Pedogenesis and Classification of Soils along a Toposequence at Omo Forest Reserve in the South-West, Nigeria

Abstract

Characterization of soil morphological, physical and chemical properties helps in delineation and management of soils. This necessitates establishing the characteristics of Omo Forest Reserve soils as well as their classification. The experimental site was delineated on a topographic map of Ijebu-East Local Government area of Ogun State and a rigid-grid method of soil survey was used to establish the mapping unit. The profiles pits were described using the guidelines of FAO (2006) and USDA Soil Survey manual and samples taken from identified horizons. Laboratory analysis was carried out to determine some physical properties like Bulk density (1.12 -1.57 g/cm3), saturated hydraulic conductivity (0.53-2.79cm3/hr), total porosity, electrical conductivity (1 -3 ds/m) and chemical properties as Particle size analysis was determined using the hydrometer method, Soil pH, soil organic carbon, total Nitrogen, available Phosphorus, Exchangeable Ca, Mg, Na and K were also determined. The result showed that the soils had high base saturation which ranges from 92.2- 98.64%, low CEC (3.15- 8.17cmol/kg), clay content increased with depth, regular decrease in organic carbon (1.47 – 0.43%) with increase in depth was also observed.   Most of the Pedons clearly expressed Kandic horizon and Udic moisture regime. Therefore, all the pedons were classified as order Alfisols. The soils were classified as Udalfs based on the prevailing moisture regime at the suborder level and they all belong to Effon series.