The object of a field experiment conducted in the years 2003–2004 was the rhizosphere soil of soybean ‘Mazowia’ cv. Before the sowing, the seeds were dressed with biopreparations (Biochikol 020 PC, Biosept 33 SL, Polyversum) or fungicide (Oxafun T). The non-dressed seeds constituted the control. The microbiological analysis of the rhizosphere soil of soybean, carried out at anthesis, showed that the greatest number of bacteria in total and bacteria Bacillus spp. and Pseudomonas spp. occurred after the application of Biochikol 020 PC, while the lowest occurred in the control combination. The smallest number of fungi was observed after the application of Biochikol 020 PC or Oxafun T, slightly bigger after the introduction of Biosept 33 SL or Polyversum into the soil, while the biggest in the control combination. Fungi from the genera of Alternaria, Fusarium, Pythium and Gliocladium, Penicillium, and Trichoderma were most frequently isolated from the rhizosphere of soybean. After the application of biopreparations the proportion of pathogenic fungi in the rhizosphere of soybean was much smaller than in the control. The highest proportion of Gliocladium spp. occurred after the application of Polyversum or Biochikol 020 PC, while that of Trichoderma spp. after the introduction of Biochikol 020 PC or Biosept 33 SL. Besides, tests on dishes showed that the biopreparations and the fungicide used in the experiment contributed to increased numbers of antagonistic bacteria (Bacillus spp. and Pseudomonas spp.) and fungi (Gliocladium spp. and Trichoderma spp.).

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