Response of soil erosion resistance to incorporated straw affected by different microbial inoculants in the black soil region of Northeast China

Straw incorporation is a widely applied conservation tillage practice that mitigates soil erosion and promotes both the ecological and productive health of the soil. The application of microbial inoculants can stimulate straw decomposition, which benefits soil properties and root traits, and likely further regulates soil erosion resistance, particularly in cold regions. However, the response of soil erosion resistance to straw decomposition influenced by different microbial inoculants remains underexplored. In this study, the flume experiments were conducted to evaluate the influence of straw decomposition on soil erosion resistance under treatments of six microbial inoculants (Chungurun, Fushite, Bangji, Gefu, Hengrun, Lvkang) as well as a control without inoculants in the black soil region of Northeast China. 175 undisturbed soil samples were taken from seven plots and were scoured under five different flow shear stresses. The results demonstrated that microbial inoculants significantly stimulated straw decomposition (15 %-36 % increase), improved soil cohesion, water stable aggregate, soil organic matter, and root mass density, while reducing penetration resistance. Among six applied microbial inoculants, Lvkang produced the most significant improvements (p < 0.05). These improvements contributed to a reduction in soil detachment capacity, ranging from 28.27 % to 57.13 %. Soil erosion resistance was significantly enhanced (p < 0.05). Compared to the control, rill erodibility (K r ) decreased by 17.24–58.62 % and critical shear stress (τ c ) increased by 21.06–109.87 %. K r was significantly and negatively correlated to soil cohesion, water stable aggregate, soil organic matter, root mass density and straw decomposition rate (p < 0.05), while τ c showed no significant correlation with the measured influencing factors. This research provides valuable insights into the application of microbial inoculants for mitigating soil erosion, and offers practical strategies to promote sustainable straw utilization and agricultural management in cold regions. • The application of microbial inoculants significantly improved straw decomposition characteristics, soil properties and root traits (p < 0.05). • The application of microbial inoculants effectively enhanced soil erosion resistance in cold regions. • Soil cohesion, water stable aggregate, soil organic matter, root mass density and straw decomposition rate were key factors affecting rill erodibility. • Lvkang microbial inoculant was the most effective inoculant in the study area.