News Release
August 20, 2007

Landscaping Tips: Composting turns yard wastes into rich humus

By Karen Panter, Extension horticulture specialist UW CES

Materials such as yard and kitchen wastes will decompose using the process of composting. The result will be rich, earthy and sweet-smelling humus that can be mixed into garden beds, tilled into soil prior to planting grass, shrubs or trees, added to flower pots or used as mulch.

            There are many benefits to small-scale composting. It reduces dependency on manufactured fertilizers while adding nutrients necessary for plant growth. Composting is inexpensive, and, by recycling organic waste materials, it reduces the need for landfill space.

            Soil pH is altered by adding compost. Ideal pH for growing most fruits, vegetables and herbaceous ornamentals is usually between 6.0 and 7.5. If the soil is too alkaline, which is common in Wyoming, compost may help lower it slowly.

            Wyoming soils tend to be either heavy clay or sandy. Adding organic matter helps improve water permeability, aeration and nutrient-holding capacity in the case of clay soils and moisture-holding capacity with sandy soils.

            Components rich in carbon and nitrogen are essential for a compost pile to work.

            Fresh “green” materials (such as green leaves, fresh grass clippings, green plant wastes from gardens, and fruit and vegetable wastes from the kitchen) will be nitrogen-rich while “brown” components (such as dried leaves, old straw, sawdust and dried grass clippings) are carbon-rich.

            The best carbon-to-nitrogen ratio for compost is about 25 to 30 parts carbon to one part nitrogen. If there is too much brown material in the pile, decomposition will be slowed. If there is too much green material, nitrogen may be lost, and the pile may smell like ammonia.

            High-nitrogen materials, high-carbon materials and thin layers of native soil should be layered when starting a compost pile.

            Organic kitchen waste can be used in a pile. Things like vegetable waste and fruit peelings can be added. Avoid anything of animal origin; these don’t decompose readily and can attract unwanted pests. Because of the potential for high salt content and the spread of disease pathogens, livestock manure is not recommended in a compost pile of this sort.

            Yard waste can be used if chopped into small pieces; however, avoid grass clippings if any type of herbicide has been applied. Also, avoid putting diseased or insect-infested yard waste into the compost bin. Temperatures may not get high enough in the pile to kill them.

            Managing the size of the pile, the carbon-to-nitrogen ratio, temperature, oxygen and moisture content can increase the biological process, which leads to a quality, finished product more quickly than unmanaged piles.

            A compost pile should be in a warm spot but out of the wind so it doesn’t dry out too quickly.

            An ideal size is one cubic yard (3 feet by 3 feet by 3 feet). A pile that is too small won’t heat up enough to kill weed seeds and other pests. If the pile is too tall, aeration needed for decomposition may not be adequate.

                Consistent moisture is important. The pile should be moist enough to feel like a wrung-out sponge. If the pile is too wet, it may give off an unpleasant odor. If it is too dry, it will not decompose.

            Periodically add a little native soil to the pile to incorporate natural, beneficial microbes, which do the decomposing.           

            Turn the pile frequently by using a tool such as a pitchfork as air is essential for the composting process to work.

            Smaller pieces of waste will decompose faster than larger pieces, which can be chopped up before being added to the pile. In Wyoming’s dry, generally cool climate, this is probably the most important factor to expedite the process.

            Backyard Composting: Simple, small-scale methods and other garden, lawn and landscape publications are available on the University of Wyoming Cooperative Extension Service Web site at http://ces.uwyo.edu/PUBS/Horticulture/Horticulture_Publications_Main.htm.    

            The composting bulletin, B-974R, is near the bottom under “Miscellaneous.”

Copies of the six-page bulletin are also available at local extension offices around the state or by calling the College of Agriculture’s Resource Center at (307) 766-2115. Copies are $4 each. Contact information for local offices is at http://ces.uwyo.edu/Counties.asp.

Contact: Robert Waggener, Editor
Phone: (307) 766-3571
E-mail: robertw@uwyo.edu

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