If switchgrass succeeds as an ethanol crop, it
will owe some of its success to glomalin, the key ingredient of soil organic
matter. In the microscopic view above, glomalin (stained green) coats the
spores (round bodies) and hyphae (threadlike filaments) of a beneficial soil
fungus. Glomalin helps the hyphae reach water and nutrients, which the fungus
funnels to plant roots in exchange for carbon. Click the image for more
information about it.
Glomalin: A Key to Switchgrass Ethanol Success
By Don Comis
October 12, 2007
If switchgrass succeeds as an
ethanol crop, it will owe some of its success to glomalin, the key ingredient
of soil organic matter.
Glomalin was discovered in 1996 by Agricultural Research Service (ARS) soil scientist Sara F. Wrightnow
retiredand ARS microbiologist
A. Nichols, then both at Beltsville, Md. Nichols is now at the
Northern Great Plains Research Laboratory in Mandan, N.D., where glomalin
A sugar protein, glomalin is excreted by soil fungi and helps them funnel
water and nutrients into plant roots. It also helps store carbon in the soil
and acts as a glue to hold soil particles together.
In assessing glomalin levels and their role in biofuel crops, Nichols has
measured higher levels of glomalin in the roots of switchgrass, big bluestem
and other warm-season grasses than in the roots of cool-season grasses such as
wheatgrass and Russian wild rye. Switchgrass is a fast-growing, warm-season
perennial with potential as a feedstock for cellulosic ethanol production.
Preliminary results show that warm-season grasses such as switchgrass and
big bluestem also give soil more stability. Nichols found a strong association
between warm-season grasses and the arbuscular mycorrhizal fungi that live on
plant roots and produce glomalin.
Glomalin may be partly responsible for the ability of switchgrass to store
more soil carbon than cornand to store it deeper, so its less
likely to be lost to the atmosphere as carbon dioxide. Thus, glomalin might not
only help biofuel crops grow and flourish under adverse conditions like
drought, but also close the carbon cycle by storing carbon released as carbon
dioxide during the burning of biofuels for energy.
Nichols work could help growers know how to best establish
switchgrass, and to make sure as much carbon as possible is stored below
ARS is the U.S. Department of
Agriculture's chief scientific research agency.