PEDOLOGICAL STUDY OF HILLY SOILS DEVELOPED ON BASEMENT COMPLEX TERRAIN IN MINNA, NIGER STATE, NIGERIA

Abstract

A pedological characterization of hilly soils developed on basement complex terrain was carried in Minna, Niger State, Nigeria. The site was delineated into three physiographic units (positions) and designated as summit, shoulder and foot slope. Two modal profile pits were excavated in each unit to permissible depths, giving a total of six (6) profiles. The soil samples were analysed in the laboratory following standard analytical procedures. Particle size analysis showed dominance of sand over other mineral fractions irrespective of the physiographic units. Silt was next to sand in dominance and clay particle was the least in particle size. Bulk density increased with increasing soil depth in all the physiographic positions while porosity decreased down the profiles. Soil reaction (pH) ranged from moderately acid to slightly acidic in all the terrains. Organic carbon, total nitrogen and available P decreased with the increased in soil depth in all the landforms. Calcium and Magnesium were moderate while Potassium rated high in the sampled soils. The mean Na in the sampled soils rated low to moderate.    Cation Exchange Capacity (CEC) in the soils rated moderate while percentage base saturation (BS) rated high. The soils are non- sodic and the electrical conductivity (EC) values are low. Thesoils of summit and shoulder were classified as Typic Paleustalfs while the footslope soils were classified as Typic Paleudalfs. The soils were classified as Plinthosols when correlated with WRB for soil resource.