There is no substitute for the complexity of human senses.  Quantitative data is cannot stand in for direct experience with compost.  But it does provide a means of directly comparing processes and feedstock mixes, as well as real-time feedback for  control.   Lacking  grad students or interns we have only robots to exploit (for now…).  To that end, we’ve been prototyping an inexpensive electronic monitoring system.

Our Current System
Once an hour a cheap analog clock wakes up an Arduino from it’s deep, power-saving sleep mode.  From the safety of our garage, the Arduino reads the temperature from five Dallas OneWire temperature sensors on a 10′ cable. Using an Ethernet Shield, the Arduino connects through our router to the internet, where it uploads the sensor values to Pachube, and puts itself back to sleep again.  Pachube saves the data as XML, which is interpreted by flash widgets on a dashboard.

Download the Arduino code (requires Dallas Temperature Library, OneWireLibrary)