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Posted October
15, 2003: Organic farming may be one of the most powerful
tools in the fight against global warming. Findings from 23-year
The Rodale Institute Farming Systems Trial®
(FST) comparing organic and conventional cropping systems show
organic/regenerative agriculture systems reduce carbon dioxide,
a major greenhouse gas—positioning organic farming as
a major player in efforts to slow climate change from runaway
greenhouse gas increases.
Besides being a significant underutilized carbon sink, organic
systems use about one third less fossil fuel energy than that
used in the conventional corn/soybean cropping systems.
According to studies of the FST in collaboration with Dr.
David Pimentel of Cornell University, this translates to less
greenhouse gas emissions as farmers shift to organic production.
66% of the
energy input in the conventional corn soybean row crop system
goes for the production of ammoniated fertilizer
generated from the energy intensive Bosch Haber process. On
the other hand, 75%
of the energy for the organic systems is devoted to energy
costs for seed inputs. Organic farming systems
use winter cover cropping not found in the conventional system.
The ability of organic agriculture to be both a significant
carbon sink and to be less dependent on fossil fuel inputs
has long-term implications for global agriculture and its
role in air quality policies and programs.
Since 1981, data from the FST has revealed that soil
under organic agriculture management can accumulate about
1,000 pounds of carbon per acre foot of soil each year.
This accumulation is equal to about 3,500 pounds of carbon
dioxide per acre taken from the air and sequestered into soil
organic matter. When multiplied over the 160 million acres
of corn and soybeans grown nationally, a potential for 580
billion pounds of excess carbon dioxide per year can be sequestered
when farmers transition to organic grain systems. The FST
compares diversified low input organic systems to conventional
corn soybean row crop systems and is the longest comparison
of this kind in existence. A wealth of information on the
performance of these systems has arisen out of this important
trial.
It is believed that agricultural soil has a significant potential
to capture and retain or sequester carbon dioxide. The 1995
Kyoto Protocol references this potential without emphasizing
its capacity nor the importance of organic agriculture management
for this purpose. Since then, researchers have moved forward
strongly with investigations to support agriculture’s
real potential to sequester carbon. The Rodale Institute®
findings have taken this one step further by measuring carbon
content and studying the positive impacts of carbon sequestration
in organically-farmed soils.
The Rodale Institute’s 23-year findings show that organic
grain production systems increase soil carbon 15 to 28%.
Moreover, soil nitrogen in the organic systems increased 8
to 15%. The
conventional system showed no significant increases
in either soil carbon or nitrogen in the same time period.
Soil carbon and nitrogen are major determinants of soil productivity.
Why does the soil carbon level increase in organic systems
but not in conventional systems when crop biomass is so similar?
We believe the answer lies in the different decay rates of
soil organic matter under different management systems. In
the conventional system the application of soluble nitrogen
fertilizers stimulates more rapid and complete decay of organic
matter sending carbon into the atmosphere instead of retaining
it in the soil as the organic systems do.
Additionally, soil microbial activity, specifically the work
of mycorrhiza fungi, plays an important role in helping conserve
and slow down the decay of organic matter. Collaborative studies
in our FST with the United States Department of Agriculture
Research Service (ARS) researchers, led by Dr. David Douds,
show that mychorriza
fungi are more prevalent in the FST organic systems.
These fungi
work to conserve organic matter by aggregating
organic matter with clay and minerals. In soil aggregates,
carbon is more resistant to degradation than in free form
and thus more likely to be conserved. Support for this work
comes from United States Department of Agriculture researchers
at the Sustainable Agriculture Laboratory in Beltsville, Maryland.
Their findings demonstrate that mychorrizal fungi produce
a potent glue-like substance called glomalin that is crucial
for maximizing soil aggregation. We believe that glomalin
is an important component for carbon soil retention and encourage
increased investigation of this mechanism in carbon sequestration.
Increasing soil organic matter for the soil’s carbon
bank is a principle goal of organic agriculture. Organic agriculture
relies on the carbon bank and stimulated soil microbial communities
to increase soil fertility, improve plant health, and support
competitive crop yields. This approach utilizes the natural
carbon cycle to reduce the use of purchased synthetic inputs,
increase energy resource efficiency, improve economic returns
for farmers, and reduce toxic effects of fertilizers and pesticides
on human health and the environment.
Global temperature is on the rise
An analysis of gases trapped within glacier ice shows that
18,000 years ago, during the last ice age, atmospheric concentrations
of carbon dioxide were 60% lower than those found in the atmosphere
today. This low concentration of carbon dioxide was associated
with a 4°C (about 10°F) drop in average temperature.
Presently, global atmospheric carbon dioxide levels are 25%
higher than in the late 1800’s. If emissions continue
at current levels, carbon dioxide in the atmosphere may double
or even quadruple within the next 100 to 300 years.
In 1938, G. Callendar published findings suggesting that
man’s burning of fossil fuels, such as coal, oil and
natural gas, would likely increase world temperatures. Since
1958, continuous carbon dioxide measurements on Mount Mauna
Loa in Hawaii confirm that carbon dioxide is increasing in
the atmosphere at a rate of about 1.3 parts per million (ppm)
per year. According to atmospheric scientists, while several
other gases contribute to the greenhouse effect in the Earth’s
atmosphere, carbon dioxide is responsible for over 80% of
potential warming. NASA scientist James Hansen tracked temperature
changes in relation to past carbon dioxide levels and correlated
the 25% increase in carbon dioxide over the last 100 years
with a 0.7°C warming of the atmosphere. A number of models
have predicted that the Earth will warm 2.5°C in the next
100 years at current rates of carbon dioxide emission.
According to climatic change models, agriculture could be
seriously affected by global warming. It is estimated that
20% of potential food crop production is lost each year due
to unfavorable weather patterns (drought, flood, severe heat
and cold, strong storms, etc.). The deterioration of weather
patterns in North America could have devastating effects on
world supplies of basic food grains such as wheat and corn.
Climate change modelers predict that higher temperatures will
generate more extreme weather events, such as severe droughts
and torrential rains. A shift of 1 to 2°C in summer temperatures
at pollination season can cause a loss of pollen viability,
resulting in male sterility of many plant species such as
oats and tomatoes.
As global temperatures rise, the glaciers and polar icecaps
will melt, leading to major island- and coastal-flooding.
About 50% of the United States population lives within 50
miles of a coastline. As coastlines move inland, coastal dwellers
will be most directly affected by uncontrolled carbon dioxide
levels. If greenhouse gasses continue to increase in the next
several hundred years, the rise of global temperature is estimated
at 7° C, or almost 15° F, and the sea level would
rise over 2 meters, or in excess of 6 feet.
Soil organic matter—key to sequestration
Normal seasonal carbon dioxide fluctuations in the atmosphere
demonstrate that plant growth governs major amounts of carbon
dioxide, enough to change atmospheric concentration by up
to 10 ppm. By increasing plant production, we can reduce carbon
dioxide concentrations in the atmosphere. Carbon dioxide levels
are minimized in summer when vegetation is lush, and maximized
in winter when plants die or go dormant. The fluctuation of
carbon dioxide from season to season (about 10 ppm) is about
7 times greater than the yearly average increase in atmospheric
carbon from fossil fuel burning and deforestation (1.3 ppm).
Plants serve as sinks for atmospheric carbon dioxide. Carbon
stored in vegetation, soil, or the ocean, which is not readily
released as carbon dioxide, is said to be sequestered. To
balance the global carbon budget, we need to increase carbon
sequestration and reduce carbon emissions. While carbon can
cycle in and out of soil or biomass material, there are methods
for building up what are called soil “humic” substances
(also known as organic matter) that can remain as stable carbon
compounds for thousands of years.
Before forests and grasslands were converted to field agriculture,
soil organic matter generally composed 6 to 10% of the soil
mass, well over the 1 to 3% levels typical of today’s
agricultural field systems. The conversion of natural grasslands
and forests around the globe works to elevate atmospheric
carbon dioxide levels significantly. Building soil organic
matter by better nurturing our forest and agricultural lands
can capture this excess atmospheric carbon dioxide, and preserve
more natural landscapes.
Agricultural and forest carbon sequestration will reduce
the dangers that carbon dioxide currently presents to our
atmosphere and world climatic patterns. These benefits will
complement energy conservation and emission control efforts.
Improved energy use is important because if all fossil fuel
reserves were used in the next several hundred years, carbon
dioxide in the atmosphere would increase 4 to 8 times present
levels. (Currently the atmosphere holds 750 Gigatons of carbon,
while known fossil fuel energy reserves hold 5,000 Gigatons
of carbon.) Soil organic carbon, even at its present depleted
level (1,580 Gigatons of carbon[C]), is still estimated to
be almost double the quantity of all the carbon currently
found in the atmosphere as carbon dioxide (800 Gigatons C),
and about three times the amount found in all living organisms
on the planet (500 Gigatons C).
Soil, agriculture, and forests are essential natural resources
for sequestering runaway greenhouse gas to help derail drastic
climate changes. The amount of carbon in forests (610 Gigatons)
is about 85% of the amount in the atmosphere. The 1998 Resources
For the Future Climate Issue Brief #12 states, “Although
it is well known that the world’s tropical forests are
declining, it is less widely recognized that the world’s
temperate and boreal forests have been expanding, albeit modestly…Nevertheless,
overall, the size of the global forest carbon stock appears
to be declining, thereby generating a net carbon source.”
The Rodale Institute Farming Systems Trial®
Findings
Agriculture is, and always will be, a major tool in carbon
sequestration. The Rodale Institute Farming Systems Trial®
(FST) 23-year research provides real world experience and
the starting point for understanding the potential for agriculture
to reduce greenhouse gases. The FST is the longest running
agronomic experiment designed to compare organic and conventional
farming methods and production systems.
Since 1981, The Rodale Institute®
has continuously monitored soil carbon and nitrogen in the
FST. Carbon and nitrogen monitoring is just one component
of a comprehensive battery of soil quality, economic and energy
data that The Rodale Institute researchers gathered over the
23-year lifespan of the FST. Researchers at The Rodale Institute
believe that soil carbon and nitrogen findings were especially
significant and dramatic.
In the organic systems, soil carbon increased 15 to 28%,
demonstrating the ability of the organic systems to sequester
significant quantities of atmospheric carbon. Specifically,
the FST organic manure system showed an average increase of
soil carbon of about 1000 lbs per acre-foot of soil per year,
or about 3,500 pounds of carbon dioxide per acre-ft per year
sequestered. When multiplied over the 160 million acres of
corn /soybeans that are produced nationally, a potential of
an increase of 580 billion pounds of carbon dioxide per year
would be sequestered by farmers switching from conventional
chemically based farming systems to organic grain farming
methods. Over the 23 year lifespan of FST, the conventional
system showed no significant increases in either soil carbon
or nitrogen.
Organic farming methods increase stored carbon and retain
other nutrients because organic soils hold these nutrients
in place for uptake by plants, and in the process, reduce
nitrate and other nutrient runoff into streams and water aquifers.
These findings can be beneficial to all farmers by helping
to increase crop yields while decreasing energy, fuel and
irrigation costs.
We believe this is the longest term scientifically replicated
study that has been continuously monitored for soil quality
including carbon and nitrogen. Certainly this is a first in
terms of its duration and comparison of the carbon sink potential
of organic and conventional agriculture soils. This study
gives us a baseline to develop an ambitious scale of work
to replicate and then accelerate the carbon sequestration
potential of organic farming methodologies.
In addition to capturing more carbon as soil organic matter,
organic agricultural production methods also emit less greenhouse
gas through more efficient use of fuels. Energy analysis of
The FST by Dr. David Pimentel from Cornell University show
that organic systems use only 63% of the energy input used
by the conventional corn-soybean production system. In all
systems, yields of corn and soybean were not different, except
in drought years, when organic systems yielded 25 to 75% more
than the conventional system. The organic yield advantage
in drought years is specifically related to the ability of
higher-carbon organic soils to capture and deliver more water
to crop plants. Dr. David Pimentel’s findings showed
that the biggest energetic input, by far, in the conventional
corn and soybean system is nitrogen fertilizer for corn, followed
by herbicides for both corn and soybean production.
Organic farming also makes economic sense. In addition to
reducing input costs, economic analysis by Dr. James Hanson
of the University of Maryland has shown that organic systems
in the FST are competitive in returns with conventional corn
and soybean farming, even without organic price premiums.
Real world organic price premiums allow farmers to take advantage
of certified organic production systems to achieve economically
viable returns without massive governmental subsidies.
How can low input organic systems be competitive in productivity
with a high input chemically based conventional system yet
not have large off farm inputs? USDA scientist, David Douds,
in collaboration with scientists at The Rodale Institute®,
has shown that in the organically managed systems, the biological
support system of mycorrhiza fungi is much more robust and
the fungi are more prevalent, active, and diverse. Synthetic
chemical fertilizers and pesticides inhibit mycorrhizae. In
organic production systems, increased mycorrhiza fungal activity
allows plants to increase their access to soil resources.
Thereby stimulating plants to increase their nutrient uptake,
water absorption, and their ability to suppress certain plant
pathogens.
The process and ability of mycorrhiza to sequester carbon
has perhaps an even greater significance. Mycorrhiza fungi
produce a novel glue-like substance called glomalin. Glomalin
stimulates increased aggregation of soil particles. Aggregation
of soil particles results in an increased ability of soil
to retain carbon. The role of mycorrhiza and glomalin in soil
carbon retention requires further investigation. Other biological
mechanisms resulting in greater ability to sequester carbon
naturally and improve soil properties require further investigation
as well.
Benefits beyond carbon sequestration
The presence of sequestered carbon in The Rodale Institute’s
FST organic field trials is an indicator of healthy soil because
healthy soil is abundant in carbonaceous matter, in particular
the organic material humus. It is humus that enables healthy
soils to retain water during periods of drought; as well as
retaining mobile nutrients found in soils such as phosphates
and nitrates, that would otherwise be lost as runoff to streams
and aquifers.
These trials are illustrative of both economic benefit as
well as environmental protection working hand in hand. The
economic benefit is realized by farmers and landowners who
see reduced costs for fertilizer, energy fuels and irrigation,
and increased crop yields at the same time. It is also economically
beneficial to the agricultural business economy, and an environmental
benefit to all of us, that specific soil management and tillage
practices can help to sequester or retain carbon in the soil--carbon
that would otherwise be lost to the atmosphere as a component
of greenhouse gases.
In summary, organic farming can reduce the output of carbon
dioxide by 37-50%, reduce costs for the farmer , and increase
our planet’s ability to positively absorb and utilize
greenhouse gases. These methods maximize societal and individual
farmer benefits. It is a winning strategy with multiple benefits
and virtually no risk. These proven approaches mitigate current
environmental damages and promote a cleaner and safer world
for future generations.
The next steps
In recent months, staff from the Rodale Institute met with
officials of the Pennsylvania Departments of Agriculture and
Environmental Protection. Together, we are working on a Statement
of Cooperation that will provide a platform for future research
and education on how organic farming can provide significant
economic and environmental benefits. With 22 years of data
from the FST field trials in place, we will explore ways to
promulgate and systematize the knowledge that has been gathered.
In recent years, other researchers around the world have also
begun to investigate and document the potential for soil carbon
and nutrient sequestration. It is important to move forward
quickly to lead the research in this field.
First,
we propose to review the current body of scientific literature
to determine if there are ways to accelerate the formation
of organic material in soil, and to determine if it is possible
to predict the rate of carbon and nutrient sequestration.
Additionally, we would like to determine if there may be
important opportunities for sequestration in manufactured
soils with expanded applications on abandoned mine lands
and conservation areas.
Second,
we propose the development of protocols whereby landowners
could adopt organic soil management practices and quantify
sequestration potential. Ultimately, this could enable landowners
to participate in carbon and nutrient trading markets, which
would provide a financial incentive to adopt organic soil
management practices.
Third,
we propose to expand the knowledge base on soil sinks through
communication and collaboration with other scientific, educational,
research and agricultural institutions.
This is a new field from the perspective of many in the agricultural
and soil management communities. While the data from the field
trials is a matter of record, much needs to be done before
we know how to transfer this knowledge for use in broader
markets and applications. Nonetheless, what has been demonstrated
is significant and shows promise in helping to reduce the
build-up of greenhouse gasses while promoting greater use
of organic agriculture.
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