Quantifying the effects of plant litter in the topsoil on the soil detachment process by overland flow in typical grasslands of the Loess Plateau, China

Abstract

Plant litter can be incorporated into topsoil by a natural process, affecting the soil erosion process. This is a widespread phenomenon in erosion-prone areas. This study was conducted to investigate the effect of litter incorporation on the process of soil detachment on the Loess Plateau, China. Four common plant litters (Bothriochloa ischaemum L. Keng., Artemisia sacrorum Ledeb., Setaria viridis L. Beauv., and Artemisia capillaris Thunb.) were collected, then incorporated into the silt loam soil at five rates (0.1, 0.4, 0.7, 1.0, and 1.3 kg m −2 ) on the basis of our field investigation. Twenty litter-soil treatments and one bare soil control were prepared. After 50 days of natural stabilization, 30 soil samples of each treatment were collected. We used a flume test to scour the soil samples under six flow shear stress conditions (5.66, 8.31, 12.21, 15.55, 19.15, and 22.11 Pa). The results showed that the different incorporated litter masses and morphological characteristics, such as litter tissue density (ranging from 0.52 to 0.68 g cm −3 ), length density (2.34 to 91.00 km m −3 ), surface area density (LSAD; 27.9 to 674.2 m 2 m −3 ), and volume ratio (0.003 to 0.050 m 3 m −3 ), caused varied soil detachment capacities (0.043 to 4.580 kgÁm −2 Ás −1 ), rill erodibilities (0.051 to 0.237 s m −1 ), and critical shear stresses (2.02 to 6.83 Pa). The plant litter incorporated within the soil reduced the soil detachment capacities by 38%-59%, lowered the rill erodibilities by 32%-46%, and increased the critical shear stresses by 98%-193% compared with the bare soil control. The soil containing B. ischaemum (L.)Keng. litter was more resistant to erosion. By comparing different parameters, we found that the contact area between the litter and soil was the main factor affecting the soil detachment process. The soil erosion resistance increased with the increasing contact area between the soil and litter. Furthermore, the litter incorporation effect on rill erodibility can be comprehensively reflected by LSAD (R 2 = .93; Nash-Sutcliffe efficiency = 0.79), which could be used to adjust the rill erodibility parameter in physical process-based soil erosion models. K E Y W O R D Scritical shear stress, incorporated plant litter, litter morphological characteristic, rill erodibility, soil detachment capacity, topsoil layer Pan-Pan Li is a co-first author.

The vertical heterogeneity of soil detachment by overland flow on the water‐level fluctuation zone slope in the Three Gorges Reservoir, China

“…The deposition of clay and silt particles from the upstream riverbank during submersion and surface runoff from high elevations during exposure may partly explain this phenomenon (Li, Bao, et al, 2019; Wang, Zhang, Yang, et al, 2018). In addition, the significantly high organic matter at the 150–170 m elevation segment may be explained by the high aboveground and underground biomasses possibly corresponding to the enhanced accumulation of plant litter in the soil, the deposition of which is conducive to the accumulation of soil organic matter (Liu, Li, et al, 2020). The significantly high MWD at the 160–170 m elevation segment may be explained by the high amounts of organic matter and roots (Table 2; Kořenková & Matúš, 2015; Bachmann et al, 2020).…”

Aboveground biomass production and dominant species type determined canopy storage capacity of abandoned grassland communities on semiarid Loess Plateau

“…Although floor litter layer can intercept a small portion of rainfall, it plays a vital role in the regional soil and water conservation. Because it can block the direct contact between rainfall and topsoil, thus weakening raindrop splashing erosion and soil moisture evaporation and slowing down the surface runoff (Liu, Li, Liu, & Flanagan, 2020).…”

Soil erosion resistance of gully system under different plant communities on the Loess Plateau of China

“…Sun et al (2016) found that rill erodibility decreased exponentially with increasing litter density, whereas soil critical shear stress increased with litter density. Liu et al (2020) also showed that the K r of soil incorporated with plant litter decreased by 32% to 46% whereas its τ c increased by 98% to 193%, compared to bare soil. With the decomposition of litter incorporated within the topsoil layer, the effects of litter on soil erosion decreased gradually (Sun, Zhang, Luan, & Liu, 2016).…”