Composting Yard and Food Wastes
Composting is important because 20% or more of household waste is
organic materials that can be composted, rather than disposed, thus
saving landfill space. Compost is a valuable soil amendment that
will help your plants thrive. Compost helps your landscape retain
water and nutrients better, and that means you can irrigate and fertilize
less in areas treated with compost.
Yard Waste disposal site
Norfolk operates a yard waste disposal site at the Transfer Station.
Lawn Care Tips
Grasscycle! Leave your grass clippings on the lawn for a healthier,
greener lawn that's more resistant to disease. It is a natural way
to fertilize without chemicals. It is much easier than bagging and
hauling and saves you money.
- Lawns are healthier when mowed at 2 1/2-3" high with clippings
left on the lawn. Mow about every 5 days. No more than one-third
of the grass blade should be cut.
- Mulching mowers cut the grass into small pieces which break
- Retrofit regular mowers with a mulching kit, or any mower can
work if grass is cut frequently
Composting Yard Wastes
To make traditional compost, alternate different types of
shredded plant materials in 6- to 8-inch layers. Layering helps
compost reach the correct nitrogen balance. Use equal parts
of dry and green plant materials in the overall mix. Use caution
when you add layers of fine green plant wastes such as grass
clippings. Grass mats easily and prevents water from moving
through the mass. Use thin, 2-inch layers of fine material or
process them through a machine shredder. Alternate the fine
material with woody plant prunings to prevent clogging of the
machine and create an equal balance of dry and green materials.
Traditional composting also includes soil as one of the layers.
While soil can serve as a source of microbes to "inoculate"
plant wastes, research has found that the microorganisms that
break down plants also are present on the surface of the leaves
and stems. It's natural for some soil to cling to pulled weeds
and uprooted vegetable and flower plants. When you add large
amounts of soil you increase the weight, which makes composting
difficult and less efficient. Large amounts of soil also can
suffocate microorganisms. "Soilless" composting is often practiced.
Add water to the compost after every few layers of material.
If the plant materials are dry and no green material is available,
add a small quantity of blood meal or a commercial nitrogen
fertilizer free of weed killers. One-half cup of ammonium sulfate
per bushel of material is sufficient. Livestock manure also
can be added and supplies some nitrogen, but it's use is optional.
Like soil, manure adds weight and bulk. The space devoted to
manure could alternatively be used to compost yard wastes.
There is no advantage in adding compost starters or inoculum
to the compost. The microbes that cause decomposition multiply
as rapidly from those that are naturally found on the plant
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Requirements for Effective Composting
The breakdown of organic yard wastes is a biological process
dependent on microorganism activity. Like most living things,
these microbes require favorable temperatures, moisture, oxygen,
Plant-digesting microbes operate in a temperature range of
70 degrees F to 140 degrees F, but breakdown occurs very slowly
at the lower temperatures. Well-managed compost rapidly breaks
down in summer when compost temperatures quickly reach 120 degrees
to 130 degrees F. If summer heat plus the heat produced by active
microorganisms causes the temperature of the plant mass to exceed
160 degrees F, the microbes will die. Winter temperatures cool
compost and greatly extend the time required to produce a finished
Moisture and oxygen
Moisture and oxygen are essential to microbial activity.
In a region of limited rainfall, add moisture regularly to maintain
composting. If parts of the composting material dry out, many
microorganisms in the dry areas die. The microbes that remain
require time to multiply and resume plant digestion even when
moisture is added. The net result is slower composting. However,
excess moisture displaces air and slows breakdown. Surplus water
creates low oxygen conditions where certain microbes multiply
and produce foul odors. The best description of the proper moisture
level is “moist” or “damp” but not soggy. The entire mass of
plant wastes should be moistened uniformly to the point where
only a few drops of water can be squeezed from a fistful of
The size of plant particles that go into the compost also
affects aeration. Large particles allow a lot of air to circulate
around the plant chunks, but breakdown is slow because microbes
can act only on the outside, not on the inside of the large
chunks. Particles chopped into smaller chunks increase the surface
area for microbes to operate but particles chopped too small
will compact and restrict air flow. Moderate-sized plant pieces
of ½ to 1-1/2 inches are the best size to use and can be produced
by hand or machine shredding. Woody materials need to be chopped
into a smaller size. Leave soft plant parts in larger pieces
for effective composting. Fluff or turn the material with a
pitchfork or aerator tool at regular intervals to provide additional
aeration and distribute microbes throughout the compost.
The microbes that break down plants use the plants for food.
Nitrogen is the most important food nutrient because a nitrogen
shortage drastically slows the composting process. Woody and
dried plant materials tend to contain little nitrogen in comparison
to the total mass of the material. Green plant material, however,
contains a high percentage of nitrogen. A mix of equal parts
green and dry plant material generally gives the best nitrogen
balance. Add a plant fertilizer high in nitrogen when green
materials are scarce.
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Materials to Use and Avoid
A variety of materials can be composted, but most gardeners
want to recycle collected yard waste. Plants lose between 50
percent and 75 percent volume in composting, so a lot of plant
material can be processed effectively.
Composting can be effective on most yard wastes such as leaves,
vegetable and flower plant parts, straw, and a limited amount
of woody prunings, grass clippings and weeds. Woody twigs and
branches that are greater than 1/4 inch in diameter should first
be put through a shredder-chipper. Avoid highly resinous wood
and leaf prunings from plants such as junipers, pine, spruce
and borvitae. The resins protect these materials from decomposition
and extend the time needed for composting in comparison with
other plant materials. High tannin-containing leaves (oak and
cottonwood) have similar problems but can be used if chopped
well in small quantities and mixed with other materials. The
easiest way to handle grass clippings is to leave them on the
lawn. Research results show they return valuable nutrients back
to the soil. Some grass clippings can be used for compost if
other green plant material isn't available. In general, catching
and bagging grass clippings is not worth the effort when they
are easily recycled right on the lawn. If clippings are too
long to leave on a lawn, composting is a better alternative
than disposal in the trash. Some weeds can be composted, particularly
if they are pulled before they produce seed.
Many, but not all plant disease organisms, are killed if
the compost reaches 122 degrees F. Temperatures will vary throughout
the compost. Outer layers stay cooler than the center and cause
uneven kill of disease organisms. If a plant is severely diseased,
it is better to dispose of it in the trash.
In general, avoid plants treated with weed killers. Small
amounts of herbicide-treated plants may be mixed in the pile
as long as you are careful to allow for thorough decomposition.
Weed killers and other pesticides break down at various rates.
If you use treated grass clippings, the breakdown of these chemicals
should be at least as fast as breakdown in the soil. Plants
killed with weed killers that are soil inactively (glyphosate
products such as Roundup or Kleenup) should present no problem
when composted in small quantities.
In addition to yard wastes, many people compost kitchen wastes
such as vegetable scraps, coffee grounds and eggshells. These
materials add to compost but should not displace yard wastes.
Animal wastes (meat, bones, grease, whole eggs and dairy products)
may cause odors and attract rodents and are not recommended.
Human, cat or dog feces may transmit diseases and should not
be used in compost. Some animal products that can be used as
organic sources of nitrogen include blood and steamed bone meal,
and livestock manures from plant eating animals (cows, sheep,
rabbits and chickens).
Compost mainly serves to reduce the volume of yard wastes
and convert plant materials into a useable soil amendment. Adding
excessive amounts of other materials, such as animal manures,
defeats the purpose.
Black and white newsprint is best recycled through community
organizations rather than converted to compost. If paper is
composted due to a shortage of dry materials, add no more than
10 percent of the total weight of material being composted.
Do not use wood ashes or lime for composting in Nebraska. Both
increase salt and alkalinity that leads to a loss of nitrogen
in the form of ammonia gas.
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|If the compost is properly mixed and maintained, a final
product may be obtained in one to two months under optimum summer
conditions. In other seasons, or with less maintenance, composting
may require six months to one year. When complete, the mass
will be about half its original size and have an earthy smell.
Maintenance consists of sustaining the required conditions
for effective decomposition. Although conditions may be present
at the start of the process, if they are not maintained as the
compost mass changes over time, decomposition will decrease
or stop. Proper moisture and air levels are especially important.
Dry plant wastes will quickly stop composting. Plant materials
often dry on the outside while the center remains moist. Water
consistently to keep compost uniformly moist but not wet.
Use an aeration tool to reach into the compost to lift and
move plant materials. Turn the entire mass occasionally to provide
Small amounts of fresh materials may be added to compost,
particularly if a vertical composting system is used. Adding
too much fresh material in other systems results in a mixture
of fully-decomposed and fresh materials at the end. If enough
material is available, it is best to make a new pile instead
of combining fresh materials with nearly finished compost.
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Location and Structures
|Choose a composting site carefully. Partial shade avoids
the baking and drying in summer but provides some solar heat
to start the composting action. A site protected from drying
winds prevents too much moisture loss. Another consideration
is convenience for moving volumes of plant materials in and
out of the area. Choose a site close to where material will
be used, but not highly visible or one that interferes with
Structures aren't necessary for composting but prevent wind
and marauding animals from carrying away plant wastes. Open
compost piles can be used in less-populated rural locales but
structures are a near-must in urban areas. Many useful structures
for composting can be purchased or built. These structures vary
in how well they can be managed to meet the requirements for
effective decomposition under Nebraska environmental conditions.
Many people cover their compost with plastic to prevent the
outer layers from drying too much. Such covers need to be removed
periodically to add more water and plant material and to aerate
A minimum volume of material is necessary to build up the
heat necessary for efficient composting. This volume is generally
around 36 inches by 36 inches by 36 inches, but well-insulated
wood or plastic structures can be smaller and still hold enough
heat to compost well. Wastes should heat up within two days
if the compost is put together correctly.
Structures built of wire also may have drying problems. This
depends on how many sides of the structure are exposed and whether
exposure is on the windward side. Plastic covers or tarps often
must be used with wire bins. Wood structures do not dry as much
but are generally more expensive to purchase or construct. An
efficient wood structure is the “three-chambered bin” system
that allows plant material to be aerated by turning from one
bin to the next as it decomposes.
Compact plastic composters are available through garden centers
and catalogs. They work well for small yards that produce few
plant wastes. Some of these use a vertical composting system
where fresh materials are added to the top and finished compost
is removed from a drawer in the bottom. This system requires
an aeration tool to reach in and stir plant materials on a regular
basis. If you use metal barrels for composting, drill holes
to allow air to enter. Turn the barrel on its side and roll
it to mix and aerate the compost.
In-ground “pit composting” presents problems with turning
or aerating the plant material and also can pool water that
leads to undesirable low oxygen conditions. There are many structures
useful for composting; no one structure is best for all people.
Choose one that is easy to manage and can hold the amount of
plant material generated by your yard.
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Compost: A Soil Amendment
|Soil amendments must be mixed well with the soil to separate
clay particles or hold water in sand. For this reason, prepare
soil before planting lawns or trees. Areas planted every year
such as vegetable or annual flower gardens can accept frequent
applications of compost. Indoor potted plants and outdoor container
plants benefit from the use of compost as an ingredient in potting
soils. As with peat-based mixes, potting soils that use compost
require a material such as perlite to avoid waterlogging. Some
weed seeds can survive composting but weed plants can be easily
pulled when they appear.
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Compost: A Poor Mulch
|Mulches suppress garden weeds, cool soil, conserve moisture
and reduce soil erosion. To mulch, apply a 4- to 5-inch layer
of organic material on top of the soil instead of mixing it
into the soil as with amendments. Compost does not make a good
mulch. It's a light material, readily blown away by wind, unlike
bark or rock mulch that stays in place. Compost mulch supports
weed growth, limits air exchange with the soil, and causes moisture
loss by wicking moisture to the surface. Compost is utilized
better as a soil amendment than a mulch.
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A Troubleshooting Guide for Effective Composting
|Compost has bad odor.
||Lack of air.
||Turn or use a tool to aerate it.
|The center of the mass is dry.
||Lack of water or failure to Moisten materials while stirring
||Regularly water the pile.
|The outside couple of inches are dry.
||Dry Nebraska air.
||Water regularly or cover with a plastic sheet or tarp.
|The center is damp and warm. Outside is cool and somewhat
||Too small a plant mass overall.
||Collect more plant materials and mix with the old to form
a new mass.
|Plant wastes are damp and sweet smelling but mass will not
||Lack of nitrogen.
||Mix in a nitrogen source such as fresh grass clippings,
granular fertilizer, bloodmeal, manure.
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