Impact assessment of oil exploration activities on soil fertility in Delta state, Nigeria

Limited information on impact of oil exploration on soil fertility in Nigeria is hindering the efforts toward soil improvement. Hence, the impact of oil exploration on soil fertility in four local government areas (LGA), Delta State, Nigeria was evaluated in 2020.

Two LGAs in oil producing (Ukwani, Ndokwa) and non oil producing (Aniocha South, Ika South) and three communities in each LGA and one crop largely cultivated was purposely chosen. Soil samples were taken from 0–30 cm depth at 10 meters intervals along transverses cut at 100 m apart. The samples were air-dried at room temperature, crushed and made to pass 2 mm sieve. Soil pH, organic matter, nitrogen, phosphorus, calcium, magnesium, potassium and sodium were measured. Data were statistical analyzed and least significance difference at a_{0 05} was used to separate means while Parker's nutrient index was used to rate the fertility.

Ukwani soil was strongly acidity (5.30), Ndokwa was moderately acidity (5.83) while Ika (6.61) and Aniocha (6.27) were slightly acidity. Organic matter (2.54 and 2.48%) and phosphorus (16.98 and 14.51 mg/kg) were medium in Ika and Aniocha whereas, both were low in Ukwani (1.49%, 10.14 mg/kg) and Ndokwa (1.74%, 12.52 mg/kg), respectively. Nitrogen was high in Ika (0.27%) and Aniocha (0.42%), medium in Ndokwa (0.18%) and low in Ukwani (0.15%). Potassium and sodium were high in Ika, Aniocha and Ukwani but medium in Ndokwa. Calcium was high in Ika, medium in Aniocha but low in Ndokwa and Ukwani. Magnesium was high in Ika, Aniocha and Ndokwa but was medium in Ukwani.