Soil Fertility after an Oil Pipeline Spill in Niger Delta, Nigeria

Studies on soil fertility were carried out following an oil spill incidence caused by crude oil theft at Ahoada East in the Niger Delta region of Nigeria. The objective was to evaluate the state of soil fertility in the affected area which is crucial for developing effective remediation strategies to restore soil health and support sustainable agricultural practices in Ahoada. Soil samples were collected from both oil-impacted and non-impacted control sites, at two depths (0-15cm and 15-30cm), using a stainless-steel auger. Subsequently, laboratory analyses were conducted to evaluate pH, electrical conductivity, chloride, and concentrations of the selected micronutrients such as iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu); and primary macronutrients such as nitrogen (N), phosphorus (P) and potassium (K). Other fertility indicators like Organic carbon and organic matter were also evaluated. Findings revealed a notable decrease in essential nutrients, particularly Cu, Zn, and Mn. The pH values for the contaminated soils varied between 5.3 and 6.65, while the electrical conductivity (EC) ranged from 9 to 48 µS/cm. These and other key indicators were higher in the control soils. However, total organic matter (TOM) ranged from 1.04-12.62% in the contaminated soils, while the control point ranged from 0.86-2.42%, indicating a decrease in TOM. These conditions generally imply low soil fertility, which in turn implies low agricultural productivity and reduced source of livelihood in the affected area. To restore the contaminated area and sustain agricultural productivity, there is need for immediate and efficient clean up exercise, beyond the sand filling observed at the site. The soil-pH should be adjusted to a range of 6.0 – 6.5 by the addition of calcitic lime, followed by the application of appropriate and sufficient inorganic N-P-K fertilizer to restore the carbon to nutrient ratios to the optimum level required to stimulate and sustain microbial activity.