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‰ 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.