By Samantha Daniel
So far this season, most of Nebraska has seen very little snow, with seasonal totals 1-12 inches below average in the east and 12-30 inches below average in the west. The absence of snow and the recent mild temperatures can have a significant impact on alfalfa when temperatures eventually drop.
A layer of snow at least 4 inches deep can provide much needed insulation from frigid air temperatures. This insulation also protects the soil from extreme drops in temperature. The lack of snow throughout much of the state has left alfalfa fields exposed and vulnerable to sudden temperature drops which can lead to winterkill. As fields begin to green-up in the spring and produce a few inches of new growth, it will be much easier to assess stands for winter injury.
Areas of Nebraska experiencing drought, including the Panhandle and north-central counties, may have reduced risk of winterkill. Although drought conditions may weaken overall plant vigor, dry conditions can have a positive effect on alfalfa winter hardiness. Alfalfa grown in well-drained areas or soils with less soil moisture tend to be less prone to winter injury due to less difficulty in losing remaining plant moisture.
However, keep in mind that extended periods of warm temperatures can cause the plant to break dormancy before spring, increasing the risk of winterkill further.
Source : unl.edu