Soil Fertility Status as Affected by Different Land Use Types and Topographic Positions: A Case of Delta Sub-Watershed, Southwestern Ethiopia

Abstract

This study was aimed at assessing the status of soil properties  under Enset (Enset ventricosum) farm, grazing and cultivated land from upper, middle and lower slope positions (15-25%, 8-15% and 3-8% slope) in Delta sub-watershed of Southwestern Ethiopia. Split block design was employed.  A total of 54 soil samples, from 3 slope positions x 3 land use types (treatments) x 2 depths (0-20 and 20-40cm)  x 3 replications, were collected and used to test for soil chemical properties. For soil physical properties assessment, 27 soil samples were collected from 0-20cm soil depth by using simple random sampling technique. The result from several soil chemical parameters revealed that  OC, TN, C/N, AvP, CEC, exchangeable bases (K⁺, Mg⁺², Ca⁺² and Na⁺), ESP, PBS were significantly lower (p<0.001) in both depths of cultivated land and upper slope position than in respective slope positions of the other two land use types. However, average soil EC and pH did not show variation with both slope positions and land use types. The result also showed that soil physical property parameters such as soil bulk density, soil moisture and clay content in grazing lands were significantly higher (p<0.001). In contrast, total porosity and silt content were relatively lower in grazing land. From this finding, it can be concluded that there needs to be a look into not only land use types but also slope positions in developing land use planning and soil management strategies in this region.

Keywords: slope gradient, land use change, soil depth, soil properties