Darryl Edwards
The compost will begin to get hot very quickly. Under ideal conditions the temperature can reach 70%C within 48 hours. This is undesirable. If the temperature in the pile reaches 70%C it becomes too hot for the microbes, which are creating the heat, to exist. Carbon also begins to be burnt and this is wasteful. This heat is created by the reproduction of thermophilic bacteria and will only occur if there is adequate water and oxygen.
Heat is however essential to kill all seeds in the compost and all undesirable pathogens. This is achieved in the temperature range from 55%C to 68%C. The temperature needs to be maintained in this range for at least 3 days. All parts of the pile need to be exposed to this heat. This heat however only exists on the inside of the pile (the outer 40cm is much cooler). This is one of the reasons why turning is important. Each time you turn the pile you should attempt to move material from the outside to the inside, and visa verse.
If the temperature of the pile is too high (ie. Approaching 70%C) then the only way to reduce it is to turn the pile. When turning the pile gauge whether the moisture content is still adequate. A lot of moisture is lost as steam and this needs to be replaced. The adding of water can also cause cooling.
The simplest way to determine what the temperature within the pile is, is by using a temperature probe. For rural folk this would be difficult to obtain or purchase, thus some simple method of ascertaining the approximate temperature by touch needs to be devised.
The turning process has thus achieved three things:
1. Exposed new material to the required heat,
2. Aerated the pile with oxygen, essential for the heat process and
3. Allowed for the lost moisture to be replaced.
At this point it is important to note that if the pile is not turned it will become anaerobic. This means that it will run out of oxygen. If this happens the desirable bacteria will die off or go dormant and undesirable anaerobic bacteria will become dominant. If this happens the temperature will drop and often a bad smell will be noticed.
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