Though snow is not always a welcome occurrence, for alfalfa growers there is nothing that aids winter survival of the crop better than a good blanket of the white stuff.
“Alfalfa loves snow,” says Bruce Anderson, University of Nebraska forage agronomist. “As single digit and below zero temperatures arrive, be happy if you received snow recently,” he notes.
In a recent edition of Nebraska’s CropWatch, Anderson explains that last fall’s moderate weather created good conditions for the alfalfa plant to harden for winter. This means there should be a high concentration of nutrients stored in plant roots. “This winterized condition enables alfalfa crowns and roots to withstand temperatures down as low as 5°F above zero,” explains Anderson.
Soil doesn’t get as cold as the air above it, even with no snow cover. For soils to reach 5°F, air temperature needs to be much colder.
“When soil is covered with a blanket of snow, this snow acts like a layer of insulation protecting the ground from bitter cold temperatures,” says Anderson. He continues, “It reduces the rate that soils and alfalfa roots dry out. This is why winters with little snow cover can cause more injury to alfalfa stands, especially if soils are dry.”
From an alfalfa winter survival standpoint, it’s never just one thing. Anderson explains that management practices in the fall influence the effect of snow on your alfalfa. Factors such as leaving tall stubble provides some insulation value itself and will often aid in catching and maintaining snow cover. Harvest management also comes into play. Explains Anderson, “Avoiding alfalfa harvest during the so-called risk period from mid-September through mid-October helps alfalfa roots winterize well by building up nutrients and reducing water content.” Good soil fertility, especially potassium, also enhances winter survival.
While snow may not always be welcome, and it can make farm chores miserable, be assured that today’s (or tomorrow’s) snow is great insurance for a lush, green alfalfa crop this coming spring.