ABSTRACT
Bioturbation is concerned with reactions between animals, plants and soil material, during which soil fabric is altered by detachment, transport, sorting and deposition of material, both within the soil mantle and on its surface. To assess the total amount of bioturbation resulting from earthworm activity means taking account of both their subsoil and surface actions. The latter is the comparatively simple task of determining the rate of surface casting; even so there are difficulties resulting from erosive loss between collections, or the possibility that collections might stimulate worms to produce more casts. However, this is straightforward compared to assessing subsoil bioturbation. The assessment of total bioturbation by ants is much more difficult than in the case of earthworms, for the amount of material not ejected at the surface in the form of mounds can be considerable and, furthermore, there is no ingestion of material that can be used to assess rates of mixing within the soil.
