Soil quality dynamics in response to land-use management types and slope positions in northeastern highlands of Ethiopia

Abstract

To address watershed degradation in Ethiopia's northeastern highlands, diverse land-use management (LUM) practices have been implemented. However, their impacts on soil quality (SQ) vary, particularly across topographic slopes, which significantly influence erosion rates, water retention, and nutrient dynamics. Understanding these variations is crucial for designing targeted soil management strategies. This study evaluated SQ under five LUM types—enhanced forest (EF), agroforestry (AF), controlled grazing (CG), croplands with improved bunds (BCL), and traditional management (TCL)—across three slope positions in the Upper Gelana watershed. Seventy-one composite soil samples (0–30 cm) were analyzed for key SQ indicators, and Principal Component Analysis identified SOC, TN, CEC, bulk density, clay fraction, and available phosphorus as a minimum dataset for computing a soil quality index (SQI). Results revealed significant (p < 0.05) impacts of LUM types and slope positions on SQ parameters. SQI rankings were EF > AF > CG > BCL > TCL. EF soils in lower slopes achieved the highest SQI (0.981) due to superior SOC, TN, and CEC, offering benchmarks for sustainable management. AF maintained high SQI (>0.8) consistently across all slopes, demonstrating its potential for restoring degraded landscapes. TCL in upper slopes had the lowest SQI (0.6), indicating severe degradation and an urgent need to implement slope-specific management strategies, such as contour bunds with vegetation reinforcements to mitigate erosion. These findings underscore the need for integrated soil management strategies tailored to each land-use and slope needs. SQI can be used as a valuable diagnostic tool for guiding adaptive management.