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• Splash erosion affected the redistribution of soil particles and SIC. • The redistribution of splashed material and SIC varied with soil type. • SIC had sorting and enrichment characteristics. Splash erosion caused by raindrops is the first stage of water erosion that detaches and transports soil particles. As an important component of soil particles, soil inorganic carbon (SIC) contains little information on its redistribution during splash erosion. In this study, two soils, purple soil and loess, were selected and placed in a soil tray with a diameter of 20 cm at the center of a splash tray, and a rainfall simulator was used to simulate three raindrop energies in experiments to investigate the migration of soil particles and SIC. The results showed differences in the amount and selective migration of splashed material between the soils, which was evident in the obvious sorting of the particle size of purple soil with distance and the insignificant change of loess soil. The SIC sorting characteristic performed differently in the two soils, that is, the SIC content of purple soil increased with particle size, while that of loess was the opposite. The enrichment and depletion of SIC during splash erosion varied with soil type, and differed from the general enrichment of soil organic carbon (SOC). The SIC enrichment ratio (ER IC) of purple soil was generally > 1, whereas the ER IC values of loess were < 1. In addition, multiple linear regression (MLR) models were established to predict the SIC content of splashed material. Rainfall splash plays an important role in SIC migration and may further affect the carbon cycle. These preliminary results provide a basis for further study of SIC response to rainfall splash. [ABSTRACT FROM AUTHOR]

Abstract: Controlling soil hydrological processes and combating soil erosion on agricultural fields are high priorities for crop production and ecological environments. In this research, the effect of land application of rock fragments on surface runoff, subsurface runoff, infiltration and soil loss on Regosols had been investigated under field conditions using a portable rainfall simulator. Experimental twin-plot (two subplot with 1-m wide by 2-m long, 32% slope) with different rock fragment covers ranging from 0–40% were exposed to three rainfall intensities, low (57±2mmh-1), medium (91±3mmh-1), and high (122±5mmh-1). Fifteen treatments were conducted in the experiments in duplicates. Surface runoff, subsurface runoff, soil moisture and sediment were measured. Results show that surface rock fragment cover retarded surface runoff, increased infiltration and subsurface runoff, and diminished sediment concentration and soil loss. The final infiltration rates, which increased with increasing rock fragment covers, were 16.5–42.7mmh-1 at low intensity, 19.7–50.8mmh-1 at medium intensity and 23.8–56.4mmh-1 at high intensity. Compared with bare soils, surface runoff rates were reduced to 24%, 51% and 64% in soils with 40% rock fragment cover at low, medium and high intensity rainfall, respectively. Subsurface runoff volume was significantly higher and time to start subsurface runoff was shorter as surface rock fragment cover increased. Compared with bare soils, subsurface runoff coefficients increased to 3.5, 3.3 and 2.9 times in soils with 40% rock fragment cover at low, medium and high intensity, respectively. Sediment concentrations increased from 9.8gL-1 for 40% rock fragment cover under high intensity rainfall to 51.5gL-1 for bare soils with rain falling at high intensity. The erosion rate was <12gm-2 min-1 for soils with 40% rock fragment cover, even when rainfall intensity was high, while it was >15gm-2 min-1 for bare soils under low intensity. The relationship between rock fragment cover and soil loss ratio can be expressed by an exponential function with a high degree of reliability, regardless of rainfall intensities. Overall, results indicate the surface rock fragments can be influential in shaping hydrological processes and soil loss from sloping farmland. [Copyright &y& Elsevier]

Abstract: Soil thickness exerts a first-order control on the hydrological processes of the hillslopes. However, from a hydropedological perspective, the knowledge of soil thickness effect on hydrological and erosion characteristics under sloping lands is limited. Based on a comprehensive survey of an experimental watershed in the Three Gorges Area of China, five typical sloping land plots (2m×1m) with different soil thickness were selected along a hillslope to investigate their hydrological processes and erosion response under three rainfall intensities (60, 90 and 120mmh−1) using a portable rainfall simulator. The results can be summarized as follows: (1) The surface flow coefficient was increased with increasing soil thickness, especially under the event of 60mmh−1. (2) The subsurface flow of the 23, 31 and 45cm plots mainly took the form of preferential flow. Conversely, the 59 and 76cm plots mainly took the form of matrix flow. (3) A prolonged low intensity rainfall is much more likely to facilitate deep percolation and subsurface flow than a short high intensity rainfall regardless of soil thickness. (4) Soil thickness and rock fragment cover were the most important factors than other soil properties in determining the hydrological and erosion behaviors. Thin soils showed higher infiltration capacity than thick soils due to their more distinct hydrological processes of subsurface flow and deep percolation. Rock fragment cover enhanced infiltration and served as a shield to protect the soil surface from detaching. Due to the synergies between thin soil thickness and high rock fragment cover, thin soils displayed significantly lower erosion rates than thick soils in all rainfall events, which increased from 211gm−2 h−1 for the 23cm plot with rainfall of 60mmh−1 to 4220gm−2 h−1 for the 76cm plot with rainfall of 120mmh−1. Our study suggested that the emerging interdisciplinary field of hydropedology promotes synergistic integration of pedology (e.g. watershed scale soil thickness investigation and soil profile description) and hydrology (e.g. rainfall simulation, subsurface flow and deep percolation) to enhance the holistic study of soil–water interactions in the sloping lands with different soil thickness. [Copyright &y& Elsevier]