Due to the microbiological resistance of epoxy resins, their disposal after the completion of their lifecycle is a pressing issue. In this respect, the use of biodegradable rice and buckwheat husk derivatives as fillers may improve the service properties of epoxy materials. The results indicate that rice and buckwheat husks, as well as their ashes, can be used by soil microorganisms as a substrate. Compared to buckwheat husks, rice husks increase the biological activity of soil microbiota to a much greater extent. However, compared to rice husks, an increase in the temperature of obtaining rice husk ash leads to a decrease in its use by soil microorganisms as a substrate. This is associated with a decreased content of the X-ray amorphous phase and an increased amount of crystalline minerals in the composition of rice husk ash. At the same time, regardless of the temperature of its production, buckwheat husk ash outperforms buckwheat husks in terms of activated soil respiration, which indicates the possibility of microbiological disposal of buckwheat husk ash during its incubation in a soil. Epoxy materials, both unfilled and filled with rice and buckwheat husk ash, are not used by soil microorganisms as a substrate. At the same time, the filling of epoxy materials with rice husks leads to an improvement in their biodegradability. The biodegradation degree of rice and buckwheat husks, as well as their ashes, determines the effect of these fillers on soil respiration in the presence of epoxy materials.