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

Drought-rewetting cycles trigger nitrous oxide (N2O) pulses in agricultural soils, how nitrogen (N) availability modulates the recovery and N2O 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 N2O 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 N2O emissions. Conversely, red soil exhibited a balanced partitioning: AOA showed high resilience (contributing 40-50% to autotrophic nitrification-derived N2O 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.