The seeding of alfalfa during the fall season is very common throughout the Northeast region of South Dakota for the following reasons:
- Alfalfa is a perennial crop, and so long as it is established by the time of the first frost, it will regrow during the following year. This is a significant advantage over traditional spring planting because the plant can take advantage of soil moisture in the spring which would otherwise prohibit field work and planting. As a result, many producers in the Upper Plains plant alfalfa in the fall and enjoy much higher yields and more cuttings the following growing season, when compared to a traditional spring planting.
- Due to the dry soil conditions of a typical fall, weed problems are usually considerably reduced. Additionally, any annual weeds that are established are typically killed in the fall by the first killing frost.
- With the fall season offering more time to work the soil and prepare for planting, seeding operations usually experience fewer problems and higher percentages of establishment in a well prepared seedbed.
- Many fields are prone to wind and water erosion over the prolonged winter season common in this region. Alfalfa planted late-summer or fall function as a cover crop preventing soil losses and help maintain and improve soil health.
There are some risks associated with late summer seeding which the producer must take into account:
- Moisture is typically limited during the fall. Producers who intend to plant alfalfa should evaluate their soil conditions and assure that moisture is adequate to support the intended seeding.
- Winter injury is very possible if the plant is not adequately established before the first killing frost. Producers who intend to commit to a fall seeding should consult with their seed provider about germination and growth times, to assure that the plant will be well established before the first frost. South Dakota State University has been tracking frost/freeze dates across the state and has a very useful tool to determine the probability of when the first frost will occur. Producers should consult this website in conjunction with their seed provider to assure that they have enough time for their planting to gain maturity. In general, most producers in South Dakota should expect the first frost (32° F) to occur in Late-September with the first “hard/killing” frost (28° F) to occur in early-October.
A general recommendation for the planting of alfalfa in this region is that it should occur by mid-August. This allows at least six-weeks for the plants to become established with a good crown structure before the first frost. The presence of a crown structure above the ground assures that some cover will be provided to insulate the roots as well as adequate carbohydrate storage within the root structure to support spring regrowth.
Source: Karla Hernandez, South Dakota State University