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 method and rate of nitrogen application on the efficiency of nitrogen utilization by cauliflower were studied during 2 seasons and at 4 locations. Maximum nitrogen uptake by the crop was ~310 kg/ha. Uptake of nitrogen was influenced neither by the method of application (band placement vs. broadcast) nor by splitting the applications (twice vs. once). The utilization efficiency decreased with increasing nitrogen rates. Independent of the amount of nitrogen applied, ~50% of the nitrogen taken up in the above-ground plant parts was removed from the field with the product. The amount of soil mineral nitrogen at harvest increased with an increase in nitrogen applied, but was not significantly influenced by band placement. With broadcast application, more nitrogen was sometimes found between the rows as compared to in the row. With band placement at the highest fertilizer rate, considerably more nitrogen was found where the fertilizer had been placed. The 'loss' of nitrogen from the crop/soil system during cultivation increased with increased availability of nitrogen. At the optimum application of nitrogen fertilizer ~100-120 kg/ha of nitrogen remained in crop residues and ~50-80 kg/ha in the soil (0-60 cm). Practical implications for the reduction of loss of nitrogen from crop and soil after harvest are discussed.