Effects of land use and sustainable land management practices on runoff and soil loss in the Upper Blue Nile basin, Ethiopia.

Understanding the effect of land use and sustainable land management (SLM) practices on runoff and soil loss (SL) is essential for adopting suitable strategies to control soil erosion. The purpose of this study was to analyze runoff and SL from different land use types and evaluate the effectiveness of different SLM practices through monitoring runoff and sediment from 42 runoff plots (30 m × 6 m) in different agro-ecologies of the Upper Blue Nile basin of Ethiopia. Four treatments for croplands (control, soil bund, Fanya juu, and soil bund reinforced with grass) and three treatments for non-croplands (control, exclosure, and exclosure with trenches) were investigated during the rainy seasons. The results showed that runoff and SL varied greatly depending on agro-ecology, land use type, and SLM practice. Seasonal runoff ranged from 52 to 810 mm in 2015 and 37 to 898 mm in 2016, whereas SL ranged from 0.07 to 39.67 t ha-1 and 0.01 to 24.70 t ha-1. The highest rates were observed from untreated grazing land in the midland agro-ecology, largely because of heavy grazing and the occurrence of intense rain events. Runoff and SL were both significantly lower (P < 0.05) in SLM plots than in control plots. On average, seasonal runoff was reduced by 11% to 68%, and SL by 38% to 94% in SLM plots. Soil bund reinforced with grass in croplands and exclosure with trenches in non-croplands were found to be the most effective SLM practices for reducing both runoff and SL. Integrating structural and vegetative measures was therefore found to be the best way to control soil erosion and its consequences. Additional investigation is needed in consideration of ecological succession and other possible effects of these types of integrated measures, for example, the effects on soil properties, biomass, and biodiversity.