膜下秸秆条带还田措施对黄土高原春玉米农田土壤碳氮过程和温室气体排放的影响及其机制

秸秆还田措施是解决黄土高原地膜农田土壤有机质含量和氮素利用效率偏低问题的重要举措，同时对减少温室气体排放具有重要作用。然而，当前覆膜玉米农田秸秆被大量废弃，覆膜条件下秸秆还田技术及其基础研究有待加强。鉴于此，本项目将秸秆条带还田技术与秋季全膜双垄沟播技术有机结合，基于多年定位试验，利用13C 和15N 同位素双标、静态箱-气相色谱法和宏转录组测序等技术，1)系统研究不同秸秆还田年限下土壤碳氮库存和组分变化，及N2O、CH4、CO2排放，探明长期秸秆条带还田下土壤碳氮固持和温室气体排放的演变规律；2)示踪秸秆碳氮在土壤团聚体中的转化、残留和去向，阐明新添加秸秆碳氮转化过程及其对土壤碳氮固持和温室气体排放的影响机制；3)深入研究土壤和团聚体中微生物群落差异，进一步明晰秸秆条带还田调控覆膜农田关键碳氮过程的微生物响应机制。以期为黄土高原覆膜农田秸秆的科学利用和土壤碳氮的优化管理提供依据。

Straw returning is an important tillage measure to solve the problem of low soil organic matter content and nitrogen use efficiency in film-mulched farmland on the Loess Plateau, and plays an important role in reducing greenhouse gas emissions. However, at present, a large number of maize straws are discarded in plastic mulching fields, and the technology and basic research of straw returning under plastic mulching need to be strengthened. Long term experiments is established with combining the ditch buried straw return technology into the ridge-furrow plastic mulching technology in autumn. Based on this long term experiment, 13C and 15N tracer, sequencing and other techniques are used in this project, (1) The carbon and nitrogen storage in soil aggregates and gas emission (N2O、CH4、CO2) will be systematically studied under different years after straw returning, to explore the evolution law of soil carbon, nitrogen retention and greenhouse gas emission with long term straw strip returning in film-mulched farmland; (2) The content of straw carbon and nitrogen in soil aggregates and its destination was traced, aiming to clarify the transformation process of newly added straw carbon and nitrogen and its effect mechanism on carbon and nitrogen retention and greenhouse gas emission; (3) The structure and function of soil microbial community will be deeply studied, to reveal the response of microbial community to the process of carbon and nitrogen after straw strip returning to field in film-mulched farmland. The results of this project will provide a basis for rational application of straw and optimization of soil carbon and nitrogen management in film-mulched farmland.