It’s long been documented that earthworms play a critical role in improving and enriching soil. In his final book, Charles Darwin said: “It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures.” Rudolf Steiner, originator of biodynamic agriculture, referred to them as the “stomach of the earth.”
At MyNoke, the world's largest earthworm farming operation, the power of worms is utilised to reintroduce organic material back into the soil as vermicast. In partnership with councils, manufacturers and other organisations that produce large volumes of organic waste materials or by-products, this is a prime example of a circular economy in action.
What are earthworms?
Although there are more living organisms in a tablespoon of soil than there are people on earth, earthworms are the largest and most abundant of them all. They belong to a class scientifically known as Oligochaeta (meaning ‘few hairs’). Worldwide, there are about 6,000 species of earthworms. New Zealand has at least 171 species of native earthworms and 23 non-native species.
Source: Te Ara – The Encyclopaedia of New Zealand
Some interesting facts:
- The word “vermi” is Latin for worm, where “noke” is the te reo Māori word for earthworm.
- Their bristle-like chaetae help worms stay anchored in the soil as they turn and churn.
- Earthworms have a small brain and five hearts that pump blood through their bodies.
- They don’t have lungs but breathe through their skin.
- They don’t have eyes and use receptors in their skin to sense light and touch.
- MyNoke’s vermicast is mostly produced by Eisenia Fetida (more commonly known as the ‘tiger’ worm) and Eisenia Andrei (or ‘red wrigger’).
Why are worms so important?
Worms feed on organic debris and soil. Their digestive system concentrates the organic and mineral constituents in the food they eat, so their casts are richer in available nutrients than the soil around them. By their activity in the soil, earthworms offer many benefits: increased nutrient availability, better drainage, a more stable soil structure, as well as providing a food source to other species in the food chain.
Improved nutrient availability
The nitrogen in vermicast is readily available to plants. Worm bodies also decompose rapidly, further contributing to the nitrogen content of soil. New Zealand research also shows that worm casts release four times more phosphorus than does surface soil. Worms often leave their nutrient-rich casts in their tunnels, providing a favourable environment for plant root growth. The tunnels also allow roots to penetrate deeper into the soil, where they can reach extra moisture and nutrients. Earthworm tunnelling can help incorporate surface applied lime and fertiliser into the soil.
Improved drainage
The extensive channelling and burrowing by earthworms aerates and loosens the soil and improves soil drainage. Soils with earthworms drain up to 10 times faster than soils without earthworms. In soils where worm populations are high, water infiltration can be up to 6 times greater than in cultivated soils. Earthworm tunnels also act, under the influence of rain, irrigation and gravity, as passageways for lime and other material.
Improved soil structure
Earthworm casts cement soil particles together in water-stable aggregates. These can store moisture without dispersing. Research has shown that earthworms which leave their casts on the soil surface rebuild topsoil. In ideal conditions, they can bring up about 50 t/ha (tonne per hectare) annually, enough to form a layer 5 mm deep. One trial found worms built an 18-cm thick topsoil in 30 years.
Improved productivity
Research into earthworms in New Zealand and Tasmania found earthworms introduced to worm-free perennial pastures produced an initial increase of 70–80% in pasture growth, with a long-term 25% increase: this raised stock carrying capacity. Researchers also found that the most productive pastures in the worm trials had up to 7 million worms per hectare, weighing 2.4 tonnes. There was a close correlation between pasture productivity and total worm weight, with some 170 kg of worms for every tonne of annual dry matter production.
Source: NSW Department of Primary Industries
How do worms process organic waste?
Worms like to feed on slowly decomposing organic materials such as fruit and vegetable scraps. They produce castings that contain beneficial microbes and nutrients, which makes a great soil amendment. Worms are highly efficient at breaking down food scraps and some, including tiger worms, can eat over half their body weight in organic matter every day.
What happens in the worm’s guts is a fascinating process. Their intestine extends over two-thirds of the worm's body length. In the intestine, food is broken down into usable chemicals which are absorbed into the bloodstream. Leftover soil particles and undigested organic matter pass out of the worm in the form of castings, or worm poop, which is dark, moist, and rich in nutrients. The technical term for it is vermicast.
Vermicomposting turns food scraps and other organic matter into this beneficial soil amendment that can be used in home gardens, landscaping, farms, orchards and more. You can read more about the benefits of vermicast in these FAQ's, and watch Seven Sharp's Ben Hurley visit MyNoke's Taupō worm farm, to find out more about vermicomposting organic matter with the power of earthworms.
Is this the future of agriculture?
Earthworms contribute to agricultural production in many ways. They help aerate, hydrate, and enrich soil and protect crops from pests and pathogens. Amending soil with vermicast causes seeds to germinate quicker, enhances the rate of seedling growth, increases root numbers and biomass, improves root stress tolerance, leads to earlier flowering of plants, and increases yields.
Global research findings suggest that earthworms are important drivers of global food production and that investment in agroecological policies and practices to support earthworm populations and overall soil biodiversity could contribute greatly to sustainable agricultural goals.
Earthworms not only play hugely productive roles in sustainable agriculture, but they also help mitigate our elevated atmospheric greenhouse gas content by enhancing carbon sequestration, reducing methane emissions, and improving soil health. In essence, earthworms enrich and improve the soil not just for plants, but for animals, humans, and the planet, too.
Reach out on info@mynoke.co.nz or call 0800 MYNOKE to find out more about how you can utilise the natural, in-built technology of earthworms and vermicomposting technology as a more sustainable method of organic waste management.