2021 Wisconsin Agronomy Update: Alfalfa and alternative forages

The University of Wisconsin-Madison Department of Agronomy and UW-Extension held two virtual Wisconsin Agronomy Updates on January 5 and 7.  During this year’s meetings, Kevin Jarek, UW crops and soils agent, provided attendees with an update on Wisconsin’s alfalfa landscape, and Dr. Matt Akins, UW-Madison assistant scientist and dairy extension specialist, explained how production of alternative forages has increased to make up for lost alfalfa yields.

“Alfalfa fields have been impacted unequally in Wisconsin,” Jarek stated.

This is particularly evident in northeast and east central Wisconsin, and he said yields continue to decrease due to late-summer establishment problems.  Jarek suggested producers evaluate individual fields and select alfalfa seed varieties with better fall dormancy and winter survival ratings.

“If you want an alfalfa that won’t try to grow during a weather warmup in January, then you want a good dormant variety,” Jarek said.

The UW Extension Wisconsin Alfalfa Yield and Perseverance (WAYP) program has been looking at alfalfa stand productivity trends since 2006.  On average, he said the data shows first-crop harvest is getting later (around late-May/early-June), yields are lower (averaging 4.4 tons of dry matter per acre), and stand production starts to drop off after the fourth production year.

As a result of these trends, Jarek said production of other hay and alternative forages has increased.  Akins explained that many producers are turning to these alternative forages, not only to make up for alfalfa winterkill, but because of their double-cropping potential and as a prevent-plant option.

Nutritionally, Akins explained that sorghum forages are similar to corn silage, but they are typically used to dilute the energy content of dairy rations.  He said sorghum-sudangrass varieties can provide up to two harvests in a season.  Multiple harvests are typical when a producer wants to maximize forage quality and feed it to lactating cows, while a single harvest is common to maximize yield of a more moderate quality forage to be fed to heifers or dry cows.

When planting sorghum forages, Akins said the soil needs to be between 60 and 65 degrees F (typically around late May/early June).  At harvest, he said these forages should be wide-swathed to help with drying down.  Nitrates can be a concern during drought or with a frost, and prussic acid can accumulate in the leaves.  However, Akins said those compounds should dissipate after seven to 10 days of drying down and during fermentation, and producers should have these forages in a lab prior to feeding.

Lastly, Akins discussed the results of a UW Extension trial that compared nutrition and cost of production of alternative forages to alfalfa.  Akins said the trial compared three different forages, including corn silage, annual ryegrass and a cocktail forage mix.  The cocktail forage mix contained a BMR sorghum-sudangrass, Italian ryegrass, and three clover species planted and grown together.

Compared to alfalfa, Akins said quality and yield were similar for the cocktail mix and annual ryegrass.  Cost per ton of dry matter per acre was lowest for corn silage at about $70, but the cocktail forage mix was the closest to alfalfa at $110 to $108, respectively.

He said this cocktail forage mix may help reduce some weather-related risks, but it can also introduce variability in quality over time and between cuttings.  If producers are thinking about using the cocktail forage mix, he recommended introducing it in a small area to get a better understanding of how to manage it.