旱作覆膜农田土壤N2O排放路径及微生物作用机制研究

农田土壤是大气氧化亚氮(N2O)重要排放源，明确农田土壤N2O产生路径及微生物机制是制定减排措施的重要前提。旱作覆膜条件下施肥对N2O排放的影响已有不少研究，但其排放路径及机制仍不清楚。本研究拟在评估旱作覆膜及不同施肥措施对N2O排放通量影响的基础上，利用稳定性同位素技术与分子生物学相结合的方法，通过田间试验（SPN2O-δ18ON2O/H2O及功能基因转录组分析）与室内培养试验（15N成对标记、15N–18O双标记法），揭示长期覆膜及施肥旱作农田土壤N2O主要排放路径、氮素初级转化过程、功能微生物及其与环境因子的关系；应用13CO2-DNA稳定性同位素探针技术及全程硝化细菌（comammox）cladeA、cladeB的氨单加氧酶基因（amoA）代谢活性，明确comammox在不施肥措施下的自养硝化活性及对不同硝化抑制剂的响应，为旱作农田N2O减排措施的制定提供理论依据。

Fertilized agricultural fields is a major source of global nitrous oxide emission, clarifying the producing pathways and associated microbial mechanisms of N2O from farmland is therefore the prerequisite to achieve worldwide N2O emission reduction. N2O emission from varid fertilization strategies in film-mulching drypland soil have drawn increasing concerns, however the underlying mechanisms responsible for N2O emission is still unclear.The main aim of the present study is to reveal the far-reaching effects of film mulching and fertilization practices on farmland soil N2O production pathways, gross N transformation rates, functional microbial communities and the relationship between N2O flux and environmental factors through in situ (SPN2O-δ18ON2O/H2O mapping approaches and transcriptome analyses) and incubation experiments (paired 15N tracing and 15N-18O labeling technique) using combined techniques of stable isotope labeling method and molecular biotechnology on the basis of comprehensive assessment of film-mulching and fertilization practices in terms of N2O flux. In addition, the autotrophic nitrification activity and response to different nitrification inhibitors of complete ammonia oxidizers(comammox) in various fertilized film-mulching soils is to be evaluated using 13CO2-DNA-stable isotope probing combined with the metabolic activity of the ammonia monooxygenase gene (amoA) of clade A and clade B comammox bacteria, thus to provide fundermental basis for N2O mitigation strategies in semiarid agricultural soils.