About the Authors
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
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,
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
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.
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.
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
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 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
Agriculture and You for more detailed information on this
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.
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
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
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
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 a surprise.
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.
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 on the pads. Our goal in turning less often
was to reduce N volatilization, but the reduced work load
and elimination of E. coli are equally important benefits.
Fifth, because the amendment mix reduced nitrogen losses
from the pile, N:P ratios were higher in the amended compost
than in the standard compost or plain manure. This fact has
very positive implications for field application, because
higher N:P ratios allow farmers to apply more compost to satisfy
a crop’s N requirement without over-applying P (which
is usually over-abundant in our local soils).
Finally, the amended compost was “finished” about
12 weeks earlier than the standard compost, based on temperature
and soluble salt measurements (the manure-only pile is still
far from being finished). The amendments quickly yielded a
light, well-crumbled mixture that made a lovely potting mix
(a bit more uniform in texture than the standard compost)
and that is easier to apply due to its drier texture and granulation.
By mixing the theory of a professor with some experimentation,
we are cooking up innovative changes in compost technology
and performance that promise to help farmers and regulators
better deal with nutrient loss issues, improve their soils,
and protect our ground and surface water resources. As more
data comes in, we’ll update you on the results and benefits
of our amended compost.