利用不同土壤Nmin目标值进行露地花椰菜氮肥推荐

Nitrogen recommendation of cauliflower based on different soil Nmin target values

确定蔬菜不同生长阶段根层土壤中既满足蔬菜氮需求但又不造成环境问题的土壤无机氮量 (土壤Nmin目标值 )是精确化氮肥施用技术的重要环节。本研究在露地条件下 ,设置不同土壤Nmin目标值 (N 0、5 0、10 0、2 0 0、30 0及 4 0 0kg hm2 ) ,依据土壤 蔬菜体系无机氮平衡的方法进行了花椰菜氮肥推荐 ,从产量、氮吸收、损失及经济等方面对合理的土壤Nmin目标值进行了初步筛选。研究结果表明 ,花椰菜不同生育阶段最佳生长及氮吸收所需的根层土壤Nmin目标值大致为N 10 0kg hm2 ,而保持土壤 作物体系无机氮平衡的氮供应量大致为 2 0 0kg hm2 ,相当于Nmin目标值为N 5 0kg hm2 。综合产量、环境、经济效益三因素 ,N 10 0kg hm2 应是满足花椰菜正常需要且不会产生较大环境问题的合理土壤Nmin目标值。

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.