Glomalin, the substance coating this microscopic
fungus growing on a corn root, can keep carbon in the soil from decomposing for
up to 100 years. Click the image for more information about it.
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Glomalin is Key to Locking up Soil Carbon
By Don Comis
June 17, 2008 A soil constituent known as glomalin
provides a secure vault for the world's soil carbon. Thats according to
Kristine
Nichols, a microbiologist at the Agricultural Research Service (ARS)
Northern Great
Plains Research Laboratory in Mandan, N.D.
Glomalin is a sticky substance secreted by threadlike fungal structures
called hyphae that funnel nutrients and water to plant roots. Glomalin acts
like little globs of chewing gum on strings or strands of plant roots and the
fungal hyphae. Into this sticky string bag fall the sand, silt and
clay particles that make up soil, along with plant debris and other
carbon-containing organic matter. The sand, silt and clay stick to the
glomalin, starting aggregate formation, a major step in soil creation.
On the surface of soil aggregates, glomalin forms a lattice-like waxy
coating to keep water from flowing rapidly into the aggregate and washing away
everything, including the carbon. As the builder of the formation
bag for soil, glomalin is vital globally to soil building,
productivity and sustainability, as well as to carbon storage.
Nichols uses glomalin measurements to gauge which farming or rangeland
practices work best for storing carbon. Since glomalin levels can reflect how
much carbon each practice is storing, they could be used in conjunction with
carbon credit trading programs.
In studies on cropland, Nichols has found that both tilling and leaving land
idleas is common in arid regionslower glomalin levels by destroying
living hyphal fungal networks. The networks need live roots and do better in
undisturbed soil.
When glomalin binds with iron or other heavy metals, it can keep carbon from
decomposing for up to 100 years. Even without heavy metals, glomalin stores
carbon in the inner recesses of soil particles where only slow-acting microbes
live. This carbon in organic matter is also saved, like a slow-release
fertilizer, for later use by plants and hyphae.
Nichols began her career with ARS working with soil scientist Sara Wright,
who first discovered and named glomalin in 1996. Wright has since retired.
Nichols will present these research results this afternoon at a public field
day in Brookings, S.D.
ARS is a scientific research agency of the U.S. Department of Agriculture.