Abstract

Tobacco-rice rotation is a common farming system in south China, and many tillage practices such as straw mulching, do-lomite dust, and quicklime application have been adopted to improve crop production. These agricultural management practices alter soil physical and chemical properties and affect microbial life environment and community composition. In this research, six tillage practices including no tobacco and rice straw mulching (CK), tobacco and rice straw mulching (TrSr), rice straw returning fire (TrSc), tobacco and rice straw mulching with dolomite dust (TSD), rice straw returning fire and quicklime (TSQ), and rice straw returning fire, quicklime and reduced fertilizer (TSQf) were conducted to detect changes in soil bacterial diversity and composition using Illumina se-quencing. The results showed that the total number of opera-tional taxonomic units (OTUs) from the six treatments was 2030, and the number of mutual OTUs among all samples was 550. The TrSc treatment had the highest diversity and richness, while TSQf had the lowest. Soil physio-chemical properties and microbial diversity can influence each other. Proteobacteria and Actinobacteria had the greatest propor-tion in all treatments. The abundance of Nitrospirae was the highest in the TrSc treatment. The TSQf treatment had the highest abundance of Firmicutes. The abundance of Nitrospira in the TrSc treatment was 2.29-fold over CK. Streptomyces affiliated with Firmicutes improved by 37.33% in TSQf com-pared to TSQ. TSQf treatment was considered to be the most important factor in determining the relative abundance at the genus level.

• Keywords: straw mulching; tobacco-rice rotation; soil bac-terial diversity and composition; illumina sequencing