Triclopyr, a herbicide approved for use in some ecosystems, might be the best compound for zapping parrotfeather plants, according to first tests against this alien aquatic weed. Named for its feathery-looking gray-green leaves, parrotfeather can quickly take over lakes, rivers, irrigation canals and farm ponds. Known to scientists as Myriophyllum aquaticum, the plant is native to South America. In the United States, it is now found in California, Oregon and Tennessee. Dense stands of parrotfeather make ideal breeding grounds for mosquitoes. The plants also crowd out desirable native vegetation, clog irrigation systems and make waterways unsuitable or unpleasant for boating, fishing and swimming. ARS scientists are the first to test triclopyr on parrotfeather. They conducted the tests at a 20-acre lake in the oak woodlands of Beale Air Force Base in northern California, under terms of an experimental use permit issued by the U.S. Environmental Protection Agency. Triclopyr, added to the lake in prescribed application rates, worked better than any other option tested at the site. The lake has been infested with parrotfeather for about 20 years. Resource managers at the Air Force base collaborated with ARS on the tests, along with specialists from Dow AgroSciences LLC. The company markets triclopyr as Garlon 3A for use in some terrestrial ecosystems.

Exotic and Invasive Weed Research Unit, Davis, CA
Lars W. J. Anderson, (530) 752-6260, lwanderson@ucdavis.edu

Because of the element vanadium, plants may experience a phenomenon similar to people who eat junk food in place of a nutritious meal--the hunger goes away, but the nutrients don't arrive. Experiments by ARS scientists over the past 3 years have found that plants confuse vanadium, a little-known soil micronutrient, with phosphorus. Vanadium appears to be harmless to crop plants. But many of them--including corn and soybean--can't use it as a nutrient. And when these crops grab vanadium instead of the phosphorus they require, their growth and development can't reach their potential yields. Standard soil tests don't measure vanadium, but an ARS-developed test does. It also measures the ratio of vanadium to soil phosphorus and other nutrients. This test could be used to recalculate phosphorus recommendations. The optimum economic amounts of phosphorus would have to be redetermined through research, this time considering the vanadium-phosphorus ratios when correlating phosphorus concentrations with plant growth.

North Central Soil Conservation Research Lab, Morris, MN
Alan E. Olness, (320) 589-3411, ext. 131, aolness@mail.mrsars.usda.gov

One grazing cow for every 16 acres makes for a more diverse and productive ecosystem than fewer or more cows, at least in the Great Plains. In a study in northern Colorado that began in 1939, ARS researchers have found a rate of one yearling heifer per 16 acres evens out the production of individual plant species, preventing any one from dominating. Ranch profitability was also highest at this moderate grazing level. The scientists counted 46 species of plants on the moderately grazed land, compared to 43 under heavy grazing and 36 under light grazing. Plant biodiversity is highest when high numbers of plant species are combined with a more even distribution of plant species. While ungrazed land also had 46 species, its biodiversity was undercut by the dominance of pricklypear cactus. Cattle weight gains drop significantly when land is grazed heavily because there are not only more mouths to feed, but also less forage to go around.

Rangeland Resources Research Unit, Cheyenne, WY
Richard H. Hart, (307) 772-2433, rhart@lamar.colostate.edu

Aerial mapping technology has helped Texas officials locate and remove thick patches of exotic weeds from the lower Rio Grande. With the ARS-developed technology, the Texas Natural Resource Conservation Commission and the Texas Parks and Wildlife Department pinpointed hydrilla and water hyacinth weeds. During a drought in the area last year, these weeds were sucking up scarce water and obstructing irrigation flow. By boat, the scientists verified the color-infrared video imagery data. The operations helped advance other research that’s aimed at conducting wider scale surveys of weed infestations. Remote sensing, global positioning system and geographic information system technologies may help scientists make timely assessments of experimental weed control measures. Hydrilla, native to Asia, and water hyacinth, native to South America, share a notoriety for clogging marinas, snarling fishing lines and interfering with flood control and hydroelectric power generation. Uncontrolled, the weeds grow so competitively with other aquatic plants that biological diversity could be threatened in many lakes and streams through southern parts of North America.

Integrated Farming and Natural Resources Research, Weslaco, TX
James H. Everitt, (956) 969-4824, j-everitt@tamu.edu

Chicory may be just the plant to grow for mopping up nutrients leached into the soil from turkey litter compost used to fertilize pastures. Chicory may also be a boon to beef and lamb producers. Turkey litter is the nitrogen- and phosphorous-rich manure cleaned from turkey houses along with wood shavings used as bedding. Sometimes the litter holds more nutrients than plants can use, posing problems for water quality. ARS scientists are finding that chicory could be a biological sponge that soaks up any excess from the soil. They found that chicory keeps taking up nitrogen and growing taller at nitrogen rates up to 424 pounds an acre of commercial nitrogen fertilizer. They are now doing similar tests with composted turkey litter. The scientists are working with British United Turkey of America, a turkey breeding firm in southern West Virginia. They are also working with USDA’s Natural Resources Conservation Service to test chicory in NRCS’ Southern West Virginia Grazinglands Program. Both agencies see chicory’s potential to provide enough protein to increase beef and lamb production per acre.

Appalachian Soil and Water Conservation Laboratory, Beaver, WV
David P. Belesky, (304) 256-2858, dbelesky@asrr.arsusda.gov

Preliminary experiments at a west Texas lab in the heart of Dust Bowl country suggest wind erosion makes soil more susceptible to drought. That's just what erosion did in the 1930's during a long drought accompanied by massive dust storms. In some mini-Dust Bowl experiments, ARS scientists planted crops on land that was left bare and exposed to the wind for the previous 9 years. Yields of these crops were 40 to 65 percent lower. The results are preliminary data from 1997 and 1998—the first 2 years of growing crops on the eroded plots. Average annual yield reductions were 65 percent for forage sorghum, 58 percent for grain sorghum and 40 percent for cotton and kenaf. The comparison is to crops grown on soil that was not allowed to erode, using tillage techniques and crop residue to protect the soil. During the 9 years of wind exposure, the eroded land lost 590 tons of soil an acre or about 10 inches of topsoil. Possible reasons for the severity of the yield losses include lower fertility and a loss in water-holding capacity for the eroded soil. The scientists found that wind erosion selectively removed phosphorus, an important crop nutrient. Phosphorus levels were about 35 percent lower on the eroded soil compared with the noneroded area. The soil loss did not affect the texture of the topsoil. But with more wind erosion, it might eventually, as the deep topsoil wears down to a clay layer that would interfere with crop roots and further threaten yields.

Wind Erosion and Water Conservation Research Unit, Lubbock, TX
Ted M. Zobeck, (806) 723-5240, tzobeck@lbk.ars.usda.gov