Compost is the end product of a complex feeding pattern involving hundreds of different organisms, including bacteria, fungi, worms, and insects.
What remains after these organisms break down organic materials is a rich, earthy substance your garden will love.
In every forest, grassland, jungle, and garden, plants die, fall to the ground, and decay. They are slowly dismantled by the small organisms living in the soil. Eventually these plant parts disappear into the brown crumbly forest floor. This humus keeps the soil light and fluffy. Composting replicates this natural system of breaking down materials on the forest floor with the added benefit of heat.
A good compost pile can heat up to over 160 degrees at it's peak, killing off most weed seeds and many harmful diseases. Keeping a compost thermometer in the pile will help guide you as to when to turn the pile during the process. Several days after reaching a peak temperature, the temperature will drop. After it drops 30 degrees or so, turn the pile. This process create suitable compost in the shortest time possible. If you don't relish the idea of turning a compost pile, just add materials throughout the summer and leave it alone. By the following summer, most of the material will be suitable to reapply to the garden.
By providing the right environment for the organisms in the compost pile, it is possible to produce excellent compost. We usually want to organize and hasten Mother Nature's process. By knowing the optimum conditions of heat, moisture, air, and materials, we can speed up the composting process. Besides producing more good soil faster, making the compost faster creates heat which will destroy plant diseases and weed seeds in the pile.
Almost any organic material is suitable for a compost pile. The pile needs a proper ratio of carbon-rich materials, or "browns," and nitrogen-rich materials, or "greens." Among the brown materials are dried leaves, straw, and wood chips. Nitrogen materials are fresh or green, such as grass clippings and kitchen scraps.
Mixing certain types of materials or changing the proportions can make a difference in the rate of decomposition. Achieving the best mix is more an art gained through experience than an exact science. The ideal ratio approaches 25 parts browns to 1 part greens. Judge the amounts roughly equal by weight. Too much carbon will cause the pile to break down too slowly, while too much nitrogen can cause odor. The carbon provides energy for the microbes, and the nitrogen provides protein.
Leaves represent a large percentage of total yard waste. If you can grind them in a shredder/chipper or mow over them, they will reduce in size making them easier to store until you can use them in the pile, and they will decompose faster - an issue with larger leaves. They are loaded with minerals brought up from the tree roots and are a natural source of carbon. A few leaf species such as live oak, southern magnolia, and holly trees are too tough and leathery for easy composting. Avoid all parts of the black walnut tree as they contain a plant poison that survives composting. Eucalyptus leaves can be toxic to other plants. And avoid using poison oak, poison ivy, and sumac.
Pine Needles need to be chopped or shredded, as they decompose slowly. They are covered with a thick, waxy coating. In very large quantities, they can acidify your compost, which would be a good thing if you have alkaline soils.
Clippings break down quickly and contain almost as much nitrogen as manure. Since fresh grass clippings will clump together, become anaerobic, and start to smell, mix them with plenty of brown material. If you have a lot of grass clippings to compost, spread them out to dry on the driveway or other surface to bake in the sun for a day or so. Once it begins to turn pale or straw-like, it can be used without danger of souring.
Avoid grass clippings that contain pesticide or herbicide residue, unless a steady rain has washed the residue from the grass blades.
Kitchen refuse includes melon rinds, carrot peelings, tea bags, coffee grounds, apple cores, banana peels - almost everything that cycles through your kitchen. The average household produces more than 200 pounds of kitchen waste every year. You can successfully compost all forms of kitchen waste.
Meat, meat products, dairy products, and high-fat foods like salad dressings and peanut butter, can present problems. These items will decompose eventually, but will smell bad and attract pests. Egg shells are a wonderful addition, but decompose slowly, so should be crushed. All additions to the compost pile will decompose more quickly if they are chopped up some before adding.
Collect your kitchen waste in a small container in the kitchen to bring to the pile every few days. Keep a lid on the container to discourage insects. When you add kitchen scraps to the compost pile, cover them with some of the brown material to reduce visits by flies or critters.
Some wood ashes from a fireplace can be added to the compost pile. Ashes are alkaline, so add no more than 1 gallon-sized buckets-full to a pile with 3'x3'x3' dimensions. They are especially high in potassium. Don't use coal ashes. Coal ashes contain large amounts of sulfur and iron that can injure plants. Used charcoal briquettes don't decay much at all, so it's best not to use them.
Garden refuse should make the trip to the pile. All of the spent plants, thinned seedlings, and deadheaded flowers can be included.
Most weeds and weed seeds are killed when the pile reaches an internal temperature above 130 degrees, but because the temperature varies from inside to the outer edges, some weed seeds may survive. To avoid problems don't compost weeds with persistent root systems, and weeds that are going to seed. Turning the compost pile on a regular basis also helps improve the chances of weed seeds surviving.
Spoiled hay or straw makes an excellent carbon base for a compost pile, especially in a place where few leaves are available. Hay contains more nitrogen than straw. They may contain weed seeds, so the pile must have a high interior temperature. The straw's little tubes will also keep the pile breathing.
Manure is one of the finest materials you can add to any compost pile. It contains large amounts of both nitrogen and beneficial microbes. Manure for composting can come from bats, sheep, ducks, pigs, goats, cows, pigeons, and any other vegetarian animal.
Avoid manure from carnivores (pets), as it can contain dangerous pathogens. Most manures are considered "hot" when fresh, meaning it is so rich in nutrients that it can burn the tender roots of young plants or overheat a compost pile, killing off earthworms and friendly bacteria. If left to age a little, however, these materials are fine to use.
Manure is easier to transport and safer to use if it is rotted, aged, or composted before it's used. Layer manure with carbon-rich brown materials such as straw or leaves to keep your pile in balance.
Seaweed is an excellent source of nutrient-rich composting material. Use the hose to wash off the salt before sending it to the compost pile.
The list of organic materials which can be added to the compost pile is long. There are industrial and commercial waste products you may have access to in abundance.
Here is a partial list: corncobs, cotton waste, restaurant or farmer's market scraps, grapevine waste, sawdust, hair, hoof and horn meal, hops, peanut shells, shredded paper and cardboard (avoid color printed materials), rock dust, sawdust, feathers, cottonseed meal, blood meal, bone meal, citrus wastes, coffee, alfalfa, and ground seashells.
The important thing is to mix whatever items you're using together into a good balance: browns / greens. Turn the pile if possible. Pay attention to the smell. If the pile smells rotten, things are out of balance with either too much water or too much matted green materials. If you suspect either of these items, try to mix the pile more often, and cover the pile loosely to keep excess rain from soaking. Don't cover with plastic.
Read also: Composting Questions & Answers