ABSTRACT
A typical mineral soil contains between 2 and 5 per cent organic matter. This organic matter is all derived from living organisms such as plants, earthworms, insects, fungi and bacteria. On death these plant and animal remains decompose and are recycled along with any other organic matter that is added. To a greater or lesser extent the plants grown in horticulture are incorporated along with bulky organic matter imported from elsewhere such as farmyard manure, compost, spent mushroom compost, coir and bark.
