EFFECT OF AN IN-SEASON LIVING MULCH ON LEACHING OF INORGANIC NITROGEN IN CAULIFLOWER (BRASSICA OLERACEA L. VAR. BOTRYTIS) CROPPING IN SLOVENIA, GERMANY AND DENMARK

Vegetables with a high nitrogen demand such as cauliflower may cause intensive leaching of nitrate to the environment in conventional as well as in organic production. In organic cropping systems, the use of an in-season living mulch may decrease the risk of nitrate leaching after harvest when left growing in the field to the end of the leaching season in spring. The aim of this study was to investigate the effect of growing an in-season living mulch including legumes on the risk of leaching of inorganic nitrogen over winter, and soil nitrogen availability the following spring. Three field experiments were carried out in Slovenia, Germany and Denmark in the frame of the Interveg project (CORE organic II). Evaluation of soil inorganic nitrogen content was done at planting, at harvest, in late autumn and in spring to a depth of 0.6, 0.9 or 1.5 m as well as nitrogen uptake by the biomass. This study reports preliminary results of the first year of experiments on soil inorganic nitrogen at harvest and the end of the leaching season. They indicate that living mulches may have a potential to decrease the nitrate leaching risk depending on the design of the cropping system.