Temporal variation in soil rill erodibility and critical shear stress during concentrated flow for three different crops

Abstract

Soil rill erodibility (Kr) and critical shear stress (τc) are important parameters in some physical soil erosion models. In the present study, the temporal variations in Kr and τc by overland flow were investigated using undisturbed topsoil samples collected from three cropped plots (ryegrass, lucerne, and corn) and a fallow plot. In this study, the potential factors leading to these changes were examined from March to September 2022 in western Sichuan Province, China. The results revealed significant seasonal variations in Kr, τc, soil bulk density (SD), soil cohesion (SC), and soil water-stable aggregate (WSA). The Kr values were significantly lower, whereas τc values were slightly higher for cropped plots when compared to that for the fallow plot. The mean Kr values for cropped plots were 4.51~17.26 times lower than that for the fallow plot. In contrast, the mean τc values for the cropped plots were 1.03~1.08 times higher than that for the fallow plots. The results also indicated a negative correlation of Kr with SD, SC, WSA, soil organic matter content (SOC), and root weight density (RWD), while a positive correlation of τc with SD, SC, WSA, and RWD. Furthermore, an exponential decrease in Kr was observed with an increase in SD, SC, WSA, SOC, and RWD. An increase in SD, SC, WSA, and RWD of the experimental plots led to a further increase in τc.

Keywords

• root weight density
• soil bulk density
• soil cohesion
•   soil organic matter content
• soil water-stable aggregate