Investigations on some hydro-physical properties of the soils under different land use types in Erfelek Dam creek watershed (Sinop)

In this study, effects of different land use types on some hydro-physical properties of soils in Erfelek Dam watershed were investigated. The study area, Erfelek Dam watershed is located in the Middle Black Sea Region 45 kilometers far from Sinop. Erfelek Dam watershed was selected for this investigation because the construction is used for irrigation and drink water purposes. Therefore, the soil samples were taken from three different land use types (rural area, cultivated and forested) and two different parent materials (mudstone and limestone) in such a way that they represented general conditions of the watershed area. Total 48 sample plots were taken, 15 in rural area, 13 in cultivated land and 20 in forested area. One soil profile per plot was investigated for two soil depths (0-20 cm and 20-50 cm). Various physical (texture, erodibility, soil moisture content, permeability, water holding capacity, bulk density, soil particle density, porosity) and chemical (organic matter and pH) soil properties were measured on each soil sample. Soil properties were significantly different among land use types and parent materials. In general average erodibility index values (dispersion ratio, erosion ratio, colloid-moisture equivalent ratio) of the soils in the study area were found to be greater than the suggested limiting value. This shows that watershed soils are susceptible to erosion. Dispersion ratio was higher than 15 in three types of land use, and it was the smallest in rural site and the highest in forest site. In general, most soil properties at 0-20 cm soil depth didn?t show significant differences between cultivated and rural area, but some soil properties (clay, available water, pH, dispersion ratio, erosion ratio, colloid-moisture equivalent ratio) show differences between forest site and the other land uses. At a soil depth of 20-50 cm there were significant differences among three land uses in terms of sand, clay, organic matter and pH. Parent material affected significantly soil dispersion ratio, and dispersion ratio of the soils formed on mudstone is higher than that of soils formed on limestone. Parent material also affected soil pH, dispersion ratio, erosion ratio, available water and permeability. The present study indicates that land use type and parent material should be taken into for further studies since they affect significantly some important soil properties. Key words: erodibility index, land use type, permeability, soil properties