Compost is a kind of soil conditioner made from partly decayed plant material. Gardeners mix it with the soil to loosen the structure of the soil. Most compost also provides nutrients (nourishing substances) to the soil. Compost may also be used as a mulch—that is, spread on top of the soil to keep moisture in (see Mulch ).
Compost is made by placing dead plant parts in a pile and allowing them to decay. Grass and garden clippings, leaves, and coffee grounds are the materials most commonly used, but any plant material is suitable. Some people use a compost pile to dispose of food wastes, rather than putting them in the garbage. All of these materials are packed in layers about 6 inches (15 centimeters) deep. After each layer, a thin layer of manure or soil is usually added to speed decay. Watering the mixture also speeds decay. If a container is used for the compost pile, its walls should allow some air to enter. The compost should decay for five to seven months before it is used.
