Mulch is any material that is spread over soil so that air can get through, but less water can evaporate from the soil. Mulch may be made of manure, straw, hay, clover, chaff, alfalfa, corncobs, leaves, sawdust, wood chips, and many other substances. It is often applied about 2 to 3 inches (5 to 8 centimeters) thick. It helps keep water in the soil by reducing evaporation, and it also decays and enriches the soil. It also reduces the number of weeds that would otherwise grow up to compete with plant crops. Mulch is valuable to home gardeners, but it often costs more than commercial fertilizers.
