Effects of Surface Seal on Interrill Erodibility at Various Slopes and Rainfall Intensities under Laboratory Conditions

Document Type : Research Paper

Authors

Abstract

Consequence of interrill erosion is a considerable issue of soil and nutrient losses especially in farmlands. Thus, factors affecting interrill erosion must be well known. The aim of the current study was to investigate the effect of surface sealing on soil interrill erodibility factor (Ki). Two sandy loam (S1) and clay loam (S2) soils from Ilkhichi farmlands with low organic matter and high Ki and one clay soil (S3) from Caleibar farmlands with high organic matter and low Ki were examined. Several pertinent chemical and physical characteristics of the three soils were measured. Rainfall simulation experiments were carried out on 200 kg of each soil sample under 5, 15, 25 % slopes and 21, 38, 50, and 81 mm/h rainfall intensities. Relative sealing index (RSI) and the time needed to reach to the final infiltration rate (tlim) were measured in every combination of slope and rainfall intensity. The results showed that S1 soil with RSI= 2.23 and tlim= 6 min was the most sensitive and S3 with RSI= 8.9 and tlim= 102 min was the least sensitive to surface sealing. The findings indicated that there were no significant differences among Ki’s at different slopes and the assumption of constant Ki for all soils was correct, except for soil S1. There were also no significant differences among Ki’s at different rainfall intensities for the examined soils.

Keywords