This research was carried out at the Plant and Screen house to study effect of different levels of spent engine oil application on soil properties, grain yield of maize and heavy metals uptake. Completely randomized design was used with nine treatment levels of spent engine oil at 0.0, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 and 1.0 L were applied to 20 kg of soil. Maize was used as a test crop. Data collected from the study were subjected to Statistical Analysis System for Agricultural Research. Spent engine oil at 1.0 l/poly bag significantly (P<0.05) increased bulk density by 24% and reduced gravimetric moisture content, total porosity and hydraulic conductivity by 125, 43 and 186% respectively when compared with the control. Similarly, organic carbon and nitrogen were significantly (P<0.05) higher by 152 and 87% when spent engine oil was applied at 1.0 l/poly bag relative to control. Furthermore, available P, exchangeable K, Mg, Na and Ca were 143, 123, 67, 34 and 48% significantly (P<0.05) lower at 1.0 l/poly bag of spent engine oil treatment compared with the control. Spent engine oil applied at 1.0 l/poly bag severely affected physicochemical properties of soil more than other levels except for OC and N. Maize seed germination was lower and delayed for minimum of 7 days at 1.0 l/poly bag of spent engine oil application. Grain yield of maize was significantly (P<0.05) lower with spent engine oil application than control. There were 197 and 83% reductions in grain yield of maize and seed germination relative to control. Significantly (P<0.05) higher lead and cadmium uptake by maize seeds was obtained in plots receiving spend engine oil. Contamination of soil with spent engine oil should be avoided in order to ensure sustainable soil productivity and risk of heavy metals toxicity of human beings.
Key words: Effect, grain yield, levels, heavy metal uptake, soil properties.
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