Utilisation of solid paper-mill sludge and spent brewery yeast as a feed for soil-dwelling earthworms

Abstract

Solid paper-mill residues amounting to thousands of tonnes per annum are usually disposed of in landfill sites. However, by the addition of spent yeast from the brewing industry, the carbon to nitrogen ratio of these paper sludges can be adjusted to make them into a feed which can satisfy the requirements of earthworm growth. Using one such feed comprising a 66 : 1 mixture, by mass, of wet paper waste and dry yeast extract, the lob worm ( Lumbricus terrestris) can be grown from the hatchling stage (50 mg) to maturity (3–4 g) within 90 days, with an acceptably low level of mortality. These large, soil-dwelling earthworms have potential value as agents in soil amelioration projects if they can be reared intensively, therefore their utilisation may be encouraged by using the type of superior feed described.