Four herbaceous plants with different characteristics significantly reduced the soil separation rate under different planting densities

Abstract

Soil erosion can be effectively mitigated through the planting of herbaceous plants. However, the understanding of the influence of different species and planting density on soil separation rates remains inadequate. This study aims to investigate the effects of various herb roots on soil separation rates under different planting densities. Four kinds of herbs, Bromus inermis, Hordeum vulgare, Trifolium repens and Fagopyrum esculentum, were planted at two different planting densities. The root characteristics and physicochemical properties of the soil in the 0–10 cm and 10–20 cm layers were analyzed. The soil separation rate was assessed using a simulated indoor erosion test. The results indicated that the roots of all four herbaceous plants significantly reduced the soil separation rate. Notably, the soil separation rate for plants cultivated at high density (D2) was lower than that for those at low density (D1). Among the tested species, Fagopyrum esculentum exhibited the lowest soil separation rate after planting. According to nonlinear fitting analyses, it was observed that the soil separation rate decreased exponentially with an increase in root surface area density, root length density, mean mass diameter, geometric mean diameter, and organic matter content of the soil. Partial Least Squares Structural Equation Modeling (PLS-SEM) concluded that soil water-stable aggregates were the main factor affecting soil separation rate, and root characteristics could also significantly affect the change of water-stable aggregates. It was also found that differences in soil separation rates between species were more significant than differences in planting density.