Two new tall-growing forage soybean varieties look awesome to Dr. Rebecca Atkinson, Southern Illinois beef forage specialist. They perfomed well in an on-farm rotational grazing study in her second year of testing and one of the varieties yielded 6 tons/acre of hay when planted late after last summer's wheat harvest. Results from a silage test at Andrews University, Berrien Springs, MI, resulted in 10 tons/acre of soybean silage, testing 14% protein, 41% ADF and 51% NDF. He grew 10 acres of the soybeans, and if the silage performs satisfactorily, he'll plant 40 acres this year.
The Roundup Ready varieties — Large Lad and Big Fellow — were developed at Eagle Seed Co., Weiner, AR. They were tested as forage crops at three universities, and the results were reported in the Hay & Forage Grower (see our story, “They're Awesome”). The soybeans were evaluated at several additional locations last year. Although they're long-season, Group 7 varieties, they can be grown anywhere in the U.S., says Brad Doyle, Eagle Seed general manager. Doyle sees them as a promising alternative to alfalfa, especially for farmers who can't grow the perennial legume. Lab tests have shown the soybeans' leaves have up to 42% protein, he says. In Illinois, Atkinson is interested in them mostly as a pasture crop for cow-calf producers.
Yields were impressive in a 2008 simulated grazing study, with Big Fellow peaking at 9.6 tons of dry matter per acre and Large Lad at 8.9 tons/acre. So last year she convinced a producer to plant 2 acres of the soybeans in one of 12 paddocks in his rotational grazing system. “I instructed him to graze it down to 10” but not past that, and that's what he did,” she reports. The producer grazed the paddock twice, but didn't apply glyphosate, so weeds took over after the second grazing. If he had sprayed, he could have gotten at least one more grazing, she says. He usually rotates his cattle every three days, but soybean growth was so great that he left them in that paddock an extra day.
“He was so impressed with them that he's going to plant 4 acres next summer to graze his cattle on again,” says Atkinson. In the double-crop hay trial, the beans were planted in 15” rows June 29 and mowed into windrows when they were 3-4' tall.
The yield was exceptional, but field drying was problematic, says Atkinson. The soybean stems weren't conditioned severely enough, and it took several days to get the crop dry enough to bale. She plans further work to find out how much conditioning is needed. Wider windrows should speed drying, too, and narrower rows might result in smaller stems that dry faster, she says. In the Michigan silage trial, Birney planted half the 10 acres to each of the varieties and mowed the crop into windrows after last fall's first frost. The beans were about 5' tall, and since both varieties are indeterminate, plant tops had new growth while the bottoms were more mature. “We had everything from blooming and putting on new leaves down to pods,” says Birney. “It had monster leaves and the silage smells just like alfalfa silage,” he adds.