Tips from Harvesting Experts

September 14, 2009 07:00 PM

Corn's journey from field to bin to market begins with your combine, which means checking settings and performance in every field. Below is advice from harvesting experts on maintaining yield and quality in tough conditions.

"Each field will harvest differently, due to differences in varieties and changing moisture levels,” says Kent Hawk of John Deere.

"We have noticed that, with new corn genetics, variety and soil conditions affect harvesting performance,” says Dan Klein of Case IH. "With the same hybrid, stalks may have more durability in a clay soil that holds more moisture, compared to a sandy soil.”

"If you're operating a brand-new machine, check the performance and settings of both the combine and the header after 50 to 75 hours of break-in time,” advises AGCO's Kevin Bien.

Kent Hawk, field service supervisor, John Deere
Conduct a preseason inspection. On a conventional machine, check the concave for wear and look for rounded-over edges on the crossbars. On a rotary combine, check the threshing elements for worn and rounded-off edges.

It's critical to have the concave level from side to side when you change the spacing for wetter or drier corn. If the concave isn't level, it may do a good job on one side but crack kernels on the other side.

At the corn head, especially if you are harvesting at 28% moisture and higher, pay attention to deck plate spacing. As corn gets drier, you may want to take in a little trash to avoid kernel damage.

Avoid running excess free grain in the tailings return. Most operators will close down the sieve to clean up the grain tank better, especially from broken cobs. Recycling free grain back into the separator will increase grain damage.

Minimize breaking cobs up front by adjusting the deck plate spacing, the feeder house chain speed, the rotor/cylinder speed and the concave clearance. Variety and cob diameters differ, so check machine performance in every field. This year will be a challenge with uneven stands, which leads to different ear sizes. 

Kevin Bien, product marketing manager for Gleaner and Massey Ferguson combines, AGCO Corporation
Today's combines record settings in all areas of the machine, so start by checking settings from the previous year. If you don't have the capability, refer to the settings guide in your operator's manual.

Start with your header. Check and adjust the stripper plates and gathering chains, and inspect the condition of the knives. Set these components to the manufacturer's recommended setting and then adjust them in the field.

In the field, watch for symptoms such as grain loss; then make small subtle changes one at a time. Observe the effect until you fix the problem.

Concave clearance is important on rotary combines. If you're cracking grain, open the concave or adjust the rotor speed. If you're breaking up the cobs, your settings are too aggressive; try increasing the concave clearance or slowing the rotor in 10-rpm increments.

If there's too much grain going over the top chaffer of the shoe, open the chaffer in small increments. If you're getting large pieces of debris in the grain tank, close the chaffer a bit. If too much clean grain is going into the tailings return, open the sieve.

Dan Klein, combine marketing specialist, Case IH
Worn or damaged combine components affect grain quality and overall performance. Grain damage may not look too bad in the combine hopper, but it will
affect grain through drying and storage.

Damaged threshing components will crack grain. Before harvest, look for worn parts. Check the impeller blades on the front of the rotor on a rotary combine, and inspect the threshing elements on conventional combines.

Ensure the concave and rasp bars are in good shape; you'll want to run the rotor a little faster and the concave a little tighter in tough conditions.

In the field, farmers slow down the rotor or open the concave to reduce grain damage. But if you set the rotor too slow or too wide, especially in tough conditions where more green leaf and stalk material go through the combine, you can block the concave. If free grain can't get through the concave into the cleaning system, you can damage grain and lose it out the rotor. You may need to slow down your groundspeed.

With tougher greener stalks, you may want to run wider stripper-plate settings to let stalk and leaf material be pulled through the knife rolls, rather than go through the combine. In the cleaning system, running wider sieve settings and a higher fan speed can save grain and blow out more leaf material.

Doing a "kill stall” in each field (see operator's manual) gives a snapshot of your combine's performance. You want grain to be distributed evenly throughout the cleaning system. Changing the rotor speed and concave clearance settings can help.

For More Information
Get Ready for Harvest

You can e-mail Darrell Smith at

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