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.

一氧化二氮（Nitrous oxide, N2O）是一种强效温室气体，施用氮肥后其排放量会显著升高。硝化抑制剂3,4-二甲基吡唑磷酸盐（3,4-dimethylpyrazole phosphate, DMPP）被广泛用于减缓这类温室气体排放，但其长期减排效果仍不明确。本研究在高排放酸性茶园土壤中开展了为期三年的田间试验，结果表明，受微生物适应性影响，DMPP对N2O排放的抑制作用随时间推移逐渐减弱。该抑制效果的衰减由功能冗余与生态位补偿机制驱动：高N2O排放潜能的氨氧化古菌（Nitrososphaera属与Candidatus Nitrosocosmicus属）相对丰度升高，以补偿被抑制的氨氧化细菌活性。微生物群落结构从亚硝化螺菌属（Nitrosospira）向对DMPP不敏感的亚硝化单胞菌属（Nitrosomonas）类群转变，维持了硝化作用与N2O产生过程。共现网络分析进一步揭示了硝化微生物之间生态位竞争加剧与代谢权衡现象。为评估上述发现的广泛适用性，我们对88项田间研究开展了荟萃分析，结果显示尽管施用DMPP平均可降低49%的N2O排放，但其减排效果强烈依赖于施用时长。随机森林建模验证了我们在不同气候与土壤类型下的田间观测结果，表明连续五年施用DMPP后，其减排潜力会下降12%。这些研究结果凸显了制定适应性氮肥管理策略（如抑制剂轮换）以应对微生物抗逆性的迫切需求。本研究将微生物生态学与农业环境政策相结合，为可持续N2O减排提供了可落地的科学见解，并丰富了关于气候-粮食安全关联的学术讨论。