I’m going to try to keep this ‘article’ as short-and-sweet as I can, so I don’t completely overwhelm you. There is a tonne of information out there about composting, so if you’d like to know more, check out resources like the Gardening Australia website, the Gardening Australia magazine, the Organic Gardener magazine and books by people like Tim Marshall.
In a nutshell, it’s all about getting the balance of ‘greens’ (things high in nitrogen, sometimes also referred to as ‘wet’ materials) and ‘browns’ (things high in carbon, sometimes also referred to as ‘dry’ materials) right, so you end up with gorgeous friable, dark brown-black, nutrient-rich soil to put around your plants, and not left with a smelly mess that attracts flies and other pests.
So what does ‘brown’ and ‘green’ mean? ‘Brown’ is anything that is a source of carbon, such as fallen leaves, paper, cardboard, straw, etc. These materials also tend to be dry, hence the other name for them. ‘Green’ is anything that is high in nitrogen, such as kitchen/fruit/vegie scraps, fresh garden prunings, weeds1, lawn clippings2, etc – anything that still has a lot of moisture in it.
Once you can identify what’s what, you need to get the balance right. Depending on what you read, some places will recommend a ’70:30’ ratio (ie 70% ‘brown’ to 30% ‘green’) or ‘2/3 and 1/3’ (ie 2/3 ‘brown’ to 1/3 ‘green’) or other similar ratios. Basically as long as you have approximately twice as much ‘brown’ as ‘green’ your mix shouldn’t get too wet or too dry. Follow this, and you should be pretty safe. If you find however, that it’s not going to plan, try these trouble-shooting tips:
Cause/s: there may be too much ‘brown’, or you may just be experiencing hot/dry weather and the moisture in the mix is evaporating too quickly.
Solution: add more ‘green’ or a bit of water. Soaking the ‘brown’s in water before adding (if using paper or cardboard) or wetting them down afterwards with a hose or watering can (if using leaves) will also help to hold the moisture in a bit longer and speed up the composting process (the little critters, like slaters, worms and micro-bugs/fungi/bacteria, that do the composting for you like moist food and living spaces).
Cause/s: there may not be enough ‘brown’.
Solution: add more dry material and mix it through to soak up excess moisture. Maintaining this balance can be as easy has having a bucket of shredded paper, old newspapers or even wood shavings next to the bin, and each time you add some vegies or fruit scraps, put in a few handfuls of ‘brown’ as well.
Starting to smell?
Cause/s: the mix may be too wet, hasn’t been mixed often enough or has too much ‘green’, which may have caused it to go ‘anaerobic’3.
Solution: give the bin a good mix to aerate it and assess moisture levels. If it appears to be too wet, add more ‘brown’, as above. Check it again in a few days and repeat if necessary.
* soak the ‘brown’ materials before adding them. This will help to both maintain moisture levels within the bin and speed up the composting process.
* make sure you aerate the compost at least once a week. I usually do this at the time of adding more materials and checking that it’s not too wet or dry. If you have one of those vertical, black plastic compost bins, like I do, I find the ‘compost screw’ a very useful tool; it saves A LOT of backache trying to mix it thoroughly with a garden fork or alternatively dumping it all out and shovelling it back into the bin. I bought my ‘compost screw’ from Bunnings, but most hardware or garden stores have them.
* like with worm farms, smaller particles will break down more quickly than larger ones, so cut up your scraps as small as possible before adding them to the compost.
You may have noted that I specifically didn’t mention manures above. Manures are somewhere in between ‘green’ and ‘brown’. Most of the time, they are slightly more ‘brown’ than ‘green’ but if you buy “stable manure” from an obliging farm, be aware that the shavings will be very high in nitrogen because they’ve soaked up the animal’s urine. Generally speaking, all manures are great additives to both compost or as a mulch in your garden, but high-nitrogen/ammonia manures, such as stable manure or fresh chicken manure, should be composted first to release this ammonia so it doesn’t burn your plants.
As Tim Marshall says in his book “Composting – the ultimate organic guide to recycling your garden”:
“Making good compost is like baking a cake. First you assemble the ingredients, then you mix them together (I would add ‘in the right proportions’), including air into the mix, and then you ‘bake’ it until ‘cooked’.” Before ‘feeding’ it to your garden :)
At the end of the day, recycling your household and garden waste into gorgeous compost is a brilliant way to improve our usually nutrient-poor Australian soils; much better than letting all those useful nutrients go to landfill, and your garden will love you for it!
So have a go! And don’t be afraid to ask questions if you get stuck! As I’ve said before, you don’t lose anything by having a go, and you don’t learn anything (and your garden and the wider environment doesn’t benefit either) if you do nothing. So get out there and have a go! Every little bit helps! :)
1 Most backyard compost bins, tumblers, etc do not reach the temperatures (usually 50-60C) required to kill weed seeds (often referred to as ‘cold’ composters), so if you have one of these, avoid putting weeds with seed heads in there, as the seeds will remain viable and be spread around your yard when you put the compost out. I tend to carefully cut the heads off before pulling the weed out, and put the seeds into the Council bin (the green bin, if your Council has those – Council landfills conduct a ‘hot composting’ operation with green waste that will kill the seeds) before pulling the weed out and either giving it to our chooks (if its chook-edible; most things are) or putting it in the compost.
2 I don’t, personally, recommend putting lawn clippings into the compost simply because there is usually way too much of them – remember you have to keep the ratio of ‘brown’ to ‘green’ right – and they tend to go mouldy instead of decomposing properly. Instead, I give mine to the chooks to pick through (they love eating the grass as well as the little bugs that get caught up as you’re mowing) and mix around with their straw and shredded paper (both sources of ‘brown’) and chook poo (a good compost ‘inoculator’ or ‘stimulator’ – I’ll write a separate ‘article’ about them shortly), this effectively makes a big compost heap inside the run, and the best thing is you don’t have to mix it because the chooks will do it for you! If you don’t have chooks, you can spread them thinly over your lawn or garden beds and they’ll break down nicely there while also helping to suppress weeds and retain soil moisture (they act as a high-nitrogen mulch).
3 The word ‘anaerobic’ simply means ‘without oxygen’. In a compost situation this generally means that the mix is too wet, so oxygen has been excluded, producing an environment where bacteria and other organisms that like these conditions can flourish. Unfortunately, a lot of these organisms also produce offensive gases, and this is what you’re smelling.