Abstract: 【Objective】 To study the effect of different wheat straw return coverage on the diversity of soil microbial communities in dry farmland in Inner Mongolia,in order to screen out the most suitable amount of straw returning to the field to provide a theoretical basis for improving the straw returning technology in Inner Mongolia.【Methods】 The experiment set a total of 5 wheat straw return coverage（0,30%,50%,70%,90%）,using high-throughput sequencing to detect fungi and bacteria in the soil,and corresponding species richness analysis and community structure analysis were performed.【Results】 The microbial community had the highest diversity,higher species richness,and better species uniformity when the coverage of wheat straw returned to the field was 50%. The peaks of fungi and bacteria appeared at different coverage,and the 70% wheat straw return coverage also had greater positive effects.【Conclusion】 With straw mulch,higher the soil microbial diversity,and also more stable the community,especially when the wheat straw return coverage was 50%,the soil microbial community can be maintained at a relatively stable level. It also had a greater positive impact on the diversity of soil microbial communities,when the wheat straw return coverage 70%.

Key words: Wheat, Straw returning to the field, Straw coverage, Soil, Microbial community, Dry farmland