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March 11, 2009

Backyard Composting

Many people that I know have a lot of questions about composting. Does it stink? How do you do it? How much space do you need? etc., etc. Spring is in the air and it's the perfect time to set up a backyard composting pile as the gardening season begins. If you're thinking about starting a compost pile, there are some basics you should know before getting started.

Here are some tips from Utah State University Extension:

"Composting is the aerobic, or oxygen-requiring, decomposition of organic materials by microorganisms under controlled conditions. Bacteria start the process and are responsible for much of the decomposition work. Their metabolism creates the heat of the compost pile. Fungi, protozoans, earthworms, centipedes, beetles, and millipedes assist the bacteria in breaking down plant tissues."

USU Extension recommends 7 steps to consider when starting and maintaining your compost pile:

"Step 1 - Select Composting Site: A good location is helpful for a successful compost pile. The compost pile should be exposed to at least six hours of sunlight each day. The location should not detract from the landscape. Water should be readily available. Good drainage is important; otherwise, standing water could impede the decomposition process.

Step 2 - Select Compost Container: Many containers are suitable provided they are accessible, resist decay, and allow air flow. How do you decide which container will work best for you? Consider the amount of time and space you have, and the quantity of materials you will be composting. For fast, hot compost, the ideal pile size is one cubic yard (3 feet x 3 feet x 3 feet). This volume effectively retains the heat generated by the bacteria. The volume of a single pile should not exceed two cubic yards in order to maintain proper ventilation of the pile. If space is a limiting factor, the pile sides can be insulated so that higher temperatures can be maintained in a smaller volume.

Heap It (no cost, good if you have ample space) Simply pile your materials in heaps, ideally at least one cubic yard in volume. If well constructed, heaps are good for “no turn” composting. Just leave the pile for several months or more.

Hoop It (low cost, tidier than heaps) Woven wire mesh or fencing make good enclosures and keep the pile tidy. If you secure it with hooks or twists of wire, you can undo the hoop, set it up next to the pile, and turn the pile back into the hoop in its new location.

Box It (looks good, easy to cover, low to moderate cost)
You can use almost any type of scrap or new lumber, bricks, or cinderblocks to build an attractive and functional bin for compost. Make sure to leave spaces in the sides for air to get through, and make the front removable for easy access to turn or retrieve the compost. Construct several bins side-by-side to facilitate turning of the compost.

Barrel It (good for limited space, easy turning, moderate to high cost) If you don’t have enough space for piles or elaborate bins, a modified 55-gallon drum can work very well. By perforating the drum with air holes and cutting an access hatch on the side you can create a system which will compost small amounts of material quickly. Usually these systems are equipped with a stand and rollers to facilitate turning, although some people just roll their barrel around the yard to achieve the same effect.

Step 3 - Select Raw Materials: Almost all natural, organic material will compost, but not everything belongs in the compost pile. Some wastes attract pests; others contain pathogens that can survive the compost process. Acceptable raw materials would be: Grass clippings, Leaves and weeds, Manures, Coffee Grounds, Wood chips and sawdust, bark, stems, stalks, gardening and canning waste, fruits and vegetables. Do not put the following items in your compost: Meats, bones, large branches, dairy products, synthetic products, plastics, and pet wastes.

Step 4 - Aerating the Pile: Aerobic composting consumes large amounts of oxygen, particularly during the initial stages. If the supply of oxygen is limited, the composting process may turn anaerobic, which is a much slower and more odorous process. Oxygen levels within the windrows or piles may be replenished by lifting and turning the materials with a pitch-fork or by means of a mechanical turner. Try to put the outside, drier materials in the center of newly-turned piles. Turning a pile weekly can produce compost in one to two months with the right combination of materials and moisture level; monthly turning will produce compost in four to six months. Without turning, composting may take six months to two years. Aeration is generally the main factor affecting the time necessary to produce finished compost.

Step 5 - Keeping the Pile Moist: Moisture is necessary to support the metabolic processes of microorganisms. Composting materials should be maintained within a range of 40% to 65% moisture. As a rule of thumb, the materials are too wet if water can be squeezed out of a handful of compost and too dry if the handful does not feel moist to the touch. If the compost pile is too dry, the process slows down. If the compost pile is too wet water will displace much of the air in the pore spaces of the composting materials which limits air movement and leads to anaerobic conditions. Moisture content generally decreases as composting proceeds; therefore, you may need to periodically add water to the compost.

Step 6 - Keeping the Pile at the Proper Temperature: Composting will essentially take place within two temperature ranges known as mesophilic (50-105 degrees F) and thermophilic (over 105 degrees F). Keeping temperatures between 110o and 150o destroys more pathogens, weed seeds, and fly larvae in the composting materials. If the temperature of your compost pile is in the mesophilic range, try mixing the pile. If the temperature still does not reach the thermophilic range, review the steps described above to determine whether one or more of the essential factors is limiting the composting process. If you are still unable to increase the compost’s temperature, the active stage of composting is complete.

Step 7 - Curing: Finished compost is dark, crumbly, and has an earthy and non-offensive odor. Pile temperature in finished compost may still be slightly higher than ambient air temperature. Most finished composts will benefit from an additional curing phase. Curing refers to leaving finished compost in a pile undisturbed for up to one month to allow any final chemical and decomposition reactions to occur and stabilize the compost. Improperly or incompletely composted materials may release ammonia and other gases, or continue to heat upon application to soil, damaging plants. Curing ensures that the composting process is indeed complete and that these potential problems are minimized. View the curing phase as extra insurance against problems arising from using compost." (For more information and other USU Extension Composting tips, visit their Composting in Utah page.)

Some other things to consider: Do compost piles stink? No. A well-maintained compost pile will smell earthy and rich, but should not stink. If it does, something is wrong and the materials may not be breaking down properly. Also, if you don't have a large yard or perhaps live in an apartment or have organic waste in the office, one this to consider would be using a worm-bin, otherwise known as vermicomposting. For more information and ideas for composting, visit Wasatch Community Garden's blog.

Credits:

Heap Compost
Hoop Compost
Box Compost
Barrel Compost

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