Cob traits may soon join the list of attributes you consider when you choose your corn hybrids.
Cob size, density, yield, field drydown and storage characteristics vary a lot, says Mike Reese, director of renewable energy at the University of Minnesota West Central Research and Outreach Center (WCROC) in Morris, MN. As biomass energy markets develop, these differences will matter, says Reese, who is leading research on biomass feedstocks and gasification.
WCROC is collecting data on 5,000 acres of corn cobs that will be burned in new biomass gasifiers at the Chippewa Valley Ethanol Company in Benson, MN, and the University of Minnesota, Morris.
Moisture is one of the most important variables for biomass energy feedstocks, Reese says. The cobs harvested this fall ranged from 31.2% to 53.2% moisture, he says. Grain moisture ranged from 19.9% to 33%. Desirable cob moisture for gasification is 25% or less.
The cobs will be stored in open piles this winter, and are expected to “dry some in storage,” Reese says. Some of the piles have also been ventilated with 12-in. corrugated drain tile. Researchers will be monitoring temperature, moisture and tonnage losses in the cob piles.
Pounds of cobs per acre is another key variable. Cobs make up 8-20% of corn residue, Reese says. A 200-bu./acre corn crop is expected to yield 1,000-2,000 lbs. of cobs/acre. However, commercial cob harvesters report extreme variability in cob yields, he says.