Pedosphere Research, vol. 5, 2025, no. 2: 65–77
Original paper
GRAPH-BASED CHARACTERIZATION OF PHYSICOCHEMICAL PROPERTIES AND MICRONUTRIENT DYNAMICS IN TROPICAL SOILS OF EKITI SOUTH-WEST, NIGERIA
Caleb Ayomide Babatunde
Department of Soil Resources and Environmental Management, Faculty of Agricultural Sciences,
Ekiti State University, Ado-Ekiti, Nigeria
Corresponding author: PhD. Caleb Ayomide Babatunde, Faculty of Agricultural Sciences, Ekiti State University, Ado-Ekiti, Nigeria, e-mail: babatundeayomide04@gmail.com; ORCID: 0009-0002-2569-8954
Citation: Babatunde, C.A. (2025). Graph-based characterization of physicochemical properties and micronutrient dynamics in tropical soils of Ekiti south-west, Nigeria. Pedosphere Research, vol. 5: 65 – 77. NPPC – VÚPOP 2025, ISSN 2729-8728. https://doi.org/10.64122/j.pedosres.2025.05.05
Abstract
Understanding the distribution of soil physicochemical properties, micronutrients, and sesquioxide fractions is critical for optimizing agricultural productivity in tropical soils. This study assessed the physicochemical characteristics, micronutrient dynamics (Fe, Mn, Zn, Cu), and sesquioxide content of soils in Ekiti South-West, Nigeria, using a graph-based analytical approach. Three representative soil profiles (ESW 1, ESW 2, ESW 3) were excavated and described. Samples were collected from distinct horizons for laboratory analysis. Particle size distribution, pH, organic carbon, available phosphorus, total exchangeable bases, and base saturation were determined using standard methods. Micronutrients were extracted with DTPA and quantified by atomic absorption spectrophotometry, while Fe and Al sesquioxide fractions were measured using dithionite–citrate–bicarbonate and ammonium oxalate extractions. Graphical analyses were employed to visualize vertical and lateral variations in soil properties. ESW 1 and ESW 2 were predominantly sandy loam with minimal clay translocation, whereas ESW 3 exhibited clay illuviation in subsurface horizons. pH ranged from slightly acidic to near neutral, with high base saturation across profiles. Micronutrients were enriched in surface horizons, with progressive declines at depth, especially for Zn and Cu. Sesquioxide fractions correlated with micronutrient retention, reflecting pedogenic processes and tropical weathering. Soil fertility in Ekiti South-West is strongly influenced by textural stability, organic matter, and sesquioxide-mediated nutrient retention. Maintaining organic matter, targeted Zn and Cu supplementation, and phosphorus management are essential for sustaining productivity, particularly for deep-rooted crops. These findings provide a framework for site-specific soil management and sustainable agriculture in tropical landscapes.
Keywords: tropical soils, physicochemical properties, micronutrients, sesquioxide characterization, soil fertility