Forage sorghum is a good candidate for biomass production in the Northeast, but its lack of stalk strength is a concern, say Penn State University researchers who evaluated the crop the past two growing seasons.
“It is of interest as a biomass energy crop,” says Glen Cauffman, manager of farm operations and facilities. “Being a rapidly growing annual, sorghum has the potential to fit into a traditional crop rotation on a short-term basis and can yield 5-10 tons per acre of dry matter.”
Two varieties were grown in 2008, and both grew more than 10’ tall and stood upright until the end of the growing season.
“Usually the crop would have been harvested just after the first killing frost; however, we decided to leave the sorghum in the field and follow the winter-drydown-and-harvest strategy often used for switchgrass,” says Don Rill, a research associate responsible for the trials. “However, by mid-December the plants had fallen over, even though there was no unusual weather event to make the crop go down.”
When it was harvested in March 2009, the yield was significantly reduced.
“There can be substantial amounts of biomass left in the field when a crop is not standing upright,” says Rill.
Last year, one variety was planted and again it grew 10-12’ tall. The intent was to harvest the crop as soon as the moisture was low enough to store it in round bales.
“Unfortunately, an unusual wet snow event in October flattened the crop,” he reports. “The biomass was harvested and removed in November, but the mowing had to be done from one direction so the plant material could be picked up off of the ground.
“So it is not a crop to be left in the field to dry and harvest in midwinter like can be done with switchgrass or sudangrass,” Rill adds. “But forage sorghum is still a viable option for biomass production, as long as it is harvested early in the fall.”