The mesophilic phase.

In the first phase of composting mesophilic bacteria will multiply in large numbers. These bacteria can live at temperatures between 30 º and 45º Celsius. They will quickly break down simple sugars and amino acids residues of lawn and food waste such as leftover vegetables. This intense bacterial activity will produce a release of byproducts, mainly CO2 and water vapor. As bacterial activity increases, the compost temperature will also increase and exceed 45 ºC.

The thermophilic phase.

As the temperature rises mesophilic bacteria are replaced by thermophilic bacteria. They prefer a temperature around 60 °C. They will continue to degrade organic matter higher in nitrogen. Thereafter, they will attack the long chains of carbon molecules. At this point, the temperature continues to rise, it will be even higher than 60 ºC. At this temperature, pathogenic bacteria are killed. The weed seeds are destroyed. Subsequently, bacterial activity will decrease and also the temperature of the compost.

Maturation of compost.

During this phase, fungi and actinomycetes come to colonize the compost. These organisms will degrade plants cellulose and lignin. Other small animals such as collembola are coming to live in the compost. They look like small insects. However, they are wingless and they do not pass through a larval phase. They are more closely related to crustaceans. Wood lice are small terrestrial crustaceans that will also come to feed in the compost. Earthworms can even come  in your compost. These organisms will slowly mineralize the organic matter. The end product of composting is a humus-rich with living creatures that can be used as a soil amendment for your plants.