The effect of land use change on land degradation in East African arid and semi-arid lands
2003
Mburu, D.M.(Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya) | Kimaru, G.(Regional Land Management Unit, Nairobi, Kenya) | Njoroge, S.N(Permanent Presidential Commission on Soil and Water Conservation and Afforestation)
Land productivity in the arid and semi-arid lands (ASAL) of East Africa has declined in the last 25 years due to inappropriate land use practices. The change in land use from grazing to cultivated agriculture by migrating populations has accelerated land degradation through soil erosion. A study was carried out in Kenya and Tanzania to evaluate the impact of land use change on land degradation. This was through field studies and interviewing farmers. The field studies included soil sampling from profile pits. Undisturbed soil samples were collected in 100 cc core rings at 20 em intervals up to one metre depth, while disturbed soil samples were taken in vinyl bags. Physical and chemical analysis of soil samples was done in the labOratory. The soils had low organic matter (OM) content as well as the cation exchange capacity (CEC). In most of the study areas in Tanzania; a hard pan had developed at a depth of 20 em from the soil surface. Vegetation cover was sparse in all the study areas while some were highly denuded due to overgrazing. Serious erosion had occurred in many places where the prominent erosion features included rill, gully and tunnel erosion. In some areas especially in Tanzania, cultivation was done up and down slope which accelerated the rate of soil. erosion. As technical solutions to land degradation are sought, the social and cultural issues will also need to be addressed for sustainability of land use systems. Research collaboration amongst the scientists in the East African region should be encouraged in order to develop workable solutions which can be extended to other arid and semi-arid areas for sustainable land use systems.
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