What is Composting?
Composting is the biological process of converting organic waste under controlled conditions into a product that provides organic matter and nutrients to the soil. Compost improves soil texture, promotes new plant growth, can suppress some plant diseases, and can prevent soil erosion when used as cover for seeded grasses.
There are two basic types of compost:
Yard Waste Compost - utilizes organic waste from lawns and gardens, such as grass, leaves, and twigs, to create an effective soil amendment. Food Waste Compost - uses food waste such as fruit and vegetable trimmings and kitchen preparation residuals. Together, yard and food wastes comprise nearly 22% of municipal solid waste.
By using compost you return organic matter to the soil in usable form. Organic matter in the soil improves plant growth by helping to break up heavy clay soils and improving their structure, by adding water and nutrient-holding capacity to sandy soils, and by adding essential nutrients to any soil. Improving your soil is the first step toward improving the health of your plants. Healthy plants help clean our air and conserve our soil, making our communities healthier places in which to live!
What Can I Compost?
Note: Care must be taken when composting kitchen scraps. Compost them only by the methods outlined on this page. Meat, bones, and fatty foods (such as cheese, salad dressing, and leftover cooking oil...or anything cooked in it) should be put in the garbage.
How Can I Use Compost?
Materials - Anything growing in your yard is potential food for these tiny farmers, or decomposers. Carbon and nitrogen, from the cells of dead plants and dead microbes, fuel their activity. The micro-organisms use the carbon in leaves or wood wastes as an energy source. Nitrogen provides the microbes with the raw element of protein to build their bodies. Organic material has a ration of carbon to nitrogen (C:N) in its tissues, ranging from 500:1 for sawdust, to 15:1 for table scraps. A C:N ratio of 30:1 is ideal for the activity of compost microbes. This balance can be achieved by mixing two parts grass-clippings (with a C:N ratio of 20:1), with one part fallen leaves (60:1) in your compost. Layering can be useful in arriving at these proportions, but a complete mixing of ingredients is preferable for the composting process. Other materials can also be used, such as weeds and garden wastes. Though the C:N ratio of 30:1 is ideal for fast, hot compost, a higher ratio (i.e., 50:1) will be adequate for a slower compost.
Surface Area - The more surface area the micro-organisms have to work on, the faster the materials are decomposed. It's like a block of ice in the sun - slow to melt when it's large, but melting very fast when broken into smaller pieces. Chopping your garden wastes with a shovel, or running them through a shredding machine or lawnmower will speed composting.
Volume - A large compost pile will insulate itself and hold the heat of microbial activity. The pile's center will be much warmer than its edges. Piles smaller than 3 feet cubed (27 cu. ft.) will have trouble holding heat, while piles larger than 5 feet cubed (125 cu. ft.) won'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.
Moisture and Aeration - All life on earth needs a certain amount of water and air to sustain itself. The microbes in the compost pile are no different. They function best when the compost materials are about as moist as a wrung-out sponge, and are provided with many air passages. Extremes of sun or rain can adversely affect the moisture balance in your pile.
Time and Temperature - The faster the composting, the hotter the pile. If you use materials with a proper C:N ratio, provide a large amount of surface area and a big enough volume, and see that the moisture and aeration are adequate, you will have a hot, fast compost (hot enough to burn your hand!).
Which Wastes? - Kitchen scraps without meat, bones or fatty foods (or foods cooked in fat).
How? - Place the holding unit where it is most convenient. As weeds, grass clippings, and harvest remains from garden plants are collected, they can be dropped into the unit. Chopping or shredding wastes, alternating high carbon and high nitrogen materials, and keeping up good moisture and aeration will all speed up the process. Advantages and Disadvantages? - The units can be portable, and moved to wherever needed in the garden. This method can take from six months to two years to compost organic materials, so you need to be patient.
Variations - Holding units can be made of hardware cloth, old wooden pallets, or wood and wire. Sod can be composted with or without a holding unit, by turning sections of it over, making sure there is adequate moisture, and covering it with black plastic.
Which Wastes? - Non-woody yard wastes are the most appropriate. Kitchen wastes without meat, bones or fatty foods can be added to the center of a pile if it is turned weekly and reaches high temperatures. If the proper temperature is not achieved, or the pile is not turned frequently enough, you might attract unwanted guests and odors to your pile.
How? - Alternate layers of high-carbon and high-nitrogen to approximately a 30:1 ratio. The layers should be moistened to the damp sponge stage. The pile temperature should be checked regularly. When the heat decreases substantially, transfer the pile into the next bin. Dampen the materials if they are not moist, and add more high-nitrogen material if heating is not generated. Start a new pile in the original bin. Repeat the process each time the pile in the first bin cools. After two weeks in the third bin, the compost should be ready for garden use. An excellent source for information on hot composting is the Rodale Guide to Composting which can be found in most libraries.
Variations - The unit can be built of wood, a combination of wood and wire, or concrete block. Another type of turning unit is the barrel composter, which tumbles the waste for aeration. The most common type of barrel composter is made from old, clean 55-gallon drums. Variations include simply leaving the barrel on the ground and rotating it 90-degrees every week.
EARTHWORM COMPOST UNITS
Which Wastes? - Kitchen scraps without meat, bones or fatty scraps.
How? - Fill a bin with moistened bedding such as peat moss or strips of newspaper (1 inch wide maximum). Rotate burying of food wastes throughout the worm bin. Every three to six months the worm population should be divided and moved to fresh bedding. For detailed information on how to compost with red wigglers, see Mary Applehof's, Worms Eat My Garbage which can be found in most libraries.
Advantages and Disadvantages? - This is an efficient way to convert food waste into high quality soil for houseplants, seedling transplants, compost tea to spray on the lawn or water your houseplants, or general garden use. The worms are also a useful product for fishing. However, worm composting is more expensive and complicated than soil incorporation (burying food) for dealing with food wastes.
BUILD YOUR OWN COMPOST UNIT
BUILDING YOUR COMPOST PILE
Build the pile. You may simply throw in organic materials as they become available. This will result in a very slow decomposition process, but may be appropriate if you are not in immediate need of finished compost. If you are building a pile using the batch process for faster decomposition (more than one bin, turning units) follow these steps:
TROUBLE-SHOOTING YOUR COMPOST UNIT
Rodents, racoons and even house pets can be a concern associated with backyard composting. They can be attracted to compost piles both as a source of food and a place to live. Visit Cornell Cooperative Extension's website for help in preventing these problems.
COMPOST IS NOT FOR ME, WHAT CAN I DO?
How? - You can simply spread leaves or grass clippings beneath plantings. For woody materials up to 1 in diameter, rent or purchase a chipper/shredder. Tree services, if they are in your neighborhood, often will deliver wood chips for free.
Advantages and Disadvantages? - All yard waste will work first as a mulch and then, as decomposition proceeds, as a soil enrichment. A disadvantage of mulching with woody yard waste is that you may have to buy or rent a chipper/shredder or make arrangements with a tree service.