Composting of yard wastes such as leaves, grass clippings,
dead garden plants and hedge trimmings, along with kitchen scraps, is popular with home
gardeners who long ago discovered the benefits of the dark, rich, sweet-smelling, earthy
end product called humus.
Benefits of composting
In about as much time as it takes to burn or bag
yard debris for disposal, you can prepare these same materials for composting and use them
as a soil conditioner. Home composters can use humus to lighten heavy, clay soils or
enrich sandy soils to improve water-holding capacity. Plants grow well in well-drained
soils that hold some moisture and the result should be a healthy, vigorous garden.
Understanding and assisting the compost
Heaping organic materials into a pile generates
heat through the activity of the microorganisms. This heat encourages activity of other
microorganisms which speeds up the composting process. High temperatures also help destroy
weed seeds and disease organisms. Before piling, shred or chop yard debris to give
organisms a larger surface area to decompose. Because nitrogen is consumed by tiny
decomposers, the addition of nitrogen fertilizer or manure assists in rapid and thorough
decomposition. A proper ratio of carbon to nitrogen is also important to the composting
process. While table scraps have a 15:1 carbon to nitrogen ratio, fallen leaves are more
in the range of 60:1. Grass clippings have a 20:1 carbon to nitrogen ratio. A C:N ratio of
30:1 is ideal for microbial activity, although a 50:1 ratio is adequate for a slower
compost. A complete mixing of a variety of materials will provide the desired ratio.
Frequent turning of the compost pile also speeds up the decay process by providing a
supply of oxygen.
Building your compost pile
Backyard composting is appropriate for all
lifestyles, because it can be done on a small, medium or large scale, using a low, medium
or high effort. Soil incorporation is perhaps the easiest way to compost in the backyard,
when space is limited and yard wastes are minimal. Kitchen scraps, minus meat, bones and
fatty foods, can be incorporated directly into the garden. Bury scraps at least six to
eight inches beneath the surface.
Mulching is another simple way of utilizing
organic materials. Simply spread leaves, grass clippings or shredded woody wastes beneath
ornamental plantings for initial use as mulch, and later, as they decompose, as a soil
enrichment. Chippers or shredders can be rented or purchased and used to chip materials
for these purposes or for informal garden paths.
Turning and holding units can be built to help
contain backyard compost piles. For yard wastes, a three- foot square holding bin made of
wire provides the simplest method of composting. Place the bin in a shady place and
gradually deposit weeds, grass clippings, leaves and harvest remains as they are
collected. Remember to layer plant materials and if desired, add a handful of nitrogen
fertilizer between each four-inch layer to achieve the proper carbon:nitrogen ratio.
Layering with topsoil adds additional decomposers to the heap.
Moisture and aeration are essential. Keep the
pile damp but not soaking. This produces a usable compost in six months to two years,
depending on the mixture of materials. Occasional turning, shredding of materials and
addition of high-nitrogen materials or fertilizer will speed the process. Gardeners with
large volumes of yard wastes may want to build a series of two or three turning units or
bins. The compost can be turned and moved to an adjacent bin on a regular schedule. Bins
can be built of wood, a combination of wood and wire, or concrete blocks. Begin the
compost pile by alternating layers of organic materials. Monitor the moisture of the pile
and check the pile temperature regularly. The pile will heat up to between 130 and 160
degrees in the middle, and the outside will be warm to the touch. During this period of
intense activity, be sure the pile does not become dry. When the pile begins to cool, turn
the pile into an adjacent bin with a shovel or manure fork. This mixes uncomposted
material from the outer edges of the pile and the temperature should start rising again.
After a few days, turn the pile into the finishing bin and start new layers of compost in
the first bin. Through persistence and a little extra effort, you can have finished
compost in a few weeks instead of a few months.
Remember, you can build simple wire bins, use
wooden pallets, or build more complex turning units. Depending on your time commitment and
quantity of materials, you can select the compost method that works best for you.
Household garbage can be easily composted by building a worm box in your basement or
backyard. Prepare a 3' by 2' by 1' wooden box with a hinged cover (this size will
accommodate the kitchen wastes from a family of four to five). Use shredded cardboard,
newspaper strips, animal manure, partially decomposed leaves or peat moss as a bedding
Add one to two pounds of red worms (can be
purchased or obtained from manure piles). Bedding material helps the worms escape when
compost gets too hot. Household garbage such as lettuce and cabbage leaves, carrot tops,
potato peels, citrus rinds, coffee grounds, eggshells and moldy left-overs can be fed to
the worms. Bury the garbage in the bedding and cover it with more bedding and let the
worms go to work. Two pounds of worms can process a pound of garbage a day. Keep the
bedding damp but not soaking. In several months you will have to move the vermicompost
(worm castings, uneaten garbage, bedding) and worms to one side of the box. Begin placing
fresh garbage and bedding on the other side and the worms will leave the finished compost,
which can then be used as a potting soil supplement. Community garden projects are ideal
for apartment dwellers and homeowners with small backyards. Participants can get rid of
kitchen wastes harvest remains and yard debris at the garden site. Kitchen wastes can be
incorporated directly into the soil and neighbors can join together to develop active
Compost contains some nutrients, but its greatest
benefit is in improving soil characteristics. If you've added fertilizer or manure during
the composting process, however, you may find the compost is all you need to achieve good
plant growth and production. To use compost for lawns, screen the material and use a
seed-starting material or as a top-dressing. When working the compost into the soil of
flower beds or the vegetable garden, (before or after planting) apply at a depth of
two-to- three inches. Compost can be mixed with topsoil for use with indoor potting
plants. Sterilize by baking in a 200- degree oven for one hour.
Compost Do's and Don'ts
- Don't use unfinished compost. It will rob your
plant's nitrogen instead of acting as a fertilizer. You can also spread garden diseases
with unfinished compost.
- Do mix finished compost with topsoil to prepare
garden flower beds or for potting mixtures.
- Do mix manure (if available) or high nitrogen
fertilize with yard wastes. Sprinklings of fish fertilizer, ammonium sulfate (20 percent
nitrogen) or urea (45 percent nitrogen) also work well.
- Do not use more than one-fourth pound of
fertilizer per 15 square feet of compost. When composting low- nitrogen materials such as
sawdust, paper and woody plants, increase fertilizer rates.
- Do add lime, small amounts of wood ashes or
crushed eggshells to neutralize acids which may form in compost and cause an odor problem.
- Do layer materials two to six inches thick, taking
care to mix up grass clippings (they tend to compact).
- Do add topsoil to layers to provide a good source
- Don't compost weeds that are heavily laden with
seeds (some will not be killed during the heating process).
- Don't ignore strong odors. Simply turn the pile
when odors are detected.
- Don't add meat or fish scraps to the compost
mixture. They may attract animals (dogs, cats, rats, etc.) and they do not decompose
- Don't add diseased vegetable plants to the pile if
compost will be used on a vegetable garden. The disease organisms may reappear the next
This information is for educational purposes and
is reprinted from the MSU Extension. This information is public property upon publication
and has been printed with credit to MSU Extension.