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Unsung Hero of Carbon Storage
By Don Comis
September 6, 2002
Glomalin, a recently discovered
major component of soil organic matter, stores about a third of the
worlds soil carbon, offsetting industrial pollution. This is according to
a recent collaborative study by scientists with the
Agricultural Research Service and the
University of Maryland (U-MD) at College
Park. The study was partially funded by the U.S. Department of Energy.
The study was done by Kristine A. Nichols, a U-MD soil science Ph.D.
candidate and technician at ARS
Systems Laboratory in Beltsville, Md., along with colleagues Sara F. Wright
and E. Kudjo Dzantor. Wright, an ARS soil scientist, discovered glomalin in
1996, and Dzantor is a U-MD soil scientist.
Glomalin is a sticky protein produced by root-dwelling fungi and sloughed
into soil as roots grow. By gluing soil particles and organic matter together,
it stabilizes soil and keeps carbon from escaping into the atmosphere. In an
earlier study, Wright found that glomalin serves as a corrective to global
warming because it increases with carbon dioxide levels.
Nichols and colleagues detected large amounts of glomalin in soils from four
states, showing it to be a major part of organic matter. The glomalin weighed 2
to 24 times as much as humic acid, which was previously thought to store the
most carbon. But Nichols found that humic acid only stored 8 percent of total
soil carbon compared to glomalins 27 percent.
Wright has found glomalin in soils from around the world, ranging in weight
from less than 1 milligram per gram (mg/g) of sample to more than 100 mg/g. She
found the highest levels in Hawaiian and Japanese soils, indicating that some
soils might be able to store large amounts of carbon in glomalin with a
turnover rate of 7 to 42 years. She is on a team investigating underground
carbon storage in tropical forests, thought to be major carbon reservoirs.
For more on glomalin, see the
September 2002 issue
of Agricultural Research magazine.
ARS is the U.S. Department of
Agricultures chief scientific research agency.