Microbial Activities in Fertilizer-Amended Contaminated Soils

Bioremediation, an affordable and environmentally friendly technique, remains a viable strategy for tackling water and soil pollution. This study investigated microbial activities in crude oil-contaminated soils amended with fertilizer. Unpolluted soil samples obtained from the bed of Ovia River, Benin City, Nigeria, were contaminated with crude oil, and thereafter remediated with NPK/urea fertilizer. Textural classification of the soils showed that the clay soil contained 77 % clay, while that of the sandy-clay soil was 72 %. Crude oil-polluted soils (3 kg) were investigated in seven groups, each for the two soil types (clay and sandy-clay). Soil microbes were enumerated using standard procedures every 6 days for 36 days. The results of this study showed that total hydrocarbon utilizing fungi (THUF), total hydrocarbon fungi (THF), total hydrocarbon utilizing bacteria (THUB) and total hydrocarbon bacteria (THB) of clay and sandy-clay soils were significantly and concentration-dependently increased by crude oil contamination as well as fertilizer remediation at day 0 to 12, and then decreased from day 18 through 36 (p < 0.05). The results indicate that with appropriate management, NPK/urea fertilizer may constitute an organic supplement for remediating hydrocarbon-polluted soils, especially in places where crude oil pollution is a major environmental challenge.