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Options for a wet harvest

Excessive rain past spring in most of the Midwest is setting the stage for a wet crop this fall. The good news is that a combine can consume corn with kernel moisture at 25% moisture or higher, observes Matthew Digman at the University of Wisconsin.

But a great many farmers could start harvest this year threshing out 30%-plus moisture corn. But be warned that corn is more susceptible to damage at higher moisture contents, warns Iowa State’s Mark Hanna.

Both Hanna and Digman offer a few to tips to get you started harvesting until moisture levels drop.

  • Operate the head as high as possible to reduce tough, wet leaves and stalks. Wet material absorbs threshing energy that normally separates grain from cobs, Digman explains. And a wet mat of material can overwhelm the separator trapping both threshed and unthreshed grain. If raising the head doesn’t reduce this problem, consider operating the head’s stripper (deck) plate wider to reduce wet material. But be aware that plates set too wide can increase butt shelling.

  • If you’ve been using the chromed rasp bars to take advantage of their wear properties, you may consider switching back to a hardened rasp bar because the “ever-sharp” edges of the chromed rasp bar may be too aggressive on this season’s soft kernel. Depending on your machine, there may be additional parts to improve threshing performance in wet crops. For example, some manufacturers recommend rear concave inserts to improve threshing, while others offer round bar concaves and separating grates to prevent crop hairpinning. Consult your operator’s manual and/or your local dealer to determine what options are available for your combine.

  • Adjust the cylinder or rotor speed to maximize threshing in wet grain, but make sure you balance this adjustment with grain damage. If grain damage becomes excessive, slow the cylinder or rotor. Do not increase the concave clearance. Concave spacing has very little affect on grain damage in corn.

  • Wet crop residue will require higher air speed compared to a dry crop to separate residue from grain. For example, if there is too much cob in the grain tank, first try increasing airflow, then close the top chaffer sieve a little and finally, lower the shoe sieve a little.

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