Pedological Characterization and Classification of Soils Underlain by Basement Complex at the Mambilla Plateau, Nigeria

The study aimed to characterize and classify selected soils underlain by a basement complex at the Mambilla Plateau in Taraba State Northeast, Nigeria. A total of 12 pedons were dug to represent sampling units. Soil samples from the pedogenetic horizons of the pedons were collected after profile description, processed and analyzed. The pedons were very deep (> 150 cm) except for pedon 3, which was shallow. The soil texture of the pedons varies from sandy clay loam, sandy loam, sandy clay, loamy sand and clay across the surface and sub-surface horizons. Sand content of the horizons varied from 28.24 to 86.88 % across the pedons. The result of the pedons shows that bulk density was moderate. Soil pH was slightly to strongly acidic, and exchangeable bases were low to medium, indicating the relatively deficient primary nutrient status of the soils and occurred in the order Ca2+ >Mg2+ >K+ >Na+. Base saturation was rated high in the soils. Organic carbon and total nitrogen varied from low to high, while available phosphorus of the pedons varied from low to medium. The soils of the pedons were classified according to the criteria of USDA soil taxonomy and correlated with World Reference Base soil classification systems at the sub-group level as Arenic Kandiustalfs (Loamic Lixisols) for the pedons 5 and 11; Typic Kandiustalfs (Hypereutric Lixisols) for the pedons 1, 2, 6, 7, 8, 9 and 10 and Typic Haplustepts (Eutric Cambisols) for the pedons 3, 4 and 12. to understand better factors controlling spatial variability of soil properties.