Effect of soil and water conservation practices and slope classes on selected soil physico-chemical properties in Damot Woyde district, southern Ethiopia

Abstract

Soil erosion caused by runoff has significantly contributed to the depletion of soil fertility and reduced crop productivity in Ethiopia. This study evaluated the effects of soil and water conservation (SWC) practices and slope classes on selected soil physico-chemical properties in Damot Woyde District, southern Ethiopia. The study considered four treatments: soil bund (SB), soil bund with Desho grass (Pennisetum pedicellatum) (SBD), Fanya juu (FJ), and untreated farmlands across three slope gradients: lower (3–8%), middle (8–15%), and upper (15–30%). A total of 36 (four treatments* three slope positions* three replications) composite and core soil samples were collected from both conserved and non-conserved plots from the top 20 cm soil depth. Data were analyzed using analysis of variance (ANOVA), and mean comparisons were performed using the least significant difference (LSD) test. Results showed that plots treated with SBD, SB, and FJ had significantly higher soil pH (5.81, 5.54, and 5.47), organic carbon (3.19, 2.54, and 2.09%), total nitrogen (0.27, 0.26, and 0.25%), and cation exchange capacity (17.11, 16.78, and 15.89 meq/100 g), respectively, compared to untreated plots. Exchangeable base cations (Ca²⁺, Mg²⁺, and K⁺) and available phosphorus were also higher in conserved plots. Moreover, lower slope positions exhibited significantly higher soil fertility indicators than middle and upper slopes. Significant interaction effects were observed for available phosphorus and soil pH. Overall, SBD was the most effective SWC practice in improving soil physico-chemical properties. It is strongly advised to highlight the urgent need for SWC training, public awareness, and government support. The study suggests prioritizing soil bunds integrated with desho grass on steep slopes exceeding 15%, where the risk of erosion is greatest; while Fanya juu structures are considered sufficient for areas with moderate slopes.