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The Cold Temperatures and Alfalfa

by Randy Shannon

As the mercury seems permanently stuck in the negative degree department, some farmers may be concerned about the effect on their alfalfa winter survival.  While the alfalfa plant will die if exposed to cold enough temperatures, Dr. Dan Undersander, Forage Agronomist says there are several reasons the crop generally survives.

  1. Alfalfa can survive temps down to 10 to 15°F
  2. That is the temperature of the crown and not the topgrowth
  3. As little as 4 inches of loose snow will insulate up to 16°F of air temperature.
  4. The crown is also insulated by soil, so the crucial temperature is at 2-4 inches below the soil surface.

The soil temperature of bare ground at 4 inches on January 8th is generally in the single digits above 0°F for the Midwest at this time of year.  The snow cover has kept the soil temperature above the air temperature for the past few days.  If you go down to the 2-4 inch level, the temperature is ranging from 28-30°F; well above critical levels.  Doesn't mean I'm not excited about the 30's this weekend!

Portions of this post taken from the UW Extension newsletter, with permission.