Backyard composting is an extension of processes that have gone on in nature since the origin of life. Without decomposition, the earth would soon be covered with dead animals and plants. With nothing going back into the soil, the soil soon would lack sufficient nutrients for the continuation of life. Natural recycling of these nutrients improves the soil in your yard and makes it more productive while reducing the rate at which landfills reach capacity.
What Is Composting?
Composting is a controlled natural biological process where bacteria, fungi (microbes), and other organisms decompose organic materials like leaves, grass clippings, and food wastes. The end product is called compost, or humus. During composting, microbes utilize the decomposable matter both as an energy source and for making additional microbes. The word “controlled” distinguishes composting from other natural processes such as rotting or putrefaction, which are less desirable.
`The practice of placing materials like compost on the surface of the soil to moderate temperature, conserve moisture, and control weeds and erosion is called mulching. Adding uncomposted materials directly to the soil may produce some undesirable effects. The microbes that break down the organic wastes will compete with the plant roots for nitrogen. This will result in nitrogen deficiency and poor plant growth. Composted materials are also easier to handle and incorporate into the soil
Materials for Composting
Any organic material can be composted. However, many are more desirable and easier to work with than others. Yard wastes such as leaves, grass clippings, straw, and nonwoody plant clippings produce high-quality compost with relative ease.
Grass Clippings and Woody Materials
Grass clippings need not be removed from the lawn. However, if they are collected, they should be mixed in with other materials such as leaves. This will prevent them from becoming matted down and anaerobic. Clippings treated with herbicides are allowable if added in small quantities and allowed to thoroughly decompose.
Woody materials such as branches, logs, and twigs may be used if they are chipped to ¼ inch or less.
Other Acceptable Materials
Kitchen wastes: Kitchen wastes such as coffee grounds, egg shells, and vegetable scraps may be added.
Sawdust: Sawdust may be added if nitrogen is supplied at the rate of one pound of actual nitrogen (6 cups of ammonium nitrate) per 100 pounds of dry sawdust.
Wood ash: Wood ash acts like lime and should not be added at more than one cup per bushel of organic matter.
Newspaper: Newspaper may be added to compost piles, although paper is very high in carbon and will slow down the rate of decomposition. Slick paper with colored inks should not be used. It is recommended that newspaper be recycled through appropriate community paper recycling centers rather than backyard composting.
Materials that should NOT be added to compost piles include human and pet feces, which can transmit diseases. Meat, bones, whole eggs, or dairy products should not be added as they may attract rodents.
Commercial microbial preparations (compost starters) that claim to enhance composting are unnecessary. Microbes necessary for the decomposition of organic matter are everywhere. You can get a faster startup of microbes by mixing a small amount of soil or finished compost in with the material to be composted.
Composting can be done in a pile, a bin, or a pit, depending on what is convenient. To save space, hasten decomposition, and keep the yard looking neat, contain the compost pile in some type of structure.
Ideally, the smallest size for a compost pile is 3 feet by 3 feet by 3 feet (1 cubic yard). This allows for moisture retention and insulation of the pile against changes in the external environment. Very large piles become anaerobic if not turned frequently.
Large plastic garbage bags may be used to form compost anaerobically. Fill a 30- to 40-gallon bag with organic wastes. Add one tablespoon of high nitrogen fertilizer and one cup of lime. Mix. Add one quart of water. Seal the bag. You will have compost in six months to a year.
A barrel or drum composter will generate compost in a shorter period of time. You need a 55-gallon plastic or metal barrel with lid. Make sure the drum has not been used for toxic chemicals. Drill six to nine rows of ½-inch holes around the barrel. Fill the barrel two-thirds full with organic matter. Add ¼ cup of high nitrogen fertilizer. Add water if necessary. Every few days, secure the lid, turn the barrel on its side, and roll around the yard to mix and aerate the compost. Compost should be ready in two to four months.
Bin-type structures handle larger volumes and can be made from woven wire without much expense. Woven wire should be 4 to 5 feet wide and 18 to 20 feet long. Bind the two ends together, and fill with compost. When it is time to turn the compost, lift the wire frame, move over a few feet, and turn the compost back into it.
A three-chambered bin will be efficient and durable. It works like an assembly line with compost turned back and forth in the first two bins and stored for future use in the third bin. Wire, wood, masonry material, or a combination may be used. All wood should be pressure treated to ensure that it will last for more than a year or two.
Uses for Compost
Finished compost will have about half its original volume. It should be dark brown or black and crumbly and have an earthy smell. The pH will be neutral to slightly alkaline.
Compost may be used as a soil conditioner. As a soil amendment, it improves the soil’s physical condition and fertility. Compost makes heavy clay soils easier to work and, as a result, improves aeration, root penetration, and water infiltration. Addition of compost to sandy soils helps retain water and nutrients.
Although compost contains some nutrients, it should not be considered a fertilizer. In most cases, additional fertilization will be necessary to achieve maximum plant growth and production. Nevertheless, the humus in compost will increase the efficiency of fertilizer used.
Compost makes a good mulching material. It can be used around both garden and landscape plants. It can also be used as a growing medium for house plants or, once pasteurized, for starting seeds.
For more information contact the Laurel County Cooperative Extension Service at 606-864-4168 or go to www.laurel.ca.uky.edu.