The response of soils and plants to oil-containing sludges was studied by pot, small plot, and field experiments. The objective was to develop a simple method of farmland disposal without detrimental effects on the environment.
Dewatered sludge from a petroleum storage plant, in combination with nitrogen fertilizer, was found most suited to farmland disposal. The sludge was applied to sandy soil at rates from 3 to 8 g oil per kilogram of soil, and during a single growing season (six months) 60 to 90% of the oil was decomposed. No oil was detected below a 60-cm depth. Some physical properties of the soil, particularly the texture and water-retaining capacity, were improved. The plants were analyzed for protein, phosphate, and potassium oxide and found to have suffered no detriment and no loss in crop yield. The method of disposal by conventional agrotechnical operations proved environmentally safe and economically superior to other alternatives.