Abstract
Soil fertility suitability assessment is essential for agricultural planning and land management, particularly in urban and peri-urban environments where land use pressures are intensifying. This study developed a GIS-based Soil Fertility Suitability Index (SFSI) for the Wukari urban area in north-eastern Nigeria using a multi-criteria evaluation framework guided by principal component analysis. Five fertility indicators: total nitrogen, available phosphorus, exchangeable calcium, total exchangeable bases, and organic matter were selected based on their demonstrated significance in the study area’s fertility structure. PCA-derived loadings were used as objective weights: Ca (0.305), TEB (0.301), TN (0.206), OM (0.155), and AVP (0.033). Kriged prediction surfaces were normalized to a 0–1 scale and combined via weighted linear combination. The resulting SFSI exhibited a mean of 0.329, median of 0.329, and near-symmetric distribution (IQR = 0.288–0.370). Classification using standard deviation thresholds revealed that the Moderate class occupied the largest proportion (39.02%), followed by Low (36.99%), Very Low (13.10%), High (7.88%), and Very High (3.01%). The spatial pattern was characterized by a Moderate-class matrix with localized High and Very High hotspots. Individual factor maps revealed distinct spatial patterns among criteria, with calcium and total exchangeable bases showing similar distributions consistent with their strong correlation, while available phosphorus exhibited a more fragmented pattern. The PCA-based weighting framework provides an objective, reproducible approach to fertility suitability mapping, with implications for targeted nutrient management and agricultural planning in data-scarce urban environments.