Driving soil N2O emissions under nitrogen application by soil environmental factor changes in garlic-maize rotation systems

In multiple cropping systems, optimizing nitrogen (N) input can mitigate N2O emissions and sustain agricultural productivity in frequently disturbed environments. Nonetheless, there remains a notable gap in understanding the role of soil environment in the N application process. Hence, a three-annual field experiment spanning six growth seasons from 2019 to 2022 was conducted to assess the impacts of surface water filled-pore space (WFPS), NO3−−N, and meteorological factors under combined N applications during garlic (G: 300 and 240 kg N ha−1) and maize seasons (M: 220, 175, and 130 kg N ha−1) on soil N2O emissions and crop yields. The findings showed that reducing the annual N application rate by 45−150 kg ha−1 led to a significant decrease in N2O emission flux by 27.7%−69.4% and 30.7%−53.6% in maize and garlic season respectively, compared to conventional N application (G300M220). However, decreasing N application notably reduced garlic yield by 4.5–22.8%. Furthermore, reducing annual N application decreased net environmental and diminished net environmental and economic benefits (NEEB) by 3.7%−28.9%. Multiple regression analysis demonstrated that the residual NO3–−N in the soil before nitrogen application significantly influenced short-term N2O emissions post-application, while WFPS exerting a more pronounced effect during the maize season. Precipitation and temperature exhibited contrasting impacts on N2O emissions in the two crop seasons. Principal component analysis revealed that supplemental irrigation enhances crop yield in the maize growing season but also exacerbated N2O emissions due to the alternation of dry and wet conditions. Precipitation in the garlic growing season emerged as a crucial meteorological factor affecting crop yield and N2O emissions. The NEEB analysis suggested that reducing 45 kg N ha−1 in the maize season (G300M175) represents a more balanced N application approach to mitigate productivity and environmental risks in rotation systems. Therefore, accounting for the stimulating effect of soil environmental factors during the short-term N application process, adjusting irrigation practices based on seasonal precipitation and temperature variations can enhance productivity and reduce gaseous nitrogen losses in multiple cropping systems within semi-arid regions.