High CO2 Stimulates Soil-Building "Glue"
ARS News Service
Agricultural Research Service, USDA
Don Comis, (301) 504-1625, firstname.lastname@example.org
August 12, 1999
In the first examination of the effects of high atmospheric carbon dioxide
levels on soil structure, an Agricultural Research Service scientist and
cooperators found that the gas stimulates soil-dwelling fungi to produce
more of a unique protein that greatly amplifies a soil's ability to store
The study's results are described in a letter published in the August 12
issue of Nature magazine. One of the letter's authors, ARS soil scientist
Sara F. Wright, previously discovered the protein and named it glomalin. She
suspects it may be the primary glue that holds soil together. Now it appears
that a little of this glue goes a long way toward helping soils keep carbon
out of the atmosphere in the form of carbon dioxide.
Carbon dioxide is a greenhouse gas contributing to possible global warming.
The lead author, Matthias C. Rillig, is with the Carnegie Institution of
Washington at Stanford, Calif., as is Christopher B. Field. The fourth
author, Michael F. Allen, is with the University of California at Riverside.
The researchers studied three different ecosystems: two grasslands in
northern California and chaparral in southern California. In all three, they
found that as more carbon dioxide was pumped into open-top chambers placed
over grassland plants growing outdoors, or in a greenhouse built around
shrubs, glomalin levels rose, along with soil stability.
The high carbon dioxide levels in the air increase the amount of carbon
taken in by plant roots. That gives the fungi more food and enables them to
produce more glomalin. The glomalin glues soil particles together and helps
them clump, improving soil structure. This eases the passage of air and
water through soil, boosting plant yields. It also helps soil resist erosion
and hold in soil carbon -- valuable organic matter that holds nutrients to
recycle slowly to plants.
Farmers can increase glomalin levels further by avoiding plowing and by
growing cover crops year-round if feasible. Fungi need live roots to produce
Scientific contact: Sara F. Wright, ARS Soil Microbial Systems Laboratory,
Beltsville, Md., phone (301) 504-8156, fax 504-8370,
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