DETAILED SURVEY OF SOIL FORMED ON A BASEMENT COMPLEX IN OGBOMOSO FARM SETTLEMENT

This study was conducted to examine the morphological, physical, and chemical properties of soils formed on the Basement Complex in the Ogbomoso Farm Settlement with the aim of improving agricultural productivity. The objective was to provide a detailed soil survey report that characterizes the soil types across different landscape positions. Three soil profile pits measuring 1.5 m × 1.5 m × 2.0 m were excavated and described according to the USDA Soil Taxonomy guidelines (2006). Soil samples collected from each genetic horizon were analyzed in the laboratory following standard IITA procedures (2016). Morphologically, Pedons 1 and 2 exhibited four distinct horizons, while Pedon 3 contained five horizons. Pedon depths varied, with the summit profile (Pedon 1) ranging between 0–151 cm, the upper slope profile (Pedon 2) between 0–148 cm, and the middle slope profile (Pedon 3) between 0–159 cm. Mottles occurred in some horizons, ranging from few to common, reflecting fluctuating moisture conditions. Moist soil consistency ranged from non-sticky to very sticky. Soil pH (H₂O) values ranged from 4.63 to 6.12, indicating moderately acidic conditions. Chemical analysis revealed moderate levels of organic carbon and total nitrogen. Available phosphorus ranged from 0.14–0.55 mg/kg and 16.04–29.30 mg/kg across horizons. Exchangeable calcium and magnesium values were between 1.56–2.51 cmol/kg and 0.41–0.71 cmol/kg respectively, while potassium ranged from 0.18–0.39 cmol/kg. Soils of the Basement Complex were found to possess moderate fertility but differed among profiles due to landscape influence. The study recommends regular soil assessment, targeted soil conservation practices, and improved nutrient management strategies as essential steps for enhancing soil productivity and ensuring sustainable agricultural use of the area.