GET A WRIGGLE ON
WORMS...WE NEED MORE WORMS
IT WAS great to receive some very positive feedback after last week’s article really hit the spot for those concerned (and we all should be) about the acceleration of climate change on this earth.
The fact that we all can contribute to the reduction of carbon dioxide in our atmosphere by simply increasing the amount of organic matter in our soils is a powerful reminder that using natural processes will be the saving grace for this planet.
(Visit the “4 per 1000” Initiative at www.4p1000.org to see how simple this can be).
Of course, increasing organic matter in your garden soil is simply the first step, as any organic matter must be processed by soil organisms to turn it into that wonderful material called humus.
Many living things play a role in this conversion, including microorganisms such as bacteria, fungi, protozoa, and algae.
Larger organisms, such as nematodes and arthropods (e.g. mites, springtails, and centipedes) also have a role to play, shredding organic matter in some instances, and sometimes predating on other organisms, including bacteria and fungi.
Most of these organisms are quite small, and whilst there may be as many as 500 million bacteria in a gram of soil, it’s hard for the everyday gardener to know whether their garden supports a healthy population of these microscopic wonders.
One macro-organism, however, can be easily seen by gardeners and their numbers will be a great indication of the health and makeup of their soils.
I’m speaking, of course, of the humble earthworm.
Charles Darwin, in his excessively-titled book “The Formation of Vegetable Mould, Through the Actions of Worms, With Observations on Their Habits”, said of earthworms: “Without the work of this humble creature, who knows nothing of the benefits he confers upon mankind, agriculture, as we know it, would be very difficult, if not wholly impossible”.
Now, whilst Darwin may have described the earthworm as “humble”, their role in creating ideal conditions for plant roots to grow could be described as nothing less than critically important.
Earthworms are, among other organisms, one of the major decomposers of dead and decomposing organic matter in our soils.
They tunnel through the earth, consuming both organic matter and soil particles, which, while working their way through the digestive system, are deconstructed by the gizzard’s grinding action in conjunction with hungry bacteria, in a process called “colloidising”.
The worm takes its nutrients from the organic matter, and ejects the waste in a form gardeners know as “castings”.
While castings are a worm’s waste product, they are invaluable for the plants we grow, as they contain around five times the nitrogen, seven times the available phosphorus, and around 11 times more potassium than the nearby soil.
Not only do earthworms concentrate vital plant nutrients in these castings, they cause an explosion of soil microbes around this waste and through their mucus-lined tunnels.
These microbes also decompose organic matter and release nutrients as they do so, and when they die.
Apart from improving nutrient availability to plants, earthworms also improve the physical characteristics of soils as they tunnel and forage for organic matter.
Their tunnels open the soil profile up to oxygen from the atmosphere, vital for plant root cells to function.
When plant roots find an old collapsed worm tunnel, they will rapidly grow into the less compacted soil which in turn allows a far larger root system to mine nutrients and water for the plants.
Speaking of water, a soil with a large worm population will easily allow heavy rainfall to infiltrate the surface rather than running off, and to percolate through the soil profile down to great depths, encouraging deep root growth once again.
What do we gardeners need to do to encourage earthworms to live, stay and play in our gardens?
Firstly, realise that we need to encourage native species of worms, and that most of the species sold as compost worms will not survive as permanent residents in our soils, as they are not suited to deep burrowing in low organic matter environments.
If you’re a bit lacking on the earthworm front, bring a couple of spadefuls of a wormy soil home from your organic gardener friends to get the ball rolling.
Secondly, earthworms need moisture and food if they are to take up permanent residency in your patch.
If one of these is lacking, they’ll pack up and migrate to a better location.
It’s important to regularly incorporate organic matter in the form of organic fertilisers, a quality compost or old manure (or worm castings from your worm farm) for a food supply.
And vitally important to keep the soil moist and cool – which means the magical properties of a good mulch come into play.
Using a finely chopped lucerne mulch is best, but bear in mind that these little critters will come up at night, grab a mouthful, and scurry back into their burrows to munch and digest your wonderful soil blanket and turn it into nutrients and humus.
This means a great organic mulch like chopped lucerne won’t last too long on a wormy soil.
That’s not a bad thing, but you may opt for a coarser mulch material such as a sugar cane product or pea straw to make it last longer.
Finally, worms detest soil compaction, so try not to trample your garden beds, particularly when they’re wet.
Consistently giving earthworms the right conditions will mean that they will reproduce rapidly and benefit your garden for years to come!