1. Good compost made better
The Rodale Institute takes “black gold” one step further.
By Christine Ziegler Ulsh with Paul Hepperly, PhD
About the Authors
Christine Ziegler Ulsh,
Research Technician at The
Rodale Institute, received a
B.A. in Biology from Smith
College and a M.S. in
Forestry at The University of
Massachusetts.
Before coming to The
Institute, Christine’s varied
career included research at
the University and with the
USDA Forest Service,
natural foods retail sales,
administration and farm
work. Her interests include
writing, gardening, singing,
walking and hiking, working
on home improvements and
spending time with her
husband, daughter, and son.
As the Research and
Training Manager at The
Rodale Institute, Dr. Paul
Hepperly has been a
regular contributor to
NewFarm.org for some time,
providing research updates,
op-ed pieces and white
papers on topics such as
carbon sequestration in
organic farming systems.
Paul grew up on a family
farm in Illinois and holds a
Ph.D. in plant pathology, an
M.S. in agronomy and a B.S.
in psychology from the
University of Illinois at
Champaign-Urbana. He has
worked for the USDA
Agricultural Research
Service, in academia, and
for a number of private seed
companies, including
Asgrow, Pioneer and
DeKalb.
April 13, 2006: For many organic and sustainable farmers,
compost is a sensible way to dispose of animal manure and crop
waste and, at the same time, add organic matter and crop
nutrients to the soil. The composting process is older than
agriculture itself, having occurred in nature long before humans
began to cultivate crops.
Over the past decade or so, farmers and soil scientists at The
Rodale Institute and other organizations began working together
to make advances in compost technology, finding even safer and
more effective and sustainable ways to convert waste materials
into resources that build healthier soil with more balanced fertility.
And now The Rodale Institute’s most recent research has the
potential to take compost science one huge step forward: We’ve
developed a new approach to composting, using amendments
designed to mimic natural soil-forming processes, in order to keep
more crop nutrients—particularly nitrogen and phosphorus—in the
compost and out of the rainwater that washes through exposed
piles during composting. Our goal is to keep these nutrients
working for us on our farm and out of our streams, rivers, ground
waters, oceans and air.
With funding from the Pennsylvania Department of Environmental
Protection (PA DEP), we began an experiment in 2005 to see how
three different kinds of compost hold nutrients both in the pile and
in the field, and how each affected crop responds. To date, we’ve
compared the nutrient content, nutrient runoff and bacterial output
of these three composts—broiler litter alone, standard broiler
litter/leaf compost, and our new recipe—during the composting
process. The results have been encouraging, indicating that our
new recipe—which incorporates clay, calcium, and humic acid
amendments in a standard leaf/ manure mix—has reduced
nitrogen (N) losses from the compost pile by up to 90 percent and
phosphorus (P) losses by up to 75 percent. The amendments also
appear to accelerate compost maturation and reduce bacterial
pathogens in the finished product.
More benefits, similar procedure
Fortunately for farmers and commercial composters, our new
recipe doesn’t much change the process of making compost,
which is very simple:
Pile up between 25 to 40 parts (by weight) of a
carbon-rich material (usually “brown” things like leaves,
hay, straw, newspaper, or sawdust) with one part of a
nitrogen-rich material (such as manure or food waste).
Stir the pile every so often to make sure everything is well
mixed and getting some air. (Letting the pile complete a
temperature cycle before turning reduces losses of
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2. He has overseen research
in Hawaii, Iowa, Puerto Rico
and Chile, and investigated
such diverse crops as
soybeans, corn, sorghum,
sunflowers, ginger and
papaya. He has witnessed
the move toward biotech
among the traditional plant
breeding community and the
move toward organics
among new wave of
upcoming young farmers.
Before coming to The
Rodale Institute, Paul
worked with hill farmers in
India to help them overcome
problems with ginger root rot
in collaboration with Winrock
Intermational.
nitrogen and lowers your labor, to boot.)
Wait three to twelve months (or more) until the pile looks
like good, dark soil with no recognizable chunks of the
starting materials.
Compost can’t be beat as a means to recycle farm wastes such
as manure, bedding, old hay, leaves, sawdust, and the like. And
because it is such a valuable soil conditioner, compost also meets
another criterion of farm friendliness: It solves two problems with
one modest operation.
As the years have progressed, agricultural science has learned
more about why this simple process works and about how to
tweak the handling and the components—material composition,
particle size, moisture, pH, pile size, and turning method and
schedule—to make a better product more quickly. Our own
Compost Utilization Trial has shown that, while compost, synthetic
fertilizer and raw manure each support competitive crop growth
and yields, only compost significantly improves soil organic
matter. Soil organic matter is the key to conditioning the soil for
better performance during drought and guarding against
excessive nutrient runoff in wet conditions.
Only in recent years, as excess agricultural nutrients increasingly
pollute the nation’s waterways, have people begun to question:
How does compost affect the nutrient pollution picture? What
quantities of nutrients are lost when compost is applied to the
field? And what quantities of nutrients are lost during the
composting process itself?
Compost reduces N losses
The Rodale Institute answered the first of these questions as part
of its 10-year Compost Utilization Trial (CUT). Using lysimeters to
collect water that passes through the crop root zone and soil of a
farm field, CUT researchers determined that compost reduced
nitrate nitrogen losses by 60 percent when compared with
chemical fertilizer and 70 percent when compared with raw dairy
manure. What’s more, the amount of nitrogen that remained in the
soil after harvest was 4.5 times greater in the compost fields than
in the chemically fertilized fields, and 1.5 times greater than in the
fields fertilized with raw dairy manure. (Check out The Rodale
Institute publication Water Agriculture and You for more detailed
information on this landmark study.)
Now, as part of our PA DEP-funded grant, we are also answering
the second question by composting plain manure and our two
different compost mixes on concrete drainage pads designed to
capture any water that runs through the compost pile. This
approach allows us to precisely measure nutrients and bacteria
that are washed out of the compost as the piles mature.
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3. Although a standard mix of three parts
leaves and one part manure (above)
performed better than plain manure
"compost" (below), it wasn't quite as good
as the amended recipe.
Our three compost
recipes are: 1) a
standard mix of
three parts leaves
and one part
manure; 2) our new
(patent pending)
amended mix that
incorporates 14
cubic yards of
leaves, 4 cubic
yards manure, 2
cubic yards clay
(taken from our farm
subsoil), 90 pounds
of gypsum (calcium),
and 110 pounds of
humic acid
(leonardite coal
dust); and 3) a plain
manure “compost”
(no leaves or other
carbon materials
added, with the
exception of minimal
bedding materials),
which represents a
worst-management
scenario.
Poultry manure
(broiler litter) was
used as the nitrogen
source for the first
round of compost in
this study, which
was initiated in May
and finished in
October of 2005.
Data from the first
part of the trial
showed that, under
slightly-lower-
than-normal
precipitation, the
poultry manure (alone) leached 70 percent more ammonium
nitrogen and 25 percent more ortho-phosphate (ortho-P) than
standard composted manure. But when reported in actual weight,
these nutrient losses were quite small; even the manure alone
leached only 2.4 ounces of ammonium N and 1.4 ounces of
ortho-P from a 20-cubic yard pile.
Downpour reveals big differences
However, after an extreme precipitation event in October—during
which the farm received 10 inches of rain in two days—the
manure-only pile lost 95 percent more ammonium N and ortho-P
than either of the other composts. And the weight of the nutrients
lost was more alarming: The manure-alone pile lost 18.3 pounds
of ammonium N and 74 pounds of ortho-P, while the standard
compost lost only 18.2 ounces of ammonium N and 49.9 ounces
(3.1 pounds) of ortho-P. These results clearly show that, to
prevent nutrient loss, standard compost is a superior way to
manage manure waste and apply its nutrients to the field—far
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4. Amended compost is a significant
improvement in terms of holding N and
ortho-P over standard compost recipes
even in extreme precipitation conditions.
better than piling and applying manure by itself.
But our specially
amended compost
performed even
better. During the
summer period with
lower rainfall, the
amended compost
lost 85 percent less
ammonium N than
the standard
compost (only 0.11
ounces) and 71
percent less ortho-P
(0.32 ounces). And
after the extreme
rain event, the
amended compost
leached the same
amount of
ammonium N as the
standard compost
(19.4 ounces) and
39 percent less
ortho-P (30.56
ounces, or 1.91
pounds).
This data demonstrates that the amended compost is a significant
improvement over the standard compost recipes of old. We are
currently performing a second round of compost-pad studies
—using dairy manure as the nitrogen source for the compost—to
corroborate our initial test. Thus far, the dairy manure has shown
results consistent with broiler litter, with a large and clear
advantage for amendments, including less leaching and even
faster processing. Dairy manure also seems to offer more rapid
and complete composting than broiler litter.
During the coming 2006 growing season, we will apply both the
dairy- and poultry-manure-based composts, along with raw dairy
and poultry manure and chemical fertilizer, to corn fields fitted with
lysimeters to see if the amended composts hold nutrients as well
in the field as they do in the pile. We also incorporated the
composts into potting mixes that we’re using to grow lettuce and
test the composts’ influence on plant growth and nutrient content
in the greenhouse.
The development of the clay-calcium-humic acid compost
amendment tests the theory of soil organic matter stabilization and
soil aggregation proposed by Frank Stevenson, PhD, at the
University of Illinois.
New recipe shows some surprise benefits
The amendment mix is designed to accelerate biogeochemical
processes involved in soil aggregation. The reaction uses calcium
ions (Ca++) as mortar to electrochemically attract and bind
negatively-charged clay and humic acid particles, generating soil
aggregates (or clumps). Clumps of soil, clay, calcium and humic
particles create the storage structures needed to bind nutrients,
thus preventing their loss through leaching or volatilization. In this
way, the nutrients are captured in stable forms that resist losses
to water and air but are available over time to help plants grow
and develop. Our data indicate that this particle-and-nutrient
binding process can have multiple benefits, some which came as
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5. a surprise.
(click on graph for larger view)
First, our amendments trapped odors much more effectively than
we expected. Amended compost cut the odors from the poultry
manure within 10 days; more quickly than standard compost (long
recognized for its ability to reduce odors), which took six weeks.
Thus, the amendments could allow composters to work in urban
environments without offending the neighborhood.
Second, we found that the amended compost aggregated
(clumped) conclusively within its first 10 days, again more quickly
than we had hoped.
(click on graph for larger view)
Third, the more stable N in the amended compost provided little
food to support bacteria such as the E. coli pathogen (found in
manure). Thus, E. coli was eliminated from the water that ran off
the amended compost pile after only six weeks. The standard
compost eliminated the E. coli by 12 weeks, and the poultry
manure alone still leached it after six months (and probably still
leaches it at the time of this writing). This data suggest that
compost, particularly the amended compost, can go a long way to
reduce potential pathogens, as well as excess nutrients, in the
water supply.
Fourth, the E.coli was eliminated by immobilization of organic
nitrogen, rather than by pile temperature. We allowed pile
temperatures to settle close to ambient temperature before turning
and actually turned the piles only three times over their six months
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