Objective   As an important cash crop in China, tobacco has been suffering from the continuous cropping obstacle in the planting process. Reductive soil disinfestation (RSD) could be an effective way to alleviate continuous cropping obstacles, while its effects on the structure and function of the microbial community in tobacco soil were rarely reported. The correlation between the changes of soil properties and microbial community under various RSD treatments was investigated by using bean dregs, sugarcane bagasse, and their mixtures in equal proportion.

  Method  The Tax4Fun and Funguild were used to predict the function of bacterial and fungal communities respectively, and used R language software packages such as Vegan and pheatmap to complete statistical analysis and drawing. Moreover, bioinformatics methods were used to analyze the changes of microbial community structure and diversity in different samples to determine the relationship between microorganisms and RSD technologies.

  Result  The abundance of fungi was increased with addition of bagasse or okara. The relative abundances at the phylum level such as Actinobacteria, Firmicutes, Acidobcteria, Ascomycota and Basidiomycota were changed, revealing the difference in community structure between different treatments. In addition, RSD effectively reduced the abundance of Fusarium, Alternaria and other soil borne pathogens. Spearman correlation analysis showed that total nitrogen, total phosphorus, available nitrogen and potassium, pH and organic matter were the main factors driving community structure differences. Moreover, community function prediction showed that RSD treatment increased the activity of bacteria related to terpenoids and polyketides metabolism as well as the population of saprotroph fungi relative to CK.

  Conclusion  Through improving soil fertility and promoting reconstruction of soil healthy microbial community, the RSD treatment with addition of bean dregs alone can alleviate the continuous cropping obstacle of tobacco-growing soil, and also it can be used as an excellent technology to control soil-borne diseases.