Changes in layers of laboratory vermicomposting using spent mushroom substrate of Agaricus subrufescens P

World mushroom production in 2018 was approximately 8.99 million tonnes. The most commonly cultivated species in the Czech Republic are Agaricus spp., which are sold fresh or canned. In 2017, 2018 mushroom production in the Czech Republic was approximately 540 tonnes. Vermicomposting is an easy and less ecologically harmful way to process the spent mushroom substrate. Earthworms, which are referred to as the engine of the process of vermicomposting, and microorganisms, help convert organic waste into fertilizer. This study is concerned with laboratory vermicomposting in a system of continuous feeding of earthworms Eisenia andrei. It compares the differences between variants with and without earthworms. The dry matter percentage was approximately 20% or more in both variants. The variant with earthworms showed a significant decrease in electrical conductivity. The C/N ratio was very low in both variants. The highest total P was recorded in the variant with earthworms, but the highest values of K and Mg were found in the control. Both variants recorded higher content of bacteria than fungi. All values of microorganism contents were higher in the vermicomposter without earthworms, but the bacterial/fungal ratio was higher in the variant with earthworms. The highest content in both variants shows the bacteria especially G-bacteria, on the other side, the lowest content shows the actinobacteria. The highest activity of β-D-glucosidase and acid phosphatase was measured in the vermicomposter with earthworms, but the activity of other enzymes was higher in the control. In both vermicomposters laccase activity was below the detection limit. The method of classical vermicomposting can be used for processing the spent mushroom substrate. However, in terms of higher content of total and available nutrients, there seems to be a better method of processing the substrate without earthworms.