Alfalfa Yields High-Protein Feed on Northern Plains
By Rosalie Marion
October 7, 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 (RRRU) at Cheyenne,
Wyo., had long been interested in interseeding alfalfa with native species on
the plains. ARS is the U.S. Department of
Agriculture's chief scientific research agency.
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.
ARS soil scientist Gerald Schuman, with the RRRU's High Plains Grasslands
Research Station, and colleagues have been working with a rancher who owns
1,500 acres of falcata, land that originally received the seeds nearly 100
years ago. On the land with falcata, Schuman and colleagues have found 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. Schuman found that soil where falcata had been
interseeded for at least three years had large increases in nitrogen.
Also, the team found evidence that falcata could lower levels of atmospheric
carbon dioxide. They saw increases in soil carbon of more than five tons per
acre on some falcata-interseeded rangeland, when compared with non-interseeded
Read more on this research in the
October issue of
Agricultural Research magazine.