CHARACTERIZATION OF SOILS IN A WATERSHED CATENA, SOUTHERN ETHIOPIA

The study was conducted to observe the impact of topography on soil development and characteristics. 7 pedons that were located at upper, middle and lower slopes of the two toposequences(Catena) and at depression were characterized and classified according to Soil Taxonomy and the WRB Soil map of the World. The result revealed that topography had major control on the distribution of soils along the toposequences. All pedons were found to be deep &had umbric surface horizons. 5 of the pedons possessed argillic subsurface horizons with PBS < 50 determined by 1M ammonium acetate pH 7 method.The pedons on the upper and middle slopes as well as the pedon on the east facing lower slope toposequences were categorized under Ultisols, whereas the pedon on the west facing lower slope toposequences and the pedon on the depression were categorized under Inceptisols and Entisols, respectively. These Ultisols, Inceptisols and Entisols are categorized as Acrisols, Cambisols and Fluvisols major groupings according to WRB soil map of the world.The study revealed the existence of three different soil orders along toposequences in an area previously mapped as Eutric Nitosols.