Linking soil erosion to on-site financial cost: lessons from watersheds in the Blue Nile basin

Abstract

Abstract. The study was conducted in three watersheds (Dapo, Meja and Mizewa) in the Ethiopian part of the Blue Nile Basin to estimate the on-site cost of soil erosion using the productivity change approach, in which crop yield reduction due to plant nutrients lost with the sediment and runoff has been analysed. For this purpose, runoff measurement and sampling was conducted during the main rainy season of 2011 at the outlet of two to three sub-watersheds in each watershed. The sediment concentration of the runoff, and N and P contents in runoff and sediment were determined. Crop response functions were developed for the two plant nutrients based on data obtained from the nearest Agricultural Research Centres. The response functions were used to estimate crop yield reduction as a result of the lost N and P assuming there is no compensation through fertilization. The results show a significant yield reduction and resultant financial loss to the farmers. Considering only grain yield of maize (Zea mays), farmers at Dapo annually lose about USD 220 ha −1 and 150 ha −1 due to the loss of N and P, respectively. In view of the importance of the crop residues, including as feed, the loss can be even greater. The study demonstrated that in addition to the long-term deterioration of land quality, the annual financial loss suffered by farmers is substantial. Therefore, on farm soil and water conservation measures that are suitable in biophysical and socio-economic terms in the landscapes and beyond need to be encouraged.

Prediction of soil and water conservation structure impacts on runoff and erosion processes using SWAT model in the northern Ethiopian highlands

“…Soil erosion is more severe in the sub-Saharan African countries where the population livelihood is dependent on the soil (Sunday et al 2012;Erkossa et al 2015). In the Ethiopian highlands, deforestation for crop production, cultivation of marginal lands, and overgrazing are the major factors that dramatically increased the vulnerability of agricultural lands to rainfall-driven soil erosion (Nyssen et al 2000;Vancampenhout et al 2006;Belay et al 2014;Adimassu et al 2014;Erkossa et al 2015;Addis et al 2016).…”

“…Soil erosion is more severe in the sub-Saharan African countries where the population livelihood is dependent on the soil (Sunday et al 2012;Erkossa et al 2015). In the Ethiopian highlands, deforestation for crop production, cultivation of marginal lands, and overgrazing are the major factors that dramatically increased the vulnerability of agricultural lands to rainfall-driven soil erosion (Nyssen et al 2000;Vancampenhout et al 2006;Belay et al 2014;Adimassu et al 2014;Erkossa et al 2015;Addis et al 2016). Intensive rainfall during rainy seasons (June to September) contributes to severe land degradation in mountainous regions, especially on steep sloping and unprotected areas (Addis et al 2016).To tackle the soil erosion problem in the Ethiopian highlands, constructing soil and water conservation structures is considered to be a top priority in halting land degradation and thus to improve agricultural productivity.…”

“…The degradation of agricultural land as a result of soil erosion is a worldwide phenomenon leading to the loss of nutrientrich surface soil and increased runoff from the more impermeable sub-soil that leads to the lowering of agricultural productivity (Erkossa et al 2015;Taguas et al 2015;Ganasri and Ramesh 2015;Keesstra et al 2016;Nigussie et al 2017). Soil erosion is more severe in the sub-Saharan African countries where the population livelihood is dependent on the soil (Sunday et al 2012;Erkossa et al 2015).…”

Estimating soil erosion risk and evaluating erosion control measures for soil conservation planning at Koga watershed in the highlands of Ethiopia

“…Nowadays, most of the people in the world remain heavily dependent on soil resources as their main livelihood source, what leads to soil degradation. Soil erosion is a worldwide environmental problem that reduces the productivity of all natural ecosystems and agriculture, which threatens the lives of most smallholder farmers (Dai et al, 2015;Erkossa et al, 2015;Gessesse et al, 2015;Ochoa-Cueva et al, 2015;Taguas et al, 2015;Prosdocimi et al, 2016). Soil erosion by water is the greatest factor limiting agricultural productivity in the humid tropical regions (Sunday et al, 2012).…”

Sustaining reservoir use through sediment trapping in NW Ethiopia

“…However, it is more severe in developing countries like Ethiopia (Hurni, 2000;Nyssen et al, 2004) and results in significant economic losses (Erkossa et al, 2015). Currently, water erosion is the most serious land degradation threat to the upper part of the Blue Nile basin within the north-western highlands of Ethiopia (Adimassu et al, 2014;Mekonnen et al, 2015a;Ayele et al, 2016).…”