Role of compost, bentonite and lime in recovering the biochemical equilibrium of diesel oil contaminated soil

The aim of the study was to determine how soil contamination with diesel oil affected biochemical properties of soil and to determine whether the application of compost, bentonite or lime could recover the biochemical equilibrium of soil. The experiments were carried out in a greenhouse. Typical Eutric Cambisols soil formed from sandy loam was polluted with the following amounts of diesel oil: 2.5, 5.0 and 10 cm3/kg of soil. The results of the tests showed that the contamination of soil with diesel oil at the amount between 2.5 and 10 cm3/kg of soil disturbed the biochemical balance of soil. Irrespective of the application of compost, bentonite or lime and regardless which plant species was grown, diesel oil significantly (P = 0.01) stimulated the activity of dehydrogenases, urease, and alkaline phosphatase as well as the nitrification of soil. Enrichment of soil with compost, bentonite or lime stimulated the activity of urease, alkaline phosphatase and nitrification. The activity of dehydrogenases, urease and nitrification of soil, in contrast to the activity of acid phosphatase, was higher in soil under spring oilseed rape than in soil under oats. The activity of dehydrogenases, urease, alkaline phosphatase in soil contaminated with diesel oil was positively correlated with the nitrification of soil. The correlation between the activity of acid phosphatase and soil nitrification was negative.