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 earthworm activity 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.