Composting

Content: What can be composted? | Where can I buy a compost? | How to make a compost? | Solving composting problems | How to make a triple-bay compost system for your school

What can be composted?
Almost anything that was once part of a plant or animal can be composted, including:

• food scraps;
• newspaper;
• grass;
• prunings;
• manures;
• weeds.

Dog and cat manures are best buried in the garden as they  can be a source of parasites. Alternatively, you can purchase a special worm farm for your dog manure which will produce a rich compost for your garden.

The ADAM principles
There are many ways of producing good compost at home. .

• Aliveness: a compost heap is a living system. 
• Diversity: the greater the diversity of material the richer the product.
• Aeration: more air means less smell.
• Moisture: the heap should be as moist as a lightly squeezed sponge.

Where can I buy a compost?
A range of compost bins and compost tumblers can be purchased from most local hardware stores and select nurseries

How to make compost

Setting up

• Choose a composting system that suits you - an open heap, an enclosure or a compost bin with lots of air holes. 
• Choose a well-drained site that receives good sunlight.
• Begin with a 10-15 cm layer of twigs, sticks and dry leaves for drainage and aeration.

Collecting materials

• Gather a range of organic materials including some manures as they’re a compost’s favourite food. 
• Keep a sealed bucket in the kitchen for food scraps, eg. coffee grounds, tea bags, vegetable peelings and household liquids like left over drinks and  rinsing water.
• Keep grass clippings and raked leaves in piles so you can add them in layers.

Adding materials

• Add the organic materials to the heap in layers no more than 10cm thick, alternating between nitrogen rich like food scraps and manure, and nitrogen poor materials like twigs and dry leaves. 
• Ensure each layer is as wet as a lightly squeezed sponge. 
• Occasionally add a thin (3-5 cm) layer of soil to keep microbe levels up. Add a sprinkling of lime, dolomite or  wood ash after layers of manure and food. 
• Cover the heap with a hessian sack.

When the heap is full

• If you have built the heap gradually, you have two options when the heap is full: 
  
  • start a second heap, leaving the first to break down; or
  • remove the enclosure from the heap and relocate it next to the original heap. Start the new heap by forking the top uncomposted material into the enclosure. The finished compost at the bottom of the original heap, is ready to use. 
• If you have built the heap all in one go, leave it for two weeks to “cook”, then turn it every week. You should have compost ready to use in eight to ten weeks.

Where to use compost
Compost adds vitality to the soil and can be used anywhere in your garden. Your energy rich compost will help retain water in sandy soil, improve drainage in clay soil and can help to prevent disease in your garden by keeping your plants healthy.

Compost can be used many ways around your garden, such as:

• potting mix for raising seed;
• a fertiliser for container plants, ornamental shrubs or trees;
• top dressing for lawns;
• soil for your vegetable garden.

Solving composting problems

Problem: Foul odours.
Cause 1: Heap is too wet.
Solution 1: Add dry leaves.
Cause 2: Not enough leaves.
Solution 2: Turn the heap to improve drainage and aeration; add 250g of garden lime; cover the heap during rain.

Problem: Slow decay.
Cause 1: Not enough nutrients
Solution 1: Add a small amount of nitrogen-based material (eg. blood and bone fertiliser).
Cause 2: Not enough air.
Solution 2: Turn the heap more often.
Cause 3: Not enough water.
Solution 3: Moisten the heap.
Cause 4: Too cold in winter 
Solution 4: Cover the heap with insulation material such as hessian or carpet; place the heap in direct sunlight.

Problem: Maggots.
Cause:Meat, seafood, fats or faeces in the heap 
Solution: Remove the cause; cover the maggots with lime; add soil to the top of the heap; turn the heap the next day.

Problem: Mice and rats 
Cause 1: Excess bread in the heap 
Solution 1: Put fine wire mesh underneath the bin/heap; turn the heap regularly.
Cause 2: Heap is too dry.
Solution 2: Moisten the heap.

Sources: 

• Recycling in your garden — Mulching and composting, Low Waste Gardening, Leaflet 4, Friends of the Earth (Sydney), 1998. 
• Don’t Rubbish Green Waste — Mulch, Compost, Worm Farms, NSW Environment Protection Authority, May, 1997.

Triple-bay compost system for your school
The Triple-Bay Compost System is an exceptional way to utilise your schools green waste to produce a rich compost for your garden. It is aesthetically pleasing as the compost is enclosed and out of sight. It is recommended to build your triple-bay compost system on flat ground and in a well drained, sunny position. You will also require an area of open ground of approximately 3.5m in length x 1.5m wide to construct your compost system. It can hold up to 2.5 cubic metres of compost, divided into three separate compartments, which allow the composting process to be started at different times in each compartment. This ensures that there is always at least one compartment containing properly “cooked” compost. Double-folding lids and removable front partitions allow for easy access when adding to, shovelling and turning the compost.

How to build:

Materials:

•  approximately 150 recycled fence palings: measuring 90x1200x12mm OR 13 sheets of plywood: 10 measuring 900x1200x12mm and 3 measuring 1200x1200x12mm;
• 12 heavy-duty stainless steel hinges, 50x300mm area;
• 15 wooden knobs, 50mm diameter OR 15 stainless steel grab handles;
• 8 timber corner posts, 75mm square (3” x 3”), each no less than 1400mm long;
• 40 timber guiding rails, 25mm square (1” x 1”), each 900mm long;
• approximately. 200 heavy-duty galvanised screws: 100x50mm long, 100x25mm long.

Equipment:

• pegs and string;
• shovel and levelling equipment, if levelling is required;
• pile driver;
• jigsaw or bandsaw;
• strong adhesive glue;
• drill and 3mm drill bit;
• screwdriver or screw-driving drill attachment;

Before you start: 

• if using fence palings, ensure they are of good quality and totally free of rot, termites, splits, nails, or anything that may affect the long-term structural integrity of the system. It is advisable not to use treated timber as this will deter the range of creatures that like to live in composts and assist in the decomposition process;
• if using plywood sheeting, the ten smaller sheets of plywood (900mmx1200mmx12mm) must be used for the fixed and sliding partitions; be sure to set the three larger sheets (1200mm x 1200mm x 12mm) aside for the lids. Note: Marine plywood is more expensive to purchase but is a hardier material and will increase the life of your compost bays.

Method:

1. choose a level patch of ground, at least 1200x3000 mm in size. The ground must be totally level and free of debris; use a shovel and levelling equipment if necessary. It is also necessary for the ground to have a firm base of clay material; do not build the bin on top of ground known to be soft, loose or sandy;
2. measure out the location for the corner posts, starting with an arbitrary benchmark - see Benchmark ‘A’ in Figure 1. Locate where the centres of each post will be driven and show each centre with pegs and strings as shown in Figure 1. It is very important you measure everything out accurately; leave 1000mm between the edges of each post along the front and backsides of the bin, and leave 930mm between the edges of each post on the left and right sides of the bin - this is also shown in Figure 1;
3. the corner posts are to be pre-cut to lengths of at least 1400mm and driven at least 500mm into the ground. Ensure that the height of the post above ground is 900mm. Consult a person qualified to operate a pile driver if this machine is used to drive the posts into the ground;
4. once the corner posts are properly driven in, measure accurately the final distance between every post. Ideally, the distance between the posts match those specified in step 1, but some variance is acceptable. If there is some variation in any of the distances, write the actual distances down and use each as the length of the fixed or sliding partition that will be placed between each post;
5. attach the guiding rails to each corner post as shown in Figure 2 using strong adhesive glue. For each guiding rail, fit 3x50mm screws spaced evenly along the length of the guiding rail. Figure 3 shows how to fit the screws to avoid fouling.
6. pre-cut and fit seven fixed partitions; they are marked with an ‘A’ on Figure 4. In the spirit of recycling, old fence palings were used for all of the fixed and sliding partitions and the folding lids in the system at Glengarry; plywood sheeting can be used as an alternative.

If using fence palings:
For each fixed partition, cut ten palings to a length corresponding to the distance you measured between two corner posts for that particular side. Apply glue to the slots created by the two guiding rails, and slide each paling into the slots, all the way to the bottom; it should be a very snug fit, which is why the measurements between the corner posts need to be accurate. No screwing or further bracing is necessary.

If using plywood sheets:
For each fixed partition, cut the 1200mm length down to the corresponding distance measured between each corner post. Apply glue to the slots as for the palings, and slide the sheet into the slots.

• Pre-cut and fit the sliding partitions, which form the front walls of each of the bin’s three compartments; they are marked with a ‘B’ on Figure 4. Each sliding partition is split horizontally into two, to allow for easy removal of each partition; this is also shown on Figure4.

For fence palings:
For each of the three compartments, cut ten fence palings using the measurements between each of the front posts. From each group of ten, take five and lash them together by gluing and screwing (using 25mm screws) two fence palings, each cut to 400mm, perpendicularly across the back of them as shown in Figure 4. Affix the knobs to the top-most paling on the front of the partition with glue and 50mm screws; if using grab handles, use the appropriate screws supplied with each handle. Do the same for the remaining five posts to create the second half of the sliding partition, and repeat the process for the remaining two compartment fronts. Once each sliding partition is finished, slide them into the slots at the front of the compartment; DO NOT apply glue to the slots.

For plywood sheets:
For each compartment, cut the 1200mm length of a plywood sheet to the correct length as measured between each front post. Then measure and mark off the half-way point, or 450mm, along the 900mm width of each sheet and cut in half, so each sheet becomes two sheets measuring 450mm in height, 1000mm (approx.) in length. Affix knobs or handles, centred at 200mm from the sides of the partition and 45mm from the top, as shown in Figure 4. Slide each partition into the slots at the front of each compartment; once again, DO NOT apply glue to the slots beforehand.

• Pre-cut, join and attach the double-folding lids for each compartment. Each lid consists of three pieces: a smaller piece, screwed to the top of the posts at the back of the compartment; a middle-sized piece hinged to the smaller piece; and the largest piece, hinged in turn to the middle-sized piece. For the compartments at either end of the bin, measure the distance between the outer edge of the outer post at the back of the compartment, to the middle of the next post at the back, as shown in Figure 5; this length is approximately 1112mm. For the middle compartment, measure between the centres of the relevant posts; this length is approximately 1075mm. Use these lengths as the length of the lids.

For fence pailings:
For each lid, start by cutting two palings to the length of the lid. These will form the smaller piece of each lid; they do not need to be lashed together by a backing piece of paling, as the hinges are big enough to perform this function. Then cut four palings to the same length, and lash them with two backing palings similar to those used in Step 7, using palings cut to 320mm lengths; these form the middle-sized piece of each lid. Cut six palings to the length of the lid again, lashing them with two palings cut to 500mm lengths. Arrange the pieces of the lid as shown in Figures 4 and 5, and place the hinges as shown, with the centre of the hinges at 175mm from the edges of the lids. Attach the hinges as per manufacturer’s instructions, and lift the assembled lid on to the top of the bin. Affix the smaller piece ONLY to the back posts with glue and 50mm screws, being careful to line up the outer corner of the lid to the outer corner of the corresponding post, also shown in Figure 6. Finally, attach a knob or handle to the exact centre of the largest piece of each lid.

For plywood sheets:
The same arrangement of pieces for the lids applies for plywood construction as for the paling construction. Cut the length for each lid as per the paling method, and cut each length to the following widths: 180mm for the smallest, 360mm for the middle-sized, and 540mm for the largest piece. Arrange the pieces, attach the hinges and knob/handle, attach the finished lid to the back posts exactly as per the paling method, and repeat for each remaining lid.