Kinasmith wrote this instructable detailing how to build a compost temperature monitoring system, a web connected wireless sensor network:
Why Measure the Temperature of Compost?
“Composting is the biological decomposition of organic matter under aerobic conditions.” Micro-organisms consume organic material and oxygen and create heat as a waste product. By measuring this heat you can predict decomposition rate, oxygen content (loosely), and the overall health and efficiency of your composting operation. It helps to predict when the pile needs to be turned to introduce more oxygen, when the pile is finished with its hot cook cycle, and if you have effectively killed any pathogens or weed seeds that might be present in the feed stocks. Monitoring is an important aspect to streamlining and creating a stable process and workflow to get a predictable and consistent result through each cook, improving the overall efficiency in the operation.
This project uses short range Radio and Cellular communication to get sensor data from individual probes in the compost to an online database. The hardware will be built on the Arduino platform using the Moteino wireless boards. We will be using thermistors for our temperature sensing, an Adafruit FONA cellular module for our cellular communication and the Sparkfun Data Service for our online database.