Effects of Soil and Water Conservation Practices and Slope Gradient on Selected Soil Physicochemical Properties in the Northwestern Ethiopia

Soil erosion is the major factor that has contributed to the reduction of soil fertility in the highlands of Ethiopia. This factor was reduced by soil and water conservation (SWC) practices. Hence, the study evaluated the effects of SWC practices and slope gradient on soil physicochemical properties in the Agemi watershed of northwestern Ethiopia. Farmland treated by SWC such as stone-faced soil bund (SFSB) and soil bund (SB), untreated farmland and slope gradient were identified in the study area. About 27 soil samples were collected from the treated farmland and untreated farmland with three slope classes, including lower (5-10%), middle (10-15%) and upper slopes (>15%). The soil physicochemical properties were analyzed by two ways analysis of variance (ANOVA) using SAS 9.2. The results of the study showed that the content of sand, clay, total porosity, pH, soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP), exchangeable cations such as Ca2+, Mg2+, K+ and cation exchange capacity (CEC) were significantly affected (p<0.01) by SWC practices and untreated farmland with slope gradients. However, the content of silt, percent of base saturation (PBS) and exchangeable Na were statistically insignificant (p>0.05). Farmland treated with SFSB confirmed higher mean values of soil physicochemical properties than SB and untreated farmland. Moreover, the lower total porosity (TP) and higher bulk density (BD) were recorded on untreated farmland and upper slopes. This study concludes that farmland treated with SFSB improved soil physicochemical properties than farmland treated with SB followed by untreated farmland. Therefore, SFSB should be implemented on farmland to improve soil fertility in the study area.