不同施肥措施下N2O来源辨析及微生物响应机制研究

Agricultural N2O emission is an important source of greenhouse gas, especially in vegetable fields, with higher N2O emissions due to the excessive nitrogen application. Clarifying the N2O source and the formation mechanism is important for controlling greenhouse gas emissions and improving nitrogen use efficiency. In this study, we firstly use the stable isotope technique to explore the N2O emission dynamic and quantify the contribution of nitrification and denitrification under different fertilizations in the cabbage field of North China Plain. Further, we use the Illumina sequencing and qPCR to detect the microbial response to different fertilizations on both taxonomic composition and functional genes level, and to verify the important role played by key microbes in nitrification and denitrification. By constructing the linkage of different methods，we try to clarify the impact of the different fertilizations on N2O emissions, which would provide insights into the improvement of fertilization measures and the control of agricultural N2O emissions.

农田N2O为重要的温室气体排放源，尤其是蔬菜田施肥量高、N2O排放量大，探明其N2O来源和排放过程对有效控制温室气体排放和提高氮肥利用效率具有重要意义。本研究以华北平原白菜田为研究对象，利用稳定同位素技术研究不同施肥措施下N2O排放规律和来源，定量不同施肥措施下硝化过程与反硝化过程对于N2O排放的贡献比例。同时利用Illumina高通量测序技术以及qPCR技术，分别在微生物物种和功能基因水平上研究参与N2O排放的关键微生物群落结构以及功能基因的动态变化，探明关键微生物在硝化过程和反硝化过程中发挥的重要作用。通过上述研究，建立不同研究方法的联系，明确不同施肥措施对N2O排放的影响，为制定合理施肥措施、调控农田土壤温室气体排放提供科学依据。

该项目利用稳定同位素技术以及扩增子测序技术研究不同肥料类型下农田土壤N2O排放规律及驱动机制，为农田菜地N2O的减排提供理论依据。具体研究成果包括以下两个方面：首先，对比了不同肥料类型下N2O排放规律与内在机理。结果显示施用无机肥释放的N2O显著高于有机肥，其累积排放量是有机肥的1.5-2倍；稳定同位素技术显示施用有机肥可以促进反硝化作用，而无机肥会使硝化作用增强。其次，探索了关键微生物类群是如何响应不同施肥措施、如何参与硝化与反硝化过程影响N2O排放。Illumina测序结果显示，施加有机肥促进了农田微生物多样性，其中参与N2O还原的微生物多样性增高，推测施加有机肥促进了反硝化作用中的N2O还原过程，降低了N2O排放。因此，在北京农田菜地通过施用有机肥可达到有效的N2O减排效果，本研究为蔬菜生产中肥料的合理应用提供科学依据。