Seminole Crop E News

Agricultural News for Farmers and Agribusiness in SW Georgia

Grain Sorghum Harvest and Dessication

Posted by romeethredge on October 22, 2015

Dr. Eric Prostko, UGA Extension agronomist says, ” We are getting questions about the dessication of grain sorghum aka milo.    The use of harvest-aids in grain sorghum has shown little effect in reducing grain moisture content.  A summary of 2 older papers is as follows:

1) Hurst, Harold.  1991.  The Use of Dessicants For Field Drying Grain Sorghum With and Without Weeds.  Mississippi Agricultural and Forestry Experiment Station Bulletin #974.

“Overall, these studies did not result in any distinct advantage for application of dessicants to reduce grain sorghum moisture.”

2) Olson, B.L.S, T. Baughman, and J.W. Sij.  2001. Grain Sorghum Dessication with Sodium Chlorate and Paraquat in the Texas Rolling Plains.   Texas Journal of Agriculture and Natural Resources 14:80-83.

“Results from our 2-year study indicate that dessicant applications were generally ineffective (and most likely uneconomical) in reducing grain moisture in late-planted grain sorghum.”

In my opinion, the major (only?) benefit of using a harvest-aid in grain sorghum would be to reduce the amount of green plant material that goes through the combine and might end up in the grain.  I know of only 3 things that will dry down grain sorghum seed: time, a hard freeze, and/or a grain dryer.”

IMG_9160

We are harvesting some grain sorghum now. We checked the moisture on some grain sorghum this week by threshing it by hand and it was 12.2% moisture (photo of it above). It’s dryland and it looks good. Generally it should be dried or let dry to 12 % if it will be stored below 80 degrees F or to 10% if not, especially for south Ga storage.

We have a good UGA publication you can access here about Grain Sorghum harvest. Here’s an excerpt from that publication.

“Grain sorghum plants mature when the moisture in the grain drops to about 30 percent; however, the seed are usually too soft for harvesting when moisture content exceeds 25 percent. Attempts to harvest above 25 percent moisture will usually produce either unthreshed heads or cracked grain. The optimum harvest moisture, about 20 percent, minimizes harvest losses and drying expense.

Because field drying is difficult and leads to excessive field losses from birds, wildlife and lodging, harvest early and dry your sorghum mechanically to maintain quality and minimize harvest losses.

You can harvest sorghum using row crop or sickle bar headers. Raise the header high enough to harvest only the grain heads with a minimum of leaves and stalks.

Narrow row spacing helps to discourage lodging due to adjacent plants supporting broken stalks. Consequently, a 30-inch row is usually easier to harvest than a 40-inch row.

Combine header losses are usually less at a speed of 2.5 to 3 miles per hour; however, this speed may exceed the capacity of the combine rack and shoe if the stand is dense. In this case, you might want to take a partial swath to prevent overloading and still maintain field speed.

Set combine reel bat speed 15 to 25 percent faster than ground speed to minimize losses. Set the reel height high enough to avoid catching under and throwing the grain heads on the ground. You may need wide reel bats if plant height varies greatly.

Set your combine cylinder and concave to separate the seed from the head without over-threshing. The cylinder speed for sorghum should be less than that for wheat. Some combine manufacturers recommend removing concave bars. Concave clearance should be about 1/2 inch in front and about 3/16 inch at the rear. Clearance for rotors in rotary combines is usually greater. See your combine instruction manual for details about adjustments.

Grain sorghum stalks contain more moisture and are smaller than most corn stalks. As a result, grain sorghum stalks are more likely to be chopped up and carried to the grain tank. Pieces of stalk returned to the cylinder in the tailings will be further ground into fines. The chaffer extension can be closed to prevent this material from entering the tailings conveyor. Sorghum stems often catch and choke the straw walkers, which may cause inconvenience and lost time. Some manufacturers make straw walker covers with smaller holes that stop stems while allowing the grain to drop through.

Inspect sieves often during operation to check for matting or clogging. Set the upper sieve 1/2 to 2/3 open with the lower sieve 1/3 to 1/2 open.”

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