Kurt M. Jones
Chaffee County Extension Director
As our gardening season comes to an end, rather than
throwing away plant waste, many gardeners will compost those materials and help
to improve their soils for future years.
Composting is an accelerated
way to reduce the volume of organic wastes and return them to the soil to
benefit growing plants. Organic matter
improves the drainage and aeration of clay soil. Compost can be thought of as a separator that
“shoulders apart” tightly packed clay particles to allow air and water to
enter. Compost also helps sandy soil
hold water and nutrients. Compost holds
moisture like a sponge and releases nutrients slowly into plants as
needed. It also increases the activity
of earthworms and other natural soil organisms that are beneficial to plant
growth. Compost should not be thought of
as a fertilizer. The amount of nutrients
in compost is limited, but the improved soil characteristics make the addition
of compost into garden or flower beds worth the effort.
your composting site carefully. Partial
shading avoids the baking and drying in summer but provides some solar heating
to start the composting process. A site
protected from drying winds prevents too much moisture loss. Choose a site that is close to where the
composted materials will be used, but not highly visible or one that interferes
with yard activities.
are not necessary for composting, but prevent wind and marauding animals from
spreading plant waste. Structures are
also more aesthetically pleasing for your family and neighbors. The structure should be large enough to
handle the amount of yard waste you are likely to produce, yet small enough to
be able to mix the contents and remove the composted materials. A suggested minimum size is 36 inches by 36
inches by 36 inches high. Some better
insulated wood or plastic structures can hold sufficient heat at smaller
breakdown of organic yard wastes is a biological process dependent on
microorganism activity. Like most living
things, these microbes require favorable temperatures, moisture, oxygen, and
digesting microbes operate in a temperature range of 70 degrees F to 140
degrees F. Well-managed compost breaks
down rapidly at internal temperatures between 120 degrees to 130 degrees
F. During the winter months, microbial
activity is slowed, thereby slowing the composting process.
the toughest balance to maintain in Colorado’s
climate is the moisture and oxygen balance.
Moisture must be added to compost piles to maintain optimal microbial
activity. Too much moisture, however,
will limit the amount of oxygen causing the compost to have a foul odor and to
not break down. The best description of
the proper moisture level is “moist” or “damp” but not “soggy.” The entire mass of plant waste should be
moistened uniformly to the point where only a few drops of water can be
squeezed from a fistful of plant material.
microbes that break down plants use the plants for food. Nitrogen is the most important nutrient. A shortage of nitrogen in the composting
materials greatly slows the process.
Green plant materials fortunately contain a high percentage of
nitrogen. Other sources of nitrogen
include animal waste, granular fertilizer, or bloodmeal. Carbon is also an important nutrient in the
composting process. Sources of carbon
include woody materials, fallen leaves, shredded newspaper and animal bedding.
particle sizes greatly enhance the composting process. Plant pieces of ½ to 1-1/2 inches are ideal,
allowing sufficient surface area for microbial activity. These different plant materials should be
layered in the composting structure in 6-8 inch layers. Use equal parts of green plant materials
(nitrogen source) and dry plant materials (carbon source). Some soil can be added to the compost pile to
inoculate the pile, but research has shown that too much soil can hinder the
composting process. “Soilless”
composting is an effective means of breaking down plant materials.