FALL HARVESTING AND ALFALFA YIELD, PERSISTENCE AND QUALITY

Fall harvesting in the northern United States and Canada has been frequently associated with winter injury to alfalfa (Medicago sativa L.). Traditionally, it has been recommended not to cut alfalfa during the "critical fall period" before the first killing frost. This recommendation ignores the influence of environmental factors and frequency of harvest before the fall. The influence of three- or four-cut systems with fall harvests in early or mid-September or mid-October on the yield, persistence, and forage quality of alfalfa cultivars was determined in five environments (locations). The effect of fall cutting (in September or October) on yield and persistence varied with location, but effects on stands were not observed until several years following establishment. Although systems with fall cutting generally provided greater risk to long-term stand persistence and to forage yield than conventional harvest systems without fall cuts, fall cutting should be considered as a management alternative for producers who might benefit from short-term high yields or high quality forage. Length of harvest interval and number of harvests during the growing season were as important as the final harvest date in determining long-term stand survival and yield.Key words: Medicago sativa L., yield, quality, persistence and fall harvests, alfalfa