The reaction of higher plants to the oil contamination of soils in the pot experiment

Abstract

In Russia, the lands with oil contaminated soils exceed tens of thousands hectares. However, to date, there were no unified approaches to the rationing of oil and petroleum hydrocarbons (PH) in soils, a guideline to choose optimal evaluation indicators. The response of plants in the pot experiment could provide significant results for assessing and rationing of PH content in soils and their use in agriculture after land remediation. In this work we assessed the response of higher plants as a marker of the direction and intensity of biological processes in soils in the pot experiment under oil contamination to justify the standards of permissible residual content of PH in soils of agricultural lands. The composition and properties of Luvic Chernozems, Calcic Chernozems, Voronic Chernozems (WRB, 2015) used in the pot experiment, which was carried out in a month after the soil contamination with crude sulfur-containing oil, were investigated. The effect of different oil doses on the bioproductivity of wheat and peas was evaluated. Wheat in terms of dry biomass showed higher sensitivity to PH, containing medium and heavy fractions, than peas. Rationing the PH content in chernozems, a nonlinear regression model described by a logistic curve was applied. The quality standard values found for wheat biomass was 0,9; 0,4; 1,0 g * kg^-1 for Luvic Сhernozems (humus content ~ 9,8%, sandyloam texture); Calcic Chernozems (humus content ~7,6%, clay loam texture), Voronic Chernozems (humus content ~12.8%, loam texture), respectively. The residual PH contents, found as 30% of soil functioning change, which corresponded to the risk level of soil degradation, estimated by the soil fertility parameter — dry wheat biomass were 1,2 g·kg^-1 for Voronic Chernozems; 0,5 g·kg^-1 — Calcic Chernozems; 1,1 g·kg^-1 in Luvic Chernozems.