A new genetically modified alfalfa may increase productivity in poor soils, according to researchers at the USDA's Agricultural Research Service (ARS).

In the southeastern U.S., millions of acres of pasture have acid subsoils that limit the productivity of forages. When crop roots in acid soils take in aluminum, the aluminum inhibits root growth and reduces a plant's yields.

Researchers at ARS are developing a new alfalfa that tolerates acid soil and aluminum by adding a gene that causes alfalfa's roots to produce more organic acids that render aluminum nontoxic. In experiments, the genetically transformed alfalfa grew longer roots in acid soils that contained aluminum. The added gene also increased the plant's ability to naturally produce and transform atmospheric nitrogen into a form that stimulates plant growth.

However, the genetically modified alfalfa does not grow as well as standard alfalfa in non-acid soil, researchers say.

ARS researchers are also studying the genome of barrel medic, a close relative of alfalfa, because many of its genetic markers can be used to find genes in alfalfa. They hope to find genes that would give the plant improved resistance to diseases and enhance its ability to fix nitrogen.

For more information, contact the ARS information staff at 301/504-1617 or visit www.ars.usda.gov.

An alternative to silage barley, a new rye variety is palatable to livestock and may reduce feed costs, according to the Lethbridge Research Centre in Alberta, Canada.

With yields and nutritional quality almost identical to barley, AC E-1, a perennial cereal (PC) rye cultivar can be grown as a silage crop. It can also be grazed before the heads start establishing ergot, the only disease noted to affect the forage.

The winter-hardy, dryland crop is a three- to four-year perennial that produces at least two crops/season and has rapid spring growth. PC rye matures a few weeks earlier than barley and may help promote soil conservation. PC rye also may reduce feed costs by as much as 20%, researchers say.

The cultivar is being commercialized this fall through Kenneth C. Long Seeds Ltd., Spring Coulee, Alberta, and should be widely available to producers by 2003.

For more information, contact Surya Acharya, Lethbridge Research Center, at 403/317-2277 or visit www.agr.gc.ca/science/lethbridge.

A sturdy rangeland grass being considered for livestock feed, switchgrass may also help curb soil runoff, say ARS scientists.

In a recent study of stiff-grass hedge planting, researchers compared narrow, parallel strips of switchgrass and gamagrass. The hedges form a porous barrier to flowing water, which researchers used to determine the depth of water that different widths of hedges can retain before being bent over and overtopped.

Switchgrass was able to withstand pressure and hold back sediment and water better than gamagrass, researchers say.

Next, researchers will focus on the ability of switchgrass hedges to protect the soil from concentrated waterflow on very steep slopes that are already eroded.

For more information, contact ARS information staff at 301/504-1617 or visit www.ars.usda.gov.

A tiny iridescent beetle may help halt the aggressive spread of a noxious weed, say ARS researchers. ARS is considering releasing the tortoise beetle as a biocontrol agent for tropical soda apple (TSA).

A resilient weed found primarily in the Southeast, TSA infests pastureland by outcompeting forage grasses. What's more, its prickly foliage drives cows from shaded areas, leading to heat stress.

Researchers say the tortoise beetle chews holes in the upper leaves of the plant, significantly reducing the weed's survivability. And it has a distinct preference for TSA, so it's not likely to devour non-target plants.

Researchers also have found that a combination of late summer mowing, fall herbicide application and normal winter conditions can prevent TSA survival.

For more information, contact Charles Bryson at 662/686-5259 or e-mail cbryson@ars.usda.gov.

Cattle eat more out of an open feeder than a closed feeder because they generally don't like to stick their heads into an enclosed area, New Mexico State University (NMSU) researchers have found. Cattle will eat about 30% more of a complete salt and mineral supplement when it's served up in a simple open feeder rather than a covered vane feeder.

Researchers say that cattle like to keep a close eye on their surroundings because they fear predators. In addition, a cover limits the number of cattle that can feed on the mineral supplement at the same time.

Covered vane feeders are more appropriate in areas with lots of moisture, especially when the mineral isn't checked often, researchers say. Cattle consumption dips when moisture causes the mineral mix to solidify.

Regardless of feeder type, relatively little of the mineral mix is lost to weather or wildlife. Each year, a producer ends up needing to buy just one extra sack of supplement, researchers say.

For more information, contact Mark Petersen, NMSU, at 505/646-1750 or e-mail marpeter@nmsu.edu.

“Research Roundup,” is compiled by Diana Barto. E-mail submissions to dbarto@primediabusiness.com or fax to 952/851-4601.