CHILDREN have a real fascination with worms matched only by smart gardeners who know that these small creatures are really doing all the hard work.
Worms turn over the soil redistributing minerals and organic matter, literally churning the soil through their bodies.
Supporting the complex life of soil biota and fauna – of which worms are just one citizen in an intricate web of decomposers and foragers – is the approach that No Dig takes. This method of gardening relies on not disturbing soil by digging or by stepping on garden beds and compacting the soil, which destroys delicate soil structure.
Instead, this approach looks to the forest: a self-sustaining system with a floor that is continually mulched by falling leaves and branches, and fertilised by passing wildlife. By not disturbing soil and continually feeding from the top, soil life and structure is maintained and supported.
Importantly, covering the soil with living green mulch (dense plantings) or traditional organic mulch (straw, garden clippings, pine bark, leaves etc) means the soil is not sterilised by the sun or eroded by rain. Good soil structure means the soil is full of pores – a dense network of large and small channels created by roots, insects and wildlife that allow water and gas to freely move through the soil profile.
One other enormous benefit of covering the soil with mulch or dense planting is eliminating weeds. And snails do not like thick mulch – a bonus when you’re planting young seedlings, which snail will devour voraciously.
Although the type of soil in your garden is determined by geology and climate – a coastal Melbourne garden has different soil from a tropical garden in the Brazilian Amazon to one on the chalky cliffs of a Greek island – they all rely on a steady stream of organic matter that breaks down into nutrients that feed plants and soil biota. Wildlife and insects are an essential part of this self-sustaining system of waste disposal, nutrient breakdown, soil formation, water drainage and purification.
Horticultural gardening breaks these links by digging in the soil, exposing it to the elements – thereby encouraging weeds – and breaking the ecological cycle, replacing this with intervention both human (inevitably the hard manual labour of weeding and constant maintenance) and chemical in the form of herbicides and other weed killers, pesticides and fungicides. Emulating what nature does with forests is a far more efficient and elegant solution; working with nature allows us to stand back from our gardens and allow the ecology to take care of all the back-breaking work. Each earthworm alone eats a third of its bodyweight daily ingesting soil full of decaying organic matter. Worms can burrow up to 2m underground, literally churning tonnes of soil and increasing soil fertility by moving nutrients around, mixing surface and sub-surface soil, aerating the soil, improving its drainage and capacity to hold water, structuring the soil and making nutrients more available to plants through their nutrient-rich casts. In fact, in humus-rich soils it is believed that each worm produces an astonishing 4.5kg of casts per year.
“Charles Darwin understood that earthworms were involved in the formation of soil and was fascinated by their behaviour, conducting a series of experiments over 40 years”
Charles Darwin understood that earthworms were involved in the formation of soil and was fascinated by their behaviour, conducting a series of experiments over 40 years. More than two decades after his groundbreaking book on evolution, The Origin of the Species, was published in 1859, his last book was entirely about the humble earthworm – The Formation of Vegetable Mould through the Action of Worms, with Observations of their Habits – published in 1881 shortly before his death.
Darwin determined that earthworms were indifferent to noise but were extremely sensitive to vibrations, that they had some degree of intelligence – although this varied among individuals – and showed a definite preference for foods such as cherries and carrots, concluding: “judging by their eagerness for certain kinds of food, they must enjoy the pleasures of eating”. He observed how earthworms pulled leaves into their burrows by the apex – the most efficient method – to plug up any openings and concluded that they were trying to keep out the chilly air.
It may be wishful thinking, but according to one old tale the price of land in old England was determined by the number of worms present in a shovelful of soil. Land price aside, now that’s what we call organic gardening.
* The term ‘No Dig’ has been loosely, and incorrectly, applied to the Ruth Stout Method where veggies are planted in raised beds on layers of straw (no soil involved) laced with manure, which is particularly effective after a few years when the organic matter has broken down and the entire bed becomes one large pool of rich plant nutrients that retain water like a sponge.
