The following is printed on the side of my Rapitest Compost Thermometer Box. I found it very informative.
Temperature plays an inportant role in the coposting process. Decompostition occurs most rapidly between 110F and 160F. Within two weeks a properly made pile will reach these temperatures. At this time, you will notice your pile settling which is a good sign that the pile is working properly.
Now you must decide how you want to compost. Do you want to add to your pile or just let it continue as is? If you want to add to your pile, you can do so throughout the growing season and into the winter months. As you add fresh material, you will need to turn and water your pile more often. Monitoring the temperature and turning whenever the piles temperature dips below 110F keeps your pile active at its highest level, and you will have the fastest breakdown. This means you turn the pile more often. This can be weekly and it is work!
There are different types of aerobic bacteria that work in composting piles. Their populations will vary according to the pile temperature. Psychophilic bacteria work in the lowest temperature range. They are most active at 55F and will work in the pile if the initial pile temperature is less than 70F. They give off a small amount of heat in comparison to other types of bacteria. The heat they produce is enough however, to help build the pile temperature to the point where another set of bacteria, mesophilic bacteria, start to take over. Mesophilic bacteria rapidly decompose organic matter, producing acids, carbon dioxide and heat. Their working temperature range is generally between 70F and 100F. When the pile temperature rises above 100F, the mesophilic bacteria begin to die off or move to the outer part of the heap. They are replaced by heat-loving thermophilic bacteria. Thermophilic bacteria thrive at temperatures ranging from 113F to 160F. Thermophilic bacteria continue the decomposition process, raising the pile temperature to 160F, where it usually stabilizes. Unless a pile is constantly fed new material and turned at strategic times, the high range temperatures typically last no more than three to five days. Thermophilic bacteria use up too much of the degradable materials to sustain their population for any length of time. As the Thermophilic bacteria decline and the temperature of the pile gradually cools off, the mesophilic bacteria again become dominant. The mesophilic bacteria consume remaining organic material with the help of other organisms.
Duane Friend, Extension Educator, Natural Resources Management University of Illinois Extension email: friend@uiuc.edu
Martha Smith, Extension Educator, Horticulture
University of Illinois Extension Email: smithma@uiuc.edu
Holly Johnson Waste Recovery Specialist, University of Wisconsin Extension
