Transcript composting(2) - Goodhue County Extension Master Gardeners

Composting 101
The what, when,
where, why and
how of composting
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Home Page: http://www.extension.umn.edu/county/sherburne/mgardeners
Minnesota waste facts
• Statewide recycling rate - 47.2%
• Minnesotans threw away 3 million tons of
garbage in 1999
• Organic materials comprise of 25.4% of
statewide residential waste (most of which is
compostable)
• Paper products make up
30.8% of statewide
residential waste
What is compost?
• End product of the decomposition of organic
materials by decomposers
• Valuable soil amendment
• Dark, crumbly and earthy
smelling material
• A resource that can be
utilized in your own back yard
Why should I compost?
• There are many benefits to
composting
– Valuable soil amendment
– Effective mulch
– Reduction in waste
Soil amendment
• Improves soil structure
– Increases aeration
– Holds moisture
– Especially important in sandy soil
• Promotes plant growth
– Contains essential micronutrients
• Stores nutrients
– Porous structure stores
nutrients
Soil amendment
• Flower and vegetable gardens
– Dig or till 8 to 10 inch deep
– Mix 3 to 4 inches of compost through entire
depth
• Seeding new lawns
– Till soil 6 inches deep
– Mix in 4 inches of compost
Mulch
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Suppress weeds
Maintain moisture levels
Control temperature
Prevent soil erosion
Mulch
• Gardens
– Sift compost to remove large, woody material
– Apply 1/2 to 1 inch layer
– Keep a few inches away from base of plants
• Trees and shrubs
– Remove sod from base of plant
– Use coarse compost
• Erosion control
– Use 2 to 4 inches coarse compost
Reduce waste
• Reduce the amount of waste sent to
landfills and incinerators
• Often illegal to dispose of yardwaste with
other municipal solid waste
How does compost happen?
• Organic material is processed (for free) by numerous
decomposers
– Bacteria
– Fungi
– Invertebrates
 Worms
 Nematodes
 Springtails
• Decomposers need food, nutrients, air and water (you
will need to supply these)
• Decomposers also need heat but they supply their own
Decomposers – microorganisms and
soil animals
The food web in
your compost
pile supports a
wide variety of
lifeforms from
microscopic
bacteria to
larger beetles
and worms.
Decomposers - bacteria
• Most numerous organisms in compost pile
• Don’t need to be added to compost pile, they are
present virtually everywhere!
• Generate heat associated with composting
• Perform the primary breakdown of organic
materials
• There are different bacteria
present at different temperatures
Bacteria groups
• Psychrophilic bacteria
– Ideal temperature is around 55°F but they are able to
survive right down to 0°F
• Mesophilic bacteria
– Thrive at temperatures between 70-90 °F and can
survive from 40-110 °F
• Thermophilic bacteria
– Work fastest in temperatures from 104-170 °F
– Most efficient decomposers
Decomposers - bacteria
• Interesting fact - “less than a teaspoon of
the common bacteria Escherichia coli, would
become a pound in 3 hours and a mass the size
of the Earth in a day and a half if sufficient
food and proper conditions were available!”
Decomposers - fungi
• Perform primary decomposition
• Identified by their root-like fibers or
presence of mushrooms
• Not as efficient as bacteria
• Less temperature tolerant
than bacteria
Decomposers - nematodes
• Most abundant invertebrate in the soil
• Usually less then 1 millimeter in length
• Prey on bacteria, protozoa, fungal spore and
each other
Decomposers - mites
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Called fermentation mites or mold mites
Transparent-bodied creatures
Feed on yeast
Masses often develop over fermenting
surfaces
Decomposers - collembula
• Also know as springtails
• Feed mainly on fungi but also eat
nematodes and organic detritus
• Major population controlling factor of
fungi
Decomposers - wolf spiders
• Build no webs
• Run freely hunting prey
• Prey on all sizes of arthropods
Decomposers - centipede
• Frequently found in soil and compost
microcommunities
• Prey on almost any type of soil
invertebrate near their size or slightly
larger
Decomposers - sow bug
• Feed on rotting woody material and leaf
tissue
• Also know as pill bugs or roly polys
Decomposers - ground beetle
• Many different types can be found in and
around compost piles
• Most feed on other organisms, but some
feed on seeds and vegetable matter
Decomposers - redworms
• Coat processed organic material with
mucus films that
– Binds small particles together
– Leads to loose and well drained soil
– Protects soil against nutrient leaching
Other compost residents - pests
• Common pests may include house and fruit flies,
rodents, raccoons, and domestic animals such as
cats and dogs
• Proper bin maintenance and selective material
usage will reduce your risk of pest problems
Pest control
• Avoid composting meat and dairy products
and other fatty foods
• Avoid adding pet food or feces to your
compost pile
• Cover other food waste with a layer of
grass, straw, leaves, paper or finished
compost
What are the key “ingredients”?
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Materials (C:N ratio)
Moisture and aeration
Particle size/surface area
Temperature
C:N Ratio
• All living organisms need relatively large
amounts of carbon and smaller amounts of
nitrogen
• Microorganisms in compost use carbon for
energy and nitrogen for protein synthesis
• Green materials = nitrogen
– ex. green grass clippings
Generally...
• Brown materials = carbon
– ex. autumn leaves, straw
• The ideal ratio of carbon:nitrogen of 30:1 will ensure
maximum bacteria decomposition
• Mix based on weight not volume
• These are only guidelines, actual values may very (Ex. leaves
from different trees will vary in their carbon content)
Average Carbon:Nitrogen Ratios
Food Scraps
Grass Clippings
Rotted Manure
Corn Stalks
Leaves
Straw
Paper
Sawdust, woodchips
15:1
19:1
25:1
30:1
60:1
40-80:1
80:1
170:1
500:1
GREENS
Ideal for Composting
BROWNS
Moisture and aeration
• All compost organisms need air and water to
survive
• Strive for moisture content around 50%
– Without 40% the bacteria will slow down
– At 80% and above there is not enough airspace and
aerobic decomposition occurs which is slower and
leads to odor problems
• Avoid compacting materials - this
limits aeration in your pile
Moisture and aeration
• Optimal moisture levels occur when
compost is as moist as a wrung out sponge
• When watering a dry pile be sure to mix
Water will just shed off a dry pile
• Mixing once or twice a month will increase
rate of decomposition by increasing air
spaces
• Takes 3–6 X’s longer if not turned
Particle size
• Particle size is an important
factor in composting
• Reducing particle size
increases the surface area
available for decomposers
• However, if the pieces are
too small they may compact
together and limit aeration
• A mixture of small and
larger particles is ideal
Temperature
• High temperature
compost pile
– Faster
decomposition
– Helps insure weeds
and pathogens are
killed
What can be composted?
Grass and yard trimmings/clippings
Leaves
Coffee grounds/filters
Tea leaves/bags
Fruits and vegetable trimmings
Wood chips
Sawdust
Egg shells
Livestock manure
What should not be composted?
Diseased or insect infested plants
Cat and dog manure
Evergreen needles
Poison ivy and other poisonous plants
Weeds that contain seeds
Meat and animal products
Fatty foods
Dairy products
Compost bin size
• For fast efficient composting your bin needs to be
– Large enough to hold heat and moisture
– Small enough to admit air through the center
• Rule of thumb
– A compost pile need to be
at least 3ft. by 3ft. by
3ft.
– Upper limits are about 5ft.
by 5ft. by any length
Building your compost pile
• Build in layers
– 8 to 10 inches of ‘brown’ material
– Several inches of ‘green’ material
– One inch of soil
• Establish proper
moisture content
• Avoid compacting
materials
Compost bin types
• There is a great deal of variety in
composting structures
• Compost bins vary in their cost,
required labor, volume, and time
required for finished compost
Open piles
• Slowest rate of decomposition
• Least expensive method
• Minimal pest control and containment
Holding units
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Helps keep decomposing materials organized
Reduces pest problems
Requires no turning
Relatively slow rate of decomposition (6
months to 2 years)
Turning units
• Allow for easier mixing of materials
• Result in a hotter pile and reduced composting time (as
soon as 2-3 weeks)
• Usually more expensive and more labor intensive
Threechambered
bin
Barrel or
drum
composter
Location
• Avoid areas with drying wind
• Partial sun will help heat the pile
• Should be easily accessible yet not
interfere with yard activities
• Should not be offensive to neighbors
Finished Compost
• Avoid using unfinished compost, organic
acids may harm plant roots
• If compost is still hot, smells like ammonia,
or
you can still identify much of the
original organic material it is not
ready to use yet
Finished Compost
• Composting is complete when the pile stays at or
near the ambient temperature
• Finished compost is dark, crumbly, and has an
earthy smell
• The volume of finished compost will
have been reduced by 30 to 50 percent
Problem solving – what if?
• The pile smells like rotten eggs?
– Not enough air/too much water
– Add coarse material like dry leaves
– Pile should be wet like a wrung out sponge
• The pile smells like ammonia?
– Too much nitrogen, not enough
carbon
– Add dry leaves, sawdust or straw
Problem solving – what if?
• My compost pile is not heating up?
– Examine bin size, moisture content, air flow,
and material ratios (C:N)
• My compost pile is attracting pests?
– Eliminate meat dairy products and
fatty foods from bin
– Bury food waste under a few inches
of material like leaves and grass
Other Options
Have too much yard waste to backyard
compost?
Want to compost kitchen waste but don’t
have the yard space to do it?
Here are some alternatives to backyard
composting...
Municipal Composting
• Municipal composting
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Available though many cities and townships
Often take larger yard trimmings (and chip them)
Usually offered as a free service
Finished compost often available for free
• Contact your local county Extension educator,
county solid waste officer, or city recycling
coordinator for more info
Grass Clippings
Grass clippings are a great source of
nitrogen for your compost pile but usually
you have more clippings then needed. What
can you do with excess clippings? Leave
them on your lawn! Leaving grass clippings
on lawn returns nutrients to the soil
(clippings will naturally decompose).
Vermicomposting
• Method of composting kitchen scraps and
other organic material
• Materials are placed in an aerated container
with redworms
– Redworms are able to digest 2/3 their body weight
in a day
• Worm bins can be made out of any material
that holes can be drilled into
Credits
• This project was developed by the
University of Minnesota Extension
Service-Sherburne County and the
Sherburne County Master Gardeners
• Funding assistance provided by the
Sherburne County SCORE grant
• Some of the graphics used were taken from the Master
Composter Manuel - Cornell Waste Management Institute
Questions?/Comments!