Influence of Surface Crusting on Infiltration of a Loess Plateau Soil

Crusting frequently occurs on farmland soil of the Loess Plateau in China and often adversely affects agricultural yields. Therefore, a study was conducted to evaluate the occurrence of soil crusting and its influence on infiltration in a Loess Plateau silt loam soil. Simulated rainfall events were conducted at two intensities (0.67 and 1.33 mm min(-1)) on four slopes (5, 9, 18, and 29%) under two soil conditions (crusted and uncrusted). Infiltration was evaluated as the difference between precipitation applied and water lost to runoff. A modified Green-Ampt model adjusted to account for soil crusting was also evaluated for predicting infiltration of crusted soil. Mean soil crust thickness was 3.33 and 3.94 mm under rainfall intensities of 0.67 and 1.33 mm min(-1), respectively. Slope had no effect on crust formation. In all instances, cumulative infiltration was lower in crusted soil than in uncrusted soil. The time to runoff decreased from 17.98 min in uncrusted soil to 4.64 min in crusted soil under a rainfall intensity of 0.67 mm min(-1). Time to runoff also decreased from 16.25 min in uncrusted soil to 4.54 min in crusted soil at a rainfall intensity of 1.33 mm min(-1). The modified Green-Ampt model provided a good estimate of soil crusting's influence on infiltration (coefficient of determination range 0.85-0.97). This suggests that the Green-Ampt model could be used as a tool for predicting soil crusting's influence on infiltration and runoff from soils of the Loess Plateau.