Manure is animal or plant material applied to soil to increase its fertility (see fertilizers). Animal manure is composed essentially of animal wastes together with some plant material, such as straw. It supplies, nitrogen, potash, and phosphates, as well as smaller quantities of copper, iron, and other micronutrients. Green manure consists of growing plants, usually leguminous plants, plowed directly into the soil. Compost comprises plant and sometimes animal material allowed to rot before application to the soil: composts are usually reinforced with nitrogen and phosphorus.