Although no significant difference in above-ground plant biomass was observed for the first maize planting (P > 0.05 in all the cases) (Fig. 2), our study showed increased biomass for tomato and the second maize planting when mineral fertilizer and vermicompost were used, without a significant difference between these two treatments (P > 0.05). The lowest biomass was always observed following application of compost. Earthworms did not influence above-ground plant biomass in the control and vermicompost treatments (P > 0.05 in all the cases). However, a significant interaction was observed between earthworm activity and plant growth when compost was used. Earthworms increased tomato plant biomass and decreased the biomass of the second maize planting in soil mixed with compost (P < 0.05 in both cases).