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Home Composting Slide Show, Part III

Thomas Richard, Robert Kozlowski, Nancy Dickson and Roger Kline
July 1989

III. Materials that can be Composted

Almost any type of organic material can be composted, but some are especially easy to manage in a home composting pile. While most leaves are fairly high in carbon, maple leaves have a C:N ratio near the optimum level of 30:1. With the right moisture and frequent turning, maple leaves can break down in just a few weeks time. Slide not available
in electronic form
Oak leaves have a C:N ratio of about 60:1, and also have high levels of tannins which are resistant to decay. Mixing these leaves with a high nitrogen materials will accelerate their decomposition. Slide not available
in electronic form
Brush can compost or be used as mulch if chipped to a reasonable size. Because wood chips have a high C:N ratio, and large particle size, they will break down relatively slowly. A better alternative is to spread them on paths or use as mulch, easily recycling them to the landscape. Chips are often available free from arborists and utility companies.
Fresh grass clippings are high in nitrogen, about 20:1. By themselves they are too wet and will mat, creating unpleasant anaerobic odors. But they will compost well when mixed with a carbon source such as leaves or brush. (Special thanks to Seattle Tilth Association.)
Short grass clippings are better left on the lawn, where they will decompose and return nutrients and organic matter to the soil. Contrary to popular opinion, clippings will not contribute to thatch buildup.
Clippings from home lawns treated with pesticides may contain chemical residues. With few exceptions, these residues will not persist from one growing season to the next. If the type and level of pesticide used is unknown, those materials should not be added to the compost pile.
Vegetable food scraps can be composted at home, but not meat scraps and grease. These can attract rodents and other varmints.
Wood ash can also be added to the compost pile. It has high levels of potassium and other nutrients for plant growth.
Manures are high in nitrogen, about 20:1, and contain many organisms helpful to the compost process. While horse and cow manure are fine to add to the compost pile, dog and cat litter may contain parasites which can cause human disease.
Other more exotic materials may be available for composting in your area. These aquatic weeds, while a problem for water recreation, make excellent compost if dried out a bit. Food processors may also have by-products that are suitable for composting. (Special thanks to David Stern).
Coarse material, such as corn stalks, small tree and shrub limbs, can also be composted. Shredding these materials increases the surface area that organisms can work on which significantly decreases the time required for composting.
While operating equipment such as chippers and mowers, safety glasses should be worn.

Continue on with slideshow: Part IV. Systems

Back to Composting Slideshow Part II: Manageable Components of the Composting Process


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