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Protective Snow
Fri Mar 05, 2004
Listen in RealAudio 
Long-range forecasts for a cold and dry winter across America's Heartland can send shivers
down the back of many Great Plains farmers, and a ripple through their wallets. Cold and snowy
is what they look for.
Winter snows are important to wheat farmers for more than the replenishment of soil and ground
moisture. In order for the winter wheat crops to survive the onslaught of arctic air masses
that often drive temperatures below zero, the young plants require a substantial snow cover.
But extreme cold is not the only worry, for winter kill can be caused by cold-warm-cold
temperature cycles, or by the crop breaking its winter dormancy too soon.
A good, lasting snow cover affords protection from all three winter wheat killers by
insulating plants from the elements. Snow's insulating properties not only keep the plants
from exposure to extreme cold, they also dampen the temperature swings of cold-warm-cold
cycles. A good snow cover that takes time to melt reduces the chances that a premature warm
spell will induce plants to break their winter sleep.
At least three inches of snow cover are required during most winters and four to six inches
increases the crop's survival chances. Therefore, agricultural specialists recommend winter
wheat be sown directly into the standing stubble of recently-harvested spring wheat. The
stubble helps retain snowfall that otherwise blow off under strong winds.
Chinook winds, those notorious snow-eaters off the Rockies, are not as welcome to the wheat
farmer as to the rancher. Their ability to melt a snow cover can often leave crops exposed to
the later desiccating winds and bitter cold.
Snow covers help in other ways as well, such as protecting soil from wind erosion and loss of
moisture, or from freezing the ground too deeply.
Thanks to our contributing writer, meteorologist Keith Heidorn. Find our show online at
www.weathernotebook.org. We are funded by Subaru of America and the National Science
Foundation.
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