EFFECTS OF CALCIUM CARBONATE ON THE ERODIBILITY OF SOME CALCAREOUSE SOILS BY WATER EROSION

Abstract

The behavioral changes in soil erodibility factor ( KUSLE ) due to Ca-carbonate content were determined in four calcareous soils located at northern Iraq. The procedure for KUSLE determination in these soils was carried out before and after carbonate removal by using a special nomograph and modified equation given by Wischmeier and Smith(1978). The results indicate that the changes in soil Ca-carbonate content caused a changes in soil erodibility factor (KUSLE).Soil texture modification due to Ca-carbonate content was the main factor affecting soil erodibility. Other unconsidered factors, such as soil permeability and structure ,could also have contributed to the remaining variability in KUSLE. Regression analysis of data showed that about 87.8% of the variability in KUSLE could be explained by a high Ca-carbonate content, as it was in these soils. This relationship give us a knowledge to make a correction for the calculated erodibility factor KUSLE of calcareous soils to distinguish it from that of non-calcareous soils.