Potential of Cyperus rotundus for Remediating Soils Polluted with Spent Engine Oil: Changes in Soil Chemical and Microbial Properties Victoria F. Ediene, Faith N. Ahuchaogu and A. E. Eneji Department of Soil Science, Faculty of Agriculture, Forestry and Wildlife Resources Management, University of Calabar, Nigeria *Corresponding author: victoriaediene@gmail ABSTRACT Recently, the use of plants to cleanup of crude oil contaminated soils has been a subject of increasing investigation. To identify native plants for the remediation of oil contaminated soil, the growth of Cyperus rotundus L. was observed under different concentrations (0, 50, 100, 150 and 200 g/kg) of the spent engine oil in pot experiment. Soil analysis showed that the oil had little effects on pH, exchangeable Na and K as well as texture but the organic C, N and total hydrocarbon (THC) increased relative to the control while concentrations of P, Ca and Mg decreased. The microbial population decreased with increasing concentration of the spent engine oil. Survival rates and dry matter yield of C. rotundus were considerably (P<0.05) reduced by soil pollution. Overall, C. rotundus had satisfactory potential for growth if soil contamination does not exceed 10%. Further research should screen more native plants with remediating ability. INTRODUCTION Crude oil exploration in Nigeria has led to the pollution of land and water ways, especially in the oil producing belt. Due to its toxicity, widespread presence and complex nature, this type of pollution is a serious problem mainly because modernization and urbanization have led to increasing use of petroleum and petroleum-based products. Contamination of soil with oil is becoming an ever increasing problem due to several breakdowns of oil pipelines and wells, negligence when transporting, collecting or storing and careless disposal of old or used petroleum products. The disposal of spent engine oil (SEO) also known as used engine oil into gutters, water drains, open vacant plots and farms is a common practice in Nigeria, especially by motor mechanics. This spent oil is usually obtained after servicing and subsequent draining from automobiles and generator engines (Anoliefo and Vwioke, 2001) and much of it is poured into the soil. International Journal Of Scientific & Engineering Research, Volume 7, Issue 7, July-2016 ISSN 2229-5518 1002 IJSER © 2016 http://www.ijser.org IJSER