition we need to understand and improve the recycling and management of all nutrients on farm to optimise crop and livestock production and quality while minimising losses.