Rich soil good for trapping carbon dioxide

September 9, 2002

Rich soil good for trapping carbon dioxide - study

USA: September 9, 2002

WASHINGTON - A sticky protein shed by fungi living on plant roots is responsible

for absorbing and storing sizable amounts of the carbon dioxide pollution linked

to global warming, U.S. Agriculture Department scientists said.

The protein, glomalin, glues soil particles and organic matter together which

stabilizes soil and keeps carbon from escaping into the atmosphere. Farmland and

forests around the world are seen as valuable to offset carbon emissions from

cars and industrial plants, offering the potential for carbon credit emission

trading.

Kristine Nichols, a soil scientist with the USDA's Agricultural Research

Service, analyzed glomalin in soils collected from Colorado, Georgia, Maryland

and Nebraska. Tests showed that the glomalin stored nearly one-third of the

carbon absorbed by soil, an amount far greater than humic acid which had been

thought to store the most carbon.

Glomalin gives soil the rich, fertile texture readily recognized by farmers and

longtime gardeners. It lasts from 7 to 42 years in soil, depending on

conditions, researchers said.

Another USDA researcher, Sara Wright, is studying glomalin levels to measure the

amount of carbon stored in soils beneath tropical forests.

" Glomalin is unique among soil components for its strength and stability, "

Wright said. Other soil components that contain carbon are quickly degraded and

break down, she said.

" Our next step is to identify the chemical makeup of each of its parts,

including the protein core, the sugar carbohydrates, and the attached iron and

other possible ions, " she said.

Global warming has been linked to the growing amount of heat-trapping gases such

as carbon dioxide in the atmosphere. Scientists say the gradual increase in

temperature may melt glaciers, increase sea levels and lead to broad weather

changes in crop-growing areas.

REUTERS NEWS SERVICE

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