ASSESSMENT OF SPATIAL VARIABILITY IN SOILS DEVELOPED ON THE BASEMENT COMPLEX OF ORILE-IGBON/GAMBARI, OGBOMOSO, SOUTHWESTERN NIGERIA

Abstract

Understanding the relationship between parent materials and soil properties is crucial for effective land use planning and management. This study aims to determine parent materials effect on the physical and chemical characteristics of a selected toposequence in the Orile-Igbon/Gambari area of Ogbomoso, Oyo State, Nigeria. Four soil profile pits were dug at identified topographic positions (summit, upper slope, middle slope and the valley bottom) on a selected toposequence. Soil profile pits were studied and morphological attributes were described using USDAsoil taxonomy guideline 2007 (color, stoniness, consistence, texture and structure). Soil samples collected from identified horizons were air dried, sieved and processed for laboratory analysis as pH, exchangeable cations, organic matters. Data collected were subjected to descriptive statistics and Coefficient of variation. The results of the analysis showed that, there was moderate variability of some soil morphological properties across the four positions on the toposequence. The textural class of the soil ranged from loamy sand to sandy loam, Available phosphorus was low in all the locations (2.5-28.6mg/kg), total nitrogen was predominantly low (0.5-3.9%). The topographic position also influenced soil properties, with valley bottom soils tending to have higher clay content and lower permeability due to the accumulation of finer particles. The results of this study can help guide sustainable land management techniques and
offer insightful information about the spatial diversity of soil qualities in the area.