abstract: In Poland, as a result of the soil-forming processes and on the base of the parent materials the following soil types were formed, corresponding to a country prevalence area: 82% is represented by Eutric Cambisols and Orthic Podzols, 9% - by Eutric Histosols, 5% - by Eutric Fluvisols and last 2% - by Mollic Gleysols, Haplic Phaeozems and Rendzina Leptosols. The soil materials used in the presented study included each of the above-mentioned soil types, which enabled the verification of the hypothesis, representative for Poland, i.e., whether dehydrogenase activity (DHA) could be employed as an indicator of both oxygen deficiency and of the good oxygenation status (normoxia). Having taken into consideration the observed soil changes in response to a broad humidity spectrum, i.e. from full water capacity conditions (pF 0) to pF 3.2, corresponding to the range of available water for plant roots, the reoxidation phenomenon was successfully recognised. The relationships between the microorganism abundance of the soils and the varying aeration parameters (pF, ODR, Eh) during reoxidation were investigated. The conducted experiments showed that DHA is significantly (p<0.05) negatively correlated with water (pF), oxygen availability (ODR) and redox potential (Eh7). The above-mentioned environmental factors can affect the presence and metabolic activity of bacteria microflorae which are crucial for soil biological life. It was also proven that microorganisms abundance is significantly (p<0.05) affected by water availability and redox potential (negative correlations), as well as by oxygen availability (positive relationships). The hypothesis suggesting that DHA could be an indicator of soil oxygenation status was confirmed.