Chemical parameters of four microcosms (sterile control microcosms without earthworms, sterile mocrocosms with earthworms, and non-sterile control microcosms without earthworms and non-sterile microcosms with earthworms) have been studied in the period from September 2013 to February 2014. Analyses included the measurement of the mass of dry matter, ash and soil organic matter, pH and electrical conductivity of the soil, and as an indicator of changes in molecular weight and source of dissolved organic matter (DOM) used ultraviolet-visible absorption spectra, or two distinct spectral slope regions 275-295 nm and 350-400 nm, and the ratio of these slopes (SR; 275295-nm slope : 350400-nm slope)and the ratio of absorption at 250 : 365 nm (E2 : E3). This study shows the significant influence of earthworms from non-sterile microcosm compared to the control for the slope ratio (SR) (cold extraction) and the absorption ratio 250: 365 nm,while no significant difference in the value of S275-295 and S350-400. There also was no statistically significant difference found in the sterile control and sterile microcosm with earthworms of value S275-295, S350-400, SR and E2 : E3 for both extraction methods (hot and cold). During the research period, there was a statistically significant difference between the two extraction methods (hot and cold) for slope ratio SR for non-sterile control microcosms without earthworms, while for the other observed parameters there was no statistically significant difference. Statistically significant differences were found between the microcosms within a month. For intestines of earthworms from sterile and non-sterile microcosm methods of cold and hot extractions showed no statistically significant differences in the observed parameters.