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Certain ratios of these materials will provide beneficial bacteria with the nutrients to work at a rate that will heat up the pile.

In that process much water will be released as vapor (" steam "), and the oxygen will be quickly depleted, explaining the need to actively manage the pile.

The hotter the pile gets, the more often added air and water is necessary ; the air / water balance is critical to maintaining high temperatures ( 135 °- 160 ° Fahrenheit / 50 °-70 ° Celsius ) until the materials are broken down.

At the same time, too much air or water also slows the process, as does too much carbon ( or too little nitrogen ).