I’m happy to say we reached 140ºF. Success! 131ºF is the temperature threshold required by the EPA for commercial composts as part of something called Process to Further Reduce Pathogens, which is often referred to as simply PFRP, to ensure the destruction of weed seeds and pathogens. This pile is made from horse bedding, weeds, brewery waste, coffee grounds, and a little bit of juice pulp and has been sitting for about a week. This particular compost thermometer is not super amazing, as the lowest temperature setting is 80ºF, and you can’t really gauge its accuracy, but it is affordable and has a nice stem for poking into the center of the pile. Since it’s new, let’s assume it’s accurate.
You can see the fervent proliferation of actinobacteria (all the white stuff), which are some of the dominant bacteria in the pile at this heat in the thermophilic phase.