Planting forage sorghum with silage corn can reduce the risk of low silage yields in years with below-average rainfall and above-average temperatures, says Chris Teutsch, Virginia Tech forage specialist.
He points out that, while corn’s silage yield potential is high, dry conditions during any growth stage can significantly reduce yield. Forage sorghum has much higher drought tolerance and water-use efficiency.
The past two years, Virginia Tech researchers planted corn alone and in mixtures with four rates of brown midrib brachytic dwarf forage sorghum (2-8 lbs/acre). The plots were established at the university’s Southern Piedmont Research Station near Blackstone in late May, about a month after the optimal planting date.
“The goal was to simulate a silage crop after a small-grain crop,” Teutsch reports. “Generally speaking, you plant sorghum about two weeks after corn because it’s not as cold tolerant.”
He planted the two crops in the same rows using a research planter.
“But on farms it’s a little bit more of a challenge to get that done correctly. It would be easier to do it by planting sorghum every other row or every two rows on an actual farm.”
He says 2010 was “miserably hot and dry.” Last year was better overall, but a hot, dry spell early in the growing season hurt the corn. Adding as little as 4 lbs/acre of forage sorghum to late-planted corn doubled (4.9 to 11.5 tons/acre) and tripled (5.4 to 14.3 tons/acre) the silage yield in 2010 and 2011, respectively, Teutsch reports.