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Beneficial effects of no-till farming depend upon future climate change
James E.
Kloeppel, Physical Sciences Editor
217-244-1073; kloeppel@illinois.edu
10/12/2005
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CHAMPAIGN, Ill.
— By storing carbon in their fields through no-till farming practice,
farmers can help countries meet targeted reductions in atmospheric carbon
dioxide and reduce the harmful effects of global warming.
Growing plants take carbon dioxide from the air and store it as carbon
in their tissues. Most of this carbon is returned to the atmosphere
as carbon dioxide when crops are harvested and consumed. Some carbon,
however, can be permanently stored, or sequestered, in the soil as organic
matter. Changes in land management can potentially increase the accumulation
of organic carbon in soil.
The amount of carbon
stored in soils also depends on how the climate changes and how much
carbon dioxide is in the atmosphere, say researchers from the University
of Illinois at Urbana-Champaign and Oak Ridge National Laboratory in
Tennessee.
“Our research focuses on the feasibility of different sequestration
schemes for reducing natural emissions of carbon dioxide or enhancing
the natural uptake of atmospheric carbon dioxide,” said Atul Jain,
a U. of I. professor of atmospheric
sciences and lead author of a paper published in the October issue
of Geophysical Research Letters. “Converting from conventional
plow tillage to no-till practice is among the most cost-effective ways
to reduce the buildup of carbon dioxide in the atmosphere.”
To study the effect of changes in climate and atmospheric carbon dioxide
on soil carbon sequestration, the researchers used a new Earth-system
model called the Integrated Science Assessment Model. Developed by Jain
and his graduate students, the model includes the complex physical and
chemical interactions among carbon-dioxide emissions, climate change,
carbon-dioxide uptake by plants and oceans, and changes in farming practices.
About 18 percent of cropland in the United States and about 30 percent
of cropland in Canada is under no-till, Jain said. By not tilling their
fields, farmers can save labor and fuel costs, reduce soil erosion and
preserve precious nutrients. No-till also increases the accumulation
of soil organic carbon, thereby resulting in sequestration of atmospheric
carbon dioxide.
Changes in no-till land management were simulated with and without changes
in climate and carbon dioxide levels over the period 1981 to 2000. All
model simulations were based upon the actual adoption of no-till practices
on U.S. and Canadian farms.
“Comparing the model results with and without changes in carbon
dioxide and climate allows us to estimate the impact of recent changes
in climate and carbon dioxide on soil carbon sequestration,” Jain
said. “Over the period 1981 to 2000, 868 million tons of carbon
were stored in solids under no-till farming. Five percent of this carbon
storage comes about because climate change and increasing atmospheric
carbon dioxide accelerate carbon storage in soil. Future increases in
no-till could sequester enough carbon to satisfy nearly one-fifth of
the total U.S. reduction in carbon-dioxide emissions called for by the
Kyoto Protocol.”
The effects of climate change on carbon storage will vary from place
to place because of differences in how soil moisture and soil temperature
change as the climate warms, Jain said. In general, in central and western
Canada, the eastern United States, and portions of Florida and Texas,
carbon sequestration may increase. In other areas, such as Illinois,
climate change will reduce the amount of sequestered carbon.
“Climate change will reduce the gains in the carbon storage from
no-till in some areas, but there is still a net gain in stored carbon,”
Jain said. “In the future, farmers could receive credit for the
carbon sequestered in their fields under a carbon-trading arrangement
such as has been proposed for the Kyoto Protocol.”
Co-authors of the paper were Oak Ridge scientists Tristram West and
Wilfred Post, and Illinois graduate student Xiaojuan Yang. The U.S.
Department of Energy funded the work.
Editor’s note:
To reach Atul Jain call 217-333-2128; e-mail: jain1@illinois.edu.
