Physicochemical Properties of Soils derived from Sandstone Parent Materials under Selected Land use types at Agoi-Ibami in Central Cross River State, Nigeria

Three profiles were sited on the major landscape elements of crest, middle slope and lower slope on three land uses; Forest (FS), Rubber (RS) and arable cropping (AS) at Agoi-Ibami in Central Cross River State, Nigeria. For study purposes, soil samples were collected from the morphogenetic horizons for the analysis of physical and chemical properties. Results showed that the surface horizon textures were mostly sandy loams with little sandy clay loam, while subsurface textures were mostly sandy clay loams with few silt clay loams and clays. The bulk densities were below the ranges of 1.46 to 1.63 g cm-3 for silts and clays and 1.75 g cm-3 for sands. This imposes stresses such as mechanical resistance to root penetration, decrease in cultivation and organic matter. The surface and subsurface pH values vary from 4.9–4.5 in FS, 4.9-4.6 in RS and 4.9 in AS, indicating that the soils are very strongly acidic. The Organic carbon contents was low with mean values of 4.33 and 0.6 % in surface and subsurface for FS, 2.10 and 0.50 % for surface and subsurface for RS, while surface and subsurface values proved to be 0.57 and 0.31 % for AS. The nitrogen contents was also low, mean values of 0.16 and 0.06 % for surface and subsurface for FS, 0.23 and 0.08 % for surface and subsurface for RS, and 0.19 and 0.10 % for surface and subsurface for AS. The content and available phosphorus are equally low, except for AS, with surface mean values ranging from 11.52 mg kg-1 to 13.87 mg kg-1. The exchangeable cations, Ca, Mg, K, and Na were very low, while exchangeable H+ and Al3+ were high. Base saturation was also low in FS and AS (< 50%) in surface soils, but higher in AS in the surface and in RS in the subsurface soils. The mean values of organic matter were 4.33 and 0.16 %. The land use should, therefore, be adjusted by application of recommended inorganic fertilizers and organic matter so as to support growth of crops such as maize, yams, cassava etc.