Objectives The study aimed to investigate the effects of different rainfall patterns on soil N₂O emission dynamics in upland agricultural systems and to elucidate the underlying mechanisms regulating N₂O production and emission under extreme climatic conditions, thereby providing a scientific basis for mitigating N₂O emissions from agricultural soil.

Methods A field experiment was conducted in Shangzhuang, Beijing, using a rainout shelter to establish the regular rainfall pattern and extreme rainfall pattern. Each rainfall pattern subjected three fertilization treatments: no fertilization, nitrogen application, and nitrogen application combined with straw return, resulting in six treatment combinations. During the summer maize growing season, at total rainfall of 450 mm, the regular rainfall treatment consisted 15 events at 30 mm each event, and the extreme rainfall treatment consisted of 3 events at 100 mm and 2 events at 75 mm. Temporal variations in soil N₂O concentration, surface N₂O flux, soil water-filled pore space (WFPS), and soil mineral nitrogen were continuously monitored.

Results Extreme rainfall significantly intensified short-term fluctuations in soil N₂O concentrations, with the maximum N₂O concentration being 59.2% higher than that under the regular rainfall. Mean N₂O fluxes under extreme rainfall were 19.3%, 37.7%, and 4.7% higher than those under the regular rainfall for the no nitrogen, optimized nitrogen application, and optimized nitrogen application with straw return treatments, respectively. Extreme rainfall also exacerbated short-term variations in soil WFPS, which stimulated N₂O emissions pulses. Overall, nitrogen fertilization significantly increased cumulative N₂O emissions by 189.7%−256.5%, while straw return had no significant influence on cumulative N₂O emissions. Compared with the nitrogen application treatment, straw return tended to increased cumulative N₂O emissions under regular rainfall, whereas an opposite trend was observed under the extreme rainfall.

Conclusions Nitrogen fertilization and soil water-filled porosity are identified as the primary drivers of N₂O emissions in upland soils. Nitrogen fertilization leads to significant increase N₂O emissions, regardless rainfall intensity and straw return. Extreme rainfall regulates N₂O emissions mainly by altering nitrogen transformation and soil water-filled porosity, leading to enhanced N₂O emissions. Therefore, avoiding the temporal coupling of nitrogen fertilization with extreme rainfall events may represent an effective strategy for mitigating agricultural N₂O emissions under future climate extremes.