The aim of the research was to determine the variability of the total numbers of bacteria, actinomycetes and fungi under stress associated with the presence of exogenous organic matter in the soil. Another goal of the experiment was to observe the effect of substrates absorbing water and minimizing drought stress on the number of soil microorganisms. The total number of aerobic bacteria was determined by serial dilution using Bount-Rovira medium with the addition of soil extract. The Actinomycete number was determined by serial dilution using Gauze medium with the addition of starch. The total number of microscopic fungi was determined by serial dilution using peptone-glucose agar with Rose Bengal according to Martin and the addition of streptomycin. The ratio of the sum of the number of bacteria and actinomycetes to the number of fungi. Organic waste materials applied to the soil did not significantly affect the number of microorganisms, i.e. bacteria, actinomycetes or the ratio of bacteria and actinomycetes on the one hand to fungi on the other. Therefore, these substances can be considered safe for soil microorganisms. The results of the research prove the possibility of utilizing organic matter produced by sewage treatment plants, waste treatment plants or mushroom farms as substances enriching the soil of urban green areas. Because the results significantly varied mainly over the years, it can be assumed that the number of microorganisms was affected by the amount of precipitation and air temperature.