Organic Amendments and Earthworm Addition Improve Properties of Nonacidic Mine Tailings

Abstract

In many mined areas, lack of topsoil limits conversion of disturbed landscapes to former or other productive uses. We examined the use of biosolids (10 or 20% by dry mass), with or without sawdust, pulp sludge, and the contribution of an earthworm species (Dendrobaena veneta) to improve the properties of nonacidic mine tailings. Pulp sludge more rapidly immobilized excessive NH4 + concentrations from biosolids early in the study; however, total mineral N concentrations were similar in pulp sludge and sawdust treatments by week 29. Although NO3 −-N concentrations were generally greater in treatments with earthworms, these trends were not statistically significant (P>0.05). In general, Bray P concentrations were greater in the presence of earthworms. Soil thin sections showed that earthworms mixed organic residues into elongated spherical units within mine tailings. Organic residues in combination with earthworm addition may improve the chemical and microstructural properties of non-acidic mine tailings, producing a substrate conducive for plant establishment.