Compost heap temperature logger helps keep things hot


HackHut user [lackawanna] is looking to start his own compost pile, but as many urban composters discover, things can get quite smelly if you don’t manage it properly. The process of composting is broken up into two phases, aerobic and anaerobic decomposition. The former is the first stage to occur and produces plenty of heat, but should be scentless. The latter gives off less heat and is more of a stink due to putrefaction. Carefully monitoring the temperature of the pile and restarting the aerobic phase when necessary helps to keep the process “healthy” and scent-free.

[lackawanna] built a simple temperature monitor that he plans on using to track the status of his compost pile once he gets started. It uses an ATmega328 as the brains of the operation and an old metal can transistor as his temperature sensor. Using relative measurements of the compost pile taken in 10 minute intervals, he can determine when the aerobic phase is underway, as well as when things begin turning anaerobic. At that point, the sensor alerts him that the pile needs to be turned.

The build is pretty simple, but leaves plenty of room for expansion. It should be relatively easy to add a more friendly notification interface as well as install multiple sensors to the pile for obtaining aggregate temperature data.


  1. AeroNotix says:

    A whole 328?

  2. MRC says:

    good to see some dead-bug construction going on. not everyone has boards etched for every project.

  3. Keith says:

    Ham radio operator by chance?

  4. Life2Death says:

    Thats not how you prototype board :(

  5. Hirudinea says:

    Hey if you want to be completly lazy make this wireless, build a motorized one of these …

    and you never have to touch it until its lovely dark dirt.

  6. Andrew Parting says:

    nice construction. Fun fact compost heaps can get hot enough to explode!

  7. Drone says:

    Dead-bug, this belongs on the compost heap!

  8. Stevie says:

    +1 MRC. I’m with you on that :)

  9. Josh says:

    Deadbug FTW!

  10. DeadlyDad says:

    @Hirudinea: +1!

  11. Tod says:

    @Hirudinea & DeadlyDad: I had the same or similar thought but more on the line of making it automatic. Compost core gets above the optimum temp and it automatically detects it and turns on the tumbler.

    Hmmm… now, if only there were some common device that could monitor this, and turn on a tumbler accordingly, and alert you it had been done…

  12. Tod says:

    Oh, dead bugs don’t help compost much. Live ones do. ;-)

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