Influence of lumbricid earthworms on yield and quality of wheat and clover in glasshouse trials

Field surveys have shown that the introduced lumbricid earthworm, Aporrectodea rosea, predominates in fields used for cereal-pasture rotations in South Australia and western Victoria. Another introduced lumbricid, A. trapezoides, also occurs in these fields, but is usually much rarer. A glasshouse experiment investigated the influences of A. rosea and A. trapezoides on wheat and subterranean clover production. The plants were grown in a red-brown earth (Palexeralf), maintained at 60% field moisture capacity with the equivalent of 460 worms m−2. Wheat was grown first and then the soil was re-used for the clover. A. trapezoides increased wheat plant biomass by 39%, grain yield by 35%, grain N content by 14% and straw N content by 19% compared with controls (no worms). A. rosea increased wheat plant biomass by 13%, but had no significant influence on grain yield or grain or straw N content. The biomass of clover herbage was increased by 21% by A. trapezoides, but A. rosea had no effect. Neither earthworm species influenced the N content of the clover or the dry weight of clover roots. The implications of these results for future management of earthworms in cereal-pasture ratations are discussed.