Compost refers to a biological process that uses any one of several methods to speed up the decomposition of raw organic matter, usually by piling, aerating, and moistening. It is also the crumbly, nutrient-rich product of this process.

Composting is an important means of recycling organic wastes to return their nutrients to the soil, where they become available to plants. Composting reduces or eliminates problems with odors and water pollution from raw waste products such as livestock manure and slaughterhouse and food-processing wastes. Many cities compost yard wastes in order to conserve scarce landfill space. High-temperature composting methods also kill weed seeds and pathogens, turning a potentially expensive health hazard into a valuable resource. The resulting product contains balanced soil and plant nutrients, including trace minerals, and is rich in beneficial microbes that further improve the soil's ability to nourish plants. Composed primarily of humus, compost also conditions...