Status of selected physicochemical properties of soils under different land use systems of Western Oromia, Ethiopia

Land use change particularly from natural ecosystem to agricultural lands in general and to crop cultivation under poor management practices in particular are among the major causes of decline in soil fertility followed by land degradation and low agricultural productivity. Achieving scientific information thereof is vital for planning management strategies; this study assessed the effects of land use on soil physicochemical properties describing soil fertility under three land use types (natural forest, grazing and cultivated land) in Guto Gida District of Oromia Region, Western Ethiopia. The natural forest land was used as a control to assess status of soil properties resulting from the shift of natural forest to other land uses. Disturbed and undisturbed surface soil samples (0-20 cm) were collected from each land use type and examined for their analysis of soils physicochemical properties. The study pointed out the difference between different land use type on soil water content, pH, Cation exchange capacity (CEC), organic carbon (OC), total nitrogen (TN), available phosphorus (P), and exchangeable bases. Correlation analysis also showed highly significant and insignificantly positive relationship of soil pH with exchangeable Mg 2+ and Ca 2+ ions but significantly with extractable Fe 3+ , Mn 2+ ions and PAS of the soils among the land uses. Relative to forest land, when the percent OC contents in cultivated and grazing lands depleted respectively, by 54.62 and 49.89%, the percent Al saturation in cultivated land increased by 65.62% and 28.57% in grazing land. Land use changes also caused a decline in CEC, PBS, exchangeable bases and increased BD and Clay content exhibited poor soil physical conditions and deterioration of soil fertility.