NITROGEN ACCUMULATION AND NITROGEN RESIDU ES OF FIELD BEANS (VICIA-FABA L) .3. UTILIZATION AND CONSERVATION OF MINERALIZED NITROGEN AFTER FIELD BEANS BY INTERPLANTING

Field trials were conducted to test methods of interplanting in order to conserve and to use mineralized nitrogen during a 6-8 months period after harvesting field beans. During flowering or at brown ripe stage of field bean crops winter rape and winter barley were undersown, res pectively. The goal was to establish reasonable crops by undersowing w ithout soil preparation, at first to ensure a quick and early uptake o f mineralized nitrogen and secondly to grow a subsequent crop for grai n production. Additionally winter rape and winter barley were sown aft er the harvest of field beans at locally conventional dates and method s. During a 6-8 months period the N-min-content of the soil (kg NO3-N/ ha, depth 0 to 90 cm) and the N-uptake (kg N/ha) by winter rape and wi nter barley were measured. At full ripe stage grain yields of winter r ape and winter barley were measured. Crops undersown during flowering emerged satisfactorily but suffered from lack of light. Crops undersow n on the soil surface at brown ripe stage did not emerge under dry con ditions. On the other hand undersown and fairly well developed crops r educed N-min-levels to 20 kg N/ha quickly and remarkably earlier as co mpared to conventionally sown rape or barley crops. Attempts to improv e the coordination of field bean crops and undersown crops are discuss sed. Grain yields of undersown winter rape and winter barley crops did not reach yield levels of conventionally sown crops, but efforts to o ptimize the lateron growth and yielding of undersown crops are under i nvestigation.