When organic matter decomposes it undergoes a complex series of changes, both in form and in composition. Learning to control this process allows anyone to create a nutrient-rich, humus-like material, we know as compost. The word compost derives from the Latin componere, meaning to put together and for centuries gardeners have used compost piles to put together the various type of organic matter which accumulate – kitchen scraps, prunings, thinnings, and dead plants – with such results. Home gardeners can easily make a useful compost pile in the backyard. Many municipalities have set up community-wide facilities to reduce landfill waste and offer the resulting compost back to residents.
Making your own compost
How does your garden grow? A lot better if the soil is enriched with compost from your own compost pile.
How compost is made: Bacteria start the process of decomposition in a compost pile by breaking down organic matter physically, so that these smaller bits can be used by a succession of other organisms. Fungi, protozoas, centipedes, millipedes, beetles and earthworms all play a part in the breaking down, eating and digesting, and further decay of the pile of material. All of the activity by these organisms creates heat and if you put your hand into the middle of an active pile it will be hot, often so hot as to be uncomfortable. The heat of a compost pile is important. Harmful soil borne diseases and seeds are killed and are not passed along in the compost.
How to make a compost pile: There are four basic styles by which compost is made: open piles, holding units, turning units and enclosed bins. The type or style you choose depends entirely on the materials you wish to use, how visible you want the pile/bin to be, and what will work in your yard.
An open pile is just that – a free form pile of organic material on the ground. In wetter regions, or where there is heavy snowfall, they are often covered with a tarp or sheet of plastic for the winter. The pile works best if it not over 4 feet tall and about 5 feet in diameter.
A holding unit is any type of open container for compost materials. They can be made of old wood, block, a combination, or wire. Ideally the bin is 3 feet tall, 3 feet wide on each side; although 4x4x4 can be successful. Smaller piles heat up too quickly; and larger ones can fail to heat up properly. It is helpful to have one side open, or have a removable side, making it easier to turn and remove the compost.
Turning units are a series of holding bins, typically three in row. Each unit is about the size of a holding unit, although some of these can be very large in commercial operations. Material is added to the first bin and when it is full, it is turned into the next bin, and new material goes into the first one. When the first bin is full again, then the material in the second is turned into the third, and that in the first bin is turned into the second and new material is once again added to the first bin. When it is time to go through the entire cycle, the material in the third bin is ready to use. These units most often are open to the air and one open or removable side makes them easier to use.
Enclosed bins may be made of any type of container which has a secure lid, such as garbage cans or barrels. In addition, there are numerous enclosed compost containers for sale through garden centers and in gardening catalogs. Some enclosed bins are stationary and others are constructed to roll or rotate. Most compost piles work best if the material is turned from time to time, and rolling or rotation replaces the need to turn the material by hand.
How to make compost: Any organic material can be used to make compost. This includes kitchen scraps, grass clippings, leaves, cuttings and thinnings, pruning waste, and so forth. Never put meat, dairy foods, animal feces, or oil, fat or grease in a compost pile. As a general rule of thumb a well mixed compost pile will have 3:1 ratio of carbon to nitrogen. You can estimate this by knowing that most material that is brown is high in carbon, and most material that is green is high in nitrogen. It is not necessary to be too precise, all of it will compost; but the relative proportions will affect how long it can take to become the black gold so desirable in the garden.
Many composters add some soil to the pile. This helps keep the population of microorganisms high and can help speed decomposition.
Material that is chopped or shredded will have more surface area for the organisms to work over and will compost faster. Again, the material will compost regardless, but it will happen much faster if it is chopped or shredded.
The microorganisms in compost need water to survive so it is important that a compost pile be moist, about as moist as a wrung out sponge. In the desert regions, this means that an open compost pile must be watered at least once a week during the summer.
The microorganisms in the pile need oxygen. Turning the pile will increase available oxygen and increase the efficiency of the pile. Turn the pile at least once a month. A pile that is never turned may take 3-4 times as long to decompose.
Time: The time it takes a pile to go from a collection of loose organic matter to a rich, dark soil-like humus varies widely; from as little as three months to as much as a year. Many factors affects the time required for completed compost but to speed the process be sure to layer the pile; keep the proportion of brown/green material at 3:1; turn the pile; keep it moist; and cut up large items and chop and shred as much as you can.
Using compost: Compost can be added at any time to a vegetable bed, flower bed or potted plant. The action of compost in the soil is complex, but it will help soil hold more moisture, increase its fertility, improve the drainage and texture. When applied to the surface it acts both as a mulch to cool the top of the soil, and as a fine soil conditioner as it works into the soil. The only real problem with compost is that there is never enough.