Looking Out for Winter Injury

Take the time to assess your fields in spring
winterkill in alfalfa

No dairy or livestock farmer likes to have another item added to their to-do list. While early spring isn’t in the height of the growing season, there’s still plenty to do. There’s seed and fertilizer to order, equipment to repair, and manure pits to empty out. And in this neck of the woods, there’s always the possibility of more snow that needs to be plowed away.

Yet there’s one more task that amounts to a good investment of time: scouting your forage stands for winter injury. It’s a sad fact of farming that wherever you have winter, you will occasionally see winterkilled fields. Alfalfa and orchardgrass are especially prone to this. In an open winter, alfalfa crowns get exposed to sharp, desiccating winds. When temperatures fluctuate between freezing and thawing, there’s a risk that sheets of ice will smother large sections of sod. Or, you may have plants that don’t harden off sufficiently, or come out of dormancy just a bit too soon. Left alone, these fields will sport wide patches where your forages are thin, or perhaps nonexistent, and they’ll be unproductive.

It would be difficult enough to predict the extent of winter injury if snow cover and temperature were the only two variables you needed to account for, but there are a few more. The age of the stand, soil drainage, the extent of disease, and soil fertility all influence whether or not your stand survives for another season of harvesting. Most people, even experts, call it wrong more frequently than they’d like when they forecast the extent of winter injury. That’s why it’s best if you step outside and take a look.

Mid-April is usually an ideal time to do this; the snow is usually gone but the soil is still too wet for field work. Walk your fields, and look out for thin spots or large bare spots. Take a spade and dig down in alfalfa or alfalfa/grass stands to pull out a few crowns; inspect them for signs of disease or other injury (University of Minnesota Extension has a fact sheet with some good photos here). If everything looks okay, you can go into the cropping season confident in your fields’ potential to be productive. If you see enough injury to give you pause, however, at least you have some time to consider your options.

You could rotate the field into corn. There’s still a lot of nitrogen locked up in that sod that would be available to feed a corn crop later this spring and summer, probably enough that you wouldn’t need to provide any additional nitrogen fertilizer. It’s also worth remembering that weed control in first-year corn after perennial forage is often considerably less expensive since there hasn’t been the opportunity to build up much of a seed bank.

If planting corn interferes too much with your planned rotation or your feed inventory and you want that field in a forage crop for another year or two, consider using a summer annual such as Japanese millet, or brown midrib sudangrass sorghum hybrid. You can follow that up with a winterhardy small grain sown in the fall for additional forage the following spring – up to two tons of dry matter per acre.

If you want to keep the field in perennial forage, remember that trying to reseeding an alfalfa stand with more alfalfa usually gives poor results. Instead, consider drilling in straight grass. Tall fescue has gotten a lot more attention over the past few years, and now we’re hearing good things about meadow fescue or short rotations of Italian ryegrass; this might be an opportunity to try one of them out.


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Anna Boudreau
State Advisory Council Chair, Natural Resources Steward and NH Coverts Cooperator