Distribution and Interactions of Soil Nutrients and Organic Carbon at University of Calabar Campus, Nigeria

Plant biodiversity depends fundamentally on soil nutrient availability. However, nutrient dynamics within university campuses remain poorly studied, and less attention has been given to soil health, plant biodiversity, and the ecosystem services supported by campus soils. This study evaluated the influence of soil depth on the distribution, relationships, and multivariate interactions of soil nutrients and organic carbon across the University of Calabar campus, Nigeria. Ten randomly selected sampling locations were established using QGIS, and composite soil samples were collected from four depth intervals (0–15, 15–30, 30–60, and 60–100 cm). Soil organic carbon, nitrogen, phosphorus, potassium, calcium, magnesium, silicon, and sulfur were determined using standard laboratory procedures. Data were analyzed using Pearson correlation, one-way ANOVA, principal component analysis, and multiple linear regression. Significant positive correlations were observed between nitrogen and phosphorus (r = 0.78, p = 0.0027), phosphorus and silicon (r = 0.72, p = 0.0082), and calcium and potassium (r = 0.62, p = 0.0331), whereas phosphorus and magnesium were negatively correlated (r = –0.65, p = 0.0227). Soil depth had no significant effect on organic carbon or nutrient concentrations (p > 0.05). The regression analysis showed that the measured nutrients did not significantly predict organic carbon. These findings indicate relatively homogeneous soil conditions within the campus and provide a baseline for future studies on nutrient dynamics and distribution within the University of Calabar campus and similar landscapes