Oxygen Availability Governs the Mitigating Effect of 3,4-Dimethylpyrazole Phosphate on Nitrous Oxide Emissions from...

Alternate wetting and drying (AWD) frequently triggers nitrous oxide (N₂O) emissions from paddy fields, while the inhibitory effect of 3,4-dimethylpyrazole phosphate (DMPP) on N₂O under various water managements remains uncertain. Here, we evaluated the effects of DMPP on N₂O emissions and associated biological indicators under three water managements: continuous flooding (CF), mild AWD (Mi-AWD), and moderate AWD (Mo-AWD). The Mi-AWD and Mo-AWD practices increased N₂O emissions by 2- and 0.9-fold compared to the CF treatment, respectively, due to enhanced oxygen availability, facilitating coupled nitrification-denitrification. DMPP application notably reduced N₂O emissions in the AWD treatments, attributed to the reductions in nitrifier abundances, nitrification rates, and nitrate accumulation. Nevertheless, DMPP failed to suppress nitrification and, thereby, N₂O emissions in the CF treatment. Overall, DMPP effectively mitigates N₂O emissions under oxygen-rich AWD rather than anaerobic CF conditions, highlighting that the trade-offs between water-saving irrigation and N₂O mitigation can be overcome via nitrification inhibitors application.