Soil property responses to land use dynamics in Wukari, Guinea Savanna of Northeastern Nigeria

Abstract

Land use and land cover (LULC) change is one of the leading drivers of soil degradation in tropical savannas, where deforestation, cultivation, and urban expansion alter soil structure, fertility, and resilience. This study assessed the effects of different LULC types on soil physical and chemical properties in Wukari LGA, Taraba State, Nigeria. Landsat imagery (30 m resolution) was classified into six LULC categories (dense vegetation, sparse vegetation, farmlands, built-up areas, bare land, and water bodies) using maximum likelihood classifier on ArcGIS. Validation with 50 randomly selected reference points against high-resolution Google Earth imagery yielded an overall accuracy of 89.7% and a kappa coefficient of 0.88, confirming the reliability of the classification. Composite soil samples were collected across representative LULC classes and analyzed for selected physical and chemical properties following standard procedures. Results showed that dense vegetation consistently sustained superior soil property, with lower bulk density (1.21 Mg m^-3), higher porosity (46.41%), and markedly higher organic carbon (1.18%), total nitrogen (0.10%), and available phosphorus (14.80 mg kg^-1) compared to other land uses. By contrast, farmland and built-up areas exhibited higher compaction, lower organic matter, and nutrient depletion. These patterns reflect the central role of vegetation in regulating soil fertility and structural stability, while disturbance accelerates degradation. The findings underscore the urgent need for sustainable land management practices such as agroforestry, organic amendments, and conservation tillage to restore soil fertility and secure ecosystem services. Future studies should explore long-term LULC dynamics, soil biological indicators, and predictive modeling to strengthen strategies for sustainable land management in tropical savannas.