Nitrogen availability shifts the microbial drivers of post-drought N2O emissions in contrasting agricultural soils

Drought-rewetting cycles trigger nitrous oxide (N 2 O) pulses in agricultural soils, how nitrogen (N) availability modulates the recovery and N 2 O source partitioning of distinct nitrifying guilds remains unclear. Using selective inhibitors, we quantified the contributions of ammonia-oxidizing bacteria (AOB), archaea (AOA), and complete ammonia oxidizer (comammox Nitrospira ) to post-drought N 2 O fluxes in acidic red and alkaline calcareous soils across N gradients. Results revealed distinct guild-specific recovery patterns driven by N availability and soil pH. In calcareous soil, high N inputs accelerated AOB recovery, accounting for 81.7% of autotrophic nitrification-derived N 2 O emissions. Conversely, red soil exhibited a balanced partitioning: AOA showed high resilience (contributing 40–50% to autotrophic nitrification-derived N 2 O emissions across N gradients), while comammox-driven emissions peaked (15.2–22.8%) under low N but were outpaced by AOB under high N. Theoretically, high N narrows the community towards AOB dominance in alkaline calcareous soils, whereas acidic red soils sustain diverse guild contributions. These results highlight the need for targeted N management that accounts for multiple soil properties, including pH, as well as carbon and nitrogen availability.