Q. How should I start a compost pile?
A. Falling tree leaves means it's time for yard cleanup and time to start or add material to a compost pile. Compost can provide valuable organic matter and nutrients to help improve the health of your flowers, vegetables, shrubs and trees. Organic matter is like a magic rejuvenating elixir for your yard. It improves soil aeration and soil drainage when added to a clay soil. Adding organic matter to a sandy soil improves nutrient and water holding capacity.
Compost can also be used as a mulch material. Mulch cools soils in the summer, helps moderate winter cold, inhibits weed growth, prevents moisture loss, and keeps string trimmers away from tree trunks.
Before you create your compost pile, consider what structure you want to use to contain the pile. There are as many ways to create a compost structure, as there are people. You can use old pallets, hardware wire or get fancy and build a structure out of cedar. If you would rather purchase a compost structure, check out the many designs of plastic or wooden composters at a garden center or in a gardening catalog.
The best size for nonplastic structures is 4 feet by 4 feet. The minimum size is 3 feet by 3 feet and the maximum is 5 feet by 5 feet for nonplastic structures. Plastic structures can be smaller because they insulate better than other materials. You can also compost without a structure by simply creating a pile of garden debris, but it takes a lot more time than with a structure and takes up a large amount of space.
After you have decided on a compost structure, select a location for your compost pile. Choose a location that is out of general view and away from where people frequently walk or play. Pack the soil underneath the pile and put down a piece of heavy plastic if trees or shrubs are nearby. This will prevent pile invasion by tree or shrub roots.
To create a pile use alternating layers of green and dried plant material. Put down five to six inches of dried material, followed by four to six inches of green material. When using green grass clippings, two to three inches is plenty. If manure is available, add two to four inches over the green materials layer. Next, add a thin ¼ inch layer of soil or finished compost to the pile. Water to wet the layers to the consistency of a damp sponge, without making the layers boggy. Repeat the process over and over again to build a layered compost pile three to four feet tall.
Nitrogen fertilizer can be substituted for green materials. Scatter one cup of 10-20-10, one-third cup of ammonium sulfate (34-0-0) or one-quarter cup of urea (46-0-0) over each layer of the dried plant material.
The soil or compost added to the pile supplies the organisms that make composting work. You can also purchase packets containing microorganisms to speed the composting process.
Your pile should start heating within several days. When all is going well, the center of the pile can reach 130 to 170 degrees Fahrenheit. If you are using a thermometer, turn the pile when the pile center reaches 140 degrees Fahrenheit. Another way to check the compost pile heat is to insert a stick or wire into the pile center. Remove the wire or stick and touch it to check for heat. When the wire or stick is too hot to hold, it is time to turn the pile. As you turn the pile, move the outside portion to the center.
The more variety of plant materials you use to build your pile, the better your compost will be. Green materials that are commonly available include grass clippings, hedge trimmings, harvested vegetable plants and flowers. Dried materials can be leaves that fall from trees and shrubs, dried grass clippings or dried up flowers and vegetables. Green plants are high in nitrogen, while dried materials are high in carbon. Both elements are necessary for composting.
Do not add pet waste, meat scraps, weeds with seeds, plants with nematodes or diseased plants to the compost pile. Do add nonmeat kitchen scraps, such as coffee grounds, eggshells, vegetable trimmings, fruit peelings, peanut shells or pecan shells.
Plant debris will compost faster if you run it through a shredder before adding it to the compost pile. At the very least, take a sharp flat spade and chop up the larger materials into smaller pieces.
Finally, to speed the compost process check your pile on a regular basis and water as needed. In the summer, you will want to water every four to seven days. In the winter, check your pile twice a month and water as needed.
Ray Ridlen is an agriculture/horticulture educator for the Oklahoma County Extension Service. For more information, call 713-1125.