Composting Home and Garden Waste
by Alix Carpenter
University Outreach & Extension Agronomy Specialist

Each summer, we spend an increasing amount of time in our gardens. The process of searching for the perfect plants and the never-ending struggle to keep the yard clean of weeds and other pests can be time consuming. There is however, one simple thing that can be done to improve the garden: make compost. Composting is an inexpensive, practical, and convenient way to transform kitchen and yard wastes into a valuable resource for use in the garden.

Since the disposal of yard clippings, leaves and branches in Missouri’s landfills was banned in 1992, home gardeners have been left with a problem: what to do with this waste? As these materials cannot be disposed of in a traditional fashion, composting is an excellent way to solve this problem, while increasing the health of the soil.

Composting is the biological decomposition, or breakdown, of organic material by organisms which live in the soil. The result of the decomposition is a dark, rich, almost sweet-smelling soil conditioner called compost, or humus. Compost contains nutrients essential to plant growth, although in low enough amounts that it cannot be marketed as a fertilizer. Compost provides great benefits to the soil: soils enriched with compost are less likely to become compacted, can hold more water, and release nutrients slowly.

Creating compost is a simple process which requires the proper ingredients, moisture, air, and time. "Growing" a rich compost requires a mixture of green and brown materials. Green materials are those which are rich in nitrogen, such as fresh grass clippings, coffee grounds, egg shells, and fruit and vegetable peelings. Brown materials are rich in carbon, and include dead leaves, dried grass, paper products, and woody materials. Paper products should be shredded and used in moderation; woody materials will decompose faster if first run through a chipper/shredder. Materials which should not be composted are diseased plants and kitchen items such as grease, fat, meat scraps, and bones.

A good mix for compost is roughly 3 parts brown material to 1 part green material, based on volume. The green and brown materials should be layered in an alternating fashion, and mixed well (a pitchfork works well for this). A compost pile should be at least three feet tall, three feet wide, and three feet deep. If a container is preferred, they are available in a wide range of shapes, sizes, and costs, from high-tech, quick-composting designs to those which can be made at home for a few dollars from items picked up at the local hardware store.

Once the ingredients are placed in their container, they should be watered until they are as damp as a wrung-out sponge, and should not be allowed to dry out (the organisms which decompose the mixture need the moisture to thrive). The container should be placed in an easy-to-access, semi-sheltered area. New ingredients can be added to the pile as they become available, and should be mixed in. When placing kitchen scraps in a compost pile or container, they should be buried in the pile at least 8 to 12 inches to prevent odors. Periodic mixing of the compost pile contents allows for air infiltration to the mixture, which also aids the decomposition process.

The time required to achieve a fully composted pile depends on several factors, and takes roughly 8 months under normal conditions. The amount and size of materials placed in the container, the type of container, and effort put into keeping the compost moist and aerated will all affect how long the composting process takes.

When the composting process is complete, the compost is dark, crumbly, and has a pleasant odor. The compost can be mixed with other growth media, such as peat moss, sand, or shredded bark, for use as a planting mix. The compost can also be tilled directly into the soil, where it will insulate the soil from temperature extremes, stimulate crop growth, loosen clay soils, and bind sandy soils.

Classes on composting for homeowners will be offered by University of Missouri Extension this summer. If you are interested in taking a composting class, or if you would like more information on composting, please call the Marion County Extension Center at (573) 769-2177.