Is enrichment with inorganic and organic compounds feasible for improving the quality of vermicomposting using water hyacinth biomass?

Abstract

In eutrophic environments, aquatic weeds reproduce rapidly, occupying extensive areas of the water body, preventing the multiple use of water resources. The use of the biomass of these plants in vermicomposting represents a sustainable alternative to the excess biomass produced by eutrophication. The enrichment of macrophyte biomass during vermicomposting was tested using an inorganic solution (NPK 1.75% and NPK 3.5%) and an organic solution with glucose (0.25 g/L and 0.5 g/L) to improve the quality of the compost. The consumption of biomass from the waterweed by the earthworms increased as the vermicomposting progressed, reaching the highest values at the end of the experimental period. The control experiment, i.e., without earthworms, remained stable. The electrical conductivity showed a tendency to increase for the treatments NPK 1.75%, Glucose 0.25 g/L and Glucose 0.5 g/L. The pH of the vermicomposting tended to be neutral in all treatments.  The control and inorganic treatments showed a reduction in both macrophyte biomass and the number of individuals of Eisenia fetida. The additions of NPK and glucose slightly improved compost quality and biomass consumption by the earthworms. However, the use of vermicompost alone does not meet the requirements for its use as a fertilizer. Thus, we suggest the use of vermicompost in association with other fertilizers, adding moisture and structuring the soil.