Effects of physical soil and water conservation practices and slope gradient on soil physicochemical properties in northwestern Ethiopia

Abstract

Soil erosion is the major factor that has contributed to the reduction of soil fertility in the highlands of Ethiopia. This factor is reduced by soil and water conservation (SWC) practices. Hence, this study evaluated the effects of physical SWC practices and slope gradient on the 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 (control), and slope gradient were identified in the study area. About 27 composite 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%). Soil physicochemical properties were analyzed using the SAS 9.4 software following two-way ANOVA procedures. 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), cation exchange capacity (CEC), and exchangeable cations (Ca2+, Mg2+, K+) were affected (p < 0.05) by SWC practices and slope gradient. The SWC practices such as SFSB have a higher mean value of soil physicochemical properties than SB and untreated farmland. As a result, farmland treated by SFSB improves soil physicochemical properties by reducing soil erosion. Therefore, SFSB should be implemented on untreated farmland to improve soil fertility in the study area.