Composting 101 - Eliminate Your Food Waste

What is compost? What's so good about it? What is it used for? Why is it so important to do? How can I make my own? Read on if any of these questions tickle your tastebuds..!

Compost is the end result of breakdown of organic matter into a reusable form. It is recycled natural matter - plants, food scraps, manure, etc. Composting, Ive just learned, was around even during Roman times and is recognised by most in agriculture, permaculture, horticulture and the likes as one of the best ways to improve the health of soil. Soil is full of living organisms, nutrients, water, carbon, and many other things. It can also absorb carbon from the air. When we grow crops or graze animals and don't replace what we remove (during harvest or animals feeding), soil health deteriorates. By creating compost, we can easily and cheaply revitalise soil to maintain great crops, on both a small and big scale.

Food waste is a HUGE problem in Australia -  we throw out one in five grocery bags of food that we buy! That equates to roughly $3500 dollars per year for the average Aussie family. One third of our rubbish bins are full of food waste - what the...! Can you think back over the last week to what food you might have thrown away? That leftover curry that was forgotten in the back of the fridge, that apple that got squashed and mouldy in the fruit bowl, that tub of yoghurt past its use-by date... OK, so you're wasting a fair bit of money, but it all just breaks down nicely in landfill anyway, right?
WRONG! This is possibly one of the scariest facts I learned last year - when organic matter is trapped underground or in plastic with no air exposure (i.e. anaerobic conditions) it takes a really long time to break down (Im talking YEARS) and produces methane in the process. Methane is climate change's arch nemesis. It's about 23 times MORE potent than carbon dioxide, contributing heavily to global warming. Don't believe it? See here for the Australian evidence from RMIT University. So, unless you're quietly facilitating a lovely aerated biodiverse environment for your food scraps, you're giving a great big middle-finger to Mother Nature. Oh dear.

Obviously, the first thing to do to combat this massive issue is to reduce your food waste - read the 'Zero Waste' webpage for more on this, there's plenty of helpful info. Once you've already made a good effort to do this, you'll notice you still have some scraps that are always left over. Can't go into soup, probably not going to make stock powder... your first thought now should be COMPOST! If you're thinking things like "I'm not a gardener, I don't know anything about composting", or "I'm in a small unit, I've got nowhere to put a compost heap", or even "Do I just buy one of those big black bin things and fill it up?" then pause, relax, and read on..

There are SO many ways you can make compost, and each gardening guru will have their own method they like to use. There isn't really one perfect way to compost, which is great because it makes it harder to get it wrong! I'll aim to cover the most important stuff to get you started, and the rest is up to you and your bin full of bacteria. At the bottom of the post are some resources to help you once you're up and going.

Firstly, a note for those living in a small space without a yard (scroll down if this isn't you). There are a few ways you can divert your food scraps from landfill without having to create a big pile. If you do grow plants (e.g. on a balcony garden) you can opt for a Bokashi system which is tiny, faster and smell-free. Read my past blog post on this for more info. If you don't grow anything, you can still collect your scraps in a separate bin and either contribute to a friend's compost or worm farm, or donate them to a local community garden or school compost. In my experience, community gardens are very open to food scrap donations as they know the true value of compost - as long as you aren't putting any nasties in with your scraps (read on to find out what's good and bad for compost heaps). Some local councils have food scrap collections just like normal rubbish collections, where your small kitchen bin (provided by them) is emptied into a big communal pile and composted by them. A worm farm is also very compact and, if you live alone, is a great way to use food scraps. They require small weekly or fortnightly donations and, in return, you get the best soil conditioner known to man - worm poo!

Compost basics to get it right
We've all heard about carbon and nitrogen - in compost, they are your core ingredients. Carbon is highest in dry, brown material, such as dried leaf litter, cardboard, newspaper, envelopes, straw, old woody plants, twigs/old plant prunings, woodchips and wood ash. Nitrogen is highest in fresh or green material, such as kitchen scraps (mould is fine), cut grass, young weeds, animal manure, comfrey and nettles, seaweed, soft prunings, and hair/fur.
Your receptacle can be anything from a plain plastic enclosed bin, to a large open timber frame. You need to keep the pile together at the very least, and enclosing it can protect it from the elements and vermin. For a hot compost, you need at least 1m cubed (ideally more) for the heap to reach 60 degrees celcius (at which most seeds and pathogens are killed). Hot compost also breaks down much more quickly, but is not always a practical option. Cold compost takes longer (months as opposed to weeks) and is suited to most gardens, and your heap can be reasonably small.
It is important to layer your compost when you first make it (take it from someone who learned the hard way) with a rough ratio of 25:1 carbon to nitrogen (note: some brown materials are higher in carbon than others, and vice versa). Start with something like cardboard or newspaper to line the bottom and keep pests out, then add your nitrogenous or green layer, followed by brown, then green, etc. Continue this until your bin is full (or you have run out of ingredients, in which case continue to build over time with this layering system). A variety of materials generally makes a better compost, as you'll have a wider array of bacteria and nutrients available at the end. Ensure throughout that you keep brown layers light and fluffy, i.e. don't compact them down. Air is vital to the process. Moisture is also essential part so, if your mix looks dry or dusty, give it a sprinkle to keep it damp. Additional animal manure and lime can be added if you want to speed up decomposition. You can opt to turn your compost weekly, though this is not essential and very much debated between gardeners! It is, however, a good opportunity to check your heap and see what it's doing, feel the temperature, and smell it. A finished compost is a rich, dark brown soil that should smell sweet - almost edible! When you use it, any big bits left are best sieved out and put back in to continue rotting in your next pile. Use your finished compost wisely - more is not always best, and it is very valuable!

What NOT to compost in your backyard heap*:
- Cat, dog or human faeces
- meat, bones, dairy and fatty food
- most diseased plants
- chemically-treated wood products
- charcoal ash
- noxious weeds

*many of these things can actually be composted, but they require specific environmental controls that are not available to the average person.
**I personally choose to avoid putting salty foods in my compost too, like leftover curry, as high salt levels are detrimental to soil in many ways.

I hope you've been inspired to stop throwing your food scraps away and to get into the garden next weekend! Share your thoughts, comments and questions in the comments below, on the SEED Facebook page, or on Instagram @seedblog. Happy composting!


Compost Science and Trouble-Shooting - SGA

Gardening Australia Compost Fact Sheets - Costa Georgiadis

International Compost Awareness Week

YouTube - War On Waste (ABC TV) Food Waste clip