Organic vegetable production is highly dependent on external nitrogen input. Frequently no manure is available, because this farm type is normally specialised and thus stockless. Consequently vegetable producers are subjected to crisis, related to severe animal diseases such as BSE.
To increase the nitrogen stocks on the farms, nitrogen fixing legumes are cultivated as green manure. However only parts of the knowledge gained in arable crops can be transferred to vegetable production systems. In this project, we investigate how to increase the benefits from a greenmanure through opimal cultivation techniques. Moreover we optimize rotations in crops which are harvested in late autumn such as cabbage or leek by undersowing greenmanure. Questions of nitrogen transfer from green manure to the following crop are in focus. However we also establish practices to control the weeds and the undersown greenmanure in the standing crop. Moreover the effects of a greenmanure on the suppression of soil born diseases and on mycorrhizal root symbiosis are assessed. Compost is used alternatively to greenmanure, as it is known that high quality composts have a high capacity to control root diseases.
