November 15, 2003
Flowering Alfalfa Yields High-Protein Feed
Nov. 2003 -- A species of alfalfa called falcata has been found to thrive on the Northern Plains, where other U.S.-grown varieties fizzle out. The seeds of the yellow-flowering subspecies of the Medicago sativa alfalfa originally came from the Siberian plains. Scientists in the Agricultural Research Service's Rangeland Resources Research Unit at Cheyenne, Wyo., had long been interested in interseeding alfalfa with native species on the plains. Falcata has a fibrous root system that allows it to compete with neighboring plant species for limited moisture on rangeland. (Other U.S.-grown alfalfas have a long, main root that burrows deep into soil to draw water.) But 80 percent of native grasses and forbs have shorter root systems that snatch the available water before it can get down to deeper roots. Soil scientists at the High Plains Grasslands Research Station have been working with a rancher who owns 1,500 acres of falcata, land that originally received the seeds nearly 100 years ago. They found on the land with falcata a large increase in forage production -- at times nearly double -- compared with rangelands not interseeded with falcata. Part of the reason for falcata's success is that alfalfa -- a legume -- brings with it friendly bacteria, called rhizobia, which thrive in nodules on the plant's roots. Rhizobia turn atmospheric nitrogen into a form that plants can use to promote their own growth. ARS is the U.S. Department of Agriculture?s chief scientific research agency.
ARS Facility Cuts Pesticide Use by 75 Percent
Nov. 2003 -- One of the Agricultural Research Service's largest research facilities has reduced pesticide use by 75 percent over the past decade by applying ARS sustainable agriculture research to its farm operations. At about 7,000 acres, the Henry A. Wallace Beltsville (Md.) Agricultural Research Center (BARC) is the agency's second-largest field location. BARC land joins other federal properties to form a heavily forested area of more than 30,000 acres near the nation's capital. Sustainable agriculture techniques in use at BARC include a combination of practices, such as weed-smothering cover crops and increased use of beneficial insects. Since 1997, the center also has produced its own compost from plant residue and manure. The compost facility is surrounded by a 20-foot-wide grass buffer strip, as are 80 percent of BARC fields. The strips filter out possible pollutants before they reach streams that feed into the Anacostia River, which flows into the Potomac River and then to the Chesapeake Bay. A pair of nesting bald eagles overlooking a swamp created by beavers is a telling symbol of BARC's environmental stewardship. Beaver Dam Creek flows below the eagles' nest, which is in an oak tree at the swamp's edge, upstream from the composting center. The streams at BARC are now clean enough to support brown trout.
Sound BASIS for Relating Sediment Flow, Stream Health
Nov. 2003 -- In their version of "keeping an ear to the ground," Agricultural Research Service (ARS) scientists at the National Sedimentation Laboratory in Oxford, Miss., are finding ways to diagnose watershed health and stability by keeping a high-tech ?ear? in the water. More specifically they are using updated acoustic technology to monitor concentrations of sediment flow within water systems. With this technology, they?re ?listening? for clues that could indicate changes -- and problems -- in these water systems. The project has led to development by the university, in collaboration with ARS, of the Bedform and Sediment Information System (BASIS). This monitoring method emits a pulse of acoustic energy and gauges the strength and travel time of the echo to detect and measure sediment's location and concentration. Like its predecessor, BASIS locates sediment on a stream's bottom, which can indicate sediment erosion or accumulation. But what makes the new system novel is that it can also detect sediment suspended in water. BASIS converts acoustic data into a digital image showing suspended sediment as a cloud, in a multitude of colors signifying concentrations. Its main unit is compact, and the entire system can run remotely from a laptop computer. Accurate determinations of sediment flow are needed because sediment can reduce reservoir capacity, fill channels and cause flooding, degrade water quality and destabilize channel banks.