Abstract

A detailed study on soil resources characterization based on the understanding of the soil system is not available at Dugda district. With the cognizance of this fact, the present study was conducted to characterize the morphological and physicochemical properties of soils, classify the soils according to World Reference Base for Soil Resources (WRB) of Argo-Gedilala Subwatershed in Dugda District of Oromia Regional State, Central Rift Valley of Ethiopia. Four slope classes were considered and one pedon was opened for each and described in the field on a standard description sheet for each slope category. Soil samples were collected from genetic horizons of each pedon for laboratory analysis of the selected physicochemical properties of the soils. The soils were classified into different Reference Soil Groups following the (WRB).The organic carbon (OC) content of the study area ranged from low to medium/moderate (0.64 to 1.83%). Total nitrogen (TN),available.phosphorus (Av.P), cation exchange capacity (CEC) and  percent base saturation (PBS) of the soils were in  the range of (0.066-0.135%), (2.24-4.81 mgkg-1), (39.52-43.52) cmol(+)kg-1) and (77.57- 89.8%), respectively. Accordingly, they were rated as low to medium, very low to low, high to very high and high to very high, respectively. The soil classification revealed that pedon 1 and pedon 2 were Cambic Chernic Phaeozems (Pantoclayic, Humic, Hypereutric); and pedon 4, Cambic Chernic Phaeozem (Pantoclayic, Humic); whereas, pedon 3 is found to be a kind of Luvic Phaeozem (Abruptic, Albic, Clayic, Differentic, Hypereutric). The soils of the study area had low organic matter, available P and total nitrogen content, which can be seen as production constraints of all cultivated lands. To overcome the identified limitations, increasing the organic matter levels through continuous application of manure.

Key words: Genetic horizons, morphological properties, pedon, physicochemical properties, slope.