Soil anti-scourability characteristics and influencing factors under different land use types in the black soil region of Northeast China

To explore the characteristics of soil anti-scourability under different land use types in the black soil region of Northeast China, surface soil samples (0–10 cm) from three main land use types in a typical black soil region, including natural grassland (uncultivated), farmland (converted from natural grassland), and the artificial forestland (grain plots converted into forests), were selected as the research objects. Soil anti-scourability test was adopted in the study, through which the soil anti-scourability coefficient was calculated and obtained. The study analyzed the differences in soil anti-scourability coefficients among various land use types, clarified the effects of soil physicochemical properties and root characteristics on soil anti-scourability, and thereby identified the key factors influencing soil anti-scourability. The results showed that (i) the soil loss amount under different land use types changes drastically in the first 2 minutes of scouring and gradually stabilizes with the extension of erosion time. Overall, the soil loss of natural grassland is the smallest, while that from farmland is the largest. (ii) The soil anti-scourability under different land use types is as follows: natural grassland > the artificial forestland > farmland. Compared with farmland, the artificial forestland significantly improves soil anti-scourability and notably reduces soil loss amount. (iii) The root geometric characteristic parameters of natural grassland and the artificial forestland are significantly larger than those of farmland, and the root volume density has the greatest impact on the soil anti-scourability coefficient. For the three land use types, the effects of fine roots of different diameter classes on soil anti-scourability are all shown as follows: 1.5~2 mm > 1~1.5 mm > 0.5~1 mm > 0~0.5 mm. The study can provide a theoretical basis for evaluating the soil and water conservation capacity of vegetation in the black soil region of Northeast China.