I sure appreciate fleece sheets in the winter. That extra layer of warmth makes sleeping so much more enjoyable. Our alfalfa and wheat crops enjoy the same protection under the fleece protection provided by a thick layer of snow.
A good look at the effect of snow cover vs soil temperature comparing 2013 to 2014 can be seen at
blog.lib.umn.edu/efans/cropnews/
Since I have trouble relating to Fahrenheit temperatures I summarized the chart data as follows.
In 2013 when air temperatures dipped to -20, soil temperatures went as low as -15C which is the threshold where damage to alfalfa crowns would occur. Soil temperatures fluctuated dramatically with little snow cover.
In 2014 despite air temperatures routinely around -30C, soil temperatures stayed around -6C with very little fluctuation.
This is not a big surprise because we all know intuitively that snow is a good insulator, however I find the data to be enlightening. It also is well known in Ontario that March is usually the month when most winter injury occurs. Most years snow cover starts to disappear in March and air temperatures can still be quite cold. Looking out the window leads us to believe the probability of snow cover disappearing in March to be very remote.
All this leaves the alfalfa and wheat crops in comfortable slumber mode for the foreseeable future.
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