Comparative Analysis of Physicochemical Properties and Heavy Metal Concentrations in Fadama and Non-Fadama Soils of Bwari Area Council, Abuja, Nigeria

Abstract

This study evaluates Fadama (lowland) and Non-Fadama (upland) soils across Kubwa, Bwari, and Ushafa in FCT Abuja, Nigeria employing 2 × 3 Factorial Design resulting in six treatment combinations. Eighteen composite samples were taken from the Fadama and Non-Fadama farms surface horizon (0–30 cm) during the dry season using a multistage stratified random sampling technique.. The samples were prepared and analyzed in triplicate for their physicochemical properties using Standardized analytical techniques of AOAC (Association of Official Analytical Chemists) and SSSA (Soil Science Society of America) methods. Data obtained were subjected to analysis of variance. The soils are predominantly coarse-textured and sand-dominated (70.91%–90.00%). Two-Way ANOVA indicated significant differences among the physicochemical properties (P < 0.05). Pearson correlation indicated correlation among the parameters temperature exhibits a near-perfect positive correlation with Nickel (r = 0.955). Baseline properties show stable pH (5.7–6.9) and Cation Exchange Capacity (17.81–21.55 cmol(+)/kg), but reveal major constraints: severe lowland compaction (up to 1.81 g/cm³), organic carbon depletion, and critical phosphorus deficiency (0.14–1.46 mg/kg).  Among the toxic heavy metals, lithogenic Nickel is naturally elevated (>108 mg/kg) which might be due the presence of specific magmatic or metamorphic rock types  like peridotite, dunite, serpentinite, or pyroxenite which naturally contain high concentrations of nickel (often 1,000 to 3,000+ mg/kg).