Impacts of land-use and topography on soil physicochemical properties in the Wamancho watershed, Southern Ethiopia

Abstract

For sustainable land management, clear information that accounts for changes in land-use types and landscapes is essential. The purpose of this study was to examine how land-use patterns and topographic variation affect selected soil property indicators in the Wamancho watershed of the Damot Pulasa district in southern Ethiopia. Soil samples were obtained from the topography of three types of land use (agroforestry, cultivated land, and grazing area). At a depth of 20 cm, 27 soil samples were collected (three land use categories × three topographies × three replications). The collected soil samples were analyzed using standard laboratory procedures. The results showed that soil texture classes, such as sand and clay, bulk density, pH, SOC, Av. P, total N, CEC, and exchangeable bases, changed considerably (p < 0.05) with land use type, whereas total N, sand, and silt did not vary significantly with slope. Soil pH, SOC, Av. P, CEC, percentage of silt, and exchangeable cations (Na+, Mg2+, and K+) were found to be highest in agroforestry, while sand concentration was highest in cultivated land. Exchangeable Mg and K were found to be lower on cultivated ground, while Ca+ was found to be lower on agroforestry land. Finally, most soil quality indicators revealed a significant (p < 0.05) difference between agroforestry and grazing land use. Despite the fact that soil quality varies based on topography and land use type, local-level planning has not been conducted on a priority basis or in specific locations. As a result, all involved parties, including local governments, stakeholders, and planners, should develop effective site-based sustainable land management interventions, as they need to be addressed quickly, particularly on cultivated land, grazing land, and upper topography.