NOVEMBER

2003

11-06-03

Compost is Recycling Naturally

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Composting is a great way to recycle the plant debris in your garden, including both crops and weeds. It's easy to do--nature does it on its own all the time. But with proper management, you can help nature move along a little faster, if needed.

Compost returns some nutrients back to the soil, but the main benefit is in the improved soil structure. Adding organic matter, such as compost, will increase soil aeration and water-holding capacity, as well as increase the ability of a soil to hold additional nutrients for plants to take up later.

Having a compost bin or wall structure to contain the pile can help keep the pile in neat formation, but heaping the contents on the ground can work just as well. (Note: some areas have mandated that compost piles must be contained; check with your local health department or the Purdue Extension office in your county.) If a structure is used to contain the compost, removable horizontal slats will help make the structure adapt to the size of the pile, as it grows or shrinks, and will allow for easier turning.

To make your own compost, construct the pile in layers, beginning with about a 2-inch layer of soil. Soil contains microorganisms, which are responsible for breaking down organic matter. Then add 6-8 inches of plant debris, such as dry leaves, lawn clippings and faded garden plants.

The microorganisms will need nitrogen to break down the carbon in the plant material. Your pile already may have sufficient nitrogen, if there is a good balance of fresh green material, such as grass clippings, along with some dried material, such as dead leaves. If the pile is mostly dried plant material, sprinkle about a cup of commercial nitrogen fertilizer over a 25-square-foot compost pile as your next layer. Manure is also an excellent source of nitrogen, and 1-2 inches of rotted manure can be substituted for the commercial fertilizer. Water the pile thoroughly, and then repeat each layer until the pile is a workable height.

As the materials decompose, the temperature in the center of a good-sized pile can reach as high as 160 F, which will kill off some disease organisms and weed seeds. The minimum-size pile for heat generation is about 3 feet by 3 feet by 3 feet. Moist compost will heat more uniformly, so be sure to water the compost occasionally if needed, but do not waterlog the materials, as that will drive out much-needed air.

You can let nature take over from here, if you're not in a hurry. But, for faster results, you'll want to turn the pile about every month or so to allow more even heating of the contents and to incorporate air into the center.

Compost is ready to use when it's dark and crumbly and looks very much like good-quality soil. No telltale signs of the original material should be recognizable. Depending on outdoor temperatures and how well you tend the pile, your compost may be ready to add back to the garden by next spring. 

For more information on how to compost, look for Purdue Extension bulletin ID-182, "Managing Yard Wastes: Clippings and Compost" online at http://www.hort.purdue.edu/ext/ID-182.pdf.