INTENSIFICATION OF AGRICULTURE ON VERTISOLS TO MINIMIZE LAND DEGRADATION IN PARTS OF THE ETHIOPIAN HIGHLANDS

This paper highlights some interventions which might alleviate agricul tural pressures on steep slopes and reduce land degradation in parts o f the Ethiopian Highlands. The Ethiopian Highlands are losing alarming amounts of soils (estimated at more than one billion, 1000 million, t onnes) annually. This loss, which is associated with nutrient losses, is manifest in declining agricultural production and biodiversity. Abo ut 80 per cent of the annual soil loss occurs from croplands during th e rainy season. The nutrient imbalance is further accentuated by fores t clearing, removal of crop residue from cultivated lands, and little use of chemical fertilizers or organic manure. Even where livestock ar e part of the production system, dung is preferentially used as a cook ing fuel. Chemical fertilizers are costly, and therefore an alternativ e land-management scheme is suggested. This is based on a new land-sha ping device for drainage which is called the BBM (broad-bed maker), an d growing forage legumes to improve soil nutrients, which should allow intensive cultivation of Vertisols in the Ethiopian Highlands. Adopti on of the broad bed and furrow land-management system would facilitate early planting and increase the yield of both grain and straw from th e major crops relative to the yield from traditional cultivation in fl at beds. While not decreasing the yield of grain, mixed cropping of gr ain and forage crops has been shown to give significantly greater tota l crop residue yields. The yield is even greater when fertilizers are applied. Supplementary irrigation can help in utilizing Vertisols on b ottom lands, and this can be expedited by constructing water reservoir s.