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).
Plant yield was always the highest in the mineral treatment
(P < 0.05 for all plantings) (Fig. 3). For the first maize planting, no
difference was observed between the control and vermicompost
treatments (P > 0.05) and the lowest yield was obtained for the
compost treatment. For the second cultivation (i.e. tomato plant),
vermicompost had an intermediate impact and the lowest yield
was measured for the compost treatment (P < 0.05). However, no
difference was measured between these two organic treatments
in the final maize planting (P > 0.05). Although plant yield was not
influenced by earthwormactivity for the control and vermicompost
treatments (P > 0.05 in all case), earthworms improved tomato yield
and decreased the yield of the second maize crop (P < 0.05) for the
compost treatment.