By Jennifer Alexander, Poultney-Mettowee Natural Resources Conservation District
A winter with heavy snowfall provides alfalfa plants with insulation and protection from deep freezes. However, that doesn't mean winter kill risks are eliminated.
A variety of winter weather and soil conditions can significantly affect plant survival. There is always a particular risk of winter kill in areas with little snow cover, which exposes plants to extended periods of below freezing temperatures. In addition, freeze-thaw cycles can push plants out of the soil, exposing roots to harsh conditions and potentially snapping taproots, killing the plants. This is known as plant heaving and is especially problematic in fields with heavy or wet soils. Another cause of winter kill in alfalfa is ice sheeting. Ice sheeting occurs when the entire crown or more of the alfalfa plant are encased in ice, which freezes and kills the plant. This is most often seen in fields with wet areas or field depressions.
Assess Stands this Spring
As the snow melts and fields begin to green up, assess your alfalfa stands for winter kill. Look for signs of dead plants or thin stands. Depending on the level of damage, you may need to:
- replant dead patches;
- interseed with grasses or clover; or
- rotate the field to a new crop.
If you need to reseed, frost seeding in March and April can be effective, or ask your local local conservation district, UVM extension office or farmers watershed alliance about borrowing a no till grain drill for best results.
Plan for Next Winter
While we can’t change the weather, other factors are within our control. It all comes down to this: don’t stress out your plants!
- Don’t overharvest in late fall.
While it is tempting to take that 4th, 5th, or 6th cut, you need to make sure that your plants going to have enough time to recover before that killing frost – and with climate change, that is increasingly uncertain.
- Raise your cutting bar.
Leave at least 4 inches of stubble on your final cut to help protect the crown and reduce regrowth energy demands.
- Optimize soil conditions.
Alfalfa prefers soils with a pH in the upper 6s and does not survive well in acid soils. Annual applications of potassium are recommended to meet the growing needs of alfalfa. Potassium assists in plant growth, stress management, drought survival, competition with grasses in mixed stands, and more. However, if using Muriate of Potash, be mindful that it can lower soil pH.
For more information, please contact Jennifer Alexander via email at acap.Jennifer@gmail.com or by phone 802-558-6470.
