Reasons to consider late summer/early fall seeding alfalfa

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Farm Forum

BROOKINGS, S.D. – Seeding of alfalfa is underway throughout northeastern South Dakota.

“Because alfalfa is a perennial crop, as long as it is established by the time of the first frost, it will regrow during the following year,” said Karla Hernandez, SDSU Extension Forages Field Specialist. “Because the plant is established in the fall, it is able to take advantage of early spring soil moisture – and growers don’t have to spend time planting alfalfa in the spring where they are busy with other field work.”

As a result, Hernandez said compared to traditional spring planting, those producers in the Upper Plains who plant alfalfa in the fall enjoy much higher yields and more cuttings the following growing season.

Hernandez outlines a number of additional benefits to fall planting alfalfa below.

Lower weed pressure: 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.

Labor saving: With the late summer/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.

Improved soil health: Many fields are prone to wind and water erosion over the prolonged winter season. Alfalfa planted late-summer or fall, functions as a cover crop preventing erosion and helping to maintain and improve soil health.

Risks associated with late summer early fall planting of alfalfa

Although there are several benefits to late summer/early fall seeding of alfalfa, Hernandez said there are some risks associated.

Limited fall moisture: 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,” Hernandez said.

Winter injury: If the plant is not adequately established before the first killing frost, winter injury is possible. “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,” Hernandez said.

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,” she said. “However, based on the expected killing frost dates for 2015, planting alfalfa before the end of September looks like a good option for growers this fall.”

Hernandez said 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.

Frost detection tool

SDSU Extension has been tracking frost/freeze dates across the state. Producers can access an online frost detection tool http://climate.sdstate.edu/w_info/frost/frost.shtm.

“Producers should consult this website in conjunction with their seed provider to assure that they have enough time for their planting to gain maturity,” Hernandez said.

In general, most producers in South Dakota should expect the first frost (temperatures drop to 32 degrees Fahrenheit) to occur in late-September with the first hard-killing frost (when temperatures drop to 28 degrees Fahrenheit) to occur in early-October.