Effects of physical soil and water conservation structures and slope gradients on selected soil properties in Ijara watershed, Nonno district, West Shewa, Ethiopia

Abstract Effective watershed development and management contribute significantly to the sustainable development goals by promoting sustainable livelihoods, bolstering resilience, and safeguarding natural resources. Implementing watersheds using physical soil and water conservation (PSWC) measures is one of the mechanisms employed to halt soil erosion and associated nutrient loss. However, no empirical study has been conducted to examine the effects of Physical Soil and Water Conservation (PSWC) structures and varying slope gradients on selected soil properties in the Ijara watershed, located in the Nonno district of Oromia, Ethiopia. Hence, this study was carried out to assess the influences of PSWC structure and slope gradients on selected soil physicochemical parameters in the study watershed. The research employed a Randomized Complete Block Design technique to collect soil data. A total of 18 composite soil samples were collected from the top 20 cm of soil depth in farmland with and without PSWC structures across three landscape positions. The General Linear Model(GLM) was applied to test the influence of environmental factors on soil physicochemical properties, using the SPSS computer program software version 25. The results showed that sand particles, clay particles, Moisture, Total Nitrogen(TN), Cation Exchangeable Capacity (CEC), Soil Organic Matter, and Soil Organic Carbon, Exchangeable Calcium and Potassium were significantly varied across various watershed management practices (p < 0.05) due to the conservation practice. Bulk Density(BD), Moisture Content, Electro Conductivity, CEC, TN, and Exchangeable P and M showed a significant (p < 0.05) variation related across slope gradients. Except for sand particles and bulk density (BD), the mean values of all analyzed soil properties increased from the upper to the lower slope. The study results have revealed that implementing PSWC measures in the farmland significantly improved most of the physicochemical parameters of the soil compared to the farmland without PSWC measures. In the study area, the stone bund structures of the watershed reduced soil erosion problems and had desirable effects on soil physicochemical properties, improving the land’s productive capacity. Responsible bodies are expected to provide technical support, training, and follow-ups for farmers in the study area to manage the watershed better.