Northern growers must consider many factors when planting alfalfa in the fall, prior to the long and harsh winter months.
Success starts with selecting the right genetics, according to Brian Buck, Pioneer Field Agronomist in Southwest Minnesota.
“Two main things I always look at is how good is the varieties’ winter hardiness score and is the fall dormancy score correct for the area,” he said. “But you also want a variety with good overall disease resistance because you want that healthy stand throughout the entire life cycle.”
Choosing the right planting time is also important to good alfalfa establishment and, ultimately, winter survival. Alfalfa should be planted early enough to establish growth before fall dormancy. Typically, growers should not harvest alfalfa before winter, but rather manage it. Cutting the crop in the fall depletes the root reserves of nutrients, potentially resulting in more winter-kill and a thinner spring stand. If growers decide to cut, they should leave at least 6-8 inches of stubble.
“pH is a huge factor in alfalfa management and winter standability,” said Buck. “A big part of pH management is making sure the pH is fixed one year before seeding alfalfa. Doing so allows the alfalfa to neutralize the soil and maximize the benefits alfalfa brings to the soil.”
For optimal production, alfalfa requires a pH of around seven. Research has shown that increase the soil pH of an alfalfa stand from 5.8 to 7.0 can result in nearly four more tons of dry matter in a single growing year.
Potassium is another part of the alfalfa equation. Growers should maintain potassium throughout the stand as alfalfa is a huge consumer of the nutrient. Additionally, a late season application of potassium before winter can aid root reserves and help alfalfa better handle potentially harsh weather.
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