Growth of Aporrectodea tuberculata (Eisen) and Lumbricus terrestris L. under laboratory and field conditions

The growth of juvenile A. tuberculata and L. terrestris under different con ditions of soil temperature (10 degrees C and 18 degrees C) and moisture (2 0 %, 25 % and 30 % (w/w) soil moisture content) was determined in a laborat ory experiment. The instantaneous growth rates (IGR) of A. tuberculata were between 10.8 x 10(-3) d(-1) and 18.7 x 10(-3) d(-1) and the IGR was lowest when A. tuberculata was placed in soil at 10 degrees C and 30 % (w/w) soil moisture content. The growth of L,. terrestris tended to be lower than tha t of A. tuberculata, and the IGR of L. terrestris ranged from 7.1 x 10(-3) d(-1) to 13.9 x 10(-3) d(-1) under laboratory conditions. L. terrestris gro wth was greatest in soil maintained at 10 degrees C and 20 % (w/w) soil moi sture content. The growth of juveniles of A. tuberculata and L. terrestris was also examined in the field in large cores containing soil from long-ter m manure-amended and inorganic fertilizer-treated plots during the spring a nd autumn of 1995 and 1996. The IGR of A. tuberculata in the field ranged f rom 7.5 x 10(-3) d(-1) to 14.6 x 10(-3) d(-1) when soil temperatures were b etween 10 degrees C and 18 degrees C, and was comparable to the IGR of A. t uberculata under similar environmental conditions in the laboratory. The gr owth of L. terrestris in the field was much lower than L. terrestris growth in the laboratory under similar environmental conditions, and the IGR of L . terrestris in the field ranged from -1.0 x 10(-3) d(-1) to 5.3 x 10(-3) d (-1) when soil temperatures were between 10 degrees C and 18 degrees C. The growth of A. tuberculata and L. terrestris was not significantly different for individuals placed in cores containing soil from either manure-amended or inorganic fertilizer-treated plots. While there appeared to be adequate soil organic substrates for A. tuberculata growth in the field, L. terrest ris growth was probably limited by the absence of sufficient surface organi c residues. The IGR equation can be used to predict the nonlinear growth of earthworms under laboratory and field conditions.