Selection of microbiological indicators to perform an integrated ecological-and-biological assessment of waterlogged soils

Integrated ecological and biological indicator provides wide possibilities for assessment of anthropogenic impact on soils and bio-monitoring. Each type of anthropogenic impact is characterized by changes in certain sets of biological soil parameters. To calculate the integrated indicator, one should select the parameters that change statistically significantly under the influence of a particular adverse factor. The article presents the results of work on the identification of microbiological parameters most sensitive to water logging in soil. The research was performed using samples of leached chernozem and alluvial sod soils which were 3.5 months in controlled conditions of the model experiment on the effect of water logging on soils. Soil samples were kept in plastic containers in conditions of water logging, at optimal moisture content, with and without addition of sucrose solution. At the end of the experiment, the population of five ecological trophic groups of microorganisms was determined by seeding on solid nutrient media. The determination was carried out in triplicate. The statistical significance of the difference in the population of microorganism groups between flooded soils and soils with optimal humidity was determined. It was shown that water logging led to a reduction in population of the most studied microorganisms. It was established that according to their sensitivity to water logging and the processes of gleization, the microorganisms can be arranged in the following series in descending order: microscopic fungi, actinomycetes, amylolyticus, ammonifiers, and spores. The spore microorganisms are most resistant to water logging. Statistical analysis did not reveal a relationship between their population in alluvial soils and ox-redox potential. It was shown that the integrated indicator calculated taking into account the population of only the three most sensitive groups of microorganisms has a higher correlation coefficient with the soil ox-redox potential than that calculated taking into account all five groups.