Earthworms of a land restoration site treated with paper mill sludge

Land restoration at a former landfill site, Bidston Moss, NW England, has involved heavy applications of paper mill sludge (PMS), a byproduct of paper recycling. The development of earthworm communities at the site has been assisted by earthworm inoculation. Initially low numbers of epigeic species were present, but as the restoration has progressed since 1996 a substantial number, biomass and diversity of earthworms has become established, including a variety of ecological types. In some areas there is substantial surface casting. Cast colour indicates selective consumption of PMS, and δ13C ratios suggest that PMS is a major nutrient source for earthworms. Although concentrations of copper in the PMS are higher than those typical for soils, concentrations in earthworm tissue are relatively low. Low availability of copper will reflect the high content of organic matter and clay, and relatively high pH, of the PMS.