Information on alfalfa cultivar performance under grazing in the northern Great Plains is very limited. Climatic and edaphic conditions of the northern Great Plains are varied, and their influence on the persistence and productivity of alfalfa pastures are also varied. At present, a standard evaluation procedure to assess grazing tolerance has been accepted by the North American Alfalfa Improvement Conference (Bouton and Smith 1996), however its applicability to the northern Great Plains region remains unanswered. Although the standard protocol is effective at "sorting out" cultivar persistence under continuous stocking, it does not specifically address grazing tolerance under rotational stocking systems or the inclusion of a grass component, both of which are likely preferred management options for western producers. A preliminary study conducted near Brandon, MB confirmed that continuous stocking as an effective management system for isolating potential sources of germplasm for breeding environmentally adapted, grazing tolerant cultivars. The same study revealed an interrelationship between winterhardiness and grazing tolerance. Observed stand losses may have been attributed to winterkill or grazing stress, or quite possibly a combination of the two. This highlights the need for grazing tolerant cultivars in the northern Great Plains to be both persistent under grazing, as well as exhibiting a high degree of winterhardiness, while maintaining high yields.

A comprehensive grazing research project is currently addressing the development of grazing tolerant alfalfa cultivars that are well adapted to the diverse environments of northern Great Plains. A collection of 23 alfalfa (Medicago spp.) Cultivars and experimental lines is being evaluated in a 3 year grazing experiment to assess persistence in pure stands and in mixture with meadow bromegrass (Bromus biebersteinii Roem & Schult.) Under both continuous and rotational stocking systems. In 1996, experimental sites were established at Brandon, MB; Swift Current, SK; and Lethbridge, AB, and in 1997 at Mandan, ND. The different soil types and extremes in moisture and temperature will provide adequate comparative data for evaluation across varying environments. Alfalfa cultivars have been traditionally categorized as hay-type (tap-rooted) or pasture-type (creeping-rooted), but many new experimentals are classified as dual-purpose cultivars, and exhibit other characteristics such as improved disease and insect resistance. In an effort to determine the most efficient and accurate method for assessing grazing tolerance in alfalfa a detailed protocol is being used for evaluation, which includes winter survival, spring vigour, percent alfalfa (within stand and row), percent grass, biomass yield, and botanical composition. This research is being jointly funded by the United Grain Growers: Proven Seed Division, ABI, Agriculture and Agri-Food Canada, and the University of Manitoba.

Bouton, J. H. and S. R. Smith, Jr.. 1996. Standard test to characterize alfalfa cultivar tolerance to intensive grazing with continuous stocking. P A-8. In C. C. Fox, R. Berberet, F. A. Gray, C. R. Grau, D. L. Jessen, and M. A. Peterson (eds.) Standard Tests to Characterize Alfalfa Cultivars (Third Edition). North American Alfalfa Improvement Conference, Beltsville, MD.