土壤N_2O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

Nitrapyrin-urea application amount with less soil N_2O emission and highest profit in summer maize and winter wheat

【目的】粮田过量施用氮肥造成土壤向大气排放N_2O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N_2O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360kg/hm^2,小麦分别为0、150、225和300 kg/hm^2,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N_2O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N_2O排放峰,土壤N_2O排放、氮素表观损失、N_2O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/hm^2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/hm^2;小麦吡啶喷涂尿素用量为225 kg/hm^2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/hm^2)相比,N2(玉米和小麦季分别施用吡啶喷涂尿素270和225 kg/hm^2)处理的作物产量相当,但土壤N_2O排放量减少1.51 kg/hm^2,土壤氮素表观损失减少39.4 kg/hm^2,施氮肥量减少165 kg/hm^2,净增收提高405.3 yuan/hm^2。【结论】玉米–小麦轮作季吡啶喷涂尿素用量分别为270和225 kg/hm^2时增产增收,且土壤N_2O排放和氮素表观损失较少。

【Objectives】Appropriate nitrapyrin-urea application amount was studied for the less soil N_2O emission and high profit in summer maize and winter wheat production system. 【Methods】Nitrapyrin was sprayed on urea in ratio of 1.1‰ 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 and360 kg/hm^2,for wheat were 0, 150, 225 and 300 kg/hm^2. Yield and nitrogen fertilizer profits were investigated;soil N_2O emission was determined using the static chamber method. 【Results】The results showed that soil N_2O emission peaks appeared after the basal or topdressing fertilization of nitrapyrin-urea. With the increase of N fertilization rates, the soil N_2O emission, N apparent loss, N_2O 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/hm^2, and the net incomes of these two treatments were 5208.0 and 5425.4 yuan/hm^2,respectively. The wheat yield and net income were both the maximum in the nitrapyrin-N fertilization rate of 225kg/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 N_2O 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 225kg/hm2 for wheat.