Compost can be made in a variety of containers. The examples below show a double bin made from recycled timber, a double bin made from recycled, heavy gauge bird wire covered with knitted polypropylene shadecloth, and a commercial single bin. Double or triple bins are best as you can turn the compost from one bin into the next, with the third bin used to start a new heap.
Compost tumblers (below, right) do the work of aerating the mixture. They are suitable for composting small quantities of fairly soft ingredients quickly, for people who are not able to turn compost easily, but the mixture may not generate enough heat to kill diseases.
Homemade containers don’t require skilled carpentry. What goes into the compost container is more important than how it looks. The main points to remember in deciding on the size and site of your compost container are:
- When ingredients form one cubic metre (i.e. 1 m. x 1 m. x 1 m.), aerobic bacteria will generate enough heat to kill diseases and weed seeds.
- Open-base bins that are in contact with soil allow earthworms to enter the mixture (when it has cooled down) and provide worm castings to the mixture while they help complete the composting process.
- Recommendations to position compost bins in full sun do not apply to many parts of Australia, as too much heat can kill off composting organisms. A shaded spot is ideal.
- Compost bins need a cover to prevent the ingredients becoming sodden in heavy rain.
Some Composting Tips
If you are new to compost making, don’t be intimidated by statements of the ratio of carbon to nitrogen in compost making. Most recommended ingredients contain a mixture of both. With a little practice, you will quickly learn to identify and correct any imbalances.
- Chop up tough items using shears, a shredder, or a sharp spade (spread items on soil or grass first to prevent jolting). This assists faster decomposition as bacteria work on the surfaces of organic waste. The more surfaces you can provide – the faster they can work.
- The secret to making compost quickly to turn it regularly to keep it aerated, and to keep it damp as aerobic bacteria that commence the process require nitrogen, air and moisture to process the carbon.
- The secret to fast composting is regular turning and mixing of the ingredients. Weekly turning while the ingredients are generating heat will produce mature compost very quickly. As the compost breaks down, the mass is reduced.
- You don’t have to wait until you have a cubic metre of ingredients – turning and mixing ingredients will get the bacteria working.
- If the pile looks grey or contains ants – it is too dry. Turn and mix the ingredients, while adding enough water to dampen the mixture.
- Don’t be concerned about slaters in your compost heap. They feed on semi-decomposed organic matter.
- If the pile is black with an unpleasant smell – it is over-wet. Air has been forced out, and anaerobic composting has begun. Turn and mix the ingredients, while dusting with agricultural lime every 15 cm, and adding some straw to the mix. Protect pile from rain.
- If the pile seems inactive – it may need more nitrogen. Turn and mix the ingredients, while adding some manure every 20 cm. If manures are unavailable, you can substitute a generous sprinkling of poultry-based, organic-allowed fertiliser.
- Your compost is ready when it is dark brown, crumbly, with a pleasant earthy smell and ingredients, apart from pieces of egg shell, are no longer recognisable. A 5 cm layer added to topsoil provides your garden with all the minerals that plants, animals and humans need for good health.