An ideal compost pile contains a mix of carbon and nitrogen. Carbon provides energy for decomposition and is composed of plant materials such as straw, wood chips and shredded leaves. Nitrogen, supplied by fresh grass clippings and manure, helps the organisms in the pile grow. For best results, the carbon-nitrogen ratio should be between 25:1 and 30:1. Conveniently, horse manure by itself is close to the ideal ratio, so it makes quick, nutrient-rich compost.
Choose your site. Pick a location that meets local codes concerning distance from streams, wetlands and wells. Your county cooperative extension agent can provide this information for your area.
Locate the pile in a flat, dry and convenient spot that is within reach of your garden hose.
Build your bins. Bins contain the materials for faster composting. Inexpensive manure composting bins can be made with shipping pallets. Wire or nail three pallets together to make a C-shaped, open-front bin. Attach another section to make a double bin.
Add materials. Add manure to the first bin. Cover the manure with a light layer of topsoil to discourage flies.
Aerate the pile to speed decomposition. To aerate the pile, turn it weekly with a garden fork. If this is not practical, obtain a 5-foot section of PVC pipe. Drill ½ holes on opposite sides of the pipe. Space the holes every 6 inches from the top of the pipe to the bottom. Insert this "chimney" into the center of the pile.
Cover the bins or piles with a tarp that extends past the edges of the mound. This will reduce runoff and prevent flies from using the pile as a breeding ground.
Monitor the temperature. Insert a compost thermometer into the center of the pile. At first, the pile will be warm---less than 110 degrees Fahrenheit. As the pile grows and decomposition increases, the temperature should rise. To kill weed seeds and pathogens, the pile should hover between 135 and 150 degrees for at least one week. Do not let the pile get too hot---over 160 degrees---to avoid killing the organisms responsible for decomposition. If your pile is too hot, reduce its size.
Add water if necessary. Your compost should be the consistency of a wrung-out sponge. It should not be dripping wet. If it seems too wet, turn the pile and add some dry materials like hay or straw.