Why a HOT Compost Pile Needs to Be Turned
Pile temperature will continue to rise as long as abundant water and air are present in the pile. But as air and water are consumed, the supplies will become too depleted to sustain the aerobic bacteria population your pile needs. Pile temperature will drop as excess bacteria begin to die. Turning your hot compost pile at this point introduces air and water into the pile, reviving the bacteria population. Temperature rises again as aerobic bacteria reproduce more rapidly.
When to Turn the Pile
Turning the pile also disturbs decomposers as they are shaken up and moved around, so don’t turn a pile more than necessary. The trick is to turn the pile just as pile temperature starts to fall. If you have a compost thermometer, you can take daily readings and turn the pile when temperatures drop.
If you don’t have a compost thermometer, you can use the turning schedule from a typical heat cycle.
RULE OF THUMB
Turn the pile every 4 or 5 days, for 4 or 5 times. Then turn it every 7 to 10 days until finished.
Turn your hot compost pile 4 or 5 days after it was built, and it will heat up again. Wait another 4 or 5 days, then turn again. Continue this pattern.
When the pile has been turned 4 or 5 times by this schedule, the choicest food is gone and natural volume reduction has reduced pile mass substantially. Pile conditions no longer support the types of bacteria that exist in high heat, so pile temperature will remain fairly stable while it finishes composting. At this point, turn it every 7 to 10 days until it is finished.
Re-stacked, Not Stirred
For safety reasons, a pile should be re-stacked, not stirred. The pile will be wet and heavy. If you try to stand beside the bin and stir the pile, you could injure your back.
A better method than stirring is to lift the Compost Bins on CompostMania up from around the pile, set it next to the pile, then turn organic waste from the pile into the bin. Use a 4-prong garden fork or shovel to lift wastes from the pile by bending at the knee and pushing up using your leg muscles rather than your back. (This is the advice many workplaces give to employees about lifting a box. Same concept.)
Inside Out, Outside In
Organic waste that has been heated in the center of the pile will be more decomposed than materials at the outer edge of the pile because they have been better insulated. For the same reason, materials at the bottom of your hot compost pile will be more decomposed than materials that were at the top.
To keep all materials in the pile at the same stage of decomposition, they should each spend some time in the hotter portions of the pile. So when you turn your hot compost pile, try to move materials as follows:
- From the outer edges of the pile to the inside of the bin
- From the inside of the pile to the outer edges of the bin
- From the top of the pile to the bottom of the bin
- From the bottom of the pile to the top of the bin
Transfer all wastes into the compost bin, watering every 6-inches. Break up clumps of material that have matted together. The compost is ready for use when contents can be sifted through a ¼” screen, or when it looks like rich, dark soil.
Mary Tynes, Master Composter, www.mastercomposter.com
Image credit: http://www.flickr.com/photos/cogdog/3475531992/