Soil Morphology, Physico-chemical Properties, Classification and Potential of Selected Soils in Kenya

Abstract

Four soil profiles (Yala, Galana, Baringo and Bondo) that represent different ecology, physiography and pedological variability were described to study their morphology, soil physico-chemical characteristics and to classify them using two internationally known soil classification systems. Soil samples were taken from designated pedogenic horizons for physical and chemical analysis in the laboratory. These soils are deep to very deep (> 110 cm) and well-drained except in Galana which was imperfectly drained, with varying textures. In Bondo, the soils are moderately acid (pH 5.6 – 6). In Baringo, the soil profile is acidic (< 5.0) while in Galana moderately alkaline (pH 7.3 - 8.3) and Yala soils are moderate to strongly acid (5.1 - 5.7). The organic carbon (< 0.6%) and organic matter levels (1 – 2%) were low and decreased down the profiles in all. The soils have low to moderate fertility. The base saturation of the studied soils is rated as very high (> 80%) in Galana and Baringo and low (< 50%) in Yala and Bondo pedons. The soils are non-saline as indicated by the low values of electrical conductivity (< 1.7dS/m) in the pedons. The soils are non-sodic (ESP < 6%) in Bondo and Yala, however moderately sodic (ESP 11-15%) in Galana and Baringo. Ochric horizon was the main diagnostic epipedon while ferralic, argillic and cambic horizons were the diagnostic B horizons. According to USDA Soil Taxonomy, the soils were classified as Typic Haplustox (Yala), Typic Haplocalcids (Galana), Typic Eutrudepts (Baringo) and Plinthic Haplustults (Bondo) corresponding to Haplic Ferralsols, Luvic Calcisols, Haplic Cambisol and Cutanic Plinthic Acrisols in the WRB for Soil Resources. The general fertility of the soils of the areas is discussed highlighting their potentials and constraints.