Response of Avena sativa L. and the soil microbiota to the contamination of soil with Shell diesel oil

This study analysed the changes in the development of Avena sativa L. cultivated on soil contaminated with diesel oil (DO; 0, 7, 14 and 21 mL/kg of soil dry matter), and in the microbiological, biochemical, chemical and physico-chemical properties of the soil. In addition to basic fertilisation fulfilling the nutritional needs of the oat plant, finely ground barley straw and finely ground charcoal was also applied. The study revealed a highly toxic effect of DO on the growth and development of Avena sativa L. The uptake of macro- and micronutrients by the tested plant decreased significantly. The active bacteria were identified based on the analysis of 16S rRNA coding sequences. In objects contaminated with DO, a more rapid development of organotrophic bacteria, actinomyces and fungi was observed, as well as higher activity of dehydrogenases, catalase, urease, acid phosphatase, alkaline phosphatase and β-glucosidase. In the soils contaminated with DO, more Corg and available and exchangeable potassium were found than in the non-contaminated soils. DO did not have such a significant effect on the contents of other elements in the soil. The use of charcoal and straw stimulated both the development of microorganisms and the activity of soil enzymes, yet it did not mitigate the adverse effect of DO on the growth or development of the oat plant.