Temporal Variation of Interrill Erosion Affected by Slope Gradient in Soils with Different Texture

The process of splash of soil particles by raindrops and their transport by splash or surface shallow flow is considered as interrill erosion, which can reduce soil fertility and cause pollution of surface water. This research was carried out to investigate the temporal variation of interrill erosion in different soils affected by surface slope. For this purpose, laboratory experiments were carried out on three soils with different texture on four slopes under simulated rainfall with a constant intensity of 30 mm.h-1 in three replications with a total of 36 test units. The results showed that there are significant differences between the slopes in terms of the threshold of occurrence of interrill erosion (P<0.0001). The threshold for the interrill erosion in the occurred speedy steeper slopes. The coarse textured soil (sandy clay loam) appended hither dependency on slope gradient witch was associated ti its more percentage of coarse particles. In lower slope gradients, the interrill erosion threshold was occurred with more delay after runoff appearance. Coarse- textured soil (sandy clay loam) showed hither dependency on slope gradient in interrill erosion that other to soils. This study revealed that slope gradients is an important factor controlling time threshold, pick time and rate of interrill erosion during rainfall in semi-arid soils.