Аннотация:Increasing oil extraction activity in Russia made the soil contamination a critical environmental issue. Stavropol region is one of the oldest oil producing regions of Russia. The objectives of this study were to evaluate a set of selected characteristics typical of steppe and semidesert soils under petroleum impact. We focus on assessing qualitatively the total petroleum hydrocarbons (TPH) contaminated soils and seek to find the acceptable norms, allowing a soil system to perform its ecological functions, using biological parameters. Catalase activity significantly correlated with the TPH dose in soils studied (R2 = 0.8, p < 0.01) and is a sensitive parameter for assessment. No correlation was revealed between urease activity and TPH content as well as phosphatase activity. The significant correlation between CO2 emission and TPH content was found only in Haplic Kastanozems Sodic soils, then how correlation between respiration intensity and water-soluble salt content in soils was significant (R2 = 0.7, p < 0.01). The germination, viability and biomass parameters of canola and alfalfa were also sensitive to TPH different dose. Biological parameters confirmed that the TPH limit was 1 and 3 g TPH kg-1 for Endosalic Gleysols Sodic and Luvic Chernozems Sodic respectively. The threshold TPH level was 4 and 5 g kg-1 in Chernozems Pachic and Haplic Kastanozems Sodic soils respectively. The results obtained proved that the combination of biological parameters could be viable indicators for soil assessment in TPH contaminated environment.