Soils contaminated with the oil (5-20 g/kg of soil) were purified by addn. of urea (N content 200 mg/kg soil) as well as of compost, bentonite, zeolite (concns. 3%, 2% and 2% by mass, resp.) and CaO (dose equiv. to 1 full hydrolytic acidity). Soils with or without the additives were used for cultivation of maize, spring barley/white mustard and oats to test the effect of oil pollution and used additives on the content of org. C in soils after crops. The type of the crop and content of oil contamination had a significant impact on the content of org. C in unmodified as well as modified soil samples. The contamination with the oil resulted in an increase in org. C content in soils, esp. in soils with small doses of heating oil. The addn. of CaO, urea and zeolite resulted in decrease in org. C content in soils after crops of all tested plants compared to their content in original soils with comparable oil content. The addn. of bentonite resulted in the opposite effect for soils after maize and spring barley/white mustard crops. The addn. of compost resulted in an increase in the org. C content in soils after cultivation of maize and a decrease in its content in soils after cultivation of other plants.