Evaluating Alfalfa Regrowth
March and early April temperatures have been cool, but alas, the snow has melted and soil temperatures are beginning to rise across the Upper Midwest. Alfalfa stands will soon emerge from winter dormancy, making it a great time to visually evaluating grass regrowth and the vitality of the alfalfa plants.
Snow cover and residual vegetative cover actually helps insulate the soil and prevent soil temperatures from reaching winter injury range. Air temperatures dropped below that 5 degree mark in both 2013 and 2014, but snow cover can actually help insulate the plant and stabilize soil temperatures. We’re hopeful that the additional snow cover in 2014 will lead to less winter injury this spring in alfalfa stands.
When evaluating alfalfa for winter injury, consider both the number of plants per square foot and the age of the stand. Winter-injured plants are often slow to recover in spring, so avoid making a quick decision to destroy a winter-injured stand. Stephen K. Barnhart with Iowa State University’s Department of Agronomy suggests these protocols:
- Wait until the spring regrowth is about 3 to 4 inches high. Then select random stand count sites and check at least one, 1-square-foot site for every 5 to 10 acres.
- Dig up all of the plants in the 1-square-foot area. Inspect plants for new growth, and examine the crown and buds to determine if the tissue is still alive.
- Count the number of live plants per square foot. For first year of seeding, 12 plants per square foot is good but consider reseeding if there are fewer than eight plants. For stands that four years old, four plants per square foot is good but consider reseeding if it’s fewer than three.
If you determine that reseeding is warranted, be aware of the potential for autotoxicity. Also consider the previous crop if you’re planning to seed new acres to alfalfa this spring. If you’re seeding alfalfa where corn was planted in 2013, try disking the ground to reduce soil particle size. A couple of passes will help the stalks breakdown better. Then incorporate and mix residue into soil from chisel plow to establish a nice seed bed. As always, we have to consider slopes. Leaving some residue helps prevent erosion, but I like smaller particle sizes as they seem to absorb moisture better from a hard rain.
Whether you need to replenish your existing stand or choose to seed new acres, Latham Hi-Tech Seeds has a complete alfalfa lineup to help meet your needs. Our products have been specifically bred to meet specific growing challenges including resistance to Aphanomyces Race 2 or leafhoppers and tolerance to salt.