Legume catch crops for reducing N leaching and substituting animal manure

Summary

Organic cereal production on coarse sandy soil is a challenge because of low soil fertility and a general limitation on the use of animal manure. The possible exclusion of conventional animal manure in organic crop production increases the challenge further. Two factorial experiments were carried out aiming at investigating the potential of legume catch crops with respect to residual effects and effects on N leaching. Legume catch crops were compared with non-legume catch crops in systems with spring barley as the main crop each year. Grain yields were determined and N leaching losses measured by means of installed ceramic suction cups. The legume catch crops, especially white clover and red clover, showed large residual effects in succeeding spring barley, and clover was efficient in reducing N leaching losses. A clover catch crop had the potential to replace animal manure but attention should be paid to the risk for poor growth in soil recently cropped to clover.