456
without addressing this major system constraint. The proximate drivers of land deg-
radation include forest clearance and surface soil exposure (high removal of vegeta-
tive cover), detrimental cultivation practices with emphasis on small-seeded crops
that require fine tillage, and overgrazing (Gebreselassie et al. 2015 ). Due to land
shortages and the lack of alternative livelihoods, farmers cultivate land that slopes
more than 60 % with shallow and stony soils prone to erosion.
Water erosion is considered the major source of nutrient depletion, with N, P and
organic carbon nutrient losses estimated to be 74, 5.5 and 539 kg ha−^1 year−^1 ,
respectively, with N and P losses estimated at more than $US 300 million per year
Fig. 4 The level of land degradation in Eastern and Southern Africa (Source: http://geoagro.
icarda.org/en/cms/category/maps/15/regional)
T. Amede and A. Tsegaye