Monitoring Your Bins
Step 5. Monitoring the Piles
“The best fertilizer is children’s footsteps” goes the revised translation of an ancient Chinese proverb. Watching and measuring the moisture, feel, smell, and temperature of a compost pile is as critical a job as any to achieving success in composting. Below is a table that gives the target pile conditions for producing high quality compost.
Monitoring of piles should be done on a weekly basis and can be done as often as every day. Kids can and should participate in this process, and schools can use Monitoring Logs (See Appendix A) as a tool to record and teach kids about what is happening throughout the deferent stages of the composting process.
Monitoring and recording temperature, moisture, and any other observations or management activities such as turning, allows you to easily track the progress of your piles over time. Closely watching the compost making process through the lens of these simple methods provides insight into the activities of microscopic life at work within your system.
Temperature - In order to track pile temperatures, you will need a composting thermometer, which costs between $30 and $145 depending on the size of the thermometer. Heat created by microorganisms (primarily bacteria) metabolizing waste throughout the decomposition process is an indication that the process is working well. Pile temperatures above 131 degrees Fahrenheit for at least 3 days are required to destroy pathogens and weed seeds, so using a thermometer probe will give you confidence in the effectiveness of your system and of the quality of the finished product. Both the inner and outer temperature of the piles are usually monitored, in order to know what is happening throughout the entire pile. Monitor at a depth of between 8-12 inches an then again at about 18-32 inches.
Moisture – Testing moisture is as simple as digging about a foot into the pile and giving a squeeze to a handful of material. If you can barely squeeze a drop of water out between your fingers, then the pile is at 50% moisture, which is lowest end of the ideal range. A few drops is about 60% moisture, which is at the high end of the ideal range. If there are many trickles of water of when you squeeze as hard as you can then the pile is greater than 65% moisture and should be fluffed with a pitch fork to aerate the piles. A small amount of dry material can also be added to a pile to absorb excess moisture, but only if it is in your first bin and fresh materials are still being added to it. You would not want to add any materials to an older bin/pile because they will have likely heated already and you could introduce weed seeds or pathogens unintentionally. If the pile is too dry you can add water, but do so in small gradual amounts, monitoring regularly.