Organic matter is anything that contains carbon compounds that were formed by living organisms. It consists of dead and decaying forms (mainly plants and manures), living plants (mostly roots) and living micro-organisms and soil animals
Why do we care?
Because nutrients taken up by plants in the natural environment (this excludes commercial agriculture) are derived largely from the decomposition process of soil organic matter It is easy (and cheap!) to make your own compost. If using your own chicken or farm manures, it is a good idea to run it through your compost system where the heat of the composting process will destroy most weed seeds. Fresh chicken manure is too ‘hot’ to use directly in the soil and should always be composted before use.
Humus, compost and organic matter are often incorrectly used interchangeably. Humus and compost are different, but both are components of organic matter.