Effect of Land use change and soil depth on selected soil physicochemical properties at Dale Sedi District, Western Ethiopia

Land use changes, mainly from natural vegetation to cultivated land brought about rapid nutrient depletion. The main objective of this study was to assess the effect of land use change and soil depth on selected soil physicochemical properties at Dale Sedi District Western Ethiopia. Eighteen soil samples were collected randomly at (0-20 and 20-40 cm) depth from the cultivated, forest and grazing lands. Then, statistical differences between the values for the various parameters of land use change and soil depth are tested using a one-way analysis of variance (ANOVA) following the General Linear Model procedure of the Statistical Analysis System SAS Version9. Soil properties PH, SOM, TN, available P, Exchangeable Ca and Mg, Exchangeable acidity, Clay, Sand, BD, and MC showed significant differences at (P?0.01) by land use change. Silt, BD, PH, Exchangeable acidity and Aluminium were not significantly different in soil depth. The highest (1.23g/cm) and the lowest mean (0.954/cm3) BD was obtained with surface of grazing and the surface layer of forest land respectively. The highest mean pH, (6.65) and lowest pH, (5.593), were obtained with surface of forest land and surface layers of cultivated land respectively. The range of pH in surface and subsurface layers of all land use types was moderately acidic to neutral. The highest means, SOM (4.9%), and total nitrogen (0.225%) were recorded the surface layer of forest land compared to the lowest (3.261% and 0.175%), in the surface layer of grazing and cultivated land, respectively. The highest and lowest available P (ppm) and organic carbon% (8.08, 2.95 and 2.84 and 1.89) were recorded in the surface layer of forest, cultivated and grazing land respectively. The mean value of P and SOC were lowest at soil depth 20-40cm than 0-20cm.CEC (32.63 cmol (+) /kg) were recorded in the surface layer of forest land than at the surface layer of cultivated land. Values of exchangeable bases, (Ca and Mg) were lower (15.167 and 9.83, and 14.5 and 11.22 cmol (+) /kg) on surface of grazing land and subsurface20-40cm soil depth respectively. The results revealed that soil fertility declines as land use changed from forest to grazing and cultivated lands as well as from surface to subsurface (0-20 and 20-40 cm) depth. The inappropriate land use management led to disturbance of soil nutrient status. This study suggests the use of more organic matter input, alternative cultivation practices, vegetation restoration, and improved crop and livestock varieties and protecting illegal settlement. Key words: Forest land, land use change, soil depths, soil physicochemical properties, organic matter.