The allocation of the large amount of swine waste from farms is an international concern. An efficient way of managing such waste is its use in farming. It is already known that the incorporation of organic waste into the soil significantly increases the microbial population. Therefore, the objective was to evaluate the impact of the use of swine manure on the soil microbiota in a Eutrophic Oxisol. The experiment was set up in a completely randomized design in a 6 × 4 factorial scheme (sixconcentrations of swine manure and four evaluation periods) with four replications. We evaluate the following characteristics: microbial respiration (C-CO2), microbial biomass (µC g-1 soil) and pH.: microbial respiration (C-CO2), microbial biomass (µC g-1 soil) and pH. A significant effect was found in the interaction between concentrations and time of incubation (p < 0.05) of swine manure on microbial activity in the soil. The amount of microbial carbon increased as a function of increased levels of liquid swine manure. No interaction was observed between concentrations and time of incubation for the pH. The evaluation of the isolated factors allowed to observe that the pH decreased as the doses of manure were incremented. Higher and lower pH values were found after 5 and 30 days of incubation. The application of liquid swine manure up to 6000 L ha-1 increases the release of CO2 and carbon in the microbial biomass. The applications of liquid swine manure cause a gradual reduction in soil pH.