Soil is an important medium of biomass production due to storing, transforming, and harmonizing natural resources. This experimental site (Kungyalu, Central-East Hungary) on Chernozem soil was examined based on: a) irrigation (linear – LI; drum irrigation – DI; no irrigation – NI); and b) mulching (mulched – M; unmulched – U). The objective was to investigate the effect of irrigation and organic mulching (wheat straw) on earthworm abundance, biomass and species composition. The earthworm abundance and biomass under U (60.7 ind m^-2, 16.8 g m^-2) and M (68.1 ind m^-2, 17.3 g m^-2) were greater in autumn compared to summer (U: 16.6 ind m^-2, 3.14 g m^-2; M: 29.9 ind m^-2, 6.6 g m^-2), but the difference was only significant in summer. Significantly greater earthworm abundance and biomass were found under NI in autumn (92.5 ind m^-2, 23.9 g m^-2). Five earthworm species were detected (Aporrectodea caliginosa, Aporrectodea rosea, Aporrectodea georgii, Proctodrilus opisthoductus, Octolasion lacteum), mostly juveniles. Soil mulching significantly increased earthworm abundance and biomass in summer, while irrigation significantly decreased it.