SPENT ENGINE OIL CONTAMINATION OF AN ULTISOL IN SOUTHEASTERN NIGERIA: COMPARATIVE EFFECTS ON TWO CROP SPECIES

Toxicity from spent engine oil contamination is a prevalent problem in Nigeria. Therefore a field investigation was carried out at the Teaching and Research Farm of the University of Nigeria, Nsukka, Nigeria to determine the effect of spent engine oil contaminated soil on growth and yield parameters of maize and cowpea. Post contamination sampling indicated that spent engine oil significantly (P < 0.05) increased total hydrocarbon content and bulk density from 825 mg kg-1 to a maximum of 25411 mg/kg and 1.50 g cm-3 to 1.68 g cm-3 respectively whereas soil water loss between 2 - 10 days after saturation was highest (40 %) in the first three months in 3 % spent engine oil contaminated. Germination was 32 % lower in maize than cowpea while spent engine oil had 29-folds more detrimental effects on leaf expansion of maize compared to cowpea. It was also observed that the dry matter content and grain yield of maize was more than 3 times and 2.5 times respectively, reduced compared to that of cowpea. It was concluded that spent engine oil had detrimental effects on soil physical properties and the test crops, however maize showed higher susceptibility compared to cowpea.