Is Leaf Mulch Good Compost?

Autumn leaves are an excellent source of free material for compost or mulch. Leaves are used as part of a compost pile recipe or alone as mulch material. Compost is a mixture of materials -- including leaves -- that have decomposed into fertilizer. Mulch is material spread as a layer around plants to enrich or insulate the soil.

Compost contains microorganisms absent in synthetic fertilizers. Microorganisms ingest and break down plant materials, releasing nutrients into the soil. Plants absorb nutrients from compost as needed at a slow rate. Carbon materials and nitrogen materials are used to create a compost pile. Leaves are one of the best sources of carbon. Piles heat up to the necessary 130 degrees Fahrenheit or more through the action of nitrogen (greens) on carbon materials (browns). A compost pile decomposes successfully when the pile has a ratio of 25 to 1 of carbon materials to nitrogen materials Other carbon materials used are sawdust, straw, newspaper, paper and corrugated cardboard. Most home gardeners rely on the ready supply of leaves for the browns needed for their compost recipe.

Green materials supply nitrogen to the compost pile, which creates the heat needed for decomposition. Heat kills weed seeds, insect eggs and plant diseases. Grass clippings, green yard debris, vegetable scraps, blood meal, dried horse manure, cottonseed meal and fruit scraps are high-nitrogen materials. Brown materials and green materials are layered in the pile, watered and occasionally aerated to speed up the decomposition process. Shredding the leaves and other materials quickens the decomposition process. Aerate by turning with a pitchfork or shovel. Rich, sweet-smelling, crumbly compost fertilizer is made in two weeks to four months, depending on conditions.

Mulches are made with many types of materials, including leaves. Mulches are used to keep moisture in the soil, provide nutrients as they decay, make landscapes more attractive, reduce weeds and the amount of maintenance for flowerbeds. Leaves used as mulch have the advantage of an attractive appearance and easy availability, but the disadvantage of blowing away easily and compacting easily. Leaf mulch needs to be replaced yearly. It is sometimes recommended that leaves be composted before they are used as mulch.

Mulches made with leaves are not considered fertilizer. Leaves release some nutrients as they decompose, but it is not enough to satisfy the needs of growing plants. Plants require 16 nutrients to grow and thrive. Mature compost that contains leaves provides the nutrients plants needs. It can be used underneath a layer of leaf mulch. Fruit trees benefit from a mulched area 3 to 4 feet in radius around the base. Soil around perennial flowers is kept cool and moist by adding a 2- to 3-inch layer of leaf mulch.