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Combine adjustments can save time, money

Time may be of the essence as Mid-South farmers begin harvesting the 2007 corn crop. But experts say taking time to properly prepare and adjust your combine before harvest can pay big dividends.

“Corn left behind when the crop is combined represents a loss of profits,” says Charles Shay, Extension agricultural engineer with the University of Missouri. “Combine losses cannot be reduced to zero, but skillful operators can reduce losses to an acceptable level without affecting the rate of combining.”

Shay and other Extension ag engineers in the Mid-South states say a properly equipped and adjusted combine could go a long way toward helping growers finish the stressful 2007 season on a good note.

“It would be a tragedy for anyone to take good care of his corn and then not harvest it well,” said Roberto Barbosa, an agricultural engineer with the LSU AgCenter who has been working with Louisiana growers.

One of the first orders of business could be making sure that the combine is, in fact, set up for corn, says John Aubin, combine specialist with John Deere’s Dallas training center.

“Some combines ordered for the Delta region are configured primarily for rice and soybeans,” says Aubin. “As a result, they may come with a fixed speed on the feeder housing that may not function properly with that of a corn header.”

To obtain maximum operating speed with their combines, Aubin says, growers should check with their dealers to make sure the picking speed of the corn header is matched with the ground speed of the combine. “Some combines come with variable speed, and it’s a matter of hitting a button to alter it. Others may require changing by the dealer.”

He says having the dealer do a pre-harvest check on the combine can prevent downtime in the middle of harvest when “having uptime is at a premium. But it’s also a good idea for the grower to grab the operator’s manual and make sure he’s as familiar with the combine as possible.”

While it may be tempting to try to harvest corn with a minimum of investment in new equipment, ag engineers advise against it.

“A corn head and rasp-bar cylinder or rotor modifications are needed for corn,” says Dennis Gardisser, Extension ag engineer with the University of Arkansas. “We have seen situations where farmers have tried to cut corn with a flat-table header. But that’s very difficult to do.”

Arkansas engineers note costs for conversion can run $25,000 to $50,000, depending on whether good, used equipment is available and some parts, such as the feed elevator, on the existing combine are compatible with corn.

Row spacing on the corn header should match the planter. Gathering losses can increase by 2.5 bushels per acre if the gathering opening on the corn header is 4 or 5 inches off the row. If damage from windstorms or corn borers cause ears in misaligned rows to drop off, field losses can exceed 10 bushels per acre.

A rasp-bar cylinder, concave and filler bars or a threshing rotor are needed for corn, they say. “Spiked-tooth cylinders can break the cob into pieces and put a lot of material into the hopper,” says Gardisser.

“Converting from a spike-tooth cylinder reduces the combine’s ability to handle down rice, weedy fields and rank, green stalk. A rasp-bar cylinder normally improves head rice yield and reduces field loss in corn, grain sorghum, wheat and soybeans.”

The University of Missouri’s Shay and fellow ag engineers Lyle V. Ellis and William Hires say the following can be major areas for harvesting losses:

— Preharvest loss. Whole ear losses from lodging can increase as the season progresses. Average preharvest losses should be less than 1 percent of total crop yield.

— Header ear loss. Driving at a ground speed that is too fast or too slow, driving off the row or operating the header too high may result in lost whole or broken ears. Losses average 3 to 4 percent of the total crop yield. With proper machine operation and adjustment, the loss should be no more than 1 percent.

— Header kernel loss. Some kernels are shelled out and lost by the header at the gathering snouts, snapping bars and snapping rolls. Those losses average about 0.6 percent. With proper adjustment and machine operation and good field conditions, the losses can be held to about 0.4 percent.

— Combine cylinder loss. Insufficient shelling action causes some kernels to remain on the cob as they pass through the machine. With the correct cylinder or rotor speed or correct concave clearance adjustment, this loss should not exceed 0.3 percent. Correct adjustment results in few or no broken cobs with no kernels attached to them. Too vigorous shelling action results in excessive kernel breakage.

— Combine separation loss. Some kernels may pass over the sieves and out of the combine. With correct sieve and wind adjustment, the loss should be held to 0.1 percent of the total crop yield.

Measuring combine losses should take about 15 minutes, the Missouri specialists say. Growers can count the number of full-size ears (about 0.75 pound) or the equivalent weight in smaller ears found in 0.01 acre. Each full-size ear represents about 1 bushel per acre loss.

“Count the kernels per 10 square feet to determine kernel losses,” they said. “Two kernels per square foot equals a 1-bushel-per-acre loss.”

For more information on combine adjustments and potential field losses, go to or to

For growers who want to learn more about setting up their combines for maximum performance, equipment manufacturers are offering computer-based programs that can help them accomplish that objective.

Case IH, for example, has introduced two interactive E-Learning Combine Educational courses that can help beginning and experienced corn harvesters learn more about the operation of their machines.

The Level 1 course, titled “Fundamentals of the Combine,” has learners exploring core combine principles. “It reviews historical harvesting techniques all the way up to today’s modern combines,” says Dan Renaud, cash crop training specialist for Case IH.

“Various combine designs are detailed, such as the single rotor, twin rotor and conventional, along with how and why the designs differ in their operation.”

The second, more advanced course, “Theory of Combine Settings and Adjustments,” expands on the basic combine information from the first course.

Level 2 challenges the learner to build a more solid understanding of the combine operation, and develop the skills and techniques to optimize performance of both the headers and the combine, says Renaud.

Specific details on settings and adjustments are included in the review of each functional system, as are operational tips on proper setup and adjustments to maximize capacity, performance and grain recovery.

“The advanced course includes the industry’s first computer-based combine operational simulator, allowing the learner to apply newly acquired knowledge,” he says. “The simulator allows you to make adjustments to the combine, such as changing the rotor speed, concave clearance and fan speed, so you can clearly see how these functions affect productivity and overall performance.”

For more information about the courses, contact the Case IH Document Management Center at (800) 635-4913.


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