Taking your compost’s temperature
If you want to start hot composting - getting your compost to heat up to at least 55o Celsius for at least 3 days - you are going to need some way to find out what temperature your compost is getting up to.
The simplest temperature check is to stick a metal rod into the middle of our compost pile. After a few minutes the rod will have stabilised at the temperature of the pile’s core. Quickly draw out the rod and cautiously touch the end, if it is 55o C or under you should just be able to hold your hand on the rod, over 55o C and it will be too hot to hold, so be careful, composts can get over 70o C. The rod will rapidly cool, so take your observational reading quickly.
If you start making hot compost regularly, perhaps using a continuous hot compost system - like our amazing team of YIMBY composters - you are going to want to get your hands on a dedicated compost thermometer.
A good thermometer will have a decent length probe (at least 300mm – so you can get down into the pile’s heating heart - but longer is better) and a clear and accurate dial.
As with most purchases in life, we can spend a lot of money on a well-made, dedicated tool or we can buy cheap, flimsy options too. My preference is always to go for things that are made to last, in the long run and we end up generating less waste, using less energy and often save money too.
At YIMBY we have found the Backyard thermometers from the Reotemp company (available for under $100 – pictured) to be a good balance of well-made, but not too pricey. We prefer if the dial reads in Celsius only, as this reduces confusion.
These compost thermometers have bi-metal tips that move the needle on the dial. This means it is reading the temperature only at the tip, so don’t worry if the rest of the probe’s shaft is sticking out of the pile, we can take an accurate reading at any depth.
A little warning; taking the temperature of your hot, or heating pile can become quite addictive, and you might find you are ducking out to the garden a couple of times a day to see what is going on down below the mulch layer of your pile.
Paying closer attention to our compost makes us better composters. Couple this with keeping good records of temperatures, ingredients and processes and we are well on the way to becoming master composters.
If you are hot composting consistently, and you have the temperature records to prove it to yourself, you can feel comfortable putting almost any organic ingredient in your pile; weed seeds, couch and kikuyu grasses, meat scraps, bones etc. knowing that the microbial heat will kill off the pathogens and stop rats and mice being able to get to any tasty scraps.
Next week we’ll have a look at machetes as a composting tool.
AUTHOR: JOEL MEADOWS
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
This was first published in the Midland Express on the 21 December 2023