Seeding Year Harvest Management of Alfalfa 1

Seeding alfalfa ( Medicago sativa L.) without a companion crop and with herbicides to control weeds has become an accepted practice in the Midwest. However, harvest strategies which maximize seeding year alfalfa yield and quality have not been investigated. The objective of this research was to determine the effect of harvest schedules during the seeding year on total season yield, forage quality, and persistence of two alfalfa cultivars established without a companion crop on several spring dates. In irrigated field studies conducted on a Udic Haploborolls in north central and on a Typic Hapludoll in southeastern Minnesota, ‘Ramsey’ and ‘Saranac’ alfalfa were seeded on several spring dates in 3 years and subjected to harvest schedules with first cuttings 40,60, or 80 days following emergence. One to three additional harvests were made in the establishment year depending on location and seeding date. First harvest dry matter yields for the earliest planting dates were increased by delaying the time of first harvest. Total season dry matter and nutrient yields were greatest for a harvest schedule within the earliest seeding dates at each location. Delaying the first harvest from 40 to 80 days after emergence usually was more detrimental to total season nutrient yields for the later emergence dates. Total season crude protein and in vitro dry matter disappearance concentrations were consistently lower for harvest schedules with the initial harvest 80 compared to 40 days after emergence. Ramsey and Saranac alfalfa did not differ in their yield or quality responses to seeding date and harvest schedule variables. Seeding year dry matter and nutrient concentrations can be maximized by early seeding of alfalfa with an initial harvest 60 days after emergence (late bud to early flowering) followed by two or three harvests. Under conditions of high soil fertility, seedling alfalfa can tolerate three to four harvests (including fall harvest) without stand loss