Soil Degradation-Induced Decline in Productivity of Sub-Saharan African Soils: The Prospects of Looking Downwards the Lowlands with theSawahEcotechnology

Abstract

The paper provides an insight into the problem of land degradation in Sub-Saharan Africa, with emphasis on soil erosion and its effect on soil quality and productivity, and proposes a lowland-based rice-production technology for coping with the situation. Crop yields are, in addition to the degree of past and current erosion, determined by a number of interacting variables. This, coupled with the generally weak database on erosion-induced losses in crop yield in spite of the region’s high vulnerability to erosion, makes it difficult to attain a reliable inference on the cause-effect relationship between soil loss and productivity. Available data suggest, however, that the region is at risk of not meeting up with the challenges of agriculture in this 21st century. Based on the few studies reviewed, methodology appears to have an overwhelming influence on the erosion-productivity response, whereas issues bordering on physical environment and soil affect the shape of the response curve. We argue that thesawahecotechnology has the potential of countering the negative agronomic and environmental impacts of land degradation in Sub-Saharan Africa. This is a farmer-oriented, low-cost system of managing soil, water, and nutrient resources for enhancing lowland rice productivity and realizing Green Revolution in the region.

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

“…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). The high erosion rates are mainly affecting the developing countries due to intensive cultivation, deforestation, plowing of marginal lands and extreme climate hazards (Biswas et al, 2015;Colazo and Buschiazzo, 2015;Ligonja and Shrestha, 2015).…”

“…About 80 % of the current agricultural land degradation is caused by soil erosion globally (Angima et al, 2003;Rodrigo et al, 2015). Sustainable agricultural practices are challenged by severe soil erosion, as it reduces on-farm soil productivity and causes food insecurity (Sonneveld et al, 2003;Moges and Holden, 2006;Bewket, 2007). In most developing countries, including Ethiopia, anthropogenic activities trigger soil erosion (Belyaev et al, 2004;Hurni et al, 2005).…”

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).…”

Assessment of Soil Erosion Vulnerability in the Heavily Populated and Ecologically Fragile Communities in Motozintla De Mendoza, Chiapas, Mexico

“…Global estimates indicate that the fraction of highly-degraded land increased from 15% of total land area in 1991 to 25% by 2011; most of which is associated with water-induced soil erosion, and is continuing to increase (UNCCD 2013, Sunday et al, 2012, Prosdocimi, 2016. Soil erosion challenges tend to be greatest in the more heavily populated, under-developed, and ecologically fragile areas, where the adaptive capacity is weakest (Leh et al, 2013, Erkossa et al, 2015.…”