CHARACTERIZATION AND CLASSIFICATION OF SOILS OF TINIKE SUBWATERSHED IN EAST HARARGHE ZONE, OROMIA REGION, EASTERN ETHIOPIA

Abstract

Providing detailed up-to-date and site-specific soil information to the beneficiaries at watershed level is essential to solve local problems restricting agricultural production. Site-specific characterization and classification of soils that provide detailed information on soil properties are vital in designing appropriate management strategies for sustainable development in agriculture and natural resources management. The present study was carried out to characterize the soils from morphological, physical and chemical perspectives at field and in laboratory and to classify the soils of Tinike sub watershed, Eastern Hararghe Ethiopia. Three representative pedons were opened at lower, middle and upper slopes: pedon 1, pedon 2 and pedon 3, respectively; and characterized in the field using as well as by laboratory methods and eventually classified. A total of 13 disturbed and 13 undisturbed soil samples were collected from each genetic horizon for laboratory analysis. Results indicated that the soils had generally high base saturation (>50%), which was dominated by exchangeable Ca, had neutral to moderately alkaline reaction and considerable OC-content and friable structural conditions especially in the surface layers, indicating that the soils of the study area may have agronomically desirable characteristics. Irrespective of the slope position of the pedons sampled, the soils of the study area showed strong similarities in terms of their soil reaction, PBS, OC-content, Calcaric material, etc., and all were found to belong to the general soil group of soils with moderate weathering (development) stage. However, there were also discernible differences which appeared to be related to the topographic positions of the pedons along the toposequence. For example, the shallowest profile with distinct textural differentiation within the profile is observed at the upper slope position and the most clayey profile was observed at the lower slope (foot-slope) position. The soil classification result showed that Vertisols (Pellic Vertisols (Calcaric, Chernic, Hypereutric, Humic, Epiloamic)) were the major RSGs at the lower slope position, whereas Vertisol related Phaeozems (Calcaric Vertic Phaeozems (Endoclayic, Anoloamic))) mainly occupied the middle slope position and Luvic Kastenozems (Luvic Kastanozem (Pantoloamic)) appear to be prevalent at the upper slope position