SOIL CHARACTERIZATION, CLASSIFICATION, FERTILITY MAPPING AND PHYSICAL LAND SUITABILITY EVALUATION FOR RAIN-FED PRODUCTION OF MAJOR CROPS AT MUGER SUB-WATERSHED, NORTHERN OROMIA, ETHIOPIA

Soil characterization, classification and land suitability evaluation are the main information sources for precision agriculture, land use planning and management. However, the fertility status of the soil and sustainable soil management practices that are based on the understanding of soil system are not available for most part of Ethiopia. On the basis of this fact, a study was conducted in Muger sub-watershed, North Shoa zone of Oromia region, Ethiopia to (i) characterize and classify the soils, (ii) assess the spatial variability of soil fertility status and (iii) evaluate the physical suitability of the land of the sub-watershed for rain-fed agriculture. Three slope classes were considered and eight representative pedons, two each on the upper and lower, and four on the middle slope were described and samples were collected from identified horizons of each pedon for the characterization and classification of soils at the study area. The soils were classified into different Reference Soil Groups following the World Reference Base for Soil Resources (WRB). Twenty-five composite soil samples (0-20cm depth) from three slope positions and from three land uses viz. cultivated, grazing and forest lands were also used for generating spatial data and mapping the status of selected fertility parameters using ordinary. Four major crops (barley, beans, wheat, and Teff) and four land mapping units (LMU1Csc, 2Ascl, 2Csc and 3Bscl) were identified for physical land suitability evaluation. The simple / maximum limitation method was used to evaluate the degree of suitability of the land mapping units. As a result, the pedons showed variability in soil physical, chemical and morphological characteristics. The field as well as the laboratory determinations revealed dominance of sand and the texture ranged from sandy loam to clay both in surface and subsurface layers. The soils showed acidic to neutral reaction (pH 5.59-7.24) and were free of salt (ECMg2+>K+>Na+. The soils were low to high in available P and total N, whereas, the concentrations of micronutrients in the soils were high (Fe), medium (Mn), very low to high (Zn) and low to high (Cu). The soil developed from mollic surface horizon and are classified as Mollic Leptosols (Eutric), Hyperskeletic Leptosols (Clayic) Pellic Vertisols (Grumic), and Rhodic Nitisols (Haplic), according to the WRB. Soil OC varied significantly (p