Green tips #3: start a worm farm
October 2009
Worm farm in backyard

Kitchen scraps...aka worm food
Kitchen scraps…aka worm food

One of the most direct ways you can reduce the waste stream is to compost organic waste at your home. With around half the average household waste being organic matter (food scraps), the benefits of composting are multiple:

  • households become less reliant on centralised dumps
  • councils reduce the continuous expense of hauling waste in rubbish trucks.
  • organic matter is steadily broken down in a controlled, small-scale fashion – rather than the anaerobic, toxic decomposition that happens in landfill.
  • households create a new source of soil-enriching fertiliser, which is continuously produced for free on-site.

In the past I have used traditional compost heaps, but for the past year I have been using a commercial worm farm system. I have been very impressed by the quick and odourless way that a box filled with thousands of worms can digest its way through food scraps, compared to the slower method of compost heaping.

Stuart's worm farm

How worm farming works:

The worm farm is essentially a small ecosystem, needing only the input of food scraps to sustain it. The unit is split into several trays, which are snugly stacked on top of each other.

Stuart's worm farm - top trayStuart's worm farm - middle trayStuart's worm farm - bottom tray
Lid removed showing the three trays of the worm farm unit

The floor of each tray contains a grid-like array of holes that allow the worms to freely migrate between the different levels of the worm farm. Typically, the worms will base themselves in the bottom layer of the unit, where they apparently spend most of their time. This is where they reproduce and lay eggs. When they become hungry, the worms will migrate to the upper layers of the unit, where their food is placed.

Each layer of food scraps becomes increasingly composted as it remains in the system. The worms will digest and re-digest the food multiple times, leaving their ‘castings’ (faeces) behind. After enough passes through the digestive system of the worm, the scraps become transformed into a rich soil high in organic matter – compost! This soil is removed from the system from the bottom tray, and the cycle continues with new matter being added to the upper trays.

Stuart's worm farm - bottom tray
Increasingly digested worm castings in the middle and bottom trays

I must mention how efficient these little decomposers are. I have had my worm farm for more than 12 months, and have continuously introduced fruit and vegetable scraps to the system. Despite the many kilograms of waste that I have fed my worms, I have not once had to remove any solid compost from the system. The only chore that is involved with operating my work farm is draining the excess liquid from the bottom of the system about once per month (there is a tap provided for this purpose). The ‘worm tea’ that comes from this tap makes an excellent fertilizer, and in fact is so concentrated that it must be heavily diluted before being applied to the garden. This worm tea contains a rich array of microbes, and is one of the best ways to add nutrients to a garden.

Stuart's worm farm - draining the worm tea into a bucketStuart's worm farm - draining the worm tea into a bucket
Draining the ‘worm tea’ from the worm farm unit’s tap

Contrary to popular conception, your worm farm will produce no odours. My system is located around three metres from the front door of my house. If I did not have the luxury of our large house and block of land, I would be happy to place the worm farm inside my house! Having said this, it is important not to add meat or dairy to the worm farm. Whilst the worms will compost meat and dairy (they are organic, after all), it will be a long and smelly process compared to the way that plant matter (fruit and veg, grains, cardboard, paper, etc) is broken down.

Besides the broader environmental, financial and societal benefits of worm farming, the entire process is also personally rewarding for the worm farmer. It is amazing to think of the volume of waste that can seemingly be reduced to zero by the biological activity of these organisms alone. The worms will digest and re-digest the food, until every possible nutrient has been unlocked and used. I see this as an analogy to the way that humanity must now look at the world; an antidote to our current ‘extract and dump’ economy. The experience of interacting with my personal ecosystem of decomposers is a fascinating and humbling experience.

Handful of worms

In my opinion composting should be subsidised by local councils, with free composter units given to households in honour of the logistical benefits they will bring to the local sanitation department. I think that there should also be disincentives for the wasteful status quo of households putting food scraps and lawn clippings into their rubbish bins. Bin sizes should be reduced so that residents take the time to consider the bulk of material that they send ‘out of sight, out of mind’ to the dump.

Convinced? How to get started:

Home worm farm units can be purchased new for around AUD$80. There also appears to be a strong second hand market through agencies like eBay. After months of patience, I managed to pick up a set of three worm farms for around AUD$100, which was a very good deal. There are also many great DIY resources available on the internet that explain how to construct worm farms/compost systems from bought materials.

To start your worm farm, you will need at least 1,000 worms, which can be bought as ‘starter kits’ from hardware stores and nurseries for around AUD$30-50. Note that you must only use these ‘composting’-type species (e.g. ‘tiger worms’) in your worm farms. Other worm species, such as the common earthworm have a great place aerating the soil around the garden, but are nowhere near as quick at composting food as the ‘red wigglers’ that worm farmers use.

So instead of asking for the usual round of consumer goods for your Christmas present this year, why not take a side-step and set your sights on a worm farm.

Update 24 June 2010: some of my expanded thoughts on worm farming can be found here. Another short article of interest is about using worm farms for document destruction.