干旱少雨和土壤瘠薄是渭北旱塬粮田增产的主要制约因素。保护性耕作能够改善旱作粮田土壤生态，提升土壤肥力与耕地质量，有助于实现“藏粮于地”战略。目前，对旱作粮田保护性耕作抗旱增产效应研究较多，但对长期保护性轮耕下“微生物群落演变—土壤碳氮转化—温室气体排放”的土壤生态机理研究较少。延续渭北旱塬冬小麦连作田、春玉米连作田和麦玉轮作田长期保护性轮耕与施肥定位试验，研究不同保护性轮耕模式（秸秆覆盖免耕、秸秆覆盖深松和秸秆还田翻耕三者组合）下土壤碳氮含量、土壤微生物多样性和温室气体排放规律，分析作物轮作、土壤轮耕和化肥配施对粮田土壤微生物多样性与固碳减排效应的影响机制，揭示旱作粮田保护性轮耕模式的土壤生态效应和土壤培肥规律，筛选有助于耕地质量提升的最优保护性轮耕模式，能为渭北旱塬粮田土壤培肥和持续增产提供科学依据。

Little rainfall and low soil fertility are main restraints of grain production on Weibei highland. Conservation tillage of dryland grain field can improve soil ecology, enhance soil fertility and cropland quality, and contribute to realize the strategy of “store grain in the land”. At present, most researches of conservation tillage on dryland grain field are about the effects of drought resistance and increase production, but mechanism of soil ecological effects of soil carbon and nitrogen content, microbial diversity and green house gas emission under long-term rotational conservation tillage on dryland grain field of Weibei highland are still lack systematic study. A long-term field experiment of rotational conservation tillage and fertilization on rainfed grain fields (which with cropping systems of winter wheat continuous cropping, spring maize continuous cropping and wheat-maize rotation separately) of Weibei highland, Shaanxi province, will be continuously conducted. The soil carbon and nitrogen content, microbial diversity and green house gas emission under different rotational conservation tillage patterns (which combined with no-tillage or subsoiling with crop residure mulching, and deep plowing with crop residure buried into soil) will be observed and measured. The mechanism of effects of crop rotation, rotational soil tillage and chemical fertilizer on soil microbial diversity, carbon sequestration and emission reduction on dryland grain fields will be analyzed. Based on exploration of soil ecological effects and soil fertility improvement of rotational conservation tillage, the optimal rotational patterns of conservation tillage for quality improvement of grain fields will be chosen, and it can supply scientific foundation for improvement of soil fertility and sustainability of yield increase on dryland grain fields of Weibei highland.