Amelioration of Spent Oil Contaminated Ultisol with Organic Wastes and its Effect on Soil Properties and Maize (Zea mays L) Yield

Contamination of soil with toxic substances can degrade its capacity to grow plants. A Randomized Complete Block Design (RCBD) experiment was set up in 2005 and 2006 to evaluate the effect of organic wastes on the physical properties and maize (Zea mays L) yield of spent oil contaminated (SOC) ultisol in Abakaliki South eastern Nigeria. The wastes comprising poultry droppings (PD) and Rice husk dust (RHD) were applied at the rate of 10tha in 2005 and their residual effect tested in 2006. The results obtained showed significant 1 decrease (P= 0.05) in soil bulk density at 48 and 90 days after planting (DAP) in waste amended plots relative to SOC plots in both seasons. Rice husk dust (ORHD) gave highest aggregate stability value of 80.3(%) in 2005. The value was 12%, 6% and 9% higher than control ©, oil + PD (OPD) and SOC plots, respectively. Waste application increased the water retention and hydraulic conductivity of the soils relative to SOC plots in both seasons. Results also show significant decrease in crop growth and yield in SOC plots relative to the waste amended plots. Yield increase of 32%, 12% and 225% were obtained in OPD amended plots relative to C, ORHD and SOC plots, respectively in 2006. Results also showed that organic amendments can improve the physical properties and productivity of spent oil contaminated soils.