Effects of spent engine oil contamination on soybean (Glycine max L. Merril) in an Ultisol
An experiment was conducted in the University of Nigeria Nsukka Teaching and Research Farm to determine the effect of spent auto-engine oil on soil and soybean in a Randomized Complete Block Design. Treatments were four levels (0, 1, 2 and 3 %) of spent auto-engine oil (SPO). Top soil samples were collected at 0, 12, 24 and 36 months and analyzed. Results indicated that infiltration rates in plots under 3 % SPO was reduced from 1.40 cm h-1 in control plots to the lowest value of 0.07 cm h-1 compared to 0.27 cm h-1 in 1 % treatment in the first 12 months. Plots contaminated with 3 % SPO gave the lowest Ks values of 6.29, 7.68 and 9.43 cm h-1 in the 12th, 24th and 36th months respectively. Data on plant samples showed that 2 % and 3 % SPO contaminations reduced soybean germination from 99 % (control) to 86 and 68 % respectively in the first cropping season whereas 1 % SPO was observed to significantly increase leaf area, dry matter content and grain yield from control values of 52.6 cm2, 3.01 t ha-1 and 0.72 t ha-1 to 54.5 cm2, 4.20 t ha-1 and 0.97 t ha-1 respectively.
Keywords: Contamination, soybean, soil physical properties, spent engine oil, Ultisol