Compost: Food Waste Turned Into More Food

In the continuing war on waste, at a household level by far the most effective strategy I have for reducing our municipal garbage output is composting. I have a very simple and comprehensive composting system.

Three large compost bins. One is filled and has been spending several months quietly composting away. One is nearly full, and one is waiting to be filled.

These bins are recycled plastic and made in Australia. They are the simplest type of compost bin - they have no base, are placed directly on the soil, they have a hinged lid. You don't need to buy compost bins - you can use any old lidded bin of any size, cut out the base and away you go. Now these bins won't make your classic turned, hot compost. They are too small to heat up properly. To make a hot compost that kills pathogens and weed seeds you need a heap that is made all at once and is at least 1 cubic metre (35 cubic feet) in size. This is generally not practical in a small suburban garden. My plastic bins are not compost bins so much as large worm farms. They produce what is called 'cold compost' but is actually pretty much worm castings, and the process takes at least a year in our temperate cool climate. If you live somewhere warmer than Tasmania the process will go quicker, and if you have snow in the winter, it will take longer.

There is no secret or complicated method to producing cold compost. You start with a bucket full of kitchen scraps on the bottom of the bin, and add some compost worms (these are the worms you buy for your worm farm. Or ask a friend with a worm farm or compost. If you live in Launceston, ask me). You will need a double handful of worm-filled compost to start. Then add all your kitchen scraps, soft weeds, autumn leaves and vegie garden prunings. Anything that isn't actually sticks can go in. Sticks take longer to break down. I throw in all my kitchen waste, even the things that you aren't supposed to put in compost bins and worm farms, like meat, bones, dairy, onions and citrus skins. The worms in my bins have never seemed to care. Mind you, I don't have rodents or a dog that digs, so I know that what goes into the bin stays in the bin. Other things I put in the compost: hair, dust and dog hair from the dust pan, a small amount of fire ash, paper towel, natural fibres of any kind, tissues that haven't been used for anything nasty. Cold compost will not kill pathogens, so I don't put anything in it that will spread germs, like cat or dog poop, or snotty tissues. Tissues I flush down the toilet. Guinea pig and rabbit poop is fine though, and their bedding, and the newspaper from the bottom of the budgie cage. Another thing cold compost will not do is kill seeds, so do not throw in seeding weeds, or plants like ivy which will cheerfully resprout under any condition whatsoever.. this also means that you will have hundreds of tomato, pumpkin, zucchini and cucumber seedlings popping up when you spread the compost in the garden. This may be a good or bad thing depending on your perspective. I do admit it is very difficult to be hardhearted and hoe all of these baby plants back into the soil.

After a year or so the compost looks like this:

The only identifiable ingredient is eggshells, which is kind of bad news for when I get chickens, as chickens who peck at eggshells can become egg eaters. From now on I will be drying and grinding up the eggshells, and saving them as a chicken feed calcium supplement for my (as yet hypothetical) chickens. Otherwise the compost looks exactly like potting mix, but has more heft to it. It is wonderful, magical stuff for the garden. It adds nutrients, but also adds organic matter to the soil, helping it to become better draining and making it a more hospitable place for plants to grow.

Things to remember - site the bins in the shade so you won't kill the worms. Keep the compost damp in the summer. Worms like alkaline, so add a little fireplace ash or garden lime occasionally. If a cloud of tiny flies fly out when you open the lid, add another handful of lime and some garden soil. You will sometimes see an explosion of tiny white wriggly worms in the bin. Do not panic. They are the baby worms, and will grow up to do important composting work like their parents, so feed them well.

For further reading, here is a list of 100 Things You Can Compost.

There are so many different ways to compost. How do you do it?