Composting - Factors That Affect The Natural Process
by John Yazo
Compost is a key ingredient in organic gardening. As basic and natural as it is, there are a few key environmental factors that affect the speed of the composting process, and the quality of the end product. Food, air, moisture, temperature, particle size, and volume are all key factors that affect composting.
Composting is a natural process of recycling organic material, and turning it into a beneficial organic matter to improve the structure quality of an organic gardens soil. This is one process that nature uses in fields, forests, and meadows naturally to help keep the ecosystem in balance. Being a natural process, there are key environmental factors that will affect the composting process.
Organic material, carbon and nitrogen, provides a food source for organisms, and the levels of carbon and nitrogen vary, depending on the material being composted. Carbon-rich materials, brown or dried material, are organics items like dried our plants, leaves, straw, and wood chips. Nitrogen-rich material, green or wet materials, are items like grass clippings and vegetable scraps, wet materials. Keeping these two in balance is very important.
Carbon/nitrogen ratio, C:N ratio, between 25:1 and 30:1 is the ideal combination for rapid decomposition of organic material. When this ratio gets to high on the carbon side, heat production will drop and the process of decomposition will drastically slow down. Dried, carbon-rich material take a lot longer to compost when not mixed with a nitrogen-rich material, and when to much nitrogen-rich material is added to a compost pile, the pile will become very wet, or soggy, and release an unpleasant odor of ammonia.
Aeration is another key environmental factor, oxygen is needed for aerobic bacteria to survive in a compost pile. This aerobic bacteria uses oxygen for growth, to produce energy, and to consume organic material. Aerating a compost pile replaces the oxygen deficient air with fresh air that contains oxygen. this process can occur naturally under the right conditions by wind and temperature.
As a pile decomposes, porosity is reduced and air movement through a compost pile is restricted. Manually aerating a compost pile can be done by simply turning, and fluffing the pile regularly. Other techniques that can be used to improve the air movement through a compost pile is by mixing coarse material into the pile, like straw, corn stalks, or twigs. Plastic perforated pipe laid horizontally or as a ventilation stack are also ways to add air into a compost pile.
Organisms that naturally decompose the organic material in a compost pile need moisture to survive, and microbial activity will occur most rapidly if thin films of water are present on the surface area of organic material. An optimum moisture content of 40 to 60 percent is needed. When the moisture content falls below 40 percent, bacteria will slow down and can even become dormant. If there is excess moisture, it will replace needed air space and suffocate aerobic bacteria. This is when anaerobic bacteria will take over the compost pile and you will notice an unpleasant odor.
Temperature of a compost pile is directly affected by both air and moisture levels. Having a temperature between 90 degrees and 140 degrees Fahrenheit is an ideal range for rapid composting. Atmospheric temperatures can also impact the decomposition process, warmer air temperatures stimulate bacteria and speed up the decomposition process, while colder temperatures will slow or temporarily stop the process.
The size of the material you compost will also affect the rate the material will breakdown. Microorganisms will digest more, generate more heat and reproduce faster with smaller pieces of organic material. Breaking up the material by shredding or chopping it into smaller pieces will definitely seep up the decomposition process.
volume, or size of a compost pile is a factor of heat retention in a compost pile. For a compost pile to be self insulating and retain the needed heat naturally in most areas, a pile needs to be about one cubic yard in size, 3'x3'x3' at a minimum, in cooler areas 4'x4'x4' is better.
Composting is not an exact science, it is more of an art. Watching and adjusting the mix in your compost pile takes a little time to learn, all materials are different.
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