How many of us have taken the time to think about the important role earthworms play in our lives, particularly their role in agriculture? Sure, we all dug up worms as kids and held them in our hands, and as a parent when the kids were little looking for worms was a great time killer.
But, as an ex-farmer, I have to honestly say that I did not count worms in my paddocks to assess paddock health. After having worked at a worm farm for two years, I now know worm counting is the first step in assessing your paddock and farm health.
I think we all have a bit of an idea that worms are involved in the decomposition of organic matter, but most of us are unaware of what happens in the gut of the worm and the amazing benefits their “output” (called castings), has for soil health, plant health and ultimately human health.
As worms tunnel their way through the soil, they digest decomposing matter and microbes. During digestion in the worm’s gut, microbes actually increase in number and are excreted in a healthy balance. This ensures there are enough beneficial bacteria (and other microbes) to keep pathogenic bacteria in check. Microbes are critical to ensuring nutrient availability, genetic expression in plants, immunity and cleaning up chemical residue.
Worms excrete humic and fulvic acids which are important in helping plants absorb nutrients. They also expel nutrients that are in plant-available forms, so are easily absorbed and utilised by the plant.
While making their way through your paddock’s soil, worms excrete mucus that lines the tunnels they leave behind. These mucus lined tunnels increase air and water infiltration and are rich in beneficial microbes with a suite of secondary metabolites that are extremely important in protecting plants from pathogens and building their immunity.
Now, without getting too complicated, secondary metabolites are compounds that the plant does not necessarily need for growth but are essential to building strong healthy plants with a robust immune system. Some of the roles secondary metabolites play are regulation of plant growth and development, launching defence response signals, responding to environmental stress such as drought and frost, repelling pests and pathogens, along with modifying microbial communities associated with enhancing the capacity of plants to adapt to their dynamic environment.
Considering worms have inhabited Earth for over 300 million years longer than dinosaurs, it is not surprising they have developed this symbiotic relationship with the soil, microbes and plants. Their contribution to agriculture was well recognised by Egyptians. Cleopatra declared them sacred and anyone caught removing earthworms from Egypt faced death. Before Cleopatra Aristotle called earthworms “the intestines of the soil”, while more recently Charles Darwin stated that – “It may be doubted whether there are many other animals which have played so important a part in the history of the world as these lowly organised creatures.”1
As worms go about their day digesting half their body weight, their castings create topsoil, something most farmers in Australia would like plenty more of! For many farmers paddock worms are in short supply and given the number of amazing functions worms support (as mentioned above), worm activity is an essential ingredient for profitable farming systems.
The presence of worms is a key indicator of soil health, when you have worms you know nutrients are cycling, plants will have improved immunity, they will have increased resilience to frost and drought and are living in soil with good aeration and water infiltration.
A farming system with healthy worm numbers requires fewer synthetic fertiliser inputs, fewer pesticides, fungicides and insecticides, which will make the accountant happy!
I have been fortunate to see firsthand the benefits worms and their products have had for many farmers across Australia in a variety of soil types and agricultural systems.
Encouraging worms into your paddocks is not as big a task as you might think, however providing biologically active soils is key. To do this there are a few things you need to think about, increasing organic matter, living roots, plant diversity, cover crops and/or soil cover (to keep soil temperatures down) and minimum soil disturbance. There are also lots of products now available to improve biological numbers and some people are starting to make their own at home.
For someone who truly believes farmers are the solution (not the problem), despite all the challenges being faced by farmers, there are some exciting times ahead for agriculture. The humble worm is an essential tool for farmers to maintain profitable and sustainable farming systems.
By Shelley Scoullar
(Photo – Earthworms at Tim and Kareena Lockery’s farm – Nunamara, Tasmania)
