Organic crop rotation experiments - short-term versus longer-term results

Summary

Danish experiments with cereal-based organic crop rotations have shown that the short-term results (the first course, up to four years after conversion) are different from those obtained in the longer-term (the second course, fifth to eighth year after conversion). Yield gain from use of manure increased from the first to the second course on a sandy soil, but decreased on loamier soils. Yield gain from leguminous catch crops increased from the first to the second course in a crop rotation without grass-clover. Some of these effects were caused by buffering effects of the grass-clover, other effects were caused by changes in soil fertility over time.