Backyard Composting
Weld County Health Department and City of Greeley
Visit Weld County’s Backyard Composting Demonstration Sites: Xeric gardens, community gardens & compost demonstration sites: Plumb Farm Learning Center 955 39th Avenue, Greeley
Greeley West High School Horticultural Department 2401 35th Avenue, Greeley
UNC Xeric Demonstration Gardens Community Gardens 17th Ave & Reservoir Road, Greeley
Clay Center of Northern Colorado 1024 6th Avenue, Greeley
Resources: Colorado State University Cooperative Extension
(Master Gardener Program) Weld County 970-304-6535 Fact sheets: http://www.cmg.colostate.edu/pubs.shtml
Weld County Department of Public Health and Environment
1555 N. 17th St, Greeley, 80631 Environmental Health Services Division 970-304-6415 www.weldhealth.org
City of Greeley
1100 10th Street, Greeley 80631 www.greeleygov.com Natural Resources Office Water Conservation Office
970-350-9783 970-350-9874
This community site is for woody materials or large volumes that the home composter may not be able to process at home. Some of the text for this brochure was adapted from materials prepared for the Community Composting education Program of the Seattle Engineering Department’s Solid waste Utility and the Seattle Tilth Association. The clip art pictures were used with permission from the Composting Council and taken from their National Backyard Composting Program training manual. We appreciate the use of their materials. Second Edition January 2011
What is compost?
Compost is a dark, loose, earthysmelling material made from decomposed organic matter. Organic matter comes from organisms that were once alive. Compost can include yard clippings, leaves, yard trimmings, and kitchen vegetative waste. It can be purchased or made at home. It includes both stabilized organic matter and living organisms necessary for healthy plants. Compost is used for fertilizing and conditioning soil. Why Should I Compost? Composting is a practical and convenient way to transform yard wastes into a resource. Compost enriches soil, increases the soil’s water-holding capacity, and improves plant growth. Soil amended with compost requires less water (as much as 30 percent less). When you properly prepare soil with compost, it will retain water while diminishing runoff from the lawn and onto paved surfaces. The use of compost can decrease the need for chemical additives to lawns and gardens. By composting, you help the City of Greeley and Weld County meet a priority for waste reduction. According to a 1997 study by Franklin Associates, compostable waste comprises approximately 24 percent of the average person’s yearly garbage (50 to 60 percent during the growing season). Rather than paying to have yard trimmings hauled away and taking up valuable landfill space, compost them in the backyard and reap the benefits in the soil and landscape. By using compost, it returns organic matter to the soil in a usable form. Organic matter in the soil improves plant growth by helping to break up heavy clay soils, by adding water and nutrient-holding capacity to sandy soils, and by adding essential nutrients to any soil. Improving the soil is the first step toward improving the health of plants. Healthy plants help clean the air and conserve our soil, making Northern Colorado a healthier place to live.
What Can I Compost? Anything that was once alive can be composted. Non-woody yard wastes such as fallen leaves, grass clippings, weeds, and the remains of garden plants make excellent compost. Use care not to include noxious weeds, weed seeds, or diseased plants, as these materials may not be completely destroyed during the composting process and could be reintroduced to the garden. However, with proper handling, some of these materials may be successfully incorporated into the compost pile. Check with local Master Composters for methods to deal with weeds and seeds. Variations Use chipped materials for informal garden paths. Woody yard wastes decompose slowly. However, there are many uses for them other than composting. As an example, you can clip or saw woody wastes and run them through a shredder for mulching or path making. When used as mulch for paths, wood yard wastes will eventually decompose and become compost. Care must be taken when composting kitchen scraps. Compost them only by methods outlined in this brochure. Meats, bones, sweets, and fatty foods (such as cheese, salad dressing, and leftover cooking oil) should be put in the garbage.
How Can I Use Compost? Compost is primarily used to: • • • •
enrich flower and vegetable gardens to improve the soil around trees and shrubs as a soil amendment for house plants and planter boxes when screened, as part of a seed-starting mix or lawn top-dressing
Water, in which compost has been soaked for four to six days, makes an excellent “tea” for watering indoor and outdoor plants. Before they decompose, chipped woody wastes make excellent mulch or path material. After they decompose, these same wood wastes will add texture to garden soils.
Composting Yard Wastes The Essentials of Composting With the following principles in mind, everyone can make excellent use of organic yard wastes. Biology The compost pile is really a teeming microbial farm. Bacteria start the process of decaying organic matter. They are the first to break down plant tissue and also the most numerous and effective composters. Fungi and protozoans soon join the bacteria and, somewhat later in the cycle, centipedes, millipedes, beetles, and earthworms do their part. Materials Anything growing in the yard is potential food for these tiny decomposers. Carbon and nitrogen from the cells of dead plants and dead microbes, fuel their activity. The microorganisms use the carbon in leaves or woodier wastes as an energy source. Nitrogen provides the microbes with the raw elements of proteins to build their bodies. Everything organic has a ratio of carbon to nitrogen (C:N) in its tissues ranging from 500:1 for sawdust, to 15:1 for table scraps (check the last page for more information on C:N ratios for selected materials). A C:N ratio of 30:1 is ideal for the activity of compost
microbes. This balance can be achieved by mixing two parts grass clippings (which have a C:N ration of 20:1) with one part brown leaves (60:1) in compost. Layering can be useful in arriving at these proportions, but a complete mixing of ingredients is preferable for the composting process. Other materials can also be used, such as weeds and garden wastes. Generally, brown materials, such as fallen leaves and sawdust, are high in carbon, while green materials such as grass clippings and weeds are high in nitrogen. If you save fallen leaves in bags or piles they will provide an excellent source of carbon to mix with grass clippings the following spring and summer. Though a C:N ratio of 30:1 is ideal for fast hot compost, a higher ratio (i.e., 50:1) will be adequate for a slower compost. The more surface area the microorganisms have to work on, the faster the materials will decompose. It’s like a block of ice in the sun – slow to melt while it’s large, but melting very quickly when broken into smaller pieces. Chopping garden wastes with a shovel or machete, or running them through a shredding machine or lawn mower, will speed the composting process. Volume A large compost pile will insulate itself and hold the heat of microbial activity. Its center will be warmer than its edges. Piles smaller than 3 feet x 3 feet x 3 feet (27 cubic feet.) will have trouble holding this heat, while piles larger than 5 feet x 5 feet x 5 feet (125 cubic feet) don’t allow enough air to reach the microbes at the center. These proportions are of importance only if the goal is a fast, hot compost. Moisture & Aeration Virtually all life on Earth needs a certain amount of water and air to sustain itself. The microbes in the compost pile are no different. They function best when the compost materials are about as moist as a wrung-out sponge. Extremes of sun or rain can disrupt the moisture balance in the pile. Therefore, you may need to add water to the compost pile if it is too dry (especially in our semi-arid Colorado
climate) or cover the pile if it is important for compost materials to receive adequate aeration. Compost piles comprised primarily of grass clipping do not allow air to circulate through the pile. By mixing leaves or small limbs and twigs with grass clippings, it provides spaces for air to circulate through the pile. Time & Temperature The hotter the pile, the faster the composting. If you use materials with proper C:N ratio, reduced particle size, sufficient volume, and see that moisture and aeration are adequate, you will have a hot, fast compost (hot enough to burn your hand!) and will probably want to use a turning unit. If you just want to deal with yard wastes in an inexpensive, easy way, the holding unit will serve you well. Both bin types are discussed in the next section. Odors The compost should have a good earthy smell. If your compost is developing odors, the conditions are not ideal for making compost. Please refer to the troubleshooting guide on the next page. The homeowner is responsible for maintaining an odor and pest free compost pile and could be cited for improperly maintained compost piles.
Compost Trouble Shooting Guide
Symptom
Problem
Solution
Too much moisture
Add dry material and mix
Too much nitrogen
Add high carbon ammonia material, such as sawdust, wood chips, or straw
The center of the pile Not enough water. is dry
Moisten materials while turning the pile
Temperature of the pile is too low
Make pile bigger or insulate sides
The compost has a bad odor
The compost has an odor
Not enough air
Pile too small
Turn it
Insufficient moisture. Add water while turning pile
Temperature of the pile is too high
Poor aeration.
Turn pile
Lack of nitrogen
Mix in nitrogen sources, such as grass clippings or manure
Cold weather
Increase pile size, or insulate pile with an extra layer of material (straw)
Pile is too large
Reduce pile size
Insufficient ventilation Turn pile
Pests: rats, raccoons, Presence of meat insects scraps or fatty food waste
Remove meat and fatty foods, cover with soil or sawdust, build an animal-proof bin, or troubleshoot pile to increase temperature
Basic Bin Types Turning Bins
A turning unit is a series of three or more bins that allows wastes to be turned on regular schedule. Turning units are most appropriate for gardeners with a large volume of yard waste and the desire to make high quality compost quickly. Which Wastes? Non-woody yard and garden wastes are the most appropriate. How? Alternate layers of high carbon and high nitrogen materials in the first bin, reducing particle size as needed, and keep the pile as moist as a damp sponge. Check the pile temperature regularly. (Using a compost thermometer will reduce the risk of burnt fingers!) Add more nitrogen rich materials (manures, grass clippings, blood meal) to the pile if it doesn’t get hot within 2 to 4 days. When the heat decreases substantially (in 5 to 10 days), turn the pile into the next bin. Repeat the process each time the pile in the first bin cools. After 2 to 4 weeks in the third bin, the compost should be ready. Advantages and Disadvantages This method produces high quality compost in a short time. It requires more effort than a holding bin. Variations This unit can be built of wood, a combination of wood and wire, or concrete blocks. Another type of turning unit is the barrel composter, which tumbles the wastes for aeration.
Holding Units Simple containers or
open piles for yard wastesare the least labor and time consuming way to compost.
How? Weeds, grass clippings, leaves, and harvest remains from garden plants are collected and can be added to the unit or pile. Chopping or shredding wastes, alternating high-carbon and high-nitrogen materials, and keeping up good moisture and aeration will speed the composting process. Advantages & Disadvantages For yard wastes, this is the simplest method. This unit or pile is portable; it can be moved to wherever needed in the garden. This method can take from 6 months to 2 years to compost organic materials, so you only need to be patient. Variations Holding units are made of circles of hardware cloth, old wooden pallets, or wood and wire. For aesthetic reasons, if you use an open compost pile, it should be placed in a spot inconspicuous to you and your neighbors. Sod can be composted with or without a holding bin. Simply turn it over, make sure there is adequate moisture, and cover with black plastic.
Composting Food Wastes Soil Incorporation Burying organic wastes is the simplest method of composting. Which wastes? Kitchen scraps without meat, bones, or fatty foods are optimal compostable materials. How? Shred any large food pieces, and then bury the materials at least 8 inches below the surface. The covered holes become usable garden space the following season. The “pit-and-trench� method recommends burying waste one year, planting the same plot the following year, then using that area as a walkway in the third season allowing the soil to rest.
Advantages and Disadvantages This is a simple method, but because of the absence of air, some nutrients may be lost. Rodents, dogs, flies, and odor can become a problem with wastes buried less than 6 inches deep. Variations Using a post hole digger, wastes can be incorporated into the soil near the drip line of trees and shrubs in small garden spaces. Care should be used to minimize damage to tree roots with this technique.
Redworm Compost
Feeding redworms in specially constructed bins is a good way to make high-quality compost from food scraps. Which wastes? Kitchen scraps without meat, bones or fatty foods are great for redworm composting.
How? Fill bin to the top with a bedding such as peat moss, or shredded cardboard or paper. Moisten the bedding and add one to two pounds of red worms. You can buy a starter batch of worms from a worm farm or find some in an old compost pile. Rotate the burial of food wastes throughout the bin. In 3 to 6 months, the worms will have turned your food wastes and the bedding into dark, rich compost known as worm castings. The volume of the materials in the bin will have been decreased by about one half. Move the compost to one side of the bin and add new bedding to the empty half. For the next month or two, bury food wastes in the new bedding only. The worms will migrate to the new side. When the month is up, harvest the finished compost and
add more bedding to the empty side of the bin. For more information on worm composting, refer to the book Worms Eat My Garbage by Mary Appellhof at available at local libraries. Advantages and Disadvantages This is an efficient way to convert food wastes into high energy soil for house plants, seedling transplants, or general garden use. The worms themselves are a useful product for fishing. However, worm composting food wastes requires more effort than soil incorporation. Variations A stationary outdoor bin can be used in all but the coldest months, or a portable indoor/outdoor bin can be used year-round. Redworms may also be added to an outdoor compost bin if the hot composting method is not used. The worms will help aerate the pile and break down the organic matter. Make sure to keep them moist.
Other Uses for Yard Waste Which wastes? Woody yard wastes, leaves, and grass clippings. Do not use clippings from a lawn that has recently been treated with chemical weed killers, because the weed killers could damage other plants. How? You can simply spread the leaves or grass clippings in a thin layer beneath plants or over vegetable and flower beds. Use shredded or chipped wood as a mulch under woody plants. You can rent or buy a chipper/shredder. Tree services may deliver wood chips free if they are in your neighborhood. Advantages and Disadvantages All yard wastes will work first as a mulch and then, as decomposition proceeds, as a soil amendment.
Mulching: • reduces weeds • modifies soil temperature • maintains soil structure • minimizes erosion • retains moisture To mulch with woody wastes, you may have to buy or rent power equipment, or make an arrangement with a tree service. Grasscycling Leaving grass clippings on your lawn after mowing saves labor and promotes a healthy lawn.
Which wastes? Grass clippings no longer than 1” in length or no more than onethird the height of the growing grass blade in the best to grasscycle How? Mow your lawn more frequently so that you are removing less of the grass blade at a time. This reduces stress to the grass plant and enables the chopped blade to fall onto the ground and decompose more easily. Mulching mowers can also be used. Advantages and Disadvantages This process requires more frequent mowing to assure proper clipping size. If the clippings are too long when left on the lawn, matting may occur. However, leaving grass clippings on the lawn requires less time and energy than bagging, and returns valuable nitrogen and other nutrients directly back to your lawn reducing the need for additional fertilizers.
Variations If the clippings are too long, use them in your compost pile or as a mulch. When using clippings as a mulch, scatter a thin layer and allow drying. Later, additional grass can be added to produce a mulch a few inches deep. Avoid mulching with clippings that have recently been treated with herbicides as they can harm desirable plants.
Carbon to Nitrogen Ratios for Selected Materials (by weight) Materials with High Nitrogen Values
Material
Vegetable wastes Coffee grounds Grass clippings Cow manure Horse manure Horse manure w/litter Poultry manure (fresh) Poultry manure (w/litter) Pig manure
C:N
12-20:1 20:1 12-15:1 20:1 25:1 30-60:1 10:1 13-18:1 5-7:1
Materials with High Carbon Values Material Foliage (leaves) Corn stalks Straw Bark
C:N 30-80:1 60:1 40-100:1 100-130:1