All organic matter eventually decomposes. Composting speeds the process by providing an ideal environment for bacteria and other decomposing microorganisms, and the final product looks and feels like fertile garden soil. Decomposing organisms consist of bacteria, fungi and larger organisms such as worms and numerous other bugs.
Decomposing organisms need four key elements to thrive: nitrogen, carbon, moisture, and oxygen. When doing your own composting, mix materials high in nitrogen (such as clover, fresh grass clippings and livestock manure) and those high in carbon (such as dried leaves and twigs) for best results. If there is not a good supply of nitrogen-rich material, a handful of general lawn fertilizer will help the nitrogen-carbon ratio. Moisture is provided by rain, but you may need to water or cover the pile to keep it damp. Be careful not to saturate the pile. Turning or mixing the pile provides oxygen and frequent turning yields faster decomposition.
1. Getting Started
Many materials can be added to a compost pile, including leaves, grass clippings, straw, woody brush, vegetable and fruit scraps, coffee grounds, livestock manure, sawdust and shredded paper. Do not use diseased plants, meat scraps that may attract animals and dog or cat manure, which can carry diseases. Composting can be as simple or as involved as you would like, and depends on how much yard waste you have, how fast you want results, and the effort you are willing to make.
2. Cold or Slow Composting
With cold or slow composting, you can simply pile grass clippings and dry leaves on the ground or in a bin. This method requires no maintenance, but it will take several months to a year or more for the pile to decompose.
Cold composting works well if you want to spend less time on composting overall, but you will need to tend the compost pile at least every other day. This method is great if you have little yard waste and are not in a hurry to use the compost. Be sure to keep weeds and diseased plants out of the mix since the temperatures reached with cold composting will not be high enough to kill the weed seeds or disease-causing organisms. Add yard waste as it accumulates - to easily shred material, run your lawn mower over small piles of weeds and trimmings. Cold composting has been shown to be better at suppressing soil-borne diseases than hot composting, but it also leaves more undecomposed bits of material, which can be screened out if desired.
3. Hot Composting
Hot composting requires more work but with just a few minutes a day and the right ingredients, you can have finished compost in a few short weeks depending on weather conditions. The composting season coincides with the growing season. When conditions are favorable for plant growth, those same conditions work well for biological activity in the compost pile. However, since compost generates heat, the process may continue later into the fall or winter.
Hot piles do best when high-carbon material and high-nitrogen material are mixed in a 1:1 ratio. A pile with the minimum dimensions of 3' x 3' x 3' is needed for efficient heating. For best heating, make a heap that is 4 or 5 feet in each dimension. As decomposition occurs, the pile will shrink. If you do not have this amount at one time, simply stockpile your materials until a sufficient quantity is available for proper mixing.
Hot piles are HOT! The temperature can reach 110 to 160 degrees Fahrenheit. This temperature is hot enough to kill most weed seeds and plant diseases. Studies have shown that compost produced at these temperatures has less ability to suppress diseases in the soil since these temperatures may kill some of the beneficial bacteria necessary to suppress disease.
1. Choose a level, well-drained site, preferably near your garden.
2. There are numerous styles of compost bins available depending on your needs. These may be as simple as a movable bin formed by wire mesh or a more substantial structure consisting of several compartments. While a bin will help contain the pile, it is not necessary. You can build your pile directly on the ground. To help with aeration, you may want to place some woody material on the ground where you will build your pile.
3. To build your pile, either use alternating layers of high-carbon and high-nitrogen material or mix and then heap into a pile. If you alternate layers, make each layer 2 to 4 inches thick. Use approximately equal amounts of each. If you are low on high-nitrogen material, you can add a small amount of commercial fertilizer containing nitrogen. Adding a few shovels of soil will also help get the pile off to a good start; soil adds commonly found decomposing organisms.
4. Water periodically. The pile should be moist but not saturated. If conditions are too wet, anaerobic microorganisms will continue the process. These are not as effective or as desirable as the aerobic organisms. Bad odors also are more likely if the pile is saturated.
5. Punch holes in the sides of the pile for aeration.
6. The pile will heat up and then begin to cool. Start turning when the pile's internal temperature peaks at about 130 to 140 degrees Fahrenheit. You can track this with a compost thermometer.
7. Move materials from the center to the outside and vice versa. Turn every day or two and you should get compost in less than 4 weeks. Turning every other week will make compost in 1 to 3 months. Finished compost will smell sweet and be cool and crumbly to the touch.
4. Common Problems
Composting is not an exact science. Experience will tell you what works best for you. If you notice that nothing is happening, you may need to add more nitrogen, water or air. If things are too hot, you probably have too much nitrogen. Add some more carbon materials to reduce the heating. A bad smell also may indicate too much nitrogen.
Cold composting often proceeds faster in warmer climates than in cooler areas. Cold piles may take a year or more to decompose depending on the materials in the pile and the conditions.
Adding kitchen wastes to compost may attract flies and insects. To prevent this problem, make a hole in the center of your pile and bury the waste. Check on any local or state regulations for composting in urban areas -some communities may require rodent-proof bins.
5. Using Compost
Compost can be used for all your planting needs. Compost is an excellent source of organic matter to add to your garden or potted plants. It helps improve soil structure, which contributes to good aeration and moisture-holding capacity. Compost is also a source of plant nutrients.
Compost can also be used as a mulch material. Studies have shown that compost used as a mulch, or mixed with the top one-inch layer of soil, can help prevent some plant diseases, including some of those that cause damping of seedlings.