KUTZTOWN, Pa. -- Not all dirt is created equal, even here in
Pennsylvania's famously fertile Dutch Country. Some soils are
merely good, while others are flat-out miraculous, such as the
remarkably talented black loam at the Rodale Institute experimental
farm.
This research center boasts a eight-acre plot of super-soil that
not only grows the finest corn and soybeans but sucks pollution out
of the air like a giant siphon. In a reverse of the "greenhouse
effect," it drinks in carbon dioxide from cars and factories and
stores it below the surface as carbon, the building material for
future plants.
The secret lies not in soil but in farming techniques, and the
possibilities it raises are huge. Rodale scientists say a few
simple practices, applied across the U.S. Corn Belt, could
transform farms into carbon-dioxide sponges that sop up millions
of metric tons a year of the chief greenhouse gas blamed for global
warming.
"That's equivalent to the total carbon-dioxide emissions for
countries like Iraq, Egypt, Greece, Denmark and Sweden," said
Laurie Drinkwater, Rodale's U.S. program director.
A battery of studies in recent months have prompted policymakers
to focus on the potential of farms and new farming techniques to
help fight global warming by offsetting emissions
from burning fossil fuels. Although much remains unknown, the
research has climate experts buzzing about possible benefits for
governments, industries and farmers, not to mention the
environment.
Under a United Nations climate agreement approved last year, the
United States and other industrialized countries would face
mandatory cuts in their greenhouse gas emissions over the next
decade. But if governments can take credit for the extra carbon
captured by farms, the task becomes much easier and cheaper.
Meanwhile, farmers could find themselves with a new cash crop:
pollution-reduction credits that can be sold to electric utilities
and other polluters.
"The good news is, farmers can actually help find a solution and
might even profit from it," said Sen. Bob Kerrey (D-Neb.), a
leading proponent of the idea in Congress. "And that's just through
traditional soil conservation practices."
The notion of a "green" solution to global warming also has won
important backing within the Clinton administration. At a
160-nation climate conference earlier this month in the Argentine
capital of Buenos Aires, U.S.
officials fought hard to put the issue on a fast track for
international debate and research. Diplomats agreed to convene a
special summit on agriculture and climate to take place this spring
in Atlanta.
No small consideration for the White House is the prospect of
winning Farm Belt support for the global climate treaty in the U.S.
Senate, where the pact now faces broad opposition. But so far,
farming groups remain skeptical, and many environmentalists also
are leery about trading away real, measurable emissions cuts for
something that seems theoretical and much harder to quantify.
The split over agriculture is part of a larger debate over the role
of carbon "sinks" in fighting global warming. Sinks are natural
systems -- forests are the best-known example -- that soak up
carbon dioxide from the atmosphere, locking it away for decades or
centuries inside tree trunks, roots and other tissues. Trees and
crops naturally take in millions of tons of carbon from the air
each year, but since the Industrial Revolution concentrations of
man-made pollutants have risen faster than plants can absorb them.
Last year's global warming treaty holds out the possibility that
countries can create new sinks to meet part of their obligations
for reducing emissions. Many governments like the idea, for obvious
reasons; it's much cheaper and more politically palatable to plant
a forest than to impose new regulations on energy use.
The problem is, scientists don't fully understand how sinks work,
or at least not well enough to establish common guidelines for
measuring their effectiveness. A special U.N. science panel has
been asked to settle the critical questions about forest sinks by
2000.
But in the meantime, new research suggests that agriculture also
could become an equally powerful "sink." In a 15-year experiment
at the Rodale Institute, Drinkwater and two colleagues discovered
they could dramatically increase the carbon content of soils simply
by changing crop rotations and cutting back on chemical
fertilizers.
Using techniques already familiar to thousands of organic farmers,
the researchers alternated their corn crops with soybeans and other
legumes that are natural sources of nitrogen. They enriched the
soil by applying manure to some fields and plowing under immature
plants on others. Over the 15 years, the experimental plots
performed at least as well as adjacent, conventionally grown crops,
while the soil's carbon level soared. Meanwhile, the nitrogen
losses were cut in half compared with crops that used commercial
fertilizer, reducing the risk of contamination of nearby streams.
"All these techniques can be integrated into any kind of farming
system," Drinkwater said last week. Using a car key, she pried up
a clod of rich, sweet-smelling loam from one of the experimental
fields and compared it with the lighter, more powdery soil from a
conventional plot. "You can literally see the difference," she
said.
In her latest study, published in last week's issue of the
scientific journal Nature, Drinkwater contends that a switch in
farming practices in the major corn-producing states could reduce
the country's net carbon-dioxide emissions by up to 2 percent. And
that doesn't include lower emissions from farms themselves, which
would burn less fuel and purchase fewer chemicals.
Other experts project the potential net savings could be as high
as 8.5 percent. Ohio State University soil scientist Rattan Lal,
co-author of a new book on agriculture and global warming, said
farms can roll back emissions substantially just by adopting
well-known soil conservation practices, such as reducing plowing,
using cover crops in winter and preserving buffer strips of trees
along river banks.
"We can decrease the carbon content in the atmosphere and at the
same time improve the quality of the soil -- and at the same time
improve the environmental quality," Lal said. "We have a win-win
situation here."
Technology challenges remain, however. Scientists and policymakers
likely face several years of work in deciding how to measure and
verify reductions in carbon from agriculture, he said.
Lal also acknowledges that agriculture cannot solve the climate
problem alone. Although farm "sinks" may buy more time for research
on alternative fuels, global levels of greenhouse gases will
continue to rise unless nations get serious about reducing
pollution, he said.
"We should never forget that this is an interim solution," Lal
said. "The long-term solution is still doing something about
getting rid of fossil fuel."
Greener Fields, Cooler Climate
Agriculture now produces about a fifth of the world's greenhouse
gases, but new research suggests a big role for farmers in fighting
global warming. By adopting new methods, farms can actually lower
the amount of heat-trapping carbon dioxide in the air.
Compared with environmentally friendly "no-till" farming,
conventional tillage releases more greenhouse gases by exposing
more soil to the air. Conventional tillage also uses more energy,
requiring the farmer to cover the same ground multiple times.
Conventional Tillage
Plowing
Disking
Cultivating
Planting
Cultivating
No-Till Farming
Planting and spraying only
SOURCES: Purdue University; Chevron Chemical Co.; Ann Arbor Press
Copyright 1998 The Washington Post Company
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