SOIL PHYSICO-CHEMICAL PROPERTIES UNDER CULTIVATED AND GRAZING LANDS AT FINCHA DEBSA WATERSHED, OROMIA REGION, WESTERN ETHIOPIA

Abstract

Land use types and the associated managements are the main causes for decline of soil fertility and agricultural productivity. A study was conducted to investigate the selected soil physico-chemical properties under cultivated and grazing lands at Fincha Debsa Watershed. Two land use types (cultivated and grazing) representative for the watershed were selected. Soil samples were collected from (0-20 and 20-40 cm) from three sites of each land use which were adjacent to each other and subjected to laboratory analysis. Among land use types, the higher mean bulk density (1.34 g/cm3) value was recorded for the subsurface layer of grazing land; while the lower mean bulk density (1.02 g/cm3) value was recorded for the surface layer of cultivated land. Soil water content at field capacity (39.24%) and available water holding capacity (14.64%) were higher for grazing land compared to cultivated land (37.53 and 7.62%), respectively. Soil pH values were higher (5.95) for subsurface layer of grazing land than surface layer of cultivated land (5.47). Soil organic matter (3.13%) and total nitrogen (0.14%) were higher in the surface soil layer of grazing land than in soil of cultivated land (3.03% and 0.09%), respectively. Higher mean values of available P (16.02 mg/kg) and cation exchange capacity (39.66 cmol (+)/kg) were recorded for the surface soil layer of cultivated and grazing land respectively. The mean value of exchangeable bases (Ca and Mg) were higher (15.52 and 12.22 cmol (+)/kg) for the subsurface layer of the grazing land than the surface soil layers (8.82 and 7.5 cmol (+)/kg) of the cultivated land, respectively. Mean values of Fe (160.1 mg/kg), Mn (147.44 mg/kg), Zn (4.83 mg/kg) and Cu (13.74 mg/kg) were higher in the surface soil of the cultivated land than in the subsurface soil. Soil fertility and quality were well maintained under the grazing land use type relative to the cultivated land. From this study it could be concluded that land use types beside soil depth is a reason for the variation in soil properties among soils of cultivated and grazing lands