土壤N2O排放量和小麦、玉米效益俱佳的吡啶喷涂尿素适宜用量研究

【目的】 粮田过量施用氮肥造成土壤向大气排放N₂O增多，土壤氮素表观损失提高，为实现粮田安全生产，研究吡啶喷涂尿素对冬小麦/夏玉米轮作系统内土壤N₂O排放和氮素表观损失、籽粒产量和净收益的影响。【方法】 按照1.1‰的比例将2-氯-6-三氯甲基吡啶喷涂在尿素表面制成吡啶喷涂尿素，进行了玉米、小麦田间试验。在磷、钾养分用量相同的条件下，设置4个吡啶喷涂尿素施用水平，玉米分别为0、180、270和360 kg/hm2，小麦分别为0、150、225和300 kg/hm2，调查作物产量和施肥效益；在2茬作物生长期间采用静态箱法收集气体，测定土壤N₂O排放量和排放强度。【结果】 各处理玉米和小麦季基肥和追肥后均出现显著的N₂O排放峰，土壤N₂O排放、氮素表观损失、N₂O排放强度等均随施氮量增加而增加。玉米季，吡啶喷涂尿素用量270和360 kg/hm2间无显著差异，2处理玉米分别较不施氮肥净增收5208.0和5425.4 yuan/hm2；小麦吡啶喷涂尿素用量为225 kg/hm2时，籽粒产量和净收益均最大。整个轮作季，与N₃处理（玉米和小麦季分别施用吡啶喷涂尿素360和300 kg/hm2）相比，N₂（玉米和小麦季分别施用吡啶喷涂尿素270和225 kg/hm2）处理的作物产量相当，但土壤N₂O排放量减少1.51 kg/hm2，土壤氮素表观损失减少39.4 kg/hm2，施氮肥量减少165 kg/hm2，净增收提高405.3 yuan/hm2。【结论】 玉米-小麦轮作季吡啶喷涂尿素用量分别为270和225 kg/hm2时增产增收，且土壤N₂O排放和氮素表观损失较少。

Nitrapyrin-urea application amount with less soil N2O emission and highest profit in summer maize and winter wheat

Objectives] Appropriate nitrapyrin-urea application amount was studied for the less soil N2O emission and high profit in summer maize and winter wheat production system.Methods] Nitrapyrin was sprayed on urea in ratio of 1.1％o to make nitrapyrin-urea.Four application rates were designed in summer maize and winter wheat in field plot experiments.For maize,the nitrapyrin-urea N rates were 0,180,270 and 360 kg/hm2,for wheat were 0,150,225 and 300 kg/hm2.Yield and nitrogen fertilizer profits were investigated;soil N2O emission was determined using the static chamber method.Results] The results showed that soil N2O emission peaks appeared after the basal or topdressing fertilization of nitrapyrin-urea.With the increase of N fertilization rates,the soil N2O emission,N apparent loss,N2O emission intensity were increased.Compared with the N0,the yields of the crops were significantly increased by 27.9％-48.9％,28.3％-51.7％ and 28.1％-48.9％ in maize,wheat and the rotation system.There was no significant difference in maize yields between the N rates of 270 and 360 kg/hm2,and the net incomes of these two treatments were 5208.0 and 5425.4 yuan/hm2,respectively.The wheat yield and net income were both the maximum in the nitrapyrin-N fertilization rate of 225 kg/hm2.For the whole rotation system,the yields of grain were increased with nitrapyrin-N fertilization rates,compared to the treatments of nitrapyrin-N rates of 360 and 300 kg/hm2 in maize and wheat,the yields of the treatments of nitrapyrin-N rates of 270 and 225 kg/hm2 in maize and wheat were similar,while the soil N2O emission was decreased by 1.51 kg/hm2 and the N apparent loss in soil was decreased by 39.4 kg/hm2,and the N fertilization amount reduced by 165 kg/hm2,net income increased by 405.3 yuan/hm2.Conclusions] Under the experimental condition,the appropriate nitrapyrin-N fertilization rates are 270 kg/hm2 for maize and 225 kg/hm2 for wheat.