Composting. Decomposition of the organic, biodegradable fraction of waste to produce a stable product such as soil conditioners and growing material for plants. Composting of garden and food waste has been encouraged for home owners as a direct way of recycling. It has been extended to the larger scale for green waste from parks and gardens and also to municipal solid waste and to sewage sludge, The quality of compost produced from waste, compared with non-waste sources , has been an issue for waste composting, particularly in the area of contamination.