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The effect of introduction of the earthworms aporrectodea caliginosa and aporrectodea longa on pasture production in Tasmania.

M G Temple-Smith, T J Kingston1, T L Furlonge and R B Garnsey

Department of Primary Industry and Fisheries. P O Box 46.Kings Meadows Tas 7249
Now with Queen Victoria Museum. Wellington St, Launceston Tas 7250

Work in New Zealand (I, 2) has shown that earthworms increase pasture production by changing soil fertility. Even 16 years after earthworm introduction, pasture production increases of 29% were recorded (2). This study quantifies the increases in pasture production associated with the introduction of two earthworm species into Tasmanian pasture soils devoid of earthworms.


In winter 1987, two earthworm species were introduced into perennial pastures at "Woolnorth" in the north-west, and at "Rushy Lagoon" in the north-east of Tasmania. The "Woolnorth- site consisted of a sandy soil, whilst a heavier clay soil occurred at the "Rushy Lagoon" site. Three treatments were arranged in a random block design and replicated nine times at "Woolnorth" and six times at "Rushy Lagoon" on 5x5 m plots. These were: (i) no earthworms; (ii) one species introduced: Aporrectodea caliginosa (@ 6 earthworms/m2, and (iii) two species introduced: Aporrectodea caliginosa (@ 6/m2 and A. longa (@ 3/m2. Pasture cuts were taken from six randomly selected 0.5x0.5 m quadrats from each plot prior to stock grazing.


Pasture responses were detected one and three years after introduction (Table 1 ). Pasture production increases of up to 75% for two earthworm species and up to 60% for one species were measured at both sites.

Table 1. Effect of introduced earthworms on pasture dry matter production at "Woolnorth" and "Rushy Lagoon".


To the authors' knowledge these results arc the first in Australia showing positive effects of introduced earthworms on plant production. The findings are similar to NZ results showing pasture production increases of 28 - Ill% (I) and 72 % (2) where only A. caliginosa had been introduced and confirm the importance of earthworms in pasture productivity.


The project was funded by the Rural Credits Development Fund and the DPIF. Tasmania. References

1. Nielson. R.L. 1951. Proc. 13th N.Z. Grassland Assoc.. 158 - 167.

2. Stockdill, S.M.J. 1966. Proc. N.Z. Ecol. Soc. No. 13, 68 - 75.

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