|Ingram, Lachlan - UNIVERSITY OF WYOMING|
|Nayiguhugu, V - UNIVERSITY OF WYOMING|
|Hess, Bret - UNIVERSITY OF WYOMING|
Submitted to: Ecology and Management of Rangelands
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 18, 2005
Publication Date: N/A
Interpretive Summary: Livestock producers utilizing rangelands for grazing have sought ways to increase forage production and forage quality for decades to reduce the demand for supplemental feed. Interseeding a legume, such as yellow-flowering alfalfa (Medicago sativa ssp. falcata), into rangelands provides increased forage production and improved forage quality. Northern mixed-grass prairie in northwestern South Dakota interseeded in 1965, 1987, and 1998 showed increased production of 796-1940 kg/ha contributed by the alfalfa and annual total production increases of 42-143%. The N fixed by the legume resulted in significant increases in soil N and hence increased forage quality for most of the native species of this ecosystem and contributed a significant high protein component represented by the alfalfa. With the natural hardiness and grazing tolerance of yellow-flowering alfalfa, the practice of interseeding it into rangelands could potentially be applied to millions of hectares of prairie and other grazing ecosystems.
Technical Abstract: Interseeding alfalfa into rangelands has been assessed for decades as a method of range improvement to increase forage production and forage quality for livestock. Research was initiated in 2001 to examine the long-term effects of interseeding yellow-flowered alfalfa (Medicago sativa ssp. falcata) on northern mixed-grass rangelands. Forage production and forage quality parameters were assessed on sites interseeded in 1965, 1987, and 1998 and compared to adjacent native rangelands. Live aboveground biomass for the 1965, 1987 and 1998 interseeded sites was 68, 143, and 42% higher, respectively, compared to their native control areas. Alfalfa aboveground biomass accounted for 1489 of the 2969 kg ha-1 live biomass harvested from the 1965 interseeded site, 1940 of the 2744 kg ha-1 on the 1987 interseeded site, and 796 of the 2322 kg ha-1 on the 1998 interseeded site. Increased soil N resulting from N fixation by the 'falcata' significantly increased the crude protein (CP) content of several native species while the alfalfa itself provided forage with 16 to 18% CP. Alfalfa had higher protein degradability and provided higher concentrations of calcium (Ca), potassium (K) and magnesium (Mg) than the native rangeland grasses. This research has shown that the practice of interseeding alfalfa into rangelands will increase forage production and improve forage quality in the Northern Great Plains.