Composting really can be simple. This is how to make a start

It seems so simple in theory. You put food scraps in the compost, you get a great soil improver, and your waste is diverted from landfill.

Win, win, win.

But then you see the dizzying array of composting systems, hear a few horror stories, and get bombarded by conflicting advice on what you can and can't include … and suddenly it all seems too hard.

Can compostable cutlery even go in the compost? Meat and dairy — yes or no? Corn cobs and avocado seeds? Egg shells and onions? What's all the hot, aerobic stuff about?

We talk to some experts to try to find some straight answers.

What is compost?

The simple answer is anything organic — that is, anything that has once been alive — will decompose and become compost, which, in its final state, will look like healthy soil.

Of course, a tree trunk will obviously take longer to break down than lawn clippings or banana peel, so how long your waste takes to become fully composted varies enormously depending on what goes into the mix, the type of bin you have, and your own approach to the process.

Samantha Grover, who is a lecturer in environmental science at RMIT and author of the children's book Exploring Soils, describes compost as "the best and cheapest way of improving soil".

"Compost is the universal soil improver and, unlike soil additives, it improves both the structural and nutritional composition."

Whatever system you use to make your compost, it will be rich in nutrients as well as bringing life to your soil in the form of microbes and microorganisms.

Many large-scale businesses recognise the value of compost as a soil improver and process it on an industrial scale, selling the end product to farmers. If there's money in it, you know they're on to a good thing.

So, why do you want to compost?

We've all heard horrific statistics about food waste and its effect on the environment.

Avoiding waste and diverting food scraps from landfill are a no-brainer. But Belinda Christie, an adjunct research fellow with Swinburne University, says thinking about your motivation to compost will help decide what system works best for you.

She also advises assessing your resources, not just in terms of time, space and garden, but also community support and local council services.

• If you simply want to reduce food waste, then maybe a kerbside collection or community scheme such as ShareWaste — which matches up composters with food scrap donors — might be an option.
• If you're hoping to meet your neighbours, then look into local community gardens for shared bins.
• If the aim is to get kids involved, then a worm farm might be a fun activity, especially if your garden has limited space. You can buy commercial ones, or make one from upcycled scrap at home.

You do need to get special worms for your worm farm — don't use garden earthworms — but there is very little odour, no need to turn over the compost, and it can sit indoors or outdoors (so long as the worms have shade). You also end up with "worm tea" and castings you can use on your plants or swap with gardening neighbours.

• For those with small or shared gardens, then a neat benchtop bin that ferments compost is useful. You can put just about anything in one of these bins, including meat and dairy, but you do need to keep buying the microbe-mix (which looks like a bag of wood shavings, and is available at most nurseries) to get the process going. You will also need some garden space to bury the end result — or a friend who will let you use their yard.
• But if your garden is big enough to grow veggies and you want to feed your soil, then a traditional bin is best. Although you still have the choice of an open-bottomed plastic one, a freestanding tumbler, or a set of home-made timber bays.
• Another option is to dig a trench about 30cm deep and gradually add your food scraps in sections, burying it as you go. It will take longer to break down — and you should avoid including meat that foxes might dig up — but it's a simple solution for those renting a house with a larger garden, and who don't want long-term infrastructure.

What can I compost?

In terms of what not to put in your compost, plant material that is obviously diseased or carrying pests, as well as perennial weeds like grass runners and bulbs are the main items to avoid. They will survive the hottest compost and come back to haunt your garden beds.

If you have one large pile that you keep adding food and garden scraps to — called a cold compost — it will slowly decompose over time (which may be up to 12 months) but will never get hot enough to kill off any weed seeds or fungal spores on leaves, so you need to exclude things like this that you don't want back in your garden.

A hot compost will kill these off but takes a lot more planning and work.

Many people avoid putting meat and bread in compost because they can attract rats and mice, but if your bin system is well sealed, by all means add everything. If your local council directs its green waste to an industrial composter, it's possible you can put fish and meat bones in your green kerbside bin; just check your council's guidelines.

"But that's with a bin connected to the ground. You wouldn't do that with a worm farm, which are more particular."

If you opt for a worm farm, there's quite a long list of foods the little wrigglers don't like, including citrus, onions, meat, dairy, spicy food and anything oily. It's also important not to overfeed your worms or the farm will start to smell.

Another no-no is dog and cat poo. While manure from cows, sheep and chickens are OK in the garden, pet poo is more likely to contain parasites that composting won't kill and that can be passed to humans. So, while the poo will eventually break down, you don't want it anywhere near your veggie patch.

But if you have pets and would like to add their waste, you can buy (or make) a composter that can be half-buried in a distant corner of your garden.

Do I just bung it in?

Cutting up garden waste (which you can do by running over it with a lawn mower) will speed up the composting process because it creates more surface area for microbes to feed on.

Cutting up scraps for a worm farm is also a good idea as it will get eaten more quickly, so it's less likely to go off.

"It depends on how much time and energy you have to manage the system," says Dr Grover.

"Some people put scraps in a blender and add it to their worm farm or compost, which really speeds up the process, but I don't have the time [and you shouldn't feel the need to].

"If there are larger items I can still recognise [when I want to use the compost on the garden], I just put them back in to decompose a bit longer."

What's more important is getting the ratio of green to brown right, Dr Grover says, and Dr Christie agrees.

"It's about the carbon to nitrogen ratio, and that is best seen as brown and green," she says.hea

Some people describe green and brown materials as 'fast' and 'slow' rotters:

• Green, nitrogen-rich items such as teabags, coffee grounds, lawn clippings, vegetable peelings and kitchen waste rot quickly but can become compacted, wet and slimy.
• Brown, carbon-rich materials such as egg cartons, twigs, dead leaves, straw/hay, manure, ripped up pizza boxes and newspaper are slow to rot and tend to stay dry with air pockets in between.

By combining the two, you get a perfect mix that has air in it, stays damp rather than wet and will therefore break down quite quickly. However, finding that perfect mix is an art in itself and the advice on the best ratio ranges from 50:50 to 30:1.

If you're looking for a 'safe side' to err on, go for more browns — you can always add more water and/or kitchen scraps, and it's less likely to smell.

The sweet smell of composting success

The two most common problems a composter will face is a pile that's too dry, or a pile that's wet and smelly.

Fortunately, the solutions are dead simple:

• Too dry — Add more green material and/or water
• Too wet — Add more brown material and get more air into the pile by giving it a mix

Smelly compost highlights the difference between aerobic and anaerobic composting; aerobic means 'with air' and the oxygen helps the materials break down quickly without smelling.

If your pile starts to decompose anaerobically — without air — it will produce smelly ammonia and methane, which is even worse than carbon dioxide as a contributor to global warming.

Compost tumblers are designed to easily turn over the scraps and keep them aerated, but they can become heavy. If you have a timber bin system, you can turn your pile with a garden fork or using a specially designed corkscrew-type tool that you twist into the pile, then pull out to create an air space.

Some people use a twin-bin system — with two bays built side by side — so they can transfer the compost between the two and keep the ingredients mixed and aerated.

It's important to remember that every time you make compost you will be using different material in different weather conditions. Simply be prepared to keep an eye on it — just once a week is fine — and adjust it as necessary.

Are you up for the challenge?

"Anyone can do it and it's fun," says Dr Grover.

"And if you live in an apartment, then donate your compost scraps; it's a perfect gift for someone with a garden."

Dr Christie recommends getting support as you're starting up, as this will iron out issues and help keep you motivated. Talk to family who compost, meet neighbours, check out what your council offers, what share services are already set up near you.

You should also expect the unexpected: "One of the most surprising things my research found was the deep sense of community that grew from setting up worm farms for apartment blocks; we weren't expecting that but it was what residents loved the most."