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.