Abstract
The changes in soil properties and root traits caused by plant growth might have great effects on the process of soil detachment by overland flow. On this basis, two typical herbaceous plants, Bothriochloa ischcemum (Linn.). Keng (BI; fibrous root system) and Artemisia vestita Wall. ex Bess (AG; tap root system), from the Loess Plateau were studied for one year under six planted densities of 5 plants m−2, 10 plants m−2, 15 plants m−2, 20 plants m−2, 25 plants m−2, and 30 plants m−2 to determine how the soil detachment rate responds to soil properties and plant root traits. In total, 24 steel tanks were planted, and two plots were used as bare soil controls. Their soil detachment rates were tested under a constant overland flow (1.5 l s−1) on a 26.2 % slope. The results showed that the soil detachment rate under the six planted densities ranged from 0.034 kg m2 s−1 to 0.112 kg m2 s−1 for BI and was ranged from 0.053 m2 s−1 to 0.132 m2 s−1 for AG, which all greatly reduced soil detachment rate and were 68.17 % to 92.33 % and 69.20 % to 87.27 % less than that of the control. In general, BI was more effective in reducing the soil detachment rate than AG, achieving a mean soil detachment rate that was 23.75 % lower. With increasing plant density, the soil detachment rate decreased as a power function (R2 = 0.23, p < 0.01). The overland flow hydraulic characteristics, soil properties and root traits influenced by plant density were positively or negatively correlated with the soil detachment rate. Specifically, the soil detachment rate decreased with velocity, bulk density, root length density, and increased with shear stress and the Darcy–Weisbach friction factor as power or exponential functions (R2 ranged from 0.16 to 0.54, p < 0.01). On this basis, the soil detachment rate (Dr) can be satisfactorily estimated by the overland flow velocity (v), soil bulk density (BD) and root length density (RLD) as a power function (Dr = 5.636v0.118 × BD−19.917 × RLD−0.170; R2 = 0.58; NSE = 0.78; p < 0.01).
Highlights
Soil erosion is a serious threat to land productivity and sustainability in both natural and human-managed ecosystems (Su et al, 2014; Fu et al, 2000; Li et al, 2015).Traditionally, soil erosion is affected by hydrology, soil, and vegetation (Foster, 1982), for which conservation tillage, vegetation and engineering measures are used to control soil loss (Rickson, 2014; García-Ruiz et al, 2015)
No significant difference was found between bulk density and plant density, maximum water stable aggregate values occurred when the plant density ranged from 10 plants m-2 to 25 plants m-2, and the soil organic matter content increased with increasing plant density
We found that the soil detachment rate significantly decreased as a power function (R2 = 0.23, p < 0.01), with increasing plant density for two herbaceous plants, becoming 85.80% and 81.19% lower than that of the control for the BI and AG
Summary
Soil erosion is a serious threat to land productivity and sustainability in both natural and human-managed ecosystems (Su et al, 2014; Fu et al, 2000; Li et al, 2015).Traditionally, soil erosion is affected by hydrology, soil, and vegetation (Foster, 1982), for which conservation tillage, vegetation and engineering measures are used to control soil loss (Rickson, 2014; García-Ruiz et al, 2015). The process of soil erosion as a result of rainfall or overland flow includes soil detachment (Wang and Zhang, 2017), sediment transport, and deposition (Ellison, 1947; Wu et al, 2018). Soil detachment rate is a key parameter for both conceptually and physically based soil erosion models, as changes in soil detachment rate and sediment load determine whether the soil detaches or deposits (Nearing et al, 1989). Simulation model (Beasley et al, 1980), and in the physically based models of Water. Erosion Prediction Project model (Nearing et al, 1999) and European Soil Erosion. In these soil erosion and sediment transport models, the hydrological part of the runoff process is simulated, which is the prerequisite or driving force for the occurrence of soil detachment
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