We might take earthworms for granted, but they are the unpaid workers
busy improving soil allowing us to grow healthier plants.
New Zealand research suggests that soil which has passed through earthworms as worm casts release four times more phosphorous as surface soil, while nitrogen in casts is readily available to plants. Tunneling by worms allows plants to grow longer and stronger roots that can access deeper nutrients and maximize the value of applied fertilizers.
Tunneling by earthworms loosens and aerates soil, improving drainage by up to 10 times, with that drained water stored in the soil rather than washed away.
So how do we encourage these unsung heroes?
Firstly, they are not keen on acid soils, so ensure the soil is above 4.5pH, applying lime if need be. Increasing soil organic matter by leaving stubbles or applying manures will provide worms with plenty of decaying plant matter to feed on. Because worms do not like acidic conditions, care and precision should be used when using fertilizers and fungicides.
Earthworms lose as much as a fifth of their body weight producing casts every day so they need moist soils to replenish themselves. Draining soil can help aerate it, improving worm conditions while reducing compaction through preventing machinery and animal movements will allow worms to move more freely. Different crop management can help encourage worm numbers with some research suggesting that zero-tilled soils have twice as many worms as ploughed ones after four years.
Worms can be transplanted from one field to another. The best technique is to move the worms along with sods of soil. One worm can produce 100 others in three months given the right soil that contains plenty of organic matter.
Soils are much richer places with earthworms, so it is only right that they get the praise and attention they deserve on World Soil Day.
Some of the information in this article was sourced from the New South Wales Department of Primary Industries in Australia.