Mechanism of microbial inhibition of rainfall erosion in black soil area, as a soil structure builder

Rainfall-driven erosion is a primary cause of land degradation in Northeast China. Soil microorganisms, drivers of agricultural ecosystems, have been applied to address soil erosion problems, but the microorganism types studied are limited, and mechanisms of rainfall erosion inhibition by other soil microorganisms are unclear. Herein, soil microorganisms were inoculated on a black soil surface, under three water content (16.5%, 20%, 24.8%), three slope gradients (3°, 6°, 9°), and one rainfall intensity (80 mm/h) condition, the soil microbial community effects on rainfall erosion and soil surface nutrients were systematically studied. Results showed that the soil surface structure changed with microbial growth and proliferation; the proportion of large- and medium-sized aggregates in microorganism-treated groups was 27.51% higher than that in control groups in average. Additionally, the microbial community enhanced soil surface erosion resistance. After two rainfall events, compared to control groups, soil loss and runoff in the microbe-treated groups decreased by averages of 93.72% and 68.88%, respectively. Due to microbial action, sloped areas maintained slow-flow states, reducing concentrated flow and weakening sediment transport by runoff. Furthermore, the organic matter content of microbe-treated groups was on average 17.69% higher than that of control groups, indicating that microorganisms have a strong ability to remediate soil nutrient, delay declines in organic matter, and restore surface organic matter in the soil. Overall, microbial inoculation of surface soil is a practical and effective method for controlling rainfall erosion. This presents a new direction in the field of soil and water conservation for the future and provides a theoretical basis and technical support for using microorganisms to protect land ecosystems.