Compost is organic matter that has been decomposed and recycled as a fertilizer and soil amendment. Modern, methodical composting is a multi-step, closely monitored process with measured inputs of water, air and carbon- and nitrogen-rich materials.
It is used in gardens and landscaping. Compost is useful for erosion control, land and stream reclamation, wetland construction, and as landfill cover. Compost is generally recommended as an additive to soil, or other matrices such as coir and peat, as a tilth improver, supplying humus and nutrients. It provides a rich growing medium, or a porous, absorbent material that holds moisture and soluble minerals, providing the support and nutrients in which plants can flourish.