You may have heard of ‘The Pub Test’, a conceptual check of a political idea with people down the pub. You might have also heard of ‘The Sniff Test’, an indicator that an idea might be ‘off’ or ‘on the nose’.
Today we’re asking “does your compost pile pass the Pub Sniff Test?”
Mikaela Beckley, YIMBY organiser and composter extraordinaire, says ”We know a composter is doing a fantastic job when we help them turn a full cubic metre of compost and can go straight from that to a café or pub and not need to change our clothes, or risk being social outcasts!”
It’s true. There are composts that are made so well that they don’t smell bad, even when we open them up and give them a turn. So, what factors lead to a compost pile passing or failing the Pub Sniff Test?
It is common for food scraps to stink, especially if left in a bucket a while before being composted. But when those same stinky ingredients are balanced with autumn leaves, straw and chopped up woody garden prunings, built up in thin alternating layers, those offensive smells go away.
It is not that a well-made compost pile has no smell at all, it is just that it smells more like ‘cooked food’ or ‘moist forest floor’ than something we want to run a million miles from.
Bad smells are indicators that something is not going well. Smells, like rotting citrus or vomit, usually indicate our compost is too nitrogen-rich and needs a good blending of carbon-rich ingredients (see above).
In very high nitrogen composts, ammonia (a sharp, distinctly medicinal smelling gas) will be given off, as well as nitrous oxide (an extremely potent greenhouse gas). These gasses let us know nitrogen is being lost from the pile, leaving our compost less nutrient rich, and less valuable when we use it on the garden. There is more than one reason don’t want stinky compost piles!
When our compost smells like the mud at the bottom of a dam, or poo, our compost is probably anaerobic (very low in oxygen) and is likely producing methane, also a potent greenhouse gas. Heavy, over-wet compost piles lack the space for oxygen to enter the middle of the pile and for carbon dioxide to escape, leaving our beneficial aerobic microbes struggling to breathe and conditions favouring the anaerobes.
Adding enough ‘structure’ (aerating woody materials) through the pile and particularly in the bottom third, should keep our compost oxygenated for the whole process and much happier.
Making much less stinky compost is not that hard, it just takes a little care to get the balance right. Perhaps your compost can pass the Pub Sniff Test.
– Joel Meadows works with *Yes In My Back Yard, (YIMBY), a community-scale composting initiative in Castlemaine and surrounds. Send questions or comments to hello@yimbycompost.com, or to book in for a compost workshop.
