Just a Sprinkle Makes the Selenium Go Down
While selenium is an essential nutrient for humans and
other animals, an excess in drainage water can be toxic to wildlife.
So researchers have been looking at using plants that absorb higher-than-average
concentrations of selenium, which is a naturally occurring element in
Earth's crust. They have done experiments to see whether kale and turnip
plants could possibly take up the excess that sometimes builds up in
drainage water from irrigation operations. Not only would this reduce
selenium concentration in the water by providing a place to store the
selenium, but the enriched crops could be used to supplement the diets
of livestock raised in selenium-deficient regions.
The scientists found that sprinkling high-selenium irrigation
water onto the plants had the best result, because it took advantage
of the plants' ability to absorb water droplets and selenium through
their leaf openings. Sprinkler-irrigated plants took up about twice
as much selenium as those that were surface irrigated and took up selenium
only through their roots.
Suarez, USDA-ARS George
E. Brown, Jr., Salinity Laboratory, Riverside, California; phone
Sheep May Happily Graze on Spurge
More than 5 million acres of the western rangeland in America are now
overgrown with leafy spurge, greatly reducing the land's plant diversity
and productivity. There's something about this noxious weed that makes
it repel cattle, horses, and some sheep. But other sheep don't seem
to mind its sticky, milky sap and will graze on it with enthusiasm.
Scientists interested in developing an array of nonchemical, spurge-curbing
measures are considering using spurge-browsing sheep to help keep the
weed in check. They've been closely observing the feeding habits of
individual animals to single out those that find it most acceptable.
They think there may be a genetic code responsible for chemical sensitivity
in sheep and other mammals. By identifying these genes, researchers
may be able to build flocks of spurge-loving sheep.
Steven S. Seefeldt
and Brent W. Woodward,
Sheep Experiment Station, Dubois, Idaho; phone (208) 374-5306.