Nitrogen fertilization in organic crop rotations

Nitrogen fertilization in stock free organic farming systems can be provided by introducing green manure fertilization or legume crops as part of the total nitrogen needed in the rotation. Another valuable source is organic waste materials. We investigate the nitrogen effect to following crops by organic waste materials and legume crops.

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Fertilization of organic crop rotation with organic waste related fertilizers. Photo: Randi Seljåsen / NIBIO
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Incorporation of legumes residues as nitrogen source for following vegetable crops. Photo: Randi Sljaasen
Nitrogen dynamics in organic farming systems with vegetables is studied on organic soils at Landvik in Grimstad. Focus has been to study the productivity of nitrogen fixating crops, nitrogen available to following crops, use of catch crops to reduce leaching. Studies have been performed on different rotations including the main crops: onion, carrots, lettuce, potatoes, head cabbage, broccoli, fava beans and peas and green manure crops of clover crops.

Research has been focused also on co-streams from agricultural farming or food industry to be used as fertilizers. Our research within this topic has be related to utilization of anaerobic digested food waste,  shrimp shell and macro algae meal in comparison with animal manure and mineral fertilizers.