Effects of Different Land Use Systems on Selected Physico-Chemical Properties of Soils in Northwestern Ethiopia

Information about effects of different land use systems on soil physico-chemical properties is crucial for best land management practices. This study was, therefore, conducted to evaluate the same on Nitosols of Achefer District, Northwestern Ethiopia. The landuse systems studied included grassland, cultivated land, plantation forest and natural forest. The research was superimposed on land use systems that were located nearby on similar soil, contour line and slope classes. Undisturbed core and disturbed composite soil samples were collected randomly from two sites with three replications for each landuse system at two varying depths (0-15 cm and 15-30 cm). The undisturbed soil samples were analysed for bulk density, particle density, porosity and moisture content at different pressures; while the composite soil samples were analyzed for pH, organic carbon, total N and available P. Results of the study indicated that the lowest bulk and particle densities, the highest total porosity, and higher moisture content at both field capacity and permanent wilting percentage were found under natural forest land use system. In contrast, the highest bulk and particle densities, the lowest total porosity and lower water contents at both field capacity and permanent wilting percentage were obtained under the cultivated landuse system. Soil pH was moderately acidic under all landuse systems. The lowest organic carbon, total N, and C-N ratio were recorded under cultivated land; whereas the highest values of the same parameters were found under natural forest. In all landuse systems, organic carbon and total N decreased with soil depth. The highest and lowest available P contents were recorded under natural forest and grassland, respectively. From the results of the study it was possible to conclude that conversion of forest lands to cultivated and grasslands had detrimental effects on the soil physico-chemical properties under subsistance farming systems of the study area. It is, therefore, recommended that appropriate and integrated land management options for different land use syetems are required to sustain agricultural productivity while protecting the environment.