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to Curb Soil Runoff
November 1, 2001
Switchgrass, a sturdy rangeland
grass being considered for livestock feed and for fuel alcohol production, may
also prove useful in stiff-grass hedge plantings that help curb soil erosion.
Agricultural Research Service
scientists are evaluating the effectiveness of switchgrass, Panicum
virgatum, and eastern gamagrass, Tripsacum dactyloides, for
controlling water-driven soil erosion.
Hydraulic engineer Darrel M. Temple at ARS
Research Laboratory in Stillwater, Okla., working with agronomist Seth M.
Dabney at ARS National
Sedimentation Laboratory in Oxford, Miss., have determined the depth of
water that different widths of hedges can retain before being bent over and
The scientists tested narrow, parallel strips of switchgrass and gamagrass
in an outdoor laboratory. In field applications, these hedges are planted close
to the contour of slopes and form a porous barrier to flowing water, causing it
to pond above them, and diffusing the flow over a large area as the water
passes through them.
Temple and Dabney tested the hedges by discharging more and more water
through them until the grasses bent and broke under the flow. Switchgrass
proved to be better able to withstand the pressure than gamagrass, standing
erect and holding back sediment and water. The one- and two-row hedges were
found to be nearly as effective as the wider three- and four-row hedges tested.
For the next two years, the scientists will focus on the ability of
switchgrass hedges to protect the soil from concentrated waterflow on very
steep slopes that are already eroded.
More about this study was published in the
October issue of
Agricultural Research magazine.
ARS is the U.S. Department of
Agricultures chief scientific research agency.