Margaret A Smith, PhD
Albert Lea Seed Forage Agronomist
Photo: Theresa Pedretti
We’ve come through a difficult 2023 growing season in much of the Upper Midwest. Below-average and poorly distributed rainfall challenged the growth and development of every crop we produced, and this was particularly hard on forage seedings. Many new perennial forage seedings, including both hay and pasture stands, have struggled to germinate and become established. Depending on the time of seeding—spring or late summer—and the timing of local rains, stands are highly variable across our local region.
Evaluating Alfalfa Stands
Now is the time to evaluate those seedings to help plan your strategy for 2024. A poor seeding now will not improve by spring, and fall seedings where alfalfa and grass plants are small and haven’t had a full six weeks of healthy growth to establish winterhardiness may be even worse following winter. Why not wait until spring when you can tell the full status of your new seeding? An assessment now of your stand allows you time for planning this winter for the coming year.
For alfalfa, the best method of stand assessment is by counting stems per square foot. This applies both for older stands, where alfalfa crowns produce multiple stems, and for 2023 seedings, where new plants may only be producing one or two stems, each. The number of stems present in the fall is an indication of potential yield next year.
Adequate or Sufficient Alfalfa Stand
An adequate stand for alfalfa in the establishment year is 39 stems or more, or 20 crowns or more per square foot. Over subsequent years, the adequate number of crowns declines, but number of stems per crown increases.
If your 2023 alfalfa stand is in the 39 stems or fewer range, consider intervening as early as possible next spring. Though older alfalfa stands are autotoxic and prevent new seedlings from becoming established, you can interseed into one-year-old stands, as the alfalfa plants are not mature enough to have developed high levels of their autotoxic compounds.
Evaluating Grass Stands
For mixed alfalfa/grass stands, evaluation of an adequate stand is more difficult. How many grass plants are needed in the seeding year and how many fewer alfalfa stems than for a pure alfalfa stand are sufficient? These levels depend, of course, on the ratio of grass to alfalfa seeded. If, for instance, you planted 60 percent alfalfa and 40 percent grass, count to see if you have roughly these percentages of seedlings. Dry conditions after seeding favor alfalfa establishment and are harder on new grass seedlings, so grass establishment has likely been even poorer than alfalfa this year.
But can you distinguish the desirable grasses you planted from undesirable grassy weeds? Helpful resources to aid with identification include: Identifying Common Pasture Plants and Guides For Identifying Pasture Grasses, a resource with further links specific for grasses in various geographic regions across the U.S. Evaluate your stand in at least five locations in the field. Even more samples will build your confidence in your final management decision for the stand.
Factors in assessing mixed grass/alfalfa stand or pure grass stands for a pasture or hayfield include both the percentage of desirable grasses and the uniformity of distribution of those plants.
Grass stands of only 40-50 percent of desirable species indicate a need to act. But also consider the uniformity of the stand. If the stand is uniformly low—for example, only 40 percent desirables species—you may well be able to interseed into that grass stand. If the stand is variable—for example, 75 percent desirable species in some areas, but only 20 percent in others—it may be best to tear out the stand and start over. “Hay and Pasture” is a great reference to help you evaluate forage stands and make decisions about further seeding.
- Alfalfa Stand Assessment: Is This Stand Good Enough to Keep?
- Evaluation and Considerations on Newly Established Forages
- Hay and Pasture
- Spring Options for Reduced Alfalfa Stands