De toepassing van gedeelde stikstofgiften bij enkele zaadgewassen

The influence was studied of split dressings of N on susceptibility to lodging, on yields of grain and straw and on seed quality of a number of seed crops: poppy (Papaver somniferum), spinach (Spinacia oleracea), radish (Raphanus sativus), caraway (Carum carvi), winter swede-like oilrape (Brassica napus var. biennis) and canary grass (Phalaris canariensis). The data on yield, lodging and quality were from field trials under normal management. The second application of N was just before flowering. Of the 6 seed crops, at least 3 (poppy, spinach, radish and sometimes caraway) increased in seed production. The other crops reacted either indifferently (caraway, winter swede-like oilrape) or always negatively (canary grass). Split dressings improved seed quality of poppy and radish. The commercial value of other crops was not affected. The effect on straw stiffness (lodging) of the crops concerned was not marked; only for poppy and to a lesser extent spinach and radish did split application provide some advantage. For poppy, spinach and radish seed N dressing could be delayed until plants were in full bloom.