ACR International Section

Worms  - Susan Girard Sept 2009

This week my friend Vickie helped me dig out one of my compost bays, spreading the new soil over the garden in readiness for spring planting. Hot composting is something I appreciate but have never managed. Probably because my food scraps go to the chooks, which doesn’t allow for the correct C:N ratio (25:1). So what I have is really a very large worm farm without the required tap for worm wee. What was dug out, a healthy wriggling mass looked wonderful,…Except it had came to my knowledge recently that worm farming has helped the spread of introduced worms to such an extent that it is likely to have an irreversible effect on our native ecosystems.

Studies are showing that entire forests are now in jeopardy as a result of feral worms. Australian naïve worms produce one baby worm per egg case whilst compost worms may have as many as 12 babies per egg case. So its easy to understand that in some forests leaf litter that would normally take three years to break down, this is now being accelerated to just months. The result is that raised amounts of Nitrogen are being released quickly, which is not so good when it is leached into waterways or taken up by weed species (Australian museum. on line, 16 Jun 2009).

The depth of forest mulch is reduced, erosion is increasing and loss of habitat is causing a reduction in the amount of creatures that would normally inhabit the leaf litter. Tree germination can also be effected, whilst the pH in our soil is changing because these feral worms excrete more lime than some of our native species.

Tasmania apparently has about thirty introduced worm species at large in its forests

We have around 1000 species of native worms in Australia, coming from three Families. Some live in the topsoil other like to stay deeper down in the soil layers. The Australian Museum admits native worms have not been well researched and they rarely seem to be considered beneficial to increasing soil fertility, although one species (Anisochaeta dorsalis) is cultivated commercially and sold in bait shops

Some Australian native earthworms grow very big. The 'Gippsland Giant' (Megascolides australis0, is cited in the Guinness Book of Records at 3 meters. Another species found near Kyogle, grows to a length of more than 150 cm and is apparently as thick as a garden hose. Closer to home the species Notoscolex grandis from around Wingecarribee and Fitzroy Falls has been recorded as reaching a length of 100 cm, (Australian museum. on line, 16 Jun 2009). Most common in the Blue Mountains area are smaller members of the Megascolecids that live in the old growth forests like Spenceriella macleay,40-75 mm long. 4 mm wide with 90 Segments (R J Blakemore. A Hundred Year Old Worm on line 3.9.09).

Although they weren’t the red tiger worms you see in many worm farms, I’m pretty sure the ones in my compost are an introduced species being slender, muscular, light-brown in colour, 100 mm -150 mm long. You need to count the number of segments and the position of the ring-shaped collar if you want to be precise (which I didn’t !)

Once again I am reminded of the problems we create by living inside a World Heritage National Park.