Nitrogen recommendation of cauliflower based on different soil Nmin target values

How to determine the optimum inorganic N rate, which will both satisfying the growth of vegetable and minimizing the pollution of nitrogen on environment, in root-distributed soil layer on different growth stages is the key factor on nitrogen recommendations. In a field experiment, nitrogen fertilizer was recommended on cauliflowe(Brassica oleracea L. var botrytis) at different Nmin target values (N 0, 50, 100, 200,3 00 and 400 kg/hm2) based on the principle of nitrogen balance in soil-plant system. The growth, nitrogen utilization of cauliflowers and the inorganic N balance and losses in soil-plant system were studied. The results showed that, the necessary target Nmin value for optimum growth and N uptake by cauliflower was N 100 kg/hm2. However, based on calculation, the highest N supply must be lower than N 200 kg/hm2, or the Nmin target value must be lower than N 50 kg/hm2 to keep nitrogen balance during the experiment. According to analysis of yield, environmental and benefit, N 100 kg/hm2 should be the best Nmin target value in the experiment. The recommendation based on reasonable soil Nmin target value has a good perspective on vegetable production in future.