Reasonable rotation fallow mode enhances the complexity of the soil bacterial network and enriches nitrogen cycling-related taxa

Rotation fallow is an effective way to overcome obstacles in crop continuous cropping, which is beneficial for crop growth and development. Soil microorganisms are closely related to soil fertility, plant productivity, soil pathogenic bacteria, and crop health in agricultural ecosystems. To explore the effects of different rotation fallow modes on soil bacterial community diversity and function, this study was conducted in the arid area at the western foot of the Daxing'an Mountains, Using spring wheat variety Longmai 36 as the research material, this study systematically analyzed the changes and functional differences in soil physicochemical and biological characteristics, as well as microbial communities (Endosphere-Rhizosphere-Bulk soil) in spring wheat fields under five rotation fallow modes: Wheat2016-Wheat2017-Wheat2018 WWW, Wheat2016-Rape2017-Fallow2018WRF, Wheat2016-Potato2017-Fallow2018WPF, Wheat2016-Fallow2017-Rape2018WFR, and Wheat2016-Fallow2017-Potato2018WFP. The results indicate that: Compared with WWW, the soil urease activity, microbial biomass nitrogen, and microbial biomass phosphorus content in WFP significantly increased (P<0.05). Among them, the soil moisture content, organic matter, and total potassium content increased by 6.88%, 3.34%, and 25.57%, respectively. The Shannon index and chao1 index of Bulk soil BS and Rhizosphere RS bacteria were significantly higher than En-dosphere ER. Both ecological niche and rotation fallow mode can affect the relative abundance of dominant bacteria, and the relative abundance of beneficial bacteria such as Bacteroidetes, Firmicutes, and Verrucomimicrobia significantly increases under rotation fallow mode. The complexity, stability, and abundance of nitrogen cycling-related functional taxa in the collinear network are also significantly increased, while plant pathogen the abundance of pathogen-related functional groups significantly decreased. The differences in soil bacterial community structure are closely related to soil physicochemical properties. Compared with ER, BS and RS bacterial communities are more susceptible to soil physicochemical properties, and soil pH is a key driving force for bacterial community distribution. In summary, compared with continuous cropping, the rotation fallow mode is beneficial for conserving soil moisture and nutrients, stabilizing soil pH, making the soil tend to be neutral, increasing the abundance of beneficial bacteria in the soil, enhancing the complexity and stability of microbial ecological networks, increasing the abundance of nitrogen cycling related functional taxa, and improving crop growth and development