Download COMPOSTING Duane Friend Educator in Environmental Stewardship and Energy

COMPOSTING
Duane Friend
Educator in Environmental Stewardship and Energy
University of Illinois Extension
University of Illinois Extension
Overview
• History of composting
• Basic processes
• Benefits of compost
• Uses of finished compost
• Field studies in Illinois using compost
World
Prehistoric farmers discovered that by piling
mixtures of animal manure, plant debris, and
• soil the process of decomposition that occurs
in nature is sped up. The resulting product –
called compost or humus – is still the primary
source of soil nutrients in many parts of the
world.
North America
 Native Americans
 Early European settlers – compost made of
10 parts muck to 1 part fish, periodically
turning the heap until fish disintegrated
 George Washington, Thomas Jefferson ,
George Washington Carver – promoted use
of compost
Composting Today
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THE COMPOSTING
PROCESS
MICROORGANISMS
OXYGEN
WATER
ORGANIC MATERIALS
HUMUS
CARBON DIOXIDE
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HEAT
WATER
THE COMPOSTING
PROCESS AND CRITTERS
INVOLVED
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Compost Biology
• Compost Ecosystems/Food Web
• Organisms
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Where do the decomposers come
from?
Penn State
• Soil
• Leaves
• Food scraps
• Manure, and
• Finished compost
“Microorganisms found on the surface of leaves,
grass, and other incoming organic matter are
fully capable of starting and sustaining the
compost process.”
Winn. Co. Master Composter Manual, 1992
(Slide courtesy John Church)
What Soil/Compost
Organisms Do
•
•
•
•
Nutrient Cycling
Nutrient Retention
Improved structure
Improved water infiltration/holding
capacity
• Disease suppression
• Degradation of pollutants
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Soil/Compost Food Web
From: The Soil Biology Primer, published by the Soil and Water
Conservation Society in cooperation with the USDA Natural
Resources Conservation Service
Seasonal Activity
From: The Soil Biology Primer, published by the Soil and Water
Conservation Society in cooperation with the USDA Natural
Resources Conservation Service
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One teaspoon of good garden soil to
which compost has been added
contains:
• 100 million bacteria
• 800 feet of fungal threads
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Bacteria
AEROBIC BACTERIA
• Bacteria that function only in the
presence of oxygen
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AEROBIC BACTERIA
• Utilize carbon as a source of energy
• Utilize nitrogen to build protein
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AEROBIC BACTERIA
• Psychrophilic- Active at 55 to 70 degrees
• Mesophilic- Active at 70 to 100 degrees
• Thermophilic- Active at 113 to 160
degrees
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ANERORBIC BACTERIA
• Bacteria that function in the absence
of oxygen
• Produce organic acids, amines, and
hydrogen sulfides, cadaverine, and
putrescine
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Fungi
• Parasitic or pathogens
• Found in later stages of the process
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MACROORGANISMS
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KEY FACTORS
AFFECTING THE
COMPOSTING PROCESS
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FOOD FACTOR
• Organic materials provides carbon
and nitrogen for microorganisms
• Nitrogen is usually the limiting
factor
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CARBON/NITROGEN
RATIO
• The amount of carbon compared to
the amount of nitrogen in a
substance
• Carbon for energy source and
nitrogen to build cells
• Carbon amounts are always higher
than nitrogen
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A C/N RATIO OF 25:1 IS
IDEAL FOR RAPID
COMPOSTING
• Blending of materials is necessary
• Try to have 1/4 to 1/2 of materials in
high nitrogen category
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MATERIALS WITH HIGH
NITROGEN VALUES
MATERIAL
Food wastes
Grass clippings
Cow Manure
Horse Manure
Coffee grounds
C/N RATIO
15:1
20:1
20:1
25:1
20:1
MATERIALS WITH HIGH
NITROGEN VALUES
•
•
•
•
Legume Hay
Dried Blood
Chicken Manure
Sheep Manure
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20:1
3:1
10:1
16:1
MATERIALS WITH HIGH
CARBON VALUES
MATERIAL
Leaves
Straw
Sawdust
Paper
C/N RATIO
80:1
80:1
500:1
200:1
MATERIALS WITH HIGH
CARBON VALUES
•
•
•
•
•
Corn stalks
Hardwood Bark
Hardwood Shavings
Softwood Bark
Softwood Shavings
70:1
225:1
560:1
500:1
640:1
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High carbon materials such as
Leaves (30-80:1)
Straw (40-100:1)
Paper (150-200:1)
Sawdust (100-500:1)
Animal bedding mixed
with manure (30-80:1)
Penn State
Slide courtesy John Church
High nitrogen materials such as
Vegetable scraps (12-20:1)
Coffee grounds (20:1)
Grass clippings (12-25:1)
Manure
– Cow (20:1)
– Horse (25:1)
– Poultry (10:1), with litter
(13-18:1)
– Hog (5-7:1)
Penn State
Slide courtesy John Church
Master Composter Resource Manual, 1998
Cornell University
Slide courtesy John Church
AIR FACTOR
• Microorganisms need oxygen to
function
• Affected by wind, moisture, and
porosity
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Oxygen Needed for Aerobic
Composting
• Optimal oxygen concentrations are
in the 10-16% range for fast
composting, although in some cases
odors may not be an issue until
oxygen levels drop below 5%
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WAYS TO KEEP OXYGEN
IN GOOD SUPPLY
• Monitor oxygen
• Periodic turning
Photo from Midwest Bio Systems
• Keep pile from being too
wet
• Add coarse materials
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Maintain moisture
similar to a
damp sponge
Slide courtesy John Church
Moisture
• Optimal range 46-65%
• Low moisture limits microbial
activity
• High moisture limits oxygen
availability
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TEMPERATURE FACTOR
• Temperatures of 90 to 140 degrees indicate rapid
decomposition
• Temperatures above 131 degrees needed to kill
pathogens
• Above 160 reduces microbial activity
• At 179 degrees, all beneficial microbes are killed
• 204 degrees- spontaneous combustion
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Temperature and Weed
Seed Mortality
• Dahlquist et al. (2007) estimated that three of
the six weed species they examined under
controlled laboratory conditions were
unaffected by temperatures of 108 °F, but 90%
of the seeds of all six species were killed after
less than three hours at 140 °F . Furthermore,
all six species suffered 100% mortality after
less than an hour at 158 °F
From : Composting to Reduce Weed Seeds and Plant Pathogens, U of I Extension
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TRACKING
TEMPERATURE
• Compost thermometers
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PARTICLE SIZE FACTOR
• Affects rate of decomposition
• The smaller the size, the more surface area
provided for microbes to work on
• Very small particles
limits oxygen
• Ideal range 1/8 to ½ inch
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VOLUME FACTOR
• Needs to be big enough to retain heat
• Can be as large as
equipment will allow,
as long as temperature and oxygen
levels are managed
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pH
• Initial pH will vary according to
feedstock, but finished compost will
generally be in the 6.0 to 7.5 range.
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WHEN TO START
• Can be started any time of year, but
may be limited by availability of
carbon rich or nitrogen rich
materials
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Recommended Conditions
for Composting
•
•
•
•
•
C:N ratio- 20:1 to 40:1
Moisture content- 40-65%
Oxygen concentration- > 5%
Particle size- 1/8 to ½ inch
Temperature- 110-150o F.
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Active Composting Time
• Passive composting- 1 to 2 years
• Infrequent turning- 6 mo. to 1 yr.
– Curing time 1 to 4 months
• Frequent turning- 2 mo. To 6 mo.
– Curing time 1 to 2 months
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PROBLEMS
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ODOR
• Not enough oxygen
– Overwatering
– Compaction
– Too much nitrogen
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PILE NOT HEATING UP
• Not big enough
• Not enough moisture or air
• Not enough nitrogen
• Compost may be finished
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COMPOST IS DAMP AND
WARM ONLY IN CENTER
• Pile is too small
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LARGE UNDECOMPOSED
ITEMS STILL VISIBLE
• Not enough surface area
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RODENTS AND PETS
• Presence of meat
• scraps
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BENEFITS AND USES OF
COMPOST
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FINISHED COMPOST
• Has dark color, earthy smell, and is
crumbly
• Let finished compost sit at least 3
weeks to make sure decomposition
process is complete
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Curing Compost
• Compost just finishing the active
cycle may contain higher amounts of
ammonium- may affect plants
especially sensitive to this type of N.
• Curing allows ammonium to convert
to more plant tolerable N.
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Simple tests for finished
compost
Bag test: sealing
compost in a plastic bag
for several days should
produce no foul odor
Germination test: will seeds
germinate in the compost?
(good test to use if compost
will be part of a potting mix)
Slide courtesy John Church
Penn State
Maturity Index
• The Solvita test measures CO2 and
Ammonia
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Solvita Tests
• Solvita® detection is based on a gelcolorimetry technique, analogous to
Beer-Lambert’s law
governing optical-chemical reactions
to changing concentrations of
dissolved molecules, such a H-CO3
and NH3OH
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Compost Application Studies in
Illinois
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Incorporating high-quality compost has been
shown to improve soil quality.
Multi-year study on irrigated plots east of
Havana, Illinois in Mason County (sandy soils).
Annually applied rates of 10 and 20 dry tons
per acre of compost to plots over a four-year
period -- Soil tests were conducted each year to
see whether there were any changes in organic
matter content, cation exchange capacity, or
other physical and chemical characteristics.
Duane Friend, U. of I. Extension Educator, NRM
Springfield, March, 2007
Nine Sub plots
• Rates of 0, 10, and 20 wet tons acre of compost
• Measure soil changes
• Measure soil moisture during growing season
• Measure yield within plots
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20 Dry Tons/Ac
60 Dry Tons/Ac
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Average Organic Matter Contents for Plots
2003- taken 11 months after 1st application
2004- taken 11 months after 2nd application
0.45
0.4
0.35
0.3
Organic
0.25
matter in
0.2
percent 0.15
0.1
0.05
0
0 tons/ac
10 tons/ac
20 tons/ac
2003
2004
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Average Cation Exchange Capacity for Plots
7
6
5
CEC value
4
0 tons/Ac
10 tons/Ac
20 tons/Ac
3
2
1
0
2003
2004
Statistically significant at 20 tons/ac
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Average Relative Soil Water
Content
70
60
50
Relative
water 40
content in 30
percent 20
0 tons/ac
10 tons/ac
20 tons/ac
10
0
2003
2004
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2004 Yield Results- Popcorn
6350
6340
6330
6320
6310
Pounds/Acre
6300
6290
6280
6270
6260
0 tons
10 tons
20 tons
Conclusions of Study
• Was slowly improving soil quality
• May take years of application to
affect yields at low rates of
application
• Phosphorus levels should be
monitored if using a high P compost
feedstock
Compost/Sediment Field
Study
• Applied ratio’s of compost and sediment for a
total application rate of 60 dry tons/ac.
•
•
•
•
25% compost / 75% sediment
50/50
75% compost / 25% sediment
0 (control)
• 3 replications of each
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Extension
Lake Decatur
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Compost
Sediment
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Compost and Sediment
Control
Compost and Sediment
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Sub plot average of popcorn yield
in pounds/acre
5000
4000
3000
2000
1000
0
0
25/75
50/50
75/25
Test Weight of popcorn
66.2
66
65.8
65.6
65.4
65.2
65
64.8
64.6
0
25/75
50/50
75/25
Conclusions of
compost/sediment study
• Yields increased, but not statistically significant
• Test weights of popcorn increased where
compost/sediment applied
• Ratios of compost/sediment did not appear to
make a difference
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USES OF COMPOST
• Mulch
• Soil Amendment
• Potting mixes
• Compost tea
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FINISHED COMPOST: SCREENING
For high quality use,
screening needed to remove
clay balls and remaining
uncompostables
Slide courtesy John Church
Compost as Mulch
• Do not use more than 2-3 inches
• Do not place in direct contact with
trunk of trees
• Excellent for erosion control
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