Home Composting Slide Show

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Home Composting Slide Show
Thomas Richard, Robert Kozlowski, Nancy Dickson
and Roger KlineJuly 1989 http//compost.css.cor
nell.edu/slideshow/home.slide.html
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Composting converts waste, leaves, kitchen scraps
and garden wastes, into a valuable product which,
when used in the garden, results in healthier
plant growth when added to garden soil.
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Composting can also help solve our society's
solid waste disposal problem. Food and yard waste
comprise over 30 of our solid wastes nationwide.
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This Slideshow Will Introduce You to Five Basic
Aspects of Home Composting

• the organisms that are involved in the composting
  process
• manageable components in the composting process
• types of materials that can be composted
• home composting systems
• uses of compost

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I. Organisms Involved in the Compost Process
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Decomposition is a natural part of the nutrient
cycle of living things. Composting is simply
human intervention to enhance and accelerate the
decay process.
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Composting is a microbiological process. Many
organisms have evolved to use decaying matter as
their food source. Bacteria are among the
simplest and most common organisms. Single-celled
and microscopic, they are found almost everywhere
in the environment. Although they are too small
for us to see, they are responsible for most
decomposition. (Special thanks to David Emerson).
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Fungi and molds are also important. White rot
fungi are well adapted to decompose woody
materials like chipped brush.
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Mites and other soil invertebrates feed on
bacteria and fungi, helping to keep their
populations in check. Competition among the
different organisms insures that only the most
efficient decomposers multiply. (Substitution -
slide not available in electronic form).
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Earthworms are perhaps the most familiar
decomposer. By blending soil and organic matter
in their digestive track, they produce stable,
nutrient-rich aggregates that improve the
structure of soil. (Substitution - slide not
available in electronic form. Special thanks to
Seattle Tilth Association).
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All decomposers are bound together in a complex
feeding web. They turn organic wastes into a
usable humus for the soil. (Substitution -
original slide not available in electronic form).
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II. Manageable Components of the Composting
Process
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While the natural process of decomposition will
occur without any assistance from us, several
factors can be managed to accelerate the compost
process. (Substitution - original slide not
available in electronic form).
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Organisms utilize carbon as a source of energy
and nitrogen to grow and reproduce. Without
enough nitrogen, there will be few
microorganisms, and decomposition will be slow.
If there is too much nitrogen in the compost,
some of it will turn to ammonia that will
volatilize, creating an odor.
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The optimum CN ratio is about 30 to 1. This
ratio will make fast, hot compost. Grass, animal
manures and fresh green plants are high in
nitrogen.
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Leaves, brush, sawdust and wood chips are all
good sources of carbon. Blending these carbon
sources with nitrogenous materials can provide a
satisfactory CN ratio.
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Surface area is another key factor to consider.
Since decomposition is a microbiological process,
it occurs in thin films on the surface of
particles. A large particle has less total
surface area than the same particle chopped into
small pieces. Therefore if particles are too big,
the process will take longer. A one-inch wood
chip will decompose much slower than grains of
sawdust. An easy way to shred fallen leaves is to
mow them before raking.
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Decomposer organisms need water also. The
decomposition process will slow down with either
too much or too little water. The optimum
moisture content for compost is about 40 to 60
percent, damp enough so that a handful feels
moist to the touch, but dry enough that a hard
squeeze produces no more than a drop or two of
water.
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Most microorganisms active in composting require
oxytgen to live. Their "aerobic" activity forms
carbon dioxide and heat as by-products. If too
little oxygen gets into the compost, the process
can become "anaerobic." This condition results in
foul odors. The by-products of anaerobic
decomposition include methane and hydrogen
sulfide gas. Hydrogen sulfide smells like rotten
eggs.
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Oxygen will move into the pile if it is loose and
there is plenty of space between particles, as
when straw is mixed in the pile. Finer material
may need to be aerated by physically turning the
pile with a pitch fork or a compost turning tool.
With the rapid decomposition that occurs with
high nitrogen materials, turning the pile becomes
necessary to prevent anaerobic conditions from
developing.
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Heat will be given off as organisms feed on
wastes and break them down into less complex
molecules. Ideal temperatures for composting are
between 90 and 150 degrees Fahrenheit. High
temperatures can help kill weed seeds and disease
organisms, but temperatures above 150 degrees
Fahrenheit will also kill the decomposers and
slow the process.
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Compost piles should be a minimum of one cubic
yard in size. Smaller piles may not have enough
mass to hold the heat of decomposition.
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Bacteria reproduce very quickly and are naturally
present in air and soil, so there is usually no
need to add them to the compost pile. Of the many
inoculants, or compost starters available, the
best is a handful of freshly made compost.
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III. Materials that can be Composted
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Almost any type of organic material can be
composted, but some are especially easy to manage
in a home composting pile. While most leaves are
fairly high in carbon, maple leaves have a CN
ratio near the optimum level of 301. With the
right moisture and frequent turning, maple leaves
can break down in just a few weeks time.Oak
leaves have a CN ratio of about 601, and also
have high levels of tannins which are resistant
to decay. Mixing these leaves with a high
nitrogen materials will accelerate their
decomposition.
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Brush can compost or be used as mulch if chipped
to a reasonable size. Because wood chips have a
high CN ratio, and large particle size, they
will break down relatively slowly. A better
alternative is to spread them on paths or use as
mulch, easily recycling them to the landscape.
Chips are often available free from arborists and
utility companies.
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Fresh grass clippings are high in nitrogen, about
201. By themselves they are too wet and will
mat, creating unpleasant anaerobic odors. But
they will compost well when mixed with a carbon
source such as leaves or brush. (Special thanks
to Seattle Tilth Association.)
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Short grass clippings are better left on the
lawn, where they will decompose and return
nutrients and organic matter to the soil.
Contrary to popular opinion, clippings will not
contribute to thatch buildup.
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Clippings from home lawns treated with pesticides
may contain chemical residues. With few
exceptions, these residues will not persist from
one growing season to the next. If the type and
level of pesticide used is unknown, those
materials should not be added to the compost pile.
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Vegetable food scraps can be composted at home,
but not meat scraps and grease. These can attract
rodents and other varmints.
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Wood ash can also be added to the compost pile.
It has high levels of potassium and other
nutrients for plant growth.
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Manures are high in nitrogen, about 201, and
contain many organisms helpful to the compost
process. While horse and cow manure are fine to
add to the compost pile, dog and cat litter may
contain parasites which can cause human disease.
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Other more exotic materials may be available for
composting in your area. These aquatic weeds,
while a problem for water recreation, make
excellent compost if dried out a bit. Food
processors may also have by-products that are
suitable for composting. (Special thanks to
David Stern).
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Coarse material, such as corn stalks, small tree
and shrub limbs, can also be composted. Shredding
these materials increases the surface area that
organisms can work on which significantly
decreases the time required for composting.
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While operating equipment such as chippers and
mowers, safety glasses should be worn.
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IV. Systems
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Yard wastes can be composted using a variety of
systems including holding units, turning units
and mulching. Food composting systems include
incorporation, vermicomposting (composting by
earthworms), and turning units.
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Many different options are available to contain
your compost. One option is a holding unit in
which wastes are accumulated. After materials are
added to the holding unit they are left
undisturbed to slowly decompose. Snow fence can
make a simple and movable holding structure.
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Another option is a wire cage made from fencing
or chicken wire. This bin works well for light
materials like leaves.
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Used pallets are often available for free from
manufacturers. Tied or nailed together, they
effectively contain compost in a stable structure.
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Moving compost from bin to bin on a weekly basis
will make rapid compost and provide considerable
strenuous exercise! The turning unit method is
used to make compost quickly and is more suitable
for food wastes. Compost is turned frequently to
provide aeration.
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Rotating drums take some of the work out of
turning, and are available from garden supply
stores. Such units often represent considerable
investment for the volume of material composted.
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Perhaps the easiest way to compost food waste is
to bury it in the garden or yard. Bury food waste
at least six to eight inches deep to keep animals
from digging it up. Care should be taken not to
damage the roots of nearby plants.
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Recycling food and yard waste can provide a host
of benefits for the garden. Compost incorporated
in the soil provides limited nutrients to plants.
However, the organic matter it provides can
significantly improve soil structure, allowing
better drainage in heavy clay soils and improved
water retention in light sandy soils. (Special
thanks to Seattle Tilth Association.)
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Screened compost can be blended with soil and
peat and used as a growing media for
containerized plants. A simple screen can be made
with hardware cloth and a wood frame.
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Coarse, partially decomposed compost can also be
used as a mulch. Mulches are useful for water
retention and weed control, but have a cooling
effect on soil and will delay maturity of warm
weather crops.
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Fresh compost should not be used for germinating
seedlings. The use of sterilized soil is
preferred because many seedlings are susceptible
to disease pathogens. Compost that has aged for
at least a year is less of a problem, and may
prove beneficial in preventing damping off
disease. (Special thanks to Nancy Trautmann.)
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Home composting provides households with the
opportunity to efficiently convert waste material
into a valuable soil amendment. The ultimate
result of the process is a healthier, more
productive and easier to maintain garden. Our
challenge is to change residents' values toward
waste disposal and make them aware of alternative
disposal practices. Home composting offers the
opportunity for residents to contribute to the
solution themselves and receive a beneficial
product for their own gardens.
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