土壤硝化作用是影响作物种植和农业面源污染的重要氮代谢过程，在肥料中添加硝化抑制剂是有效提高氮肥利用率的重要手段。常规抑制剂主要依靠抑制氨氧化细菌(AOB)的活性达到效果，本研究中采用的一氧化氮清除剂Carboxy-PTIO通过抑制土壤氨氧化古菌(AOA)的活性达到抑制剂效果，但其在土壤中的作用机制和有效性尚不明确。本课题通过模拟实验，利用分子生态学和DNA-SIP技术阐释PTIO调控土壤硝化作用的微生物机制；与DCD实验对比探明两种抑制剂对AOA和AOB不同抑制强度，揭示两类氨氧化微生物对土壤硝化过程的贡献率；并从土壤微生物学和土壤学两方面综合评价PTIO应用时的有效性和安全性，阐明其影响农田土壤氮素转化的机制。本课题为发展氮肥高效利用新技术提供新的靶标，为进一步深入研究土壤氨氧化微生物生理功能与群落结构提供重要参考，也为土壤施用PTIO的生态安全提供必要的理论依据。

Nitrification is a very important nitrogen metabolism process in terrestrial ecosystem , which could affect crop production and cause many environmental issues. Nitrification inhibitors are therefore widely used as an effective agricultural management practice to improve the efficiency of nitrogen fertilizers. The common inhibitors depend on inhibiting ammonia-oxidizing bacteria (AOB) activity to have the inhibitory effect, but carboxy-PTIO in our study has an inhibitory effect on ammonia-oxidizing archaea (AOA). The mechanism and efficiency of PTIO in soil remain unclear. Though the undisturbed soil incubation experiments, we adopted molecular ecology and DNA-based stable isotope probing technology to investigate the microbial mechanism of soil nitrification under the Inhibitor PTIO; compared with DCD inhibiting experiment, the effects of PTIO and DCD on AOA and AOB are evaluated, and the different microbial relative contribution on soil nitrification process in the typical farmland are explored; based on microbiology and soil science, the efficiency and safety of PTIO are evaluated and the mechanism of soil nitrogen transformation in farmland under PTIO is clarified. This research can be used to provide new target for the development of nitrogen fertilizer efficient utilization, to provide important reference on AOA and AOB physiological function and community structure study, and also to provide an important theoretical basis of ecological safety for using the ammonia-oxidizing archaea Inhibitor PTIO in the farmland ecosystem.