Making the most of soil nitrogen

Summary

Optimising the amount of nitrogen captured by fertility building crops is essential for successful organic farming. This study used a combination of literature review, empirical measurements, model development and farmer participation to produce improved guidelines on making the most of soil nitrogen for organic farmers and growers. The main field experiment examined the impact of cutting and mulching on the build up of soil nitrogen. Recommendations to organic farmers from this part of the work, are that cutting and removing herbage during the fertility building phase promotes the highest amount of nitrogen fixation. However the highest soil residues occurred when clover was mulched in situ. Application of organic manures to legumes should also be avoided if the maximum amount of atmospheric N is to be fixed. The fi ndings from the study have been made available in a Guidelines Booklet.