Compost is the material result of decomposed organic matter. It is dark in color, crumbly to the touch and smells like rich soil. Finished compost has a high organic content and is filled with microbes and insects, all which contribute to a healthy soil. The composting cycle includes the breaking down of plant and animal life, and the concentration of carbon and nitrogen.
Finished compost is a soil amendment, used in agricultural applications such as vegetable gardens. Composting differs from the decomposition that occurs naturally, such as in forests, in that the waste matter is contained and controlled. The organic matter in a compost heap or pile is manipulated by humans into decomposing at an accelerated rate.
A compost heap consists of a balance of carbon and nitrogen. Materials high in carbon include shredded twigs and tree branches, grass clippings and leaves, and spent plants. Nitrogen is found in vegetable and fruit scraps as well as coffee grounds and eggshells. The ratio of carbon material to nitrogen material should be approximately three to one.
Microbial and insect activity breaks down the waste materials in the compost heap. These organisms feed on the waste, creating chemical reactions that break the materials down into elemental components. This is the same process seen in natural decomposition. It is the control over environmental factors that accelerates the decomposition, resulting in finished compost.
Initially, the microorganisms in the compost pile are actively feeding on the waste, subsequently creating waste and dying off. This feed and die cycle is essential to the breaking down of the organic waste in the compost pile. As the resulting chemical reactions cause the materials to begin transforming into carbon dioxide, nitrogen, phosphate and other elements, microbial activity slows down. The chemical reactions necessary to transforming the waste into compost kick into high gear.
Consistently turning the compost pile adds oxygen to the process. Moving the organic materials around provides motion and air; the motion revitalizes microbial activity by moving unprocessed waste around while the air acts as a catalyst for further decomposition. A compost pile that is turned every few days will decompose faster than one allowed to sit idle. An idle pile may take more than a year to break down while a well-tended pile may break down within a two to three months. Adding moisture to prevent the materials from drying out also accelerates the decomposition. Moisture not only makes the waste more palatable to insects, it encourages the growth of fungi and bacteria. The pile should be kept moist, but not wet. Too much moisture may result in excessive fungal growth.
Finished compost may be gleaned from the compost pile, while some of the matter is still in a transitory state. Remove the finished compost and add it to the garden soil. Use the remaining waste to jump start the new compost pile. The partially decomposed materials serve to attract and maintain the necessary microorganisms.