Effects of Anaerobic Soil Disinfection on the Quality and Bacterial Community of Tobacco-growing Soils

In order to explore the effects of anaerobic soil disinfection (ASD) with the additions of different organic substances on the quality and bacterial community structure of the soil, ASD treatments were carried out by adding tobacco stem, rice straw, rapeseed meal, rice bran, sugarcane bagasse, with no addition (CK1), and the primary soil (CK) as controls. The results showed that ASD increased soil pH and reduced soil EC and Eh significantly, and improved soil nutrients. Tobacco stem increased the contents of available potassium and organic matter significantly, while rapeseed meal raised the contents of total nitrogen, organic matter, available nitrogen and the activities of catalase and urease. Sequencing of soil bacteria by 16S rDNA showed that ASD changed the ratios of soil bacterial communities at the phylum level, and there were obviously differences in the treatments of different organic substances. Significant differences were found in the bacterial composition of rapeseed meal and tobacco stem treatments when compared with CK and CK1. The relative abundances of the anaerobic bacteria Clostridiaceae, Ruminococcaceae, and Bacillaceae were also greatly improved, while the numbers of R.solanacearum treated with ASD were greatly reduced, especially for the treatments of adding rapeseed meal and tobacco stem. In conclusion, ASD with the addition of different organic substances had obviously different effects on the physical and chemical properties and bacterial community structure of the tobacco-planting soil. ASD by adding rapeseed meal and tobacco stem significantly improved the soil nutrients, and changed the composition and diversity of the bacterial community, and increased the abundance of anaerobic and tolerant bacteria, which, in turns, decreased the number of R.solanacearum significantly.