Dynamics of Selected Soil Quality Indicators in Response to Land Use/Cover and Elevation Variations in Wanka Watershed, Northwestern Ethiopian Highlands

Abstract

Soil quality (SQ) dynamics assessment vis-à-vis land use/land cover (LULC) and elevation variations in Ethiopia is desirable as elevation impact on land use is highly pronounced. This study examined SQ indicators dynamics across LULC and elevation variations. For this, surface soil samples (0−20 cm) were collected from the recognized LULC categories of different elevations in Wanka watershed, northwestern Ethiopian highlands. Both disturbed and undisturbed soil samples that were taken from three adjacent LULC (natural forest, grazing and cultivated lands) and elevation (2238–2300, 2400–2600, and 2700–2800) classes analysed for the selected physico-chemical SQ indicators. Two-way ANOVA, Tukey’s multiple comparison test and SQ deterioration index were computed. The impact of LULC and elevation was found significant on key SQ indicators. In cultivated and grazing lands, soil organic matter (SOM) and soil nutrients like total nitrogen declined significantly (p < 0.01). Conversely, bulk density increased significantly (p < 0.01). The divalent basic cations (Ca2+ and Mg2+), cation exchange capacity and pH significantly (p < 0.01) decreased in upper elevation. Synergetic effect of LULC and elevation variations was found significant (p < 0.01) on SOM, total nitrogen, available phosphorus, water content at field capacity and soil particle distribution (silt and clay). Thus, elevation specific land management strategies that improve these SQ indicators need to be emphasized.

Keywords

• soil quality
• soil quality deterioration index
• cultivated land
• grazing land
• natural forest land