The earthworm inoculation unit technique: An integrated system for cultivation and soil-inoculation of earthworms

The introduction of earthworms into degraded or newly restored land is known to promote soil improvement. Obtaining the most appropriate species in the large numbers required can be costly and time consuming using traditional techniques. Research and development of a novel approach, the Earthworm Inoculation Unit (EIU) technique, may help to overcome this. This technique combines cultivation of selected earthworms in small soil-based units, with an effective method of direct soil introduction. Successful cultivation of deep burrowing species, e.g. Lumbricus terrestris L. and Aporrectodea longa (Ude), and shallow working species, e.g. Allolobophora chlorotica (Savigny), has been achieved by optimizing environmental factors. Accelerated rates of reproduction compared with field data have been recorded. At soil-inoculation, each EIU was found to contain all three earthworm life stages, adults, cocoons and hatchlings, promoting maximum opportunity for successful colonisation. Results from field trials suggest, that for A. longa, the EIU technique can enhance survivorship in compacted clay soils compared with a more conventional inoculation method. Earthworm inoculation, where appropriate, should become an integral component of sustainable land restoration practice. In hostile soils, often associated with reclaimed land, the EIU technique may provide a means of ensuring long term survival for earthworm populations. (C) 1997 Elsevier Science Ltd.