composting 101
"Composting is proof that there is life after death."
- Unknown
- Unknown
introduction
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The practice of composting has been around for two and a half million years, beginning back in the Stone Age. There is evidence of composting being used as a technique of improving soil health in many historical societies, including the first documented efforts made in the modern-day Iraq area (Akkadian Empire) about 2,000 years ago.
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Composting has been used in many societies worldwide over time, employed in North America by Native American populations for many years before settlers invaded and forcibly stole their land and livelihood. Over time, advancements in techniques have been made to accommodate differences in climate, available composting materials, and space limitations. In both urban and more rural settings across the globe, composting is used as a way to both reduce waste sent to landfills and to create amendment material for healthy soil maintenance.
Quick Question: Did you know that there is an International Compost Awareness Week?
Well, there is! International Compost Awareness Week (ICAW) is the first full week of May, and represents the largest and most comprehensive education initiative of the compost industry. The goal of ICAW is to work together to raise public awareness about why we should all be composting our organics and how to use compost to create healthier soil. For more information on this celebration, visit the Compost Research and Education Foundation website.
Well, there is! International Compost Awareness Week (ICAW) is the first full week of May, and represents the largest and most comprehensive education initiative of the compost industry. The goal of ICAW is to work together to raise public awareness about why we should all be composting our organics and how to use compost to create healthier soil. For more information on this celebration, visit the Compost Research and Education Foundation website.
Put simply, composting is a process in which organic substances are reduced from large volumes of rapidly decomposable materials to small volumes of materials that continue to decompose slowly. During the process, carbon excess is released as carbon dioxide, and the ratio of carbon to other elements is brought into balance. This avoids temporary immobilization of nutrients due to lack of nitrogen when compost is added to the soil as an amendment. The end products of the composting process are water, carbon dioxide, and minerals important to plant growth and development as well as overall soil fertility and health. One of the most important benefits of adding composted materials to soil is that the nutrients in compost are released slowly, making them available to plants over a long period of time. The length of time it takes fresh organic matter to become compost depends on the composition and condition of the materials in the pile and the management practices used by the composter. The general rule of composting is that the pile must be warm, aerated, and moist, and should be made up of equal proportions of chopped, fresh green materials and dry brown materials.
Rapid Backyard Composting
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The traditional method of composting was to pile organic materials and let them be for about a year. The main advantage of this method is that it required few hours of labor, but the disadvantages included a large space being occupied for an entire year, nutrient leaching from rainfall, disease-producing organisms, weeds, seeds, and pests not being managed, and odor. A new process used by backyard gardeners addresses some of these drawbacks of traditional composting methods. Backyard compost can be made in an average of 4-6 weeks, and with a little extra effort, can be created in as little as 14 days. The following guidelines and considerations are followed by users of this composting method.
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Material Quality and Size
In general, material will compost best if pieces are between a half inch to an inch and a half in size. Soft, succulent tissues do not need to be chopped into small pieces because they will decompose rapidly regardless of their size. Woodier and harder materials, on the other hand, will need to be chopped up either with pruners or with a sharp shovel. In general, the materials added to compost piles should have a C:N ratio of 30:1. Although there isn't a great way to measure the exact C:N ratio of everyday items added to compost, a good guideline is to mix equal volumes of green plant material with naturally brown (dead and dried) plant material. Green material is fresh and moist, most easily found in springtime, and includes:
In general, material will compost best if pieces are between a half inch to an inch and a half in size. Soft, succulent tissues do not need to be chopped into small pieces because they will decompose rapidly regardless of their size. Woodier and harder materials, on the other hand, will need to be chopped up either with pruners or with a sharp shovel. In general, the materials added to compost piles should have a C:N ratio of 30:1. Although there isn't a great way to measure the exact C:N ratio of everyday items added to compost, a good guideline is to mix equal volumes of green plant material with naturally brown (dead and dried) plant material. Green material is fresh and moist, most easily found in springtime, and includes:
Grass Clippings
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Uncooked Food Scraps
(No meats, fats, or grease) |
Weeds
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Manures
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Dry, brown plant materials added to compost piles commonly include:
Wood Chips
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Dried Leaves
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Dried Grass and Straw
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Prunings
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Adding Eucalyptus and Oleander to compost piles is regarded by many gardeners as a no-go due to their toxicity; however, this aversion is misinformed. During the composting process, these materials are detoxified. Paper bags, egg cartons, cereal boxes, milk cartons, newspapers, and paper can be used as brown additions to compost piles, but need to be shredded before being added. Knowing what materials can be composted is as important as knowing what materials cannot be. The following materials should not be added to compost piles:
Soil
Soil adds nothing but dead weight to compost piles, and will make it difficult to turn the pile. |
Ash
Ashes, even from wood, will not decompose. |
Meat, Fat, and Cooked Fruits/Veggies
The oils in these items make them difficult to decompose. |
Manure from Meat-Eating Animals
Excreta can contain disease-producing organisms that can infect humans. |
Certain Seed-Bearing Weeds
Most weed seeds are killed by the high temperatures of composting. Those that are not include Burclover, Amaranth, and Cheeseweed. |
Diseased Plant Materials
Rapid composting kills most, but not all, organisms that cause plant disease. Examine all green material for disease before adding it to the pile. |
Compost Pile Size, Volume, and Heat
An optimal size for a compost pile is between 3 and 4 square feet. Larger piles will hold moisture for longer, and decompose faster as a result. Compost piles should be soaked with water to create uniform dampness and be covered with a tarp or other material to retain moisture and prevent oversoaking from rainwater. Heat will accelerate composting and is supplied for the most part by the microorganisms as they break down the organic materials in the pile. To conserve this heat, a minimum pile size of three feet square is required. Bins retain heat better than open piles (especially if they have lids) and are neater. Heat can also be conserved by placing a sheet of polyethylene plastic over the top of the pile and tucking it in around the edges. As the pile decomposes, even bins with lids will lose heat off the top, and using a plastic covering can really help with heat retention.
The microorganisms in compost piles function best at a temperature of about 160 degrees Fahrenheit, and temperature gradually tapers off as these organisms finish their processing work and die off. These high levels of heat both encourage microorganisms in their work, and also have the added benefit of killing any insect eggs or larvae that may have found their way into the pile. Most piles reach between 135 and 150 degrees Fahrenheit in their first week, drop to 130 by the end of the second week, and continue to drop as time progresses. By the sixth week, temperatures are around 90 degrees. A composting thermometer can be used to measure the temperature of compost piles quickly and easily.
An optimal size for a compost pile is between 3 and 4 square feet. Larger piles will hold moisture for longer, and decompose faster as a result. Compost piles should be soaked with water to create uniform dampness and be covered with a tarp or other material to retain moisture and prevent oversoaking from rainwater. Heat will accelerate composting and is supplied for the most part by the microorganisms as they break down the organic materials in the pile. To conserve this heat, a minimum pile size of three feet square is required. Bins retain heat better than open piles (especially if they have lids) and are neater. Heat can also be conserved by placing a sheet of polyethylene plastic over the top of the pile and tucking it in around the edges. As the pile decomposes, even bins with lids will lose heat off the top, and using a plastic covering can really help with heat retention.
The microorganisms in compost piles function best at a temperature of about 160 degrees Fahrenheit, and temperature gradually tapers off as these organisms finish their processing work and die off. These high levels of heat both encourage microorganisms in their work, and also have the added benefit of killing any insect eggs or larvae that may have found their way into the pile. Most piles reach between 135 and 150 degrees Fahrenheit in their first week, drop to 130 by the end of the second week, and continue to drop as time progresses. By the sixth week, temperatures are around 90 degrees. A composting thermometer can be used to measure the temperature of compost piles quickly and easily.
Turning the Pile
Turning compost prevents overheating, which will kill the beneficial microorganisms doing the important decomposing work. If these organisms die, the process will stop and the pile will have to be started from scratch again. Turning the pile also serves to aerate the mass, which keeps the decomposers functioning well. Material on the outer edges should be moved into the middle of the pile, and vice versa. Composting bins make this process easier, as well. Having at least two bins is helpful so that the material can be turned from one bin into the other. Bins that can be moved section by section and bins with removable slats on one side make the turning process easier. Longer intervals between turnings lengthens the time needed to complete the composting process. Turning every 3-10 days results in finished compost in 4-6 weeks. If the pile is turned every other day composting can take around 3 weeks. For composting to be finished in just two weeks' time, the pile needs to be turned daily.
Turning compost prevents overheating, which will kill the beneficial microorganisms doing the important decomposing work. If these organisms die, the process will stop and the pile will have to be started from scratch again. Turning the pile also serves to aerate the mass, which keeps the decomposers functioning well. Material on the outer edges should be moved into the middle of the pile, and vice versa. Composting bins make this process easier, as well. Having at least two bins is helpful so that the material can be turned from one bin into the other. Bins that can be moved section by section and bins with removable slats on one side make the turning process easier. Longer intervals between turnings lengthens the time needed to complete the composting process. Turning every 3-10 days results in finished compost in 4-6 weeks. If the pile is turned every other day composting can take around 3 weeks. For composting to be finished in just two weeks' time, the pile needs to be turned daily.
Adding Water
In a well-mixed compost pile that contains 50% green material and 50% brown material, only water needs to be added. Monitoring moisture content in a compost pile is essential because piles will dry out due to their high temperatures. The composting process functions best at a 50% moisture content (about the same as a wrung-out sponge). Too much moisture can lead to a soggy mess, slow decomposition, and increased odor. When turning a pile, a good practice is to moisten each layer with a hose equipped with a spray nozzle. Excess materials that are waiting to be added to the next compost pile should be kept as dry as possible; moist materials will start to decompose and will not be effective in the next pile.
In a well-mixed compost pile that contains 50% green material and 50% brown material, only water needs to be added. Monitoring moisture content in a compost pile is essential because piles will dry out due to their high temperatures. The composting process functions best at a 50% moisture content (about the same as a wrung-out sponge). Too much moisture can lead to a soggy mess, slow decomposition, and increased odor. When turning a pile, a good practice is to moisten each layer with a hose equipped with a spray nozzle. Excess materials that are waiting to be added to the next compost pile should be kept as dry as possible; moist materials will start to decompose and will not be effective in the next pile.
Compost Pile Maintenance
A well-constructed compost pile will heat to optimal temperatures within 24 to 48 hours. If it does not, the pile is either too wet, too dry, or does not have enough green material present. For a pile that is too wet, spread out the mass so that it dries a bit, and then re-pile it. If it needs more water, hose the pile down. If moisture is not a problem, there is likely a deficit of nitrogen and more green material should be added to compensate. If no green material is available due to the time of the year, nitrogen fertilizer can be used (1 pound per 10 cubic feet). Mix the fertilizer into the pile well to distribute evenly. A smell of ammonia coming from a compost pile signals that the pile is losing valuable nitrogen to the air, and occurs when the C:N ratio of the pile is less than 30:1. To combat this issue, add material that has a high C:N ratio, like sawdust; this will tie up (immobilize) the nitrogen.
A well-constructed compost pile will heat to optimal temperatures within 24 to 48 hours. If it does not, the pile is either too wet, too dry, or does not have enough green material present. For a pile that is too wet, spread out the mass so that it dries a bit, and then re-pile it. If it needs more water, hose the pile down. If moisture is not a problem, there is likely a deficit of nitrogen and more green material should be added to compensate. If no green material is available due to the time of the year, nitrogen fertilizer can be used (1 pound per 10 cubic feet). Mix the fertilizer into the pile well to distribute evenly. A smell of ammonia coming from a compost pile signals that the pile is losing valuable nitrogen to the air, and occurs when the C:N ratio of the pile is less than 30:1. To combat this issue, add material that has a high C:N ratio, like sawdust; this will tie up (immobilize) the nitrogen.
A well-decomposing compost pile will have a pleasant odor, produce heat (visible as water vapor released as the pile gets turned), reduce in volume over time, and change in color to a dark brown. As composting nears completion, the temperature will drop and the pile will eventually cease to give off any heat at all. After the composting process is complete, the pile should be left to sit and cure for about two weeks. Next the pile can be sifted through to remove any larger pieces that were not fully composted, and then it can be used in the garden. The larger pieces that are removed can be added to the next pile. Because composting is an involved, somewhat laborious process that takes a while to get a real hang of, here's a handy list of troubleshooting tips for home gardeners:
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Alternatives for Recycling Organic Kitchen Waste
Some composters have great success adding kitchen waste to compost piles, but others complain of the slow decomposition of these items and that their odor attracts roaming neighborhood animals who burrow into the pile and spread it out over the yard. To avoid these issues, a great alternative to throwing organic kitchen waste in the compost pile is to bury the waste 2-3 feet down in the ground. Another option is to begin engaging in vermiculture. Vermiculture is the practice of raising redworms (also called manure worms) in boxes and feeding them kitchen waste. A pound of worms can go through a pound of waste per day. |
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Many home gardeners engage in this practice, as it is a simple way to create worm casting fertilizer. The first step to engaging in vermiculture is finding a box with a hinged lid that is about 4 feet long and 2 feet wide. 3/4-inch holes should be drilled on all sides, and the box should be covered with a screen and placed on a stand so that air can circulate underneath and around it. Divide the box into two sides using a screen or other divider. Place bedding (either well-shredded newspaper or another loose organic matter) in the box on one side and add worms. Place the box in a cool, shady place and feed the worms daily or every other day with kitchen scraps. After the worms have turned their bedding and food into worm castings, prepare a new bed with shredded organic matter and kitchen scraps on the other side of the box and remove the divider. In a few days to a week, the worms will have migrated, and the divider can be replaced. Remove the castings for use in the garden, and continue with this two-compartment tango for as long as desired.
