Assessment of Fertilizer-Related Pollution in Farmlands of Oghara, SouthSouth Nigeria, Using 2D Electrical Resistivity Tomography

Fertilizer application is essential for agricultural productivity but can pose significant risks to soil and groundwater quality when mismanaged. This study employed twodimensional Electrical Resistivity Tomography (2D ERT) to assess fertilizer-related contamination in selected upland and lowland farmlands in Oghara, Delta State, Nigeria. Field data were acquired using the Wenner array configuration of the ABEM Terrameter SAS 300C, with a 10 m electrode spacing and profile lengths of 100–140 m. Data processing and inversion were carried out using RES2DINV software. The results revealed subsurface anomalies with resistivity values of 45–95 Ωm, interpreted as possible fertilizer-induced contaminant plumes. Lowland sites showed deeper, more continuous, and lower-resistivity anomalies, indicating greater susceptibility to leaching due to poor  drainage and waterlogging. Conversely, upland areas exhibited shallower and more localized anomalies with relatively higher resistivity, suggesting limited infiltration. 
Overall, the study demonstrates the usefulness of 2D ERT in delineating subsurface contamination and underscores the higher risk of groundwater pollution in lowland farmlands. These findings support the need for improved fertilizer management practices to protect soil and groundwater resources in Oghara and similar agrarian settings.