THE EFFECTS OF SPENT ENGINE OIL ON THE GROWTH AND YEILD RESPONSE OF MAIZE (Zea mays L.) AND JUTE MALLOW (CorchorusolitoriusL.)

Abstract

A field study was conducted to demonstrate the effects of spent engine oil on the growth and yield response of maize (Zea maysL.) and jute mallow (CorchorusolitoriusL.). The soil was a well-drained loamy soil, slightly acidic (pH 4.2), high in phosphorus and nitrogen but low in hydrocarbon contents. Four different volumes of spent engine oil; 00ml (control), 50ml, 100ml and 150ml were applied to 5kg of dry loamy soil in perforated bowls. The seeds were grown in the screen house for four weeks and then the seedlings transplanted to the soil polluted with spent engine oil. The soil was mixed homogenously by hand with 50ml, 100ml and 150 ml of spent engine oil(spent oil in soil generally resulted in delayed seed emergence, poor plant growth and inhibition of germination at higher concentration). The experiment was Completely Randomized Block Design (RCBD) and replicated five times. Data on plant height, number of leaves, leaf area and stem girth were recorded for a period 10 Week after Transplant (WAT). In both plants, there was a significant reduction (P<0.05) in plant height, number of leaves, leaf area, stem girth and fresh and dry weight when compared with the control. The reductions observed in the parameters were spent oil concentration dependent. No death was recorded in Corchorusolitoriusindicating that the plant tolerated all the levels of spent engine oil used, although, the rate of tolerance decreased as the levels of treatment increased. Reduction in growth parameters as a result of spent engine oil effects was higher in Zea mays than Corchorusolitorius, which indicates that Corchorusolitoriuswas more tolerant than Zea mays. It was observed in this research that the polluted soils appear darker in colour than the control soils and darker soils absorb a lot of heat which may be responsible for the germination inhibition. There was significant difference in the pH of soils following application of spent engine oil. It was revealed from the result that spent engine oil contamination increased the soil pH from acidic towards neutral for each treatment. The concentrations of chromium, cadmium, copper, lead and nickel in soil contaminated with spent engine oil increased with the volume of the pollutants added. Heavy metal concentrations in the shoots (leaves and stems) and roots of treated plants were higher than that of the control. Apart from copper and lead that were relatively higher in both plant parts, there was no significant difference in the concentration of heavy metals in both plants. Similarly, there was no significant difference in the quantity of heavy metals absorbed in both plants.