Soil erosion by water is one of the most pressing environmental challenges in Ethiopia where small-scale agriculture is the main source of livelihood for about 87% of country’s population. In the past few decades, huge financial and labor resources have been invested for the implementation of sustainable land management (SLM) practices in many regions of Ethiopia to mitigate soil erosion and related consequences. Relevant studies are, however, limited for the wetter and actively eroding regions like the Upper Blue Nile basin due partly to insufficient policy attention and difficulties inherent in collecting sufficient and reliable runoff, soil, and sediment data at wider spatial and temporal scales. This study was, therefore, conducted in three contrasting agro-ecologies (lowland, midland, and highland) of the Upper Blue Nile basin to quantify the influence of land use and management practices on runoff, soil loss (SL), and soil properties. The analysis of runoff and SL was based on the data collected during the rainy seasons of 2015 and 2016 using runoff plots (30 m × 6 m) from three land use types (cropland, grazing land, and degraded bushland) with four treatments (control, soil bund, Fanya juu, and soil bund reinforced with grass) for croplands, and three treatments (control, and exclosure with and without trenches) for non-croplands (grazing land, and degraded bushland). Topsoil (0–20 cm) samples were collected from the runoff plots in 2015 (at the beginning of the experiment) and 2018 (three years later) and analyzed for nine soil properties—texture, bulk density (BD), pH, electrical conductivity (EC), cation exchange capacity (CEC), total nitrogen (TN), soil organic carbon (SOC), available phosphorus (Pav), and available potassium (Kav). The results show that runoff, SL, and soil properties varied greatly across land use and SLM practices in all three agro-ecologies. The highest rates of both seasonal runoff (898 mm in 2016) and SL (39.67 t ha−1 in 2015) were observed from untreated grazing land in the midland agro-ecology, largely because of heavy grazing and intense rain events. Whereas, the lowest values of pH, CEC, SOC, and TN values were observed in croplands, probably owing to unsustainable cropping systems practiced over centuries. In all agro-ecologies and land use types, both runoff and SL were significantly lower (P < 0.05) in plots with SLM than without: SLM practices reduced runoff by 11% to 68%, and SL by 38% to 94% depending of land use and agro-ecology, and sensitive soil properties (BD, SOC, TN, Pav, and Kav) were markedly improved three years after the implementation of SLM practices. 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 runoff and SL, and improving soil properties, indicating that combined structural and vegetative measures are the best way to control soil erosion and related consequences.

Mitigating soil nutrient depletion and increasing utilization efficiency is a prerequisite of sustainable agriculture. Therefore, a field experiment was carried out for 2 years in the midland agroecology of Ethiopia, to identify soil amendment types that can improved soil nitrogen (N) and phosphorus (P) balances at the same time maximize utilization efficiency and profitability under teff cultivation. Using RCBD with three replications, the soil amendments applied on the degraded acidic farmland plots were polyacrylamide (PAM = 40 kg ha−1), biochar (B = 8 t ha−1), lime (L = 4 t ha−1), gypsum (G = 5 t ha−1), PAM+B, PAM+L, PAM+G, and a control. N and P inflows from (atmospheric deposition, biological fixation, and fertilizers), and outflows by (water erosion, leaching, gaseous emissions, and harvested products) were monitored in the 24 plots via NUTrient MONitoring model. Results showed that all of the applied soil amendments improved nutrient balances (by 8–134%) compared with the control. Of the measured outflows, harvested products (43–60%) and water erosion (14–31%) were the major contributors to N depletion, followed by leaching (15–23%) and gaseous emissions (11–13%). Among the applied soil amendments, PAM+L appreciably reduced P loss from water erosion by 61% and N losses from erosion, leaching, and emissions by 55%, 10%, and 3%, respectively, and increased N use efficiency by 31% compared to control plot. Moreover, PAM+L provided a net benefit much higher compared with others. Thus, application of PAM+L would be an effective strategy to combat nutrient depletion and foster crop production in dryland agriculture.

Land degradation due to soil erosion presents a challenge for sustainable development. We investigated the impact of land use type and land management practices on runoff and sediment yield dynamics in the northwestern highlands of Ethiopia. The study area included 14 zero-order catchments with a surface area ranging from 324 m2 to 1715 m2. V-notch weirs produced from plastic jars were introduced as measuring alternatives that met local constraints. Runoff depth at the weir was registered at 5-min intervals during two rainy seasons in 2018 and 2019. Rainfall was measured using tipping-bucket rain gauges. Runoff samples were collected in 1-L bottles and suspended sediment concentration (SSC) was determined. The mean event runoff coefficient ranged from 3% for forests to 56% for badlands. Similarly, the mean annual sediment yield (SY) was lowest for forests (0.8 Mg ha-1 yr-1) and highest for badlands (43.4 Mg ha-1 yr-1), with significant differences among land use types (14.8 Mg ha-1 yr-1 in cropland, 5.7 Mg ha-1 yr-1 in grazing land, and 2.9 Mg ha-1 yr-1 in plantations). Soil organic matter (SOM) reduced runoff and SY, necessitating the consideration of agronomic and land management practices that enhance SOM. Annual SY decreased exponentially with the rock fragment cover (RFC). In fields where RFC was less than 20%, collecting rock fragments for installing stone bunds resulted in a net increase in SY. Rehabilitating badlands and enhancing SOM content in croplands can substantially reduce catchment SY and, hence considerably contribute to the sustainability of this type of environment.