The aim of the research was to determine the changes in number of microorganisms in soil under ecological and conventional cultivation of winter wheal. The number of bacteria was presented as a number of colony forming unit (CFU) acc. to Parkinson and after using all the observations according to FOR model. The number of colony forming units was presented in relation to: 1 g of fresh soil, 1 g of dry soil, 1 cm3 soil, 1 cm3 of soil dilution and 1 cm3 of soil porosity. The obtained results depended not only on the method of dealing with the samples and the way of measuring. They depended also on the used method of presenting the results. The used of FOR model allowed for evaluating the adequacy of the media for the needs of the observed microorganisms.
The influence of soil bulk density and suction on the number of proteolytic bacteria was statistically significant. The model was found to adequately describe real reactions of the experiment. Both density and humidity can influence the number of proteolytic bacteria. These factors both stimulate and inhibit multiplication of microorganisms. Statistical treatment of the results excluded the significance of the influence of humidity and the density on the number of oligotrophic microorganisms on the DNB medium, soil extract medium and Martin’s medium. Interaction coefficients, which determine the simultaneous influence of all the independent variables, were also not significant.