Assessment of Agroecological Indicators of Oil-Contaminated Chernozem in Rostov Oblast after Remediation with Urea and Potassium Humate

As a result of a model experiment, changes in the agroecological soil indicators have been evaluated after the introduction of remediating agents, urea and potassium humate, into ordinary chernozem contaminated with oil. It is shown that oil pollution has a toxic effect on the germination capacity and the length of radish roots and shoots. The introduction of potassium humate and urea led to significant changes in the phytotoxic properties of ordinary chernozem. In most cases, the introduction of urea into unpolluted soil had a phytotoxic effect: the length of radish shoots and roots decreased by 20–80%. The introduction of potassium humate did not significantly influence or stimulate seed germination and the early growth of the plants. The introduction of these remediating agents 90 days after soil contamination with oil resulted in the recovery of the values of the indicators under study. The introduction of oil led to a decrease in the content of nitrates, which is probably due to a decrease in the extraction of nitrates to the solution as a result of the formation of complex aggregates of products of oil decomposition with ammonium formed during the decomposition. Potassium humate had a favorable effect on the content of nitrates in the soil.