Indirect and direct effects of soil properties on soil splash erosion rate in calcareous soils of the central Zagross, Iran: A laboratory study

• We model splash erosion in part of the calcareous soils.
• Quantifying the effects of soil properties can provide a better understanding of the soil detachment process.
• Soil splash erosion in lands with low vegetation cover is influenced by the soil attributes.
• The two parameters MWD and SSS are more appropriate indices for determination of splash erosion.

Detachment of soil particles by means of raindrop impact is mainly affected by soil properties especially in the absence of vegetation cover. This study was conducted to investigate the direct and indirect effects of soil properties on splash erosion rate in calcareous soils of low vegetation cover in Lordegan region, Iran. For this purpose, Total Soil Splash (TSE), downslope (DSE) and upslope (USE) Splash erosion rate are measured under the following four conditions that comprised different values of Slope (S:%) and Rainfall Intensity (RI:mm h− 1): 5–50, 5–80, 15–50, 15–80, respectively, using Multiple Splash Sets (MSS). As potential estimating parameters, Surface Shear Strength (SSS), Mean Weight Diameter (MWD), Organic Matter (OM), calcium carbonate, clay content, silt and sand fractions were estimated. The effects of soil estimators on soil splash erosion rate were quantified using a path analysis and Multi-Linear Regression (MLR) approaches applied to data collected from 105 points of soil profiles (A horizon). The results showed that the particle size distribution, SSS and MWD are sensitive to some of the parameters for estimating TSE, DSE and USE rate. MWD carried the highest direct effects while SSS the highest indirect ones (via MWD) on splash erosion. Particle size effects on soil splash weren't in general observed in higher slopes and rainfall intensities. The Particle size has in general a more direct rather than an indirect effect on splash erosion. Fine silt exerted an ambivalent role on splash erosion: A high detachability of fine silt directly increases splash erosion while its capability to form a surface crust, reduces splash erosion. Indirect effect of OM through its association with MWD and SSS is more than it's direct effects. Positive direct effect of calcium carbonate is more than its indirect negative effect via its association with MWD, probably due to the presence of calcium carbonate within the size of silt and fine sand in the studied soils, causing an increase in soil detachability.