Synergistic effects of precipitation events and long-term N addition on N2O emissions in a temperate meadow steppe, Northeast China

Precipitation events and nitrogen (N) addition play important roles in regulating nitrous oxide (N2O) emissions in semi-arid grassland ecosystems. The effects of precipitation events, long-term N addition, and their interaction on N2O emissions, however, remain largely unclear. We conducted a mesocosm experiment to examine how long-term N addition (0 and 10 g N m- 2 yr ? 1, from 2011 to 2020) affects N2O emission responses to a gradient of manipulated precipitation events (0, 5, 10, 20, and 50 mm). The precipitation events had pulsing effects on N2O emissions due to the stimulation of microbial activity and substrate availability. Precipitation events significantly parabolically increased cumulative N2O emissions. Long-term N addition substantially enhanced cumulative N2O emissions response to precipitation events. The precipitation events and long-term N addition synergistically improved cumulative N2O emissions. The water-filled pore space and ammonium nitrogen content were the most important factors driving the temporal dynamics and accumulation of N2O emissions following the precipitation events and long-term N addition. Our study indicates that N addition affects the N2O emissions responses to precipitation events, which are essential for understanding the response of N2O emissions to global change.