Adopting different irrigation and nitrogen management based on precipitation year types balances winter wheat yields and greenhouse gas emissions

The implementation of appropriate irrigation and nitrogen (N) measures is essential for obtaining higher grain yields while minimizing environmental risks. To determine whether deficit irrigation combined with reduced N-fertilizer rate can mitigate greenhouse gas (GHG) emissions and maintain yield under different precipitation year types (wet, normal, and dry years), a six-year (2014–2020) field experiment was conducted in the North China Plain during the winter wheat growing seasons. There were two irrigation schedules (conventional irrigation, W2; deficit irrigation, W1) and two levels of N application (conventional fertilization, N2; nitrogen reduction, N1), which resulted in four treatments: W2N2, W2N1, W1N2, and W1N1. Irrigation, fertilization, and precipitation year types all affected the GHG emissions and yield of winter wheat. Compared with conventional irrigation and nitrogen management (W2N2 treatment), appropriate nitrogen reduction (W2N1) and deficit irrigation (W1N2) decreased CO 2 emissions by 17.7–19.8% and 14.8–25.2%, respectively, and reduced N 2 O by 34.4–36.3% and 21.0–25.8%, respectively. Without compromising crop yield, the W1N2 treatment with deficit irrigation resulted in 17.1% lower net greenhouse gas (NGHG) and 16.5% lower greenhouse gas intensity (GHGI) in wet years; and the W2N1 treatment with nitrogen reduction reduced NGHG and GHGI by 20.5% and 18.7%, respectively, in normal years; and it also led NGHG and GHGI to decrease by 18.5% and 18.1%, respectively, in the dry year. Therefore, deficit irrigation in wet years and N reduction in normal years and dry year can reduce GHG emissions and maintain yield. Optimizing N fertilizer and irrigation management according to variation in precipitation conditions can mitigate GHG emissions, enhance yield, and promote the sustainable development of agriculture and the environment. • Greenhouse gas emissions significantly differed among different precipitation year types in a six-year field experiment. • In wet years, deficit irrigation reduced net greenhouse gas by 17.0% and maintained wheat production. • Nitrogen reduction decreased net greenhouse gas by 20.5% and 18.5% in normal and dry years, respectively. • Optimized water and fertilizer management schemes for winter wheat in different precipitation year types were proposed.