The introduction of selected earthworms into degraded or newly restored land is known to promote soil improvement. However, to collect and introduce the large numbers required for use in land restoration can be costly and time consuming. To overcome these problems, an Earthworm Inoculation Unit (EIU) technique combines cultivation of selected earthworms in soil-based units with an effective method of direct soil introduction. Cultivation of a particular deep-burrowing species was achieved through optimizing temperature, nutrition and population density. At soil inoculation, after 3 months, each 2-1 EIU contained all three life stages - adults, cocoons and hatchlings - providing maximum opportunity for successful colonization. Compared with a conventional method of inoculation, the EIU technique gave rise to enhanced survivorship in a compacted clay soil during the first year after inoculation. Earthworm inoculation should become an integral component of sustainable land restoration practice and the EIU technique provides the most effective means of ensuring long-term earthworm colonization, particularly in hostile soil environments.
