The aim of the study was to evaluate the influence of post-fermentation liquid on the chemical and microbial properties of soil as expressed by the total number of bacteria and fungi and by changes in the population of selected groups of soil microorganisms:  amylolytic, cellulolytic, pectinolytic and proteolytic bacteria as well as actinobacteria. Samples obtained from the surface layer of luvisol, fertilized with post-fermentation liquid produced in an agricultural biogas plant processing pig slurry, maize silage and post-slaughter waste, were analyzed. The effect of fertilization with digestate was evaluated in a pot experiment performed on a laboratory scale. The applied fertilization affected the chemical properties of the soil, which depended on a dose of post-fermentation liquid, as well as on the duration of the experiment. The addition of post-fermentation liquid to the luvisol significantly increased the level of total nitrogen and content of organic carbon. The analysis of the fractional composition of humus compounds showed an increase in the carbon content of the humic acid fraction (CHA) in the luvisol. Analyses of infrared spectra in the present study indicate a similar effect of post-fermentation liquid as in the case of humus-forming slurry. A higher concentration of post-fermentation liquid (255 kg N ha-1) usually resulted in an increase in the number of individual groups of microorganisms, in particular fungi and actinobacteria, as well as the total number of bacteria.

25.2.2020