Lack of Snow Cover on Alfalfa
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.
Selecting Alfalfa Varieties
Are you planning to establish a new alfalfa stand this spring? Site selection, weed control, fertility and seedbed preparation all matter — but variety selection plays a major role in determining how that stand performs over time. The right variety affects yield, forage quality, pest resistance, and how long the stand will last.
When choosing a variety, there are several key factors to consider: winter survival, fall dormancy, disease and insect resistance, persistence and yield potential.
Winter survival and fall dormancy are expressed using numerical ratings. These ratings influence not only stand survival, but also regrowth speed and yield. We’ll dive into more detail on these ratings in future recordings, but for now, it’s helpful to know that for most of Nebraska, a winter survival rating of 3 or 4 works well. In the northern parts of the state, a rating of 2 may be more appropriate. For fall dormancy, ratings of 3 or 4 generally provide a good balance between yield and winter hardiness across the state.
Disease and insect resistance should be matched to your farm’s history. Selecting varieties with strong resistance to the pests and diseases you’ve dealt with in recent years can reduce the need for chemical control, saving both time and input costs.
Persistence is another important consideration. Winter hardiness, weather, management and pest pressure all influence persistence. Operations targeting three- to four-year stands may favor higher-yielding varieties and practices, while those aiming for five or more years place greater emphasis on winter hardiness and long-term persistence. Your specific farm plan and goals will determine how important stand longevity is for your operation. And while yield potential is set by genetics, the actual yield you achieve depends on how well that variety fits your field conditions and management system.
Taking the time to match alfalfa varieties to your site and goals can pay dividends over the life of the stand.
