A shorter, leafier, brown midrib forage sorghum delivers the yield and quality of taller BMRs without the lodging risk, say farmers and forage agronomists who’ve tried it.
Brachytic dwarf forage sorghum is a “show stopper” for farmers who want to grow BMR forage sorghum but fear it’ll fall down, says Greg Roth, Penn State University agronomist.
“In our area, if we get a lot of rain they (taller BMRs) can create a mess,” he says. “And actually, that’s been a little bit of a problem with the taller BMRs this year, even the new-generation ones.”
Lodging has been an issue with forage sorghum since the first varieties were introduced, points out Chris Teutsch, Virginia Tech forage specialist. Some early ones grew 12-14’ tall. Newer varieties are shorter and less susceptible, but adding the BMR trait reduces lignin, creating “a recipe for lodging, especially if we get a hurricane or thundershower or something with wind,” says Teutsch.
The brachytic dwarf trait shortens the stalk internodes, creating compact plants. Plants grow just 5-6’ tall, but they tiller more than other forage sorghums, enabling them to produce as much tonnage as taller varieties.
Despite the leafiness, Teutsch and Roth haven’t seen a forage quality advantage for brachytic sorghum vs. taller BMRs. They put the yield potential at equal to, or slightly higher than, other varieties. Roth got similar yields when comparing a 110-day brachytic variety with a shorter-season conventional BMR. But the brachytic – the only commercially available variety of that type – doesn’t quite reach its full potential in central Pennsylvania, he says.
Developed by Advanta US, the variety is marketed under the company’s Alta Seeds brand as AF7401 and with different variety names by several other seed companies. Advanta’s Chris McCracken says his company is developing shorter-season brachytics, and the first two – 95- and 100-day varieties – will be introduced next year.
Because of the enhanced tillering, McCracken recommends a lower planting rate. He puts the optimal rate at about 80,000 seeds per acre vs. 150,000 for other forage sorghums. Brachytic seed is higher priced, but the per-acre seed cost remains below $20, he says.
Brachytic sorghum has the BMR-6 gene, which McCracken and Ernest Weaver say improves digestibility more than other BMR genes. Weaver is a Dongola, IL, dairy farmer and seed dealer who grows forage sorghum as a hedge against drought.
“In conditions that corn struggles to grow quality forage in, we can still grow really good sorghum,” he says.
In normal years, forage sorghum outyields silage corn by 10-15%, but sorghum yields were double those of corn in 2012, says Weaver. He grows the brachytic variety plus slightly taller BMR-6 varieties that he calls semi-brachytic. Several years ago, he grew brachytic dwarf sorghum in test plots, and says it was still standing at Thanksgiving.
Weaver is convinced that the feed value of BMR-6 sorghum silage is at least equal to that of corn silage, primarily because of its high fiber digestibility. While corn silage is high in energy due to the starch in its grain, much of sorghum’s energy comes from sugar, and methods of measuring sugar in forages aren’t reliable, he says.
When silage supplies are sufficient, he feeds 10-15 lbs/cow/day of BMR sorghum dry matter to his milking herd.
“We’ve had cows on sorghum silage that were producing over 150 lbs of milk a day,” says Weaver.
While sorghum silage traditionally has been fed only to dry cows and heifers, the BMR trait “can really change the game,” says Teutsch. When balancing a dairy ration with BMR sorghum, be sure to base it on the sorghum’s NDF digestibility, he adds.
Teutsch says forage sorghum can’t beat silage corn on better-quality soils, but thinks the brachytic dwarf BMR trait would be a much better choice on soils with poor water-holding capacity. Too often, he says, farmers plant silage corn on those soils and don’t get a good crop. Forage sorghum can deliver better yields when moisture is limited and is about 15% less expensive to grow.
“I think people really need to take a close look at it and see if it fits into their system,” he says. “I don’t think it’s ever going to replace corn silage completely, but it certainly can supplement it on some farms and even replace it on marginal soils.”
For more on brachytic dwarf forage sorghum, contact McCracken at 570-660-3359 or firstname.lastname@example.org.