The subject of our research is the comparative ecotoxicological examination of the bacterial slurry treatment system distributed by NCH Magyarorszag Kft. The experiment was carried out on a cattle calf rearing farm, in the 0-6 months age group section. The bacterial strains available in tablet form were multiplied in a container and added weekly to the slurry collected in the shaft. The purpose of bacteria treatment was to promote homogenization of the manure, reduce odors, and break down organic impurities. The ecotoxicological tests were carried out before, during and after the manure treatment at three sampling times. As a result of our research, it has been revealed that during the slurry treatment, the internal content values increased significantly, mostly the nitrogen forms, the biological oxygen demand and the dry matter content. The presence of the estrogenic effect remained considerable even at the end of the treatment. Based on the phytotoxicity test, the fertilizer treatment had a positive effect on the stem and root growth of each plant. The results of the soil toxicity test proved that untreated slurry loses its inhibitory effect on the vital activity of sensitive bacteria at higher dilutions. The common duckweed test revealed that above 150 dilution, the inhibitory effect of the slurry ceases in the samples at all three sampling times. In order to inhibit the growth of algae, the liquid fertilizer showed a stagnant-inhibiting tendency during the treatment. Based on our results, we came to the conclusion that the bacterial slurry treatment system was effective in terms of homogeneity, deodorization and decomposition of organic matter. However, it is recommended to apply it to the fields at a higher dilution rate or with a high soil water content. Further studies are needed regarding the removal of substances with hormonal effects, based on which recommendations can be developed for farmers.