The main by-product of wine-making is grape marc. With proper treatment, grape marc may return to the vineyard as a fertiliser. This study deals with the vermicomposting of grape marc in a continuous feeding system in outdoor conditions for more than 12 months. The N-NH4+, dissolved organic carbon (DOC), and N-NH4+/N-NO3- contents were greater in the top layers. The pH value was about 8 in all the layers. The electrical conductivity was the greatest in the bottom layer. The ion-exchange capacity did not modify significantly during vermicomposting. The microbial biomass was the greatest in the upper layer, as well as the number and the biomass of the earthworms. The process of vermicomposting seems to be an ideal way of processing residues from the winemaking industry. This vermicompost has very good properties for use as a fertiliser, and for returning the nutrients and organic matter to the soil, for example, in a vineyard.
