A gene borrowed from yeast might yield bioengineered plants that clean up sites polluted by heavy metals. ARS scientists and colleagues at the University of California at Berkeley uncovered a gene in lab experiments with Schizosaccharomyces pombe yeast. Eventually, they hope to insert the gene into hardy, fast-growing plants that could be seeded as metal scavengers for bioremediation of abandoned mines or other metal-contaminated lands. They have dubbed the gene hmt1 for heavy metal tolerance. Like plants, yeast produces small molecules called peptides that bind to metals such as cadmium. The hmt1 gene cues the yeast to make a protein that pumps more peptide-bound cadmium into vacuoles, structures that serve as cellular trash bags. Currently, the scientists are evaluating hmt1 genes they inserted into test plants in a greenhouse.
ARS/University of California Plant Gene Expression Center, Albany, CA

David W. Ow, (510) 559-5900

Give a green thumb to the yellow pages. Phone books, newspapers and other waste paper are being recycled into pellets that serve as "green manure" and ground cover. Soybeans do as well on soil with the pellets mixed in as they do on soil with a winter wheat crop mixed in as green manure. Other benefits: The pellets save the expense of tearing up the cover crop and may replace herbicides. ARS researchers in cooperation with colleagues at Auburn University have planted soybeans without applying herbicides before planting--with no loss in yields. Weeds are suppressed by either being smothered by the mulch or by some chemical compounds in the waste paper, or both. In addition, the researchers are cooperating on projects in North Dakota and Texas--using larger pellets two to four inches long--to hold down highly erodible soil. The larger pellets are applied with fertilizer spreaders while the smaller ones are applied by fertilizer dispensers.
Soil Dynamics Research, Auburn, AL
J.H. Edwards, Jr., (205) 844-3979

A motor-driven roof on wheels, called a rainout shelter, could yield new scientific clues to help sustain Northern Great Plains rangelands during and after drought. ARS scientists developed the rainout shelter to create an artificial drought. Raindrops trigger the shelter's motor, which moves the roof to cover six 15- by 30-foot test plots. When the rain stops, the shelter uncovers these plots. They receive no surface runoff or underground water, because they're surrounded by foam-filled trenches and sit atop an impermeable layer of soil. Six adjacent rangeland plots are used to compare the artificial drought to natural conditions. Since drought often results in overgrazing, the scientists designed the experiment to separate effects of these two plant stressors. In 1994, sheep grazed a set of four from each group of six plots. Of these four plots, two from each group will be rested and two will continue to be grazed in 1995 when the artificial drought is halted. This will help scientists identify the length of time that range plants need to rest from grazing once drought ends. Scientists will measure root growth, seed germination, tiller growth and soil moisture and structure.
Fort Keogh Livestock and Range Research Laboratory, Miles City, MT
Rodney K. Heitschmidt, (406) 232-4970

Farmers can cut soil erosion and pesticide runoff by at least 30 percent on silty soils by burying plastic drainage pipes under their crop fields, according to a long-term ARS study. The four-inch-diameter, perforated pipes allow water to drain into the soil more quickly after heavy rains. This reduces the chance that soil and pesticides will be washed away. Researchers found that burying the pipes three feet below a 10-acre test plot on silty, alluvial soil cut water losses and erosion by about one third. Runoff of the herbicide trifluralin dropped about 30 percent, compared to fields without the pipes. Trifluralin and other pre-emergence herbicides--applied to bare soil before crop seeds emerge--are particularly vulnerable to being washed away.
Soil and Water Research, Baton Rouge, LA
Lloyd M. Southwick, (504) 387-2783

Ranchers can provide more pump water for their thirsty livestock by installing small wind turbines. These pumps, powered by two or three aerodynamic blades, discharge water more than twice as fast as solar pumps and traditional, 16-blade windmills. A wind turbine pumped six to eight gallons of water per minute last year, compared to two to three for the windmill and one for the solar pump. The turbines power generators which are connected to submersible well pumps that lift water in a steady flow. Traditional windmills pump water in spurts by driving a piston pump up and down. The wind turbine system costs almost $1,000 less than the $6,000 price for a windmill. Solar pumps cost about $3,500. Options that are being developed and evaluated by ARS include combining solar and wind power, and supplementing wind power with generators powered by a vegetable-oil-based fuel. Farmers and ranchers, pump dealers, electric utilities and government agencies are inquiring about the turbine-operated pumps. Two companies--Bergey Windpower, Inc., of Norman, OK, and World Power Technologies, Inc., of Duluth, MN, are manufacturing an improved version of an electrical controller, a device designed by the ARS team to turn the turbine's water pump on and off in response to wind speed.
Conservation and Production Research Laboratory, Bushland, TX
R. Nolan Clark, (806) 356-5734

Last Updated: December 13, 1996
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