Impacts of green manure rotations and alkaline amendments on soil health and assembly and function of bacterial communities

Green manure rotation and alkaline amendments have been extensively utilized in soil remediation and disease control, with notable effects. Despite their effectiveness, the specific health-promoting mechanisms of these soil management practices remain unclear. This study investigated the assembly and function of root-associated microbial communities in a five-year field treated with green manure rotation and lime amendments. Compared to the control (CK), the disease incidence decreased by 20.48 % and 43.18 % in the green manure rotation (VV) and combined green manure rotation and lime amendment (VL) treatments, respectively. Meanwhile, the VL treatment notably reduced the soil density and instant nitrogen, while enhancing pH levels, effective phosphorus, exchangeable calcium content, ventilation porosity, and catalase activity. Additionally, VL treatment reduced the diversity and co-occurrence networks of root-associated bacterial communities. Crucially, functional genes related to the nitrogen (e.g., nitrogen fixation) and carbon (e.g., including carbon fixation and degradation) cycles were enriched in the VV and VL treatments. Notably, genera such as Chryseobacterium and Pseudomonas, were significantly enriched in the VL treatment. Experimental validation revealed that the strain Chryseobacterium sp. Cas268 was particularly abundant in the VL treatment, aiding host resistance bacterial wilt, which may adopt various defence mechanisms for protection, including inhibiting the expression of virulence genes, reducing biofilm formation of pathogens, and rapid growth rates. In summary, this study indicated that green manure rotation and lime amendments enhance plant disease resistance by modifying soil physiochemical properties and enriching beneficial bacteria and offers insights into environmentally friendly approaches to disease control in agricultural systems.