Two new forage soybean varieties have the potential to produce more than 9 tons of dry matter per acre with up to 28% protein, university research has shown.

The Roundup Ready varieties — Large Lad and Big Fellow — were developed primarily for planting in wildlife food plots, and the seed has been sold for that purpose the past two years, says Brad Doyle, general manager of Eagle Seeds, Weiner, AR. Compared with other forage and food-plot varieties, they grow taller with bigger leaves and have greater browsing tolerance, he says.

“When nitrogen prices were high last year, several universities called us wanting to test them for hay,” Doyle reports.

The varieties were grown at Southern Illinois University, the LSU Ag Center in Louisiana and Oklahoma's Noble Foundation in 2008. Testing is planned this year at a number of additional universities, including the University of Nebraska and North Dakota State University. Although they're long-season Group 7 varieties, they can be grown anywhere in the U.S., says Doyle.

The most promising 2008 results came from Southern Illinois University, where they were evaluated by beef forage specialist Rebecca Atkinson. When they reached 3' tall about 10 weeks after planting, she clipped them down to 10” to simulate a grazing situation. They regrew, so she's planning additional studies to find out if the soybeans can be grazed or mechanically harvested multiple times.

“I would say you would be able to get at least two cuttings of hay,” says Atkinson. “But until we actually do the research, I don't know.”

She harvested them again 16 weeks after planting, when the plants had pods with green soybeans inside. Big Fellow averaged 6.5 tons/acre of dry matter; Large Lad, 5 tons/acre; but the highest-yielding plot of Big Fellow came in at 9.6 tons/acre, while Large Lad peaked at 8.9 tons/acre.

“They're awesome,” Atkinson says. “They got up to almost 6' tall.”

Clipped, early season forage tested 16-22% protein, and silage made from plants harvested later ranged from 21 to 28% protein. Fiber levels didn't change much as the plants matured, with ADF at 31% for both varieties and harvesting times, and NDF mostly in the low 40s.

In addition to her full-season plots, Atkinson doublecropped the forage soybeans after wheat harvest. Yields ranged from 3.2 to 3.5 tons/acre dry matter.

“But our wheat harvest was late because of our weather, and these went in pretty late,” she says. “I think they'd do better if you could get them in when you're supposed to.”

Severe drought damaged yields in last year's Noble Foundation plots, reports Twain Butler, research forage agronomist. “From the time we planted until we harvested, we didn't get any rain at all,” says Butler.

Still, he harvested approximately 1 ton/acre of soybean forage on a dry matter basis at one location, which was more than he got from any of the 20-some other summer legumes in the test. The other species included lablab, cowpeas, burgundy beans, lespedeza, wild beans, prairie acacia and bundleflower.

Deer annihilated his forage soybean plots at the other location.

“Initially, they left all the other summer legumes and took out the soybeans,” he says. “I had a slew of legumes, and the deer didn't like the other ones as well.”

Butler plans to plant the soybeans again this year.

So does Guillermo Scaglia, LSU Ag Center animal scientist based in Jeanerette, LA. Too much rain from two hurricanes hurt the soybeans and prevented a timely harvest last year, he says.

“From the standpoint of good information, last year is probably not the one to cite,” says Scaglia.

He grew 39.5 acres of forage soybeans and made bale silage for wintering a beef cow herd. They were harvested a month later than they should have been, when the crop was almost mature and the leaf-to-stem ratio was low. Moisture content averaged 28-30%; protein, 17%.

“We're feeding it and the cows are eating it, but I think we can obtain a better-quality forage if we harvest it earlier than we did,” says Scaglia.

The 39.5 acres yielded 316 round bales weighing 1,400 lbs each, or about 5 tons of dry matter per acre.

The soybeans also help control weeds and add nitrogen to the soil, Scaglia points out. Ryegrass was seeded after the soybean harvest.

“We haven't needed to fertilize to help tillering. That has helped us reduce the nitrogen applied, thanks to the residual after the soybeans,” he says.

A good supply of seed is available for 2009 plantings, at $56.50/50-lb bag, says Doyle. He recommends planting a bag, roughly 155,000 seeds, per acre.

“You probably could get by with a lower seeding rate, but the stalks might be a little larger,” he says.

For more information, contact Doyle at 870-684-7377 or brad@eagleseed.com.