Effects of straw incorporation on soil erosion resistance along a land degradation gradient in the black soil region of China

•Soil erosion resistance was significantly affected by straw incorporation.•Land degradation regulated the roles of straw incorporation in mitigating erosion.•Clay and organic matter contents were the key to improve soil erosion resistance.•Straw incorporation was not recommended in strong degraded cropland. Soil erosion resistance (reflected by rill erodibility and critical shear stress) is a useful parameter for evaluating soil erosion subjected to concentrated flow. The changes in soil properties and root trait induced by straw incorporation and land degradation likely affect soil erosion resistance considerably. Nevertheless, few studies have been conducted to quantify the effects of straw incorporation on soil erosion resistance of degraded croplands in the black soil region. In this study, a large hydraulic flume (5.0 m in length and 0.4 m in width) was utilized to quantify the impacts of straw incorporation on soil erosion resistance of four croplands with different degradation degrees (non-degradation, light degradation, moderate degradation and strong degradation) and further to determine the related influencing mechanisms in Northeast China. The results showed that straw incorporation reduced rill erodibility by 44.9%, 41.2%, 27.1% and −11.4% for non-degradation, light degradation, moderate degradation and strong degradation croplands, respectively. Land degradation degree had much stronger influence on soil erosion resistance than that of straw incorporation and regulated the roles of straw incorporation in mitigating erosion. Rill erodibility was significantly and negatively correlated with clay content, organic matter content, aggregate stability, soil cohesion, physical crust thickness and root mass density, whereas positively correlated with silt content. The increase in soil organic matter and clay content was the key to improve soil erosion resistance and prevent land degradation. Straw incorporation was suggested in non-degradation, light degradation and moderate degradation croplands, but vegetation restoration was recommended in strong degraded cropland. The results are helpful to understand the mechanism of straw incorporation to improve soil erosion resistance and make reasonable agricultural management strategies in semi humid region.