Mechanisms of microbial inhibition of freeze-thaw hydraulic alternating erosion in cold black soil region: Reconstructing soil structure with indigenous bacteria.

Soil erosion is a primary driver of land degradation in global black soil regions. Soil microorganisms, as key drivers of ecosystems, have been applied in the field of soil and water conservation. However, current studies on microbial species and erosion types are relatively limited, and the mechanisms by which other soil microorganisms inhibit alternating erosion remain unclear. This study takes black soil as the research object, under three slope gradients (3°, 6°, 9°) and two rainfall intensities (70 mm h, 100 mm h) conditions, and the effects of indigenous mixed bacteria inoculation on freeze-thaw hydraulic alternating erosion and carbon cycling functional genes were systematically studied. Results show that during the freeze-thaw cycle, the proportion of large particle-size soil aggregates in the bacterial treatment group increased by an average of 95.68 %, thereby significantly enhancing soil structural stability and erosion resistance. Meanwhile, the bacterial regulatory effect improved the soil pore structure and reduced the sensitivity of soil porosity to the freeze-thaw cycle. Additionally, bacterial inoculation regulated the expression of key functional genes involved in the carbon cycling process. During the simulated rainfall erosion phase, the soil loss and runoff volume in the bacterial treatment group were reduced by an average of 61.28 % and 34.51 %, respectively, compared to the control group. In conclusion, the inoculation of indigenous bacteria, as a promising measure for soil improvement, offers practical application value for controlling soil and water loss and degraded soil restoration in cold black soil regions.