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Switchgrass, Panicum virgatum. Click
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Energy Farming With Switchgrass Saves Carbon
By Don Comis
July 19, 2006
Agricultural Research Service scientist
Liebig has discovered how the potential bioenergy crop switchgrass stores
more soil carbon than its competitor for ethanol production, corn. His studies
show that a greater abundance of deep roots under switchgrass acts to increase
soil carbon levels. Boosting carbon storage in the soil mitigates the
greenhouse effect and improves soil quality
While previous studies only measured carbon retained in the top foot of
soil, Liebig, rangeland scientist
Johnson and other ARS colleagues sampled down to four feet beneath fields
of switchgrass, corn and wheat on 42 farms in North Dakota, South Dakota and
Minnesota. Liebig is a soil scientist at the ARS
Great Plains Research Laboratory in Mandan, N.D.
Switchgrassa warm-season perennial indigenous to America's native
tallgrass prairiehas been identified as a promising bioenergy crop
because of the wide range of conditions under which it can grow. There is
interest in converting switchgrass biomass into ethanol for use as a biofuel or
burning it to generate electricity.
Liebig found that switchgrass fields had an average of about seven tons more
soil carbon per acre than nearby corn and wheat fields. Greater soil carbon
under switchgrass was observed at all depths, but it was most pronounced at one
to three feet downa depth in the soil profile where switchgrass has more
root biomass than corn or wheat. Switchgrass roots grow as long as eight feet,
compared to three to six feet for corn and wheat.
The sites Liebig and Johnson studied are representative of about 74 million
acres of the Northern Plains and northern Corn Belt. Evaluations of switchgrass
are being conducted to determine if this deep storage of soil carbon holds true
more about the research in the July 2006 issue of Agricultural Research
ARS is the U.S. Department of
Agricultures chief scientific research agency.