Impact of ameliorants on the biological condition of oil-contaminated black soil

The impact of ameliorants on the biological condition of ordinary black soil in the south of European Russia (Rostov district) after oil pollution has been analyzed. The impact of ameliorants of different nature like urea, glauconite, potassium humate and Dop-Uni (bacterial preparation) on the biological condition of oil-contaminated ordinary black soil has been analyzed. According to the stimulating effect on the biological activity of oil-contaminated black soil, ameliorants were ranked in the following order: potassium humate > Dop-Uni > urea. According to the efficiency in stimulating oil breakdown, the ameliorants studied form the following sequence: potassium humate > Dop-Uni > urea. The above rank did not include glauconite since its mode of action is based not on the stimulation of oil breakdown, but on its fixation. In case of combined application of urea and potassium humate, there was a synergistic effect indicating the reasonability of their combined application. When applying urea and Dop-Uni, there was an antagonistic effect. According to the sensitivity to ameliorants in oil-contaminated black soils, biological parameters form the following sequence: content of labile organic matter ≥ invertase activity > catalase activity > phosphatase activity > root length ≥ shoot length. According to information value, the used biological parameters of soil condition form the following sequence: invertase activity > content of labile organic matter ≥ catalase activity > root length > shoot length > phosphatase activity.