Response of winter wheat yield and soil N<sub>2</sub>O emission to nitrogen fertilizer reduction and nitrapyrin application in North China Plain
Mohan Bhandari, Yang Ma, Mingxin Men, Min Wu, Cheng Xue, Yanqun Wang, Yingchun Li, Zhengping Peng
Abstract
Over-fertilization could lead to nitrogen (N) losses and environmental risks, and the appropriate nitrogen fertilizer could reduce the nitrous oxide (N2O) emission and increase the N utilization of crops in the North China Plain. We investigated the effects of rationally reduced N fertilizer input and nitrapyrin (CP) application on N2O dynamic emission, soil N balance, yield, N utilization and net income during the whole wheat season. Five fertilization treatments included zero N (CK), farmers’ traditional N rate (FN), recommended N rate (RN), the 20% reduction of RN (80%RN) and the 20% reduction of RN added with CP (80%RN+CP). The N2O emission fluxes from seedling stage to greening stage contributed to 51.1%-74.2% during the whole wheat growth stages. Moreover, the first peak of N2O emission was observed within half a month after N basal fertilizer, irrigation, and sowing, which was two times higher than the other peaks occurred after N top-dressing and irrigation. The cumulative N2O emission and N2O emission factor were significantly declined by 27.3%-43.4% and 8.9%-51.1% with 80%RN and 80%RN+CP as compared to FN, respectively. Grain yield, agronomic N use efficiency, apparent N use efficiency and N production efficiency with 80%RN+CP were increased by 1.74%-10.83%, 0.9–8.91 kg kg−1, 1.9%-27.5% and 1.22–22.79 kg kg−1 than other N treatments, respectively. Moreover, 80%RN+CP also decreased N loss by 7.88–55.62 kg ha−1 as compared to FN and RN, which resulted in less soil NO3− retention. Consequently, the application of nitrapyrin with 20% reduction of N rate should be recommended to increase winter wheat economic benefits and mitigate environmental pollution in North China Plain.