Prolonged use of DMPP reduces its effectiveness in mitigating nitrous oxide emissions
Nitrous oxide (N2O), a potent greenhouse gas, exhibits increased following nitrogen fertilizer application. While the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) is widely employed to mitigate these emissions, its long-term effectiveness remains unclear. Through a three-year field experiment in high-emission acidic tea plantation soils, we demonstrated that the inhibitory effect of DMPP on N2O emissions progressively weakened over time due to microbial adaptation. This attenuation was driven by functional redundancy and niche compensation mechanisms: the relative abundance of high-N2O-emitting ammonia-oxidizing archaea (Nitrososphaera and Candidatus Nitrosocosmicus) increased to compensate for the inhibited activity of ammonia-oxidizing bacteria. A compositional shift from Nitrosospira to DMPP-insensitive Nitrosomonas clusters sustained nitrification and N2O production. Co-occurrence network analysis further revealed intensified niche competition and metabolic trade-offs among nitrifiers. To assess the broader implications of these findings, we conducted a meta-analysis of 88 field studies, demonstrating that while DMPP application did reduce N2O emissions by an average of 49%, its efficacy was strongly dependent on duration of use. Random forest modeling corroborated our field observations across diverse climates and soil types, revealing a 12% decline in mitigation potential after five consecutive years of DMPP application. These results highlight the urgent need for adaptive nitrogen management strategies, such as inhibitor rotation, to counter microbial resilience. Bridging microbial ecology with agro-environmental policy, our study advances actionable insights for sustainable N2O mitigation and enriches the discourse on the climate-food security nexus.