UTILIZATION OF SOLID PAPER-MILL SLUDGE AND SPENT BREWERY YEAST AS A FEED FOR SOIL-DWELLING EARTHWORMS

Solid paper-mill residues amounting to thousands of tonnes per annum a re 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 ca n satisfy the requirements of earthworm growth. Using one such feed co mprising a 66:1 mixture, by mass, of wet paper waste and dry yeast ext ract, the lob worm (Lumbricus terrestris) can be grown from the hatchl ing stage (50 mg) to maturity (3-4 g) within 90 days, with an acceptab ly 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.