EFFECT OF NITROGEN AND HUMIC FERTILIZERS ON THE BIOCHEMICAL STATE OF OIL‐CONTAMINATED CHERNOZEM

Abstract

Aim. In this paper, we aim to assess the effect of nitrogen and humic fertilizers on the biochemical state of oil‐contaminated chernozem.Methods. In order to simulate the oil pollu‐ tion, chernozem was exposed to oil doses constituting 1, 5 and 10% of the soil mass for 30, 60 and 90 days. For simulating bioremediation of oil‐contaminated chernozem, the following fertilizers were used: potassium and sodium humates, urea and nitroammophos. Nitrogen fertilizers – urea and nitroammophos having a nitrogen content of 46% and 15%, respectively – were applied to the soil for the purposes of restoring the equilibrium between carbon and nitrogen. Humic fertilizers (potassium and sodium humates) were applied to the soil for stimulating the indigenous oil destructive microbiota. In order to assess the biological activity of the soil, we determined catalase activity, invertase activity, as well as CO2 emission intensity.Results. The effect of urea, nitroammophos, potassium and sodium humates on the enzymatic activity and CO2 emissions of ordinary chernozem, which had been exposed to various doses of oil (1, 5 and 10% of the soil mass) for 90 days, was studied in a model experiment. Following the introduction of nitroammophos into soil with low levels of oil pollution, catalase activity decreased, whereas respiration and invertase activity increased. Urea introduced into the soil contaminat‐ ed with a 10% dose of oil stimulated catalase activity. At oil concentrations of 1 and 5%, the introduction of potassium and sodium humates had a stimulating effect on enzymic activity and carbon dioxide evolution.Conclusions. It is advisable to use the intensity of CO2 emissions released from the soil, as well as the invertase activity for diagnosing the state of chernozem con‐ taminated with oil (5‐10%) following the introduction of nitrogen and humic ameliorants. At lower doses of oil, it is advisable to assess the state of the soil following the introduction of nitrogen fertilizers by catalase activity.