Composting is a great way to discard yard waste and kitchen scraps. In many cases, it's more economical than paying to have these wastes hauled away. And you can improve the health of your soil by adding the compost to your garden or yard.

To construct a composting area, determine the size. "A large compost pile will insulate itself and hold the heat of microbial activity," said Joe Heimlich, environmental science leader for Ohio State University Extension. "Its center will be warmer than its edges. Piles smaller than 3 feet cubed (27 cu. ft.)will have trouble holding this heat, while piles larger than 5 feet cubed (125 cu. ft.) don't allow enough air to reach the microbes at the center. These proportions are of importance only if your goal is a fast, hot compost. Slower composting requires no exact proportions."

First, remove the grass and sod from the designated area. This allows decaying materials direct contact with soil microorganisms. Heimlich suggests the following "recipe" for constructing compost heaps that work the fastest:

• First layer: about 3-4 inches of chopped brush or other coarse material on top of the soil surface allow air circulation around the base of the heap.

• Second layer: About 6-8 inches of mixed scraps, leaves, grass clippings or sawdust. Materials should be "sponge damp."

• Third layer: One inch of soil serves as an innoculant by adding microorganisms to the heap.

• Fourth layer (optional): About 2-3 inches of manure will provide the nitrogen needed by microorganisms. Sprinkle lime, wood ashes and/or rock phosphate over the layer of manure to reduce the heap's acidity. Add water if the manure is dry.

• Fifth layer: Repeat steps 1-4 until the bin is almost full. Top off the heap with a 4-6 inch layer of straw and scoop out a basin at the top to catch rainwater.

Your compost heap should reach temperatures between 120 and 140 degrees Fahrenheit in four to five days. The pile should then begin to settle-a sign the heap is working properly.

After five or six weeks, move materials into a new pile and turn the contents so that the outside of the old heap is now the center of the new heap. Add water if necessary.

Your compost should be ready to use in three to four months. For spring compost, start a heap in late autumn. For fall compost, start a pile in early spring. The more often you turn the pile, the faster you will have compost. Check the internal temperature regularly and if it changes substantially (usually after about a week), turn the pile.

You'll know when your compost is done "baking" because it will be dark brown, crumbly and earthy-smelling. Be sure to let it stabilize for a few extra days and screen it through a half-inch screen if you want a finely textured material.

For more detailed information, read Composting at home