Soil credibility factor in relation to soil development in some Duhok governorate locations northern Iraq

Abstract EN

Soil erodibility (K-Factor) was determined in Duhok Governorate, northern of Iraq, in five locations (Duhok, Zakho, Zawita, Sarsenk and Amadia).

The objective of this study is to determine relative (K-Factor) by indirect methods based on USLE (Universal soil loss equation) and nomograph then compare the results of nomograph with that mathematically determined by equation.

According to the basic soil loss equation(A= R*K) we can use (K-Factor) to estimate soil loss (A) t./ha./year of the study locations when annual values of erosivity index( R ) is available, as well as evaluate soil development depending on the k-factor values.

It can be seen that the determine K-factor values in the study locations by equation is considerably lower than that measured with using nomograph, but the correlation between the results of both methods are very strong, (r2 = 0.90) .Soil erodibility values varied between (0.010 to 0.033) in Zawita and Amadia respectively, the other values are between negligible and low, according to the erodibility classification.

The results indicated to negative correlation between soil organic matter and annual precipitation with (K-factor) values, (r2=0.52) and (r2=0.30) respectively, while positive relationship was observed between silt content and the measured (K-factor), (K = 628.19x+17.689) (r2= 0.52).

The difference in soil erodibility is due to the variations in particle-size distribution that is consider as the most important factor affecting on the (K-factor) value in Duhok governorate soils.

The soils in Amadia are more erodible followed by Duhok and Zakho where as the least erodibility indices were found in soils of Zawita and Sarsenk, as a result of high organic matter content and high permeability in soils under forest cover therefore these soils were more stable and development as compared with arable soils in Amadia, Duhok and Zakho.