Plant Height as Determinant for Harvesting Alfalfa
Dwain W. Meyer
North Dakota State University
Plant maturity of alfalfa has been used to determine when to harvest alfalfa for several decades. Every producer knows that as plant maturity increases, forage yield increases. But if you wait until the late flowing stage for maximum yield, every producer knows that forage quality suffers. The typical relationship between plant maturity and forage quality is illustrated in Figure 1 developed by Garry Lacefield at the University of Kentucky. Forage quality, digestibility and intake potential, decrease with increasing maturity.
Some producers have tried to harvest at a given maturity stage like late bud for all harvests during a season. When they do this, however, they find that forage quality is less than they need for high-quality hay, frequently in the 120 to 130 relative feed value (RFV), especially in the first harvest. In the second and third harvests, however, harvesting at late bud may result in extremely high quality, in excess of 190 RFV, with lower forage yield.