Dairy producers short on forage may want to take an early cutting from older alfalfa stands before rotating to corn this year, says Phil Kaatz, Michigan State University Extension educator.

“If they need the feed, go get it, then plan on planting the corn afterwards,” says Kaatz. “The early spring provides time to harvest the alfalfa and still have nearly full potential for the corn crop if planted before May 15.”

However, he says to consider the following points when making the decision:

● Alfalfa with a 24-30” height usually tests between 34 and 37% NDF, scores 160-190 for relative forage quality, and would be priced at nearly $235/ton as dry hay.

● High-quality dairy hay available for purchase is in short supply.

● Alfalfa regrowth makes a difference in nitrogen (N) credits. University of Wisconsin research indicates that alfalfa over 8” tall will provide an extra 40 lbs of N/acre.

● When analyzing the amount of N left in the field following alfalfa plowdown, consider recent N prices. Urea is near $775/ton and 28% N costs almost $450/ton. That puts the cost of N at 80-85¢/lb, so the extra 40 lbs would be worth roughly $34/acre.

● There is a substantial N-credit difference between sandy and finer-textured soils.

Kaatz says recent university research suggests that, when adequate alfalfa stands (four plants per square foot) are plowed down, first-year corn grain yield is often maximized without fertilizer N, regardless of the amount of alfalfa growth. But small N applications may be needed to maximize silage yield.

“If producers decide to rotate their alfalfa fields to corn, they may want to consider adding 40 lbs of N if they are in a sandy, coarse-textured soil,” he says. “Additional N above the 40-lb level would not be recommended.”