Tips for terrific compost
The single best way to reduce your waste and give something back to the soil in the process, is to make compost. ELIZABETH SWANE explains how to do it
The best way to dispose of your organic waste is to compost it. Companies have been busy developing composting systems to suit even the tiniest space, so there is no excuse to continue throwing food and other organics into the garbage bin. Here are a number of different ways to compost.
HOT COMPOSTING
With the potential to convert your waste into compost in just 6–8 weeks, this is one of the quickest methods. In a hot compost pile, optimum temperatures of 40–60°C are maintained within the pile for several weeks, which is also enough to break down weed seeds and disease pathogens.
The heat is generated by microbes breaking down the materials. To create this level of heat, you need to have a cubic metre or more of organic materials. These are piled up and moistened in layers all in one go in a compost bay or on open ground. To monitor the heat, which builds up quickly, use a compost thermometer. Maintain the temperature by turning and aerating the pile with a garden fork when the temperature drops below 45°C. This also helps to move materials on the outer edges into the centre where they are more likely to break down. You may need to turn the heap two or three times over its life, so give it some muscle!
COLD COMPOSTING
This is typically the method that most people practise at home. Materials are constantly added as they become available. It doesn’t generate the heat of a hot compost system, so it takes longer and it won’t break down most seeds and pathogens. Therefore, avoid adding weed seeds or diseased plants.
An open compost bin is ideal for containing the materials and they are cheap to build from recycled timber or chicken wire and metal fencing posts
(star pickets). Vermin can be an issue, and if so, don’t add kitchen scraps to the pile. Put these into a trench or benchtop system (see Other Methods) or add them to a worm farm. Turning the heap regularly will speed up the breakdown.
Plastic compost bins with an open base are a tidy option and easy to install as you just need to sit them on the ground. Investing in a corkscrew-style compost turner is worthwhile as aerating the contents inside the bin with a garden fork is awkward. Keep it by the bin and give it a twirl once a week. Once the bin is full, the materials will take 3–6 months to
break down. Having two or more bins allows you to continue piling in materials while the other batches are decomposing.
Bin sizes start at 150L (for smaller gardens), 220L (family of four), or 400L (round or flat-pack). Some feature a handy flap so you can dig out compost at the base as it breaks down.
OTHER METHODS
Compost tumblers can be rotated, which makes aerating easy. Sealed containers hold the heat, speeding up the breakdown process. All materials must be added in one go.
Trench composting is done directly in-ground, where worms and microbes break down materials. Dig a trench 30–40cm deep where you want to enrich soil, drop in your organic materials, then cover with soil. The materials are buried deeply, so you can plant straightaway. Visit abc.net. au/gardening/factsheets/compost-trench/10213610 to see Tino Carnevale creating a compost trench.
Benchtop compost bins are an option for recycling food scraps indoors. As scraps are added, they are sprinkled with a special mix of bacteria and fungi which break down materials without producing unpleasant odours. A liquid by-product can be diluted and used as fertiliser and the microbe-rich solids buried in the garden.