Contact: Diane Relf, Extension Specialist, Environmental Horticulture
Posted April 1997
As most Virginians already know, we are rapidly running out of landfill space. Since yard wastes (leaves, grass clippings, tree prunings) comprise an estimated 15 to 20 percent of landfill space, composting this material would help save a significant amount of room in the landfill.
Composting is the natural decomposition of organic matter by a mixed population of microorganisms (mainly bacteria, fungus, and protozoa) in a warm, moist, aerobic (oxygen-demanding) environment. These microbes are normally found on the surface of leaves, grass clippings, and other yard wastes.
Backyard composting is the first logical step in reducing the amount of organic wastes going into our landfills. Processing yard wastes at the point of generation not only has a positive environmental impact, but also the major costs of collecting, transporting, processing, and marketing by the municipality can be reduced if home composting is encouraged.
Construction of a simple compost bin out of wire or snow fencing, wooden slats, or even old shipping pallets will provide the backyard composter with a suitable area to layer organic wastes such as leaves, grass clippings, and kitchen vegetable scraps and turn them into a soil conditioner. Compost can be made in open piles; however, bin systems keep piles neat and are more appropriate for urban situations. The bin should be large enough to contain a pile capable of holding heat while small enough to allow air to the center of the pile. Generally, the minimum dimensions should be 3 feet square to hold heat. If the bin is too large, air flow will be restricted to the center of the pile and turning it will become quite a chore. Turning the pile is probably the most important and, unfortunately, most ignored step in producing compost.
The microorganisms that decompose yard waste and other materials and turn it into compost require oxygen, moisture, and nutrients to thrive. The oxygen is supplied by aerating (or turning) the pile. Moisture should be added to the pile as the material is layered if it is not already sufficiently moist. You may need to add more water during dry spells. Organic material contains both carbon and nitrogen, the nutrients necessary for energy and growth. The microbes are most active when the ratio of carbon to nitrogen is about 30 to 1. Materials such as leaves, straw, and sawdust are high in carbon; grass clippings, manure, and vegetable scraps are high in nitrogen.
There are unlimited variations of materials that can be added to a compost pile. Any type of yard waste such as leaves, grass clippings, immature weeds, and shredded woody waste can be successfully composted. Materials that should not be composted include meat, bones, fish, fatty food wastes (cheese, oils), dog and cat litter, perennial weeds, and diseased plants.
The addition of compost rich in organic matter has many beneficial effects for the soil, including:
(Originally published by Jim May, Research Assistant, Department of Crop and Soil Environmental Sciences, Virginia Tech, in The Virginia Gardener Newsletter, Volume 9, Number 10.)
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