Potential of Sorghum bicolor L. (Moench) and the Effectiveness of Some Organic Amendments in Remediation of Petroleum Oil-Vitiated Soils of an Automobile Repair Workshop in Urbanite Kampala

Aims: To determine the potential of sweet sorghum (Epuripur 1995) and the effect of organic biostimulators: NPK fertilizer, cow dung and sewage sludge in remediation of petroleum oil-adulterated soils from a garage in Kampala Metropolis, Uganda.

Place and Duration of Study: The contaminated soils were obtained from New Katanga Boys automobile repair workshop in Wandegeya, Kampala, Uganda. Experiments were conducted between September 2018 to November 2018 at Department of Food Processing Technology, College of Agriculture and Environmental Sciences, Makerere University, Kampala, Uganda.

Methodology: 50 kg of petroleum oil-contaminated soils were collected from the garage and divided into 5 kg portions; four portions were potted with four sorghum grains with three subjected to 5% w/w amendment using NPK fertilizer, cow dung and sewage sludge under normal growth conditions for 72 days. Representative soil samples were collected from spots at 0-10 cm and 10-20 cm from the potted soils and subjected to Soxhlet extraction. Growth parameters (leaf surface area, root mass and mass of sorghum heads) of the potted plants were measured.

Results: The sorghum plants grew normally and survived in the petroleum-contaminated soils. Sorghum potted in contaminated soil without any amendment did not flower. Amendment of the vitiated soils with NPK fertilizer, cow dung and sewage sludge biostimulated the phytoremediation capacity of sorghum by 9.1%, 12.5% and 6.3% respectively.

Conclusion: Addition of cow dung to spent-oil contaminated soils could make such soils fully re-established for agricultural activities. Further research should assess the chemical properties of the investigated vitiated soils and the effectiveness of other biostimulants such as vermicompost in biostimulating phytoremediation by Sorghum bicolor. The potential of other cereals such as corn, barley, rye and millet in phytoremediation of petroleum-adulterated soils should be investigated.