I’ve been inspired by the worms in our compost heap, to do a little research on the lowly worm. I’ve unearthed a number of useless but intriguing facts, & of course some useful info if you’re a gardener.

  • Darwin was one of the earliest champions of the earthworm, obviously he was fascinated by their habits, & took the time to work out how long things like Stonehenge would take to become buried.
  • We have over 200 species in NZ, all but 10 or so are native. They have quite specific habitat requirements, so we’re most likely to find them in the bush, not in our paddocks or gardens.
  • The 10 introduced species are thought to have been introduced by the early settlers. The ships used soil as ballast on their trips, then emptied the soil out near the ports. The worms are of significant value to our land: they break up organic matter, making the nutrients more accessible to plant roots, they increase microbial activity in the soil, they improve soil structure & increase it’s ability to hold water. Calcium, Magnesium, Phosphorus & Molybdenum are much more available to plants from worm castings than in the surrounding soils.
  • Worm numbers in pasture range from 7-12 million per hectare, thats 1-3 tonnes of worms!!
  • Worms can bury up to 6 tonnes of pasture litter per hectare, per year.

Main species of worms are:

  • Allobophora calignosa- most active in Autumn & Winter, it helps to recycle the “topsoil mat”
  • Lumbicus rubellus works away at dung on pastures
  • Lumbricus terrestris, the common earthworm, is a large surface feeder, it can drag leaves down into it’s burrow. It has a slight irridescent sheen. Pic below…

  • Allobophora chlorotica, is described as a small, agile worm, greenish coloured. Most commonly found in Hawkes Bay. It lives quite happily in waterlogged conditions & curls into a ball when disturbed. (I’m on the look-out for this worm & shall add a pic if & when I find one.)
  • Tiger worms, Eisenia foetidus, & the red worm, Eisenia andrei are the worms who do all the work in our compost heaps, & multiply rapidly in the dank depths, but put them in the garden & they will languish & die. (Tiger worm below)

blog11-7-003.jpg

  • Worms don’t drown in water, but they do come to the surface when it rains. I was told, but can’t verify it, that some birds do a little dance on the lawn (a rain dance?) pretending to be rain, & so secure their lunch. How is it that we find worms in buckets of water, or in a bowl on an outdoor table? any theories?
  • Once a worm is in the sunshine, the ultra violet light immobilises it, so it can’t retreat back to the safety of it’s burrow, now that’s sad. So rescuing worms on the lawn is an act of kindness.
  • Longevity: did you know? a Tiger Worm can live up to 4 1/2 years, L. terrestris can live for 6 years & Allobophora longa for 10 1/2 years Who finds these things out?
  • To encourage worms in your garden cultivate gently, add lime now & then, they like a Ph between 5.8 & 6.3. Keep the soil moist, like a good fruit cake, & add plenty of organic matter. Pesticides, chemical sprays & harsh fertilisers are detrimental to your earthworm population.
  • From the dim memories of studying 6th Form Zoology, over 30 years ago, I’ve remembered the following, which may not be 100%
  • The old story about cutting a worm in half & getting 2 worms, is partially correct, worms have 5 hearts in a row, part way along the body, I think if they are severed between hearts, both halves can survive.
  • Worms have little bristles called chatae, which help them to move, they can also expand or contract their segments in sequence. If a worm expands it’s tail end, it braces itself, so it can thrust forward. In soft soils it tunnels like this, but in hard soils it simply eats it’s way through.
  • Worms have gizzards, like chickens do. The gizzard has small stones, pieces of glass & brick etc which help to grind up organic matter.
  • Worms are hermaphrodite, having both male & female reproductive organs, twice the chance of fertilisation!
  • A mature worm has a saddle, the smooth raised section, part way along it’s body. It takes from 4 to 12 months for a worm to mature.
Advertisements