The aim of the work was to evaluate the impact of use of conventional and organic cultivation systems on selected param‑eters of microbial activity in the soil under wheat, barley and oat cultivation. Microbiological, biochemical, enzymatic and metabolic activities were analyzed during three seasons over 3 years in soil. The more beneficial effect of organic cultivation was reflected in the increase in bacterial growth, the intensification of the nitrification and higher activity of all analyzed enzymes. The conventional system was more favorable for the development of fungi. The assessment of the metabolic profile of soil microorganisms demonstrated clear differences between the activity of microorganisms in the organic and conventional systems. The results indicate that cultivation of soil in the organic system is more conducive to the environment. The authors conducted research, because there is no unambiguous answer to the question which growing system is more beneficial for soil biological life, i.e., the basis for food production. Microorganisms that are the object of these studies form the basis for the fertility of all soil ecosystems.