Composting

Backyard Composting Flier
Backyard Composting Guide

Composting is a means of using natural decomposing processes to turn kitchen and yard wastes into a nutrient-rich soil supplement for your yard or garden. Returning organic matter to the land perpetuates natural biological cycles and is an ecologically sensible means of using organic wastes. It also has the potential to divert a significant amount of waste from our landfill. If proper composting techniques are followed, composting can require very little work and be odor and rodent free.

What Can I Compost?

	Compostable	Do Not Compost
Kitchen and Household Wastes	fruit wastes vegetable wastes coffee grounds coffee filters* paper towels, tissues* tea bags egg and nut shells bread, grains pasta, legumes spoiled food, left-overs houseplants, flowers	beef, poultry, fish bones dairy products grease, fat, oil human and pet feces “compostable” diapers
Yard Wastes	most weeds grass clippings plants, flowers chopped twigs tree leaves, needles prunings, hay, straw sawdust, wood chips	invasive weeds** badly diseased plants large branches

* unbleached paper products are best
** but hot piles will kill most weed seeds

Essentials of Composting

Composting will happen naturally in your compost pile as microorganisms, bacteria and fungi break down organic material into humus, or compost as we usually call it. There are four essential factors for maintaining a healthy microbial population in your compost pile:

1. Aeration: A compost pile should be turned once a week so that it remains aerobic (oxygenated). If you do not turn your pile regularly it will become anaerobic (lacking oxygen) and will begin to emit foul-smelling odors as well as slow down decomposition. Chop materials into small pieces to enhance airflow and increase surface area.

2. Temperature: The higher the temperature of the pile, the more rapid the decomposition rates. A proper “hot” pile will reach 120-180 degrees Fahrenheit. A pile that is smaller than 1 yard in any dimension will have insufficient internal volume to maintain high temperatures.

3. Moisture Content: The pile should be kept moist but not soggy. If the pile is too wet, water will fill up the air spaces and the pile will become anaerobic. If your pile is usually uncovered, you should cover it with some type of lid during heavy rains to prevent over saturation.

4. Carbon-Nitrogen Balance: Wet or “green” materials such as fresh grass clippings and food wastes tend to be high in nitrogen, while dry or “brown” materials such as leaves and dried yard waste are high in carbon. You should try to maintain a balance of 50% dry carbon-rich materials, 35% nitrogen-rich materials, and 15% soil or finished compost.

Adding Material

Surface Area: It is best to have your materials properly shredded before putting them into a compost pile. Doing so will increase the surface area that the decomposer organisms have to feed upon, which makes the organisms more efficient and able to create compost faster. Always mow or chop up material before it is added to the compost pile. Proper particle size reduction can be explained by an analogy using a block of ice. A block of ice will melt very slowly. Crush that same amount of ice, and it will melt much more quickly. The same principle works for a compost pile. A large piece of organic material will decompose slowly, taking longer to compost. That same item, when chopped up, will decompose much more quickly.

Layering: In order to provide a balanced diet for the microorganisms, fungi and bacteria that will do your composting for you, it is recommended that you layer the material that is going into your pile. You can start by adding a layer of carbon-rich brown material, then a layer of nitrogen-rich green material etc. This will give the microbes a proper balance of carbon and nitrogen and help them to break down the material faster.

Kitchen Scraps: If you incorporate fruit and vegetable trimmings into your compost pile, please follow these guidelines:

1. Incorporate a week's worth of trimmings at one time. You may want to store the trimmings in a sealed container (a coffee can with lid will make a good storage container) in your refrigerator.
2. Always chop up this material. Remember, material that is shredded or chopped up will compost faster than material that is not.
3. When you incorporate this material into the pile, dig into the center of the pile, six to twelve inches down. Pour the material in and then cover the trimmings. This will prevent pests (rodents and insects) from infesting your compost pile. It is important to avoid having exposed food waste on the exterior of your pile.
4. Infestation by either rodents or insects is usually an indication that too much fruit or vegetable trimmings are being added to the pile. Stop adding this material; add some fresh green material to increase the heat of the pile. After the infestation has ended, you can begin to add trimmings to the pile, but in reduced amounts. If you find you usually have more kitchen scraps than is healthy for your compost pile, you might want to try worm composting.

Compost Bins

Compost bins can be constructed from any combination of wood, wire, and concrete. The piles and bins illustrated below represent just a few of the most basic designs. Choose a design and materials to suit your needs, taste, and pocketbook. If you do not want to build your own bin, a wide variety of commercial compost bins are also available. For more ideas, check out the compost demonstration area at the Community Gardens on Fifth Street and see composting happening in a variety of different bins built from reused materials.

1. Loose Pile—The loose pile is easier to turn but takes up more space than a bin and is not rodent-proof.
2. Chicken wire/hardware cloth loop bin—This is one of the simplest and least expensive kinds of bins. You will need about 10 feet of chicken wire or hardware cloth, and a few stakes. The ends should be fastened together with wire or zip-ties and the sides should be attached to stakes to give it some stability. Once the pile is filled, the stakes can be removed.
3. Wooden pallet bin—you can nail a few pallets together to get a easy to turn compost bin. To make composting even easier, if you have room, you might want to consider having two or three open wooden compost bins, so that you can easily turn the compost from one bin to another. You can also create a bin system like this by zip-tying nursery flats together. Check out our nursery flat compost bin we created at the compost demonstration area at the Community Gardens on Fifth Street.
4. Presto hoop bin—The City of Davis Public Works Department gives these compost bins away for free to Davis residents in single-family homes. To get a free composting bin you can call the Public Works Department (757-5686) and sign up for the free compost correspondence class.

Troubleshooting Guide for Aerobic Composting

Symptoms	Problem	Solution
Pile not heating up.	Not enough water.	Add water.
	Pile or bin too small.	Build the heap to at least 3’X3’X3’.
	Lack of nitrogen-rich materials.	Mix in grass clippings, kitchen scraps, or fresh manure.
	Particle size too big.	Chop or grind materials.
Pile smells bad.	Not enough oxygen.	Aerate; turn the heap.
	Too wet.	Add sawdust, dry leaves, etc.
	If odor smells like ammonia, too much green material present.	Turn pile; add dry-woody materials
Rodents in pile.	Non-compostable material present.	Do not include dairy products, meat, or bones.
	Food scraps not covered.	Cover green wastes with dry materials.
	Heap accessible to rodents.	Rodent-proof your bin.

Maintaining Your Compost Pile

1. Turn the pile: For fast results and for a healthy aerobic compost pile, remember to turn the pile once a week.
2. Maintain moisture: Add water to your pile if it starts to dry out. A pile should always be kept moist. There is a simple test to make sure that your pile has enough water. Grab a handful of the material from your pile and squeeze it tightly in your fist. If your pile has the right amount of moisture, the material will clump together and there will be a few drops of water in your hand. If the material is too dry and will not clump together, you need to add more water. If the material is too soggy and drips water when squeezed, you may want to stop adding water for a while, turn the pile more frequently and maybe add more dry material (dried grass or straw).

Harvesting Your Compost

It will take 3 to 6 months for your pile to turn into compost. During this time, you can continue to add more material to the pile, just be aware that the material added later will not be ready at the same time as the first material you added.

You can tell that the material in your pile has turned to compost when you can no longer recognize it. The material will undergo a transformation, and instead of looking like the materials you incorporated into your backyard compost container, the materials will take on a soil- or humus-like appearance. When the majority of the pile seems to have composted, you can use a seed-planting tray to screen out the unfinished bits. The screened material can go into a wheelbarrow, and the larger pieces can be tossed back into the pile for additional composting. When you have collected all the compost you may want to spread it out on a tarp and leave it exposed to the air. Drying out the material will work to cure the compost. It will also make this material easier to spread.

Common Ways to Use Compost

Soil Amendment Finished compost can be turned into the soil as a soil amendment. As much as six inches of compost can be added to your soil each year. When used as a soil amendment, compost reacts with soil to slowly release both plant nutrients and essential trace elements. Compost can be turned into the soil in the spring in preparation for planting. It can also be spread on soil at the end of the gardening season and allowed to leach into the soil. If only a small amount of compost is available, it can be incorporated in the seed furrow, or a handful can be added to each transplant hole of annuals, perennials, or vegetables. Large amounts of compost can be used to plant trees, shrubs, and vegetable gardens, or to repair or replace lawn areas.

Mulching Compost is not mulch, yet it can be applied in the same ways that mulches are used. Compost is a stable product that will not deprive your soil of nitrogen. Spread compost two to six inches thick around plants, trees, shrubs, and exposed slopes. This will deter weeds, prevent crusting, curtail erosion, attract earthworms, and conserve water.

Potting Mix
Finished compost can be combined with equal parts of sand and soil to create an excellent potting mix. The compost should be screened to ensure that only fine particles are used in the mix. A simple screen can be made of ½-inch or other small-gauge fencing material and a wooden frame.

Want to learn more about composting?

City of Davis Compost Correspondence Class:
The City of Davis offers a year-round compost correspondence course to Davis residents in single-family homes. to enroll, call the Public works Department (757-5686) to request a compost packet mailed to your home. Once you receive the packet, read the materials inside, fill out the enclosed quiz and return the quiz to the Public Works Department. A city staff-person will contact you to let you know that your quiz was received and that your free compost bin is available for pick-up.

You can also visit the new compost demonstration area at the Community Gardens and see composting happening in a variety of different bins built from reused materials. The demonstration area has recently been revamped with new signs and free brochures about composting—a walk-by composting class!

UC Davis Project Compost Classes:
See www.projectcompost.ucdavis.edu for more UC Davis compost class information. Contact Project Compost at 754-8227 or email at projectcompost@yahoo.com.

For More Information

The following books are available at the Davis Branch of the Yolo County Library:

Backyard Composting: Your Complete Guide to Recycling Yard Clippings, by Harmonious Technologies (Harmonious Press), 1992.

Let it Rot: the Gardener’s Guide to Composting, by Stu Campbell, updated and revised edition, (Storey), 1990.

The Rodale Guide to Composting, by Jerry Minnich, Marjorie Hunt, and the Editors of Organic Gardening magazine, (Rodale Press), 1979.

Easy Composting created and designed by the editorial staff of Ortho Books, Cynthia Putnam, project editor (Ortho Books), 1992.

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