Composting is the purposeful biodegradation of organic matter, such as yard and food waste. The decomposition is performed by micro-organisms, mostly bacteria, but also yeasts and fungi.[1] In low temperature phases a number of macro-organisms, such asspringtailsantsnematodesisopods and earthworms also contribute to the process, as well as soldier flyfruit flies and fungus gnats. There are a wide range of organisms in the decomposer community.[2]

  • biodegradable material is capable of being completely broken down under the action of microorganisms into carbon dioxide, water and biomass. It may take a very long time for some material to biodegrade depending on its environment (e.g. wood in an arid area versus paper in water), but it ultimately breaks down completely. Many contaminating materials not dealt with in common composting are in fact "biodegradeable", and may be dealt with via bioremediation, or other special composting approaches.[3]

Stable bedding after shredding and three weeks of hot aerobic composting.
  • compostable material biodegrades substantially under specific composting conditions. It is metabolized by the microorganisms, being incorporated into the organisms or converted into humus. The size of the material is a factor in determining compostability, and mechanical particle size reduction can speed the process. Large pieces of hardwood may not be compostable under a specific set of composting conditions, whereas sawdust of the same type of wood may be. Some biodegradeable materials are only compostable under very specific conditions, usually with an industrial process.