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Making hay with soybean in the West

When soybean was popularized in the U.S. in the 1800s, farmers eagerly embraced the legume from East Asia as a forage crop. Today, it is more commonly grown as an oilseed crop rotated with corn throughout the Farm Belt.

Western hay producers, though, hope the high-protein crop could work yet again as a cost-reducing annual forage that could replace or compliment perennial hay crops like alfalfa and timothy.

Bale of soybean hay

Steve Norberg, a CPAg and Washington State University extension forage specialist in Pasco, WA, has finished his second year of researching how soybean hay can help save farmers on labor by reducing the number of cuttings to one per year, rather than having four or more cuttings per year with the traditional perennial crops. 

“One of the biggest expenses that producers have is the four cuttings they have in alfalfa hay,” Norberg explains. “They’ve got to have help all year long, and they have to move their equipment four times a year to all their different locations. What if you could condense that to a shorter period of time with a one-cut system? This benefit would increase with fields far away from each other. This was my train of thought when trying to figure out how to make haying more profitable for our producers.”

Fertilizer savings would also be a benefit to the farmer, he notes. “Since it’s a legume, we don’t have to worry about the nitrogen cost, which in the last few years has been significant.”

Hay farmer Craig George put Norberg’s idea of growing soybean hay to work on his farm near Ellensburg, WA, by testing it on 10 acres. Despite never having grown soybeans on his farm, which is comprised mostly of timothy and oat hay, George saw soybean hay’s potential as a high-protein feed for his cow-calf operation consisting of 60 mother cows.

The $140/ac price tag for seed, though, caused sticker shock. But when he figured the cost savings of not having to apply fertilizer, George calculated that the crop could potentially find a place in his crop rotation.

Other hay farmers might reject the idea of growing soybean in the West, Norberg admits. But the crop already has a proven track record on yield when harvested for oilseed, he says. It’s also easy to grow and is supported by ample scientific research. 

“Normally the West isn’t a typical soybean production area, but we can grow soybeans in the West,” he says. “We’ve had irrigated oilseed soybean yields in Idaho, Oregon, and Washington as high as 80 bushels to the acre in recent years, similar to Midwest irrigated areas.”

While soybean hay could reduce farmers’ labor and fertilizer costs, Norberg is hopeful it that as an annual crop, it would allow them to increase marketing opportunities that perennial crops might miss out on. Other annual crops could follow soybean in the rotation, he points out, including wheat, corn, potatoes, onions, sugar beets, field beans like great northern and garbanzo beans, and other high-value crops commonly grown in the Columbia Basin in Washington.

The increased crop diversity, he adds, could also improve control over weeds, diseases, and insects.

That’s especially attractive for growers like George who, after years of growing timothy and oats, is looking for a way to control grassy weeds. A Roundup Ready variety of soybean would allow him to use glyphosate as another tool for controlling the bluegrass, ryegrass, crabgrass, and cheatgrass that have emerged in his hay fields.

That’s no small problem among other hay growers in his local area east of the Cascade Mountains where the main hay crop, timothy, is grown for the high-value export market to Japan.

“Export timothy hay is very fickle,” George explains. “You cannot have any weeds in export hay. It’s got to be absolutely, completely clean.”

Scientific approach

Soybean’s early history as a hay crop lends support to the idea that it could still compete for acreage as a reliable cost-cutting hay source, according to Norberg.

To test the idea, Norberg and collaborator Earl Creech, crops agronomist at Utah State University, researched different soybean maturity groups and harvest dates and their relationship to yield and forage quality on irrigated plots at the Washington State University Othello Research Farm near Othello, WA, and at the Greenville Farm near Logan, UT.

Each plot was planted at a population of 140,000 seeds/ac on May 15, 2012 at Othello and May 30 at Logan. The varieties selected for the study included Asgrow 1431, maturity group 1.4; Asgrow 4531, maturity group 4.5; Eagle Seeds Large Lad, maturity group 7; and Eagle Seeds Big Fellow, maturity group 7. Maturity groups with higher numbers have a longer growing season, while groups with a lower number are shorter-season varieties. All cultivars were Roundup Ready.

The maximum accumulation of dry matter occurred in late September, 134 days after planting with yields ranging from 4 to 6 tons dry matter/ac at both locations in 2012 and 7.5 to 10 tons/ac at Othello in 2013, he says, depending on time of harvest and variety. Preliminary economic crop production budgets for soybean hay, he notes, are encouraging.

Delaying harvest from early to mid- or late-September produced the most tonnage, Norberg says.

“For our area, I would say you would want a 4.5 maturity group or longer,” he says, adding that a later-maturity soybean allows the crop more time to grow and add yield without mold and oil palatability issues with seed development in hay. 

“It is important to grow a longer-season maturity than is typical for grain production to avoid these issues,” he says. “Our typical grain maturity group soybean is 1.5.”

George’s on-farm experiment with soybean hay, though, wasn’t as promising. Yields averaged approximately 2 tons/ac, which compares to the 4 tons or more he can harvest from oat or timothy hay.

George admits to one stumbling block that held his yields in check: He failed to inoculate the soybean seed at planting, which prohibited the crop from fixing nitrogen. In fields that have no history with soybean, agronomists warn of the absence of rhizobia in the soil, a bacterium necessary for nitrogen fixation. Without inoculation, the soybean plant will instead be forced to use the available soil nitrogen. And if soil nitrogen is low, then yield will be limited from nitrogen deficiency.

Nutrition wise, the soybean hay fully met George’s expectations as feed for his beef cattle herd.

“Steve pulled some tests on the hay when we bailed it, and the protein was about as high as we expected at about 12%,” George recalls. “Relative feed value was pretty high at 174. The cows just absolutely love it.”

More work to be done

Soybean hay in modern times has traditionally been relegated to only emergency situations during drought when the crop cannot be harvested for the oilseed, says Dan Undersander, a veteran forage specialist at the University of Wisconsin–Madison.

While the hay does have benefits in cutting labor and fertilizer costs, it has not caught on as a mainstay among hay growers due to reduced yield compared with traditional hay sources, he says. “There is a yield penalty. It’s going to be about 30 to 40% lower yielding compared with alfalfa.”

In research conducted in Wisconsin, soybean hay yielded 1.5 to 2.5 tons/ac under drought conditions while alfalfa yielded 4 to 5 tons/ac. In normal growing conditions, Undersander expects soybean hay to produce as much as 3 tons with alfalfa yielding 5 to 6 tons.

The best time to harvest soybean hay, advises Undersander, is at maturity stage R3 to R4, or the green pod stage just before the seeds have begun to fill. Harvesting at later stages such as R6 or R7 can cause the plant to shatter when it is mowed. Quality is also lost at later stages as the plant becomes woodier.

The high oil content of the hay will also affect palatability, he cautions. “The hay quality is high, but the palatability is not as good as alfalfa because of the oil content. What we’ve found in a number of on-farm trials is that we can feed it up to about 20% of the ration and get good animal performance. Once you get over that amount, they’ll quit eating it if you don’t dilute it out.”

And because of soybean hay’s high crude protein content of about 18 to 24%, it can be used to improve lower quality forages, Undersander notes. “If your other forages are a low protein source, such as a fairly mature grass or corn silage, then it fits very well for improving the ration.”

One limiting factor for hay producers in northern regions of the U.S., is climate, notes Undersander. Hay crops like timothy are cool-weather crops that will perform better with temperatures of 72 to 75 degrees Fahrenheit, while soybean is a warm-weather crop that prefers 85 to 90 degrees Fahrenheit.

Quality wise, soybean hay can maintain its RFV over a long period of time, adds Norberg. While it may not beat the quality of alfalfa hay needed for dairy cattle, it can still be used in rations for other animals.

Meanwhile, George plans to continue trying soybean hay on his farm in the future, but it isn’t something he’s ready to implement across his whole farm yet.

“It’s something I might use sporadically as a rotation,” he says. “And it still has some tweaking. The jury’s still out whether it’s really going to be worth it to do it or not.”

This story first appeared in the Mar.-Apr. 2014 issue of Crops & Soils magazine.