Yard and Garden: Constructing and Managing Compost Piles


October 20, 2016, 9:52 am | Richard Jauron, Greg Wallace

AMES, Iowa – The fall season brings with it a lot of yard waste and debris. What should be done with it? Try starting a compost pile, which can then be used to enhance soil, garden and plant growth. What are the keys to a great compost pile?

ISU Extension and Outreach horticulturists can help answer your questions about compost piles and how to create them. To have additional questions answered, contact the ISU Hortline at 515-294-3108 or hortline@iastate.edu.

How do you construct a compost pile?

When sufficient materials are on hand, build a pile that is at least 3 feet by 3 feet square and 3 feet in height, but no larger than 5 feet by 5 feet square and 5 feet in height. Use a mixture of garden debris, leaves, grass clippings and other yard waste. Build the compost pile in layers. Start with a 6-to-8-inch-layer of plant material topped with a 1-to-2-inch-layer of soil or previously made compost. Sprinkle 1 to 2 pints of a complete analysis fertilizer, such as 10-10-10, over each layer to supply nitrogen to the microbes. Barnyard manure may be used as an alternative to a commercial fertilizer. A 1-to-2-inch-layer of manure should be sufficient. Continue these layers until the compost pile is 3 to 5 feet in height.

Composting Pic

What types of material can be placed in a compost pile?

Suitable materials for the compost pile include garden debris, leaves, grass clippings, straw, sawdust, and small twigs and branches. You can also add food scraps from produce items, such as apple cores, potato and banana peels, and melon rinds. Coffee grounds and eggshells can also be placed in the compost pile.

What types of material should not be placed in a compost pile?

Don’t add meat scraps, bones, grease, whole eggs or dairy products to the compost pile because they decompose slowly, cause odors, and may attract rodents. Also, don’t add dog feces or spent cat liter to the compost pile. Dog feces and cat liter may contain harmful pathogens that may not be destroyed during the composting process.

Can I put disease-infested plant material in the compost pile?

Temperatures of 150 to 170 degrees Fahrenheit are required to kill most plant disease pathogens. Unfortunately, the internal temperatures of most home compost piles don’t reach this level and the disease organisms are not destroyed. For most home gardeners, it’s best to dispose of diseased plant materials at a public or private yard waste site.

Will a compost pile produce objectionable odors?

A properly prepared and maintained compost pile will generate little, if any, objectionable odors. Unpleasant odors may arise if the compost pile contains excessive amounts of wet plant material (such as fruit or grass clippings), is kept too wet, or is not turned on a regular basis. When constructing the compost pile, mix wet plant material with dry plant debris. Keep the compost pile moist, but not wet. The composting materials should feel damp like a wrung-out sponge. Turn the compost pile at least once or twice a month. Odors are emitted by poorly prepared or maintained compost piles.

How long does it take a compost pile to break down?

The rate of decomposition depends upon the composition of the compost pile, level of management, and other factors. A well-managed compost pile (one that is watered and turned regularly) containing a mixture of plant materials should be ready in two to four months. A good compost pile contains a mixture of green material, such as grass clippings, and brown material like leaves and straw. 

The timing of compost pile construction is another important factor. Compost piles prepared in fall will not be ready until early summer of the following year.  (Little decomposition occurs during the winter months.) Compost piles constructed in spring should be ready in late summer.  

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