THE EFFECT OF NITROGEN AND THE METHOD OF APPLICATION ON NITROGEN UPTAKE OF CAULIFLOWER AND ON NITROGEN IN CROP RESIDUES AND SOIL AT HARVEST

The effects of the rate of nitrogen and of the method of application o n the nitrogen utilization of cauliflower were studied during two seas ons and at four locations. Maximum nitrogen uptake by the crop was aro und 310 kg per hectare. Uptake of nitrogen was influenced neither by t he method of application (band placement vs broadcast) nor by splittin g the applications (twice vs once). The utilization efficiency decreas ed with increasing nitrogen rates. Independent of the amount of nitrog en applied, about 50 per cent of the nitrogen taken up in the above-gr ound plant parts was removed from the field with the product. The amou nt of soil mineral nitrogen al harvest increased with an increase in n itrogen applied, but was not significantly influenced by band placemen t. With broadcast application, more nitrogen was sometimes found betwe en the rows as compared to in the row. With band placement at the high est fertilizer rate, considerably more nitrogen was found where the fe rtilizer had been placed. The 'loss' of nitrogen from the crop/soil sy stem during cultivation increased with increased availability of nitro gen. At the optimum application of nitrogen fertilizer around 100-120 kg ha(-1) of nitrogen remained in crop residues and about 50-80 kg ha( -1) in the soil (0-60 cm). Practical implications for the reduction of loss of nitrogen from crop and soil after harvest are discussed.