Harvesting, Drying and Storing Grain Sorghum
B. A. McKenzie and C. B. Richey, Agricultural Engineering Department
Harvesting
HARVEST CONDITIONS
Grain sorghum is physiologically mature when moisture content drops to about 30%. At moistures higher than 25%, however, the seeds are too soft to withstand adequate threshing action, leading to either unthreshed heads or cracked seeds.
Sorghum dries rapidly in the Great Plains, often down to the 12% moisture level needed for safe storage. But, because of the danger of shatter loss and lodging from wind and rainstorms when moisture is under 20%, many western operators prefer to harvest early (20-25%) and dry artificially .
Early harvesting is also advisable in Indiana, but for a different reason. Our more humid conditions delay field drying and encourage mold development, even though shattering and lodging would be less likely than in the west.
COMBINE HEADS AND GATHERING UNITS
Grain sorghum, if it is standing, can be combined with a regular grain header.
It should be cut as high as possible without skipping too many heads. Cutter bar guard extensions are helpful if heads droop.
As with soybeans, reel bat speed should be only about 25% faster than ground speed to avoid shatter losses. The reel should be set high enough to avoid catching under the heads and throwing them over. Wider reel bats may be needed to prevent this.
Gathering losses in a standing crop are usually less at 2.5 to 3 mph, but this speed may overload the rack and shoe. In such a case, it is best to maintain this optimum speed but take a partial swath to prevent overloading.
If lodging is a problem, consider a row-crop attachment to help pick-up and intake of the crop. These fit in front of the grain header cutter bar and have gathering points, gathering chains and kicker wheels, somewhat like a forage harvester head. Vertical finger cylinders and spiral gathering cones are also used in row-crop attachments. Also, lodging is less severe at row spacings of 30 inches or less than at 38 to 40 inches, because adjacent plants are more likely to support the heads of broken stalks and keep them from settling to the ground.
THRESHING -- CYLINDER AND CONCAVE ADJUSTMENTS
Threshing action should be only enough to detach the seed from the heads. Cylinder
COOPERATIVE EXTENSION SERVICE • PURDUE UNIVERSITY • WEST LAFAYETTE, INDIANA