Impacts of land-use changes on the soils of the Nguruman area, Kajiado district.

Abstract

This paper considers the impact on soils physical (texture and structure) and chemical (pH, electrical conductivity and exchangeable sodium percentage) characteristics of changes in land use following clearing of vegetation for cultivation under both rain fed and irrigated conditions in the Nguruman area of Kajiado District, Rift Valley Province, Kenya. The results show that the accumulation of salts was directly related to the physiographic position of the soils and their texture. Lower values of both physical properties were observed in the upper part of the piedmont plains where soil texture was coarse and the moist consistencies were friable. In the lower part of the plains, high electrical conductivity and exchangeable sodium percentage were measured in the medium textured soils, which do not allow for free leaching of excess salts vertically or laterally. This results in deposition of salts dissolved in the irrigation water as the water passes from the higher locations into the lower concave-shaped locations limiting overland flow of salts. Most of the water is therefore lost via evaporation leaving behind dissolved salts. It is suggested that reclamation is required before the land be used for agriculture.