Temporal variation in soil detachment processes under litter incorporation effects in typical grassland on the Loess Plateau of China

Plant litter incorporation into soil is a widespread phenomenon in the natural environment. Accurate estimation of the soil detachment capacity (Dc) driven by overland flow under litter incorporation effects is crucial for improving soil erosion prediction. However, the effects of litter incorporation on soil detachment processes are often ignored, and the temporal variation of Dc under litter incorporation effects remains unclear for grassland in the Loess Plateau of China. In this study, two litter incorporation soil treatments (Bothriochloa ischaemum (L.) Keng. litter, and Artemisia sacrorum Ledeb. litter) and one bare soil treatment (control) were set. Flume tests with flow shear stress ranging from 5.66 to 22.11 Pa were conducted to simulate overland flow scouring and determine the temporal variation of Dc between May 2017 and October 2018 (nine times, a 524-day period). Furthermore, the key factors affecting Dc were identified. Our results showed that the temporal variation in Dc was consistent across the different soil treatments (two litter incorporation treatments and one bare soil control), showing a rapid decline and then fluctuating at a low level, with Dc ranging from 0.115 to 6.876 kg m(-2) s(-1). Incorporation of litter effectively reduced Dc, with the Dc of soil treatments incorporating litter being 15% to 29% lower than that of bare soil (2.110 kg m(-2) s(-1)). Further analysis showed that the temporal variation in Dc was mainly affected by the development of a physical soil crust. Dc can be successfully estimated using a nonlinear equation incorporating flow shear stress and soil cohesion (R-2 = 0.77, NSE = 0.65), which represent the erosive force and soil erosion resistance, respectively. Our study reveals the important role of plant litter in the soil detachment process and aids the understanding of soil erosion pathways. Further studies are needed to investigate the effects of a physical soil crust on the soil detachment process driven by overland flow.

Automated summary

Plant litter has a significant impact on soil detachment processes and can reduce soil detachment capacity. The temporal variation of soil detachment capacity is mainly affected by the development of a physical soil crust.