Enhancing soil quality and crop yield by increasing dominant bacterial abundance and reducing bacterial diversity under no-tillage with total green manure incorporation

The abundance and diversity of soil microbial communities are important indicators for evaluating soil health. However, the microbial mechanism by which green manure incorporation affects soil quality and crop yield remains unclear. Field research was conducted in the Hexi Corridor to investigate the correlations between microbial communities and soil quality across various green manure management strategies. During the flowering period of common vetch, four management strategies were implemented: tillage with total green manure incorporation (TG), no-tillage with mulching using total green manure (NTG), tillage with only root incorporation (T), and no-tillage with the removal of aboveground green manure (NT), with conventional tillage without green manure as the control (CT). Total green manure incorporation significantly improved the soil quality index (SQI) and maize yield, with NTG demonstrating a more pronounced effect than TG. Soil organic matter (SOM) and total nitrogen (TN) were the primary contributors to the SQI. The relative abundances of the predominant phyla and genera increased in NTG, particularly Actinobacteria and Arthrobacter, which correlated with soil characteristics. Furthermore, the application of NTG and TG resulted in a reduction in bacterial alpha diversity. Regression analysis revealed negative correlations between bacterial alpha diversity and the SOM, TN, and mineral N contents. The diversity of the bacterial community negatively affected SQI. The primary factors contributing to the decrease in bacterial diversity were soil pH, nitrate nitrogen (NO₃⁻-N), and ammonium-nitrogen (NH₄⁺-N). In summary, NTG reduced bacterial diversity, and improved the abundance of dominant bacteria by optimizing soil characteristics, thereby increasing soil quality.