Alfalfa winterkill in northeast Iowa

by Brian Lang, extension crops specialist for northeast Iowa

Alfalfa winterkill is worse than anticipated--up to as high as 85 percent in some areas in northeast Iowa. A major contributing factor is whether the alfalfa stand was harvested in the fall. All of the fields I checked that were not harvested in the fall are in great shape. However, many of the alfalfa fields that were harvested in the fall show significant winter injury and may not be economical to keep. Winneshiek and northern Fayette counties have about 60 percent winterkill, with smaller regions within these counties about 85 percent. Winterkill drops to about 30 percent in Delaware County and to about 20 percent closer to the Mississippi River. Refer to articles on pages 44-46 of last week's ICM to evaluate your alfalfa stands.


Here are additional tips if you do not keep your alfalfa stand:

  • Although alfalfa is dead from winterkill, the full nitrogen fertilizer credit still applies for rotating to corn.
  • If a field already planned for corn had manure or fertilizer nitrogen applied to it, this will not interfere with seeding the field to alfalfa. Just be sure that the manure is well mixed with the soil.
  • If a small grain companion crop is used, the small grain should be harvested as silage because the high nitrogen level would most likely cause the mature plants to lodge.

This article originally appeared on page 54 of the IC-478 (7) -- May 5, 1997 issue.

Updated 05/04/1997 - 1:00pm