Home and Community Action - Composting

Composting is a natural process where plant and other organic wastes are broken down biologically, resulting in a nutrient-rich material. This material is compost and it can be used to improve the quality of our soil.

Between 20% and 30% of our waste stream is made up of organic materials. There is no need for these materials to be in our landfills. Each autumn, this amount more than doubles when fall leaves and garden trimmings are added to what the municipal trash collection services pick up. Each year, over 24 million tons of leaves and grass cuttings are thrown out. Yard and kitchen waste takes up a lot of landfill space needlessly, as these materials could be added to our gardens and public lands to enhance the quality of the soil through composting.

Composting works by the action of microorganisms (microbes) such as bacteria and fungus which decompose organic materials. The microbes consume the carbon in the waste, thus turning it into carbon dioxide, water, and humus (partially decomposed plant and animal material). This action warms up the compost pile to 160 degrees Fahrenheit, which kills the harmful organisms such as weeds and pathogenic bacteria. The resulting by-products of this process become the food for other microbes. This biodegrading chain of events continues until the waste disintegrates into compost.

Small-scale composting such as that in single family households can produce up to 300 pounds of compost a year. This completely eliminates the need to buy commercial fertilizers for the garden and diverts waste from the landfills. Compost made at home is also a lot safer to use, because you know what's in it. Commercial compost may contain toxic waste from our garbage and thus heavy metals may exist in the finished product. This is an issue currently being studied.

A backyard compost system is easy to build. As an alternative, a commercial compost container can be purchased from a home and garden supply store. The key is to keep the air flowing through the pile of waste - this will ensure that the microbes are able to complete the decomposition process. Simply turn the pile often with a shovel to allow the air to reach all portions of the heap. Large items added to the pile should be chopped or shredded first to speed the decomposition process along.

The compost pile should be moist, but not dripping wet. Normal rainfall generally does this. However, you may need to sprinkle the pile in dry spells and cover the pile when rainfall is heavy. If you see water vapor rising from the pile, this is normal - remember the metabolic action of the microbes raises the temperature of the pile to 160 degrees Fahrenheit.

The figure shows an example of a commercial composting kit which the City of El Monte, California, makes available to the community for a nominal fee.

If you choose to compost at home, you will find that the resulting material is far better for growing plants than the most expensive potting soil you can buy and it's free! Below is a list of what can be composted and what cannot be composted: