Worm farms contain composting worms that eat food scraps and turn them into a natural liquid (worm leachate) and compost (castings) that can be used in the garden. Composting worms thrive in a moist, high nutrient environment and we create this environment in a worm farm.
- Decrease the amount of organic waste sent to landfill.
- Close the recycling loop by changing food waste back into organic fertiliser for growing food.
- Reduce greenhouse gases. In a well-maintained worm farm the decomposition process is aerobic (with oxygen), rather than anaerobic (without oxygen).
The earthworms used in worm farms are a different species to those we find in our garden. The best worms for worm farming are European worms such as the red wriggler (lumbricus rubellis) and the tiger worm (eisenia fetida). These species are accustomed to soils high in nutrients. They eat and breed much faster than other earthworms and can quickly transform food scraps into worm castings. They do this in a small amount of space, while other earthworms are better equipped for burrowing and searching for food in our drier, nutrient poor soils.
Worms are blind, but sensitive to light. Their instinct is to move away from light due to their two ‘photoreceptors’, which are sensitive nerve endings located near the saddle (Murphy, 2005).
Living conditions in a worm farm
Worm farms should be situated in a cool, shady spot. Worms need cool, moist conditions and a temperature of 25–26 degrees. They need a layer of bedding to live in, which can include castings, shredded paper, newspaper, cardboard, brown leaves, and straw. As food scraps decompose, they will make the worm bedding more and more acidic, therefore it is a good idea to occasionally add some garden lime to maintain the pH as worms prefer a neutral environment.
School worm farms
A worm farm is made from a container that has a drainage hole for water and a lid that keeps out vermin but allows air in.
You can buy worm farm containers, make your own, or have one custom made. Some schools use old bathtubs but most use old fridges that have been safely degassed. Look at the ‘How to build a worm farm’ fact sheet to find out more. For most schools, at least one large worm farm (such as a fridge or bathtub) is needed.
For information on what to feed a worm farm and what to keep out, see the ‘Waste wise worm farming’ and ‘How to make a fridge worm farm’ fact sheets: www.wasteauthority.wa.gov.au/wws/teaching-resources/list/fact-sheets