The efficient and effective use of a combine during the harvest of crop can help growers achieve higher seed yield and quality which can maximize profitability, says veteran combine specialist John Aubin.

“The grower spends a lot of time, effort, and resources to bring a crop to harvest,” Aubin says. “The combine needs proper configuration and adjustments to achieve maximum performance.”

Aubin owns Combine Harvesting Solutions based in Lewisville, Texas. Aubin, who retired from John Deere, has helped growers in 46 states, plus Australia and Europe, maximize combine performance across a wide range of crops during his 35-year career.

In mid July, Aubin led a half-day workshop and field demonstration on ways to improve combine performance in alfalfa seed during a Combine Clinic held in El Centro in Imperial County, Calif.

The event was sponsored by the California Alfalfa Seed Production Research Board, University of California Cooperative Extension, and Imperial Valley Milling.

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California is the nation’s largest alfalfa seed producer. While most alfalfa seed is grown in Imperial County, other California growing locations include Fresno and Kings counties in the San Joaquin Valley, plus the Sacramento Valley. 

Alfalfa seed is also grown in Arizona with the majority in Yuma County. Seed is also grown in Maricopa and Mohave counties.

Speaking to a large crowd, Aubin discussed the six basic functions of a combine: cutting and feeding, thrashing, separating, cleaning, grain handling, and residue management. He also shared common problems and solutions.

A common theme through Aubin’s presentation was to always operate a combine in all crops according to the manufacturer’s recommendations outlined in the owner’s manual.

#1 - Cutting and feeding – Cutting and feeding is the first function of a combine where the alfalfa seed plant is cut above the ground and moved into the combine.

Aubin says a common problem during cutting and feeding occurs in the platform cross auger and pickup reel areas.

“The combine operator should keep a sharp eye on the crop flow from the header into the combine feeder house,” Aubin said. “The crop should not fall over the front of the cutter bar onto the ground or get stuck on the reel.”

In addition, the platform auger should be properly adjusted to the platform auger strippers. This will prevent crop from back feeding (moving past the strippers over the top of the auger) which can result in early threshing of the seed from the seed pod.

Thrashing

#2 - Thrashing - This occurs in the combine’s concave area where the seed pod is separated from the plant stalk. A common thrashing problem is that not all plant material is thrashed. This occurs with uneven crop flow from the header.

“This amounts to lost yield which translates into lost potential profit for the grower,” Aubin said.

Adjust the concave per the manufacturer’s recommendations and make sure the platform feeds properly.

#3 - Separating – Thrashing and separating occur simultaneously in the concave area. The operator seeks maximum seed separation and breaking larger stalk pieces into smaller ones. From the separation area, seed and small chaff move through the combine into the cleaning system.

Following the manufacturer’s settings helps keep larger plant material in the rotor area for discharge later on the ground.

“Make sure the concave opening is set at the optimal position and the rotor speed is set at the optimum speed,” Aubin said. “This creates maximum thrashing and separation with the least amount of grain damage.”

A common problem during thrashing and separating is the operator tends to make adjustments to the concave opening and adjusts the rotor speed at the same time. When results are not obtained, the question is which one of the adjustments caused the undesired result.

Aubin suggests, “Make one adjustment at a time to determine of this alone resolves the problem. If not, then make the second adjustment.”

Cleaning

#4 - Cleaning - This area is generally referred to as the ‘cleaning shoe.’  The cleaning function separates the seed from the finer chaff. This can be adjusted by changing the fan speed or modifying the chaffer or sieve settings so the seed falls into the clean grain tank auger for movement into the grain tank. The remaining chaff is blown out the back of the combine.

Aubin says the most common sieve used is a three millimeters round hole sieve.

To help ensure the system is working correctly, Aubin encourages operators to stop the combine and walk about 25 feet behind the machine. Check the ground for excess seed blown on the ground.

If too much seed is lost, likely culprits include the fan speed is too high or the chaffer position is too tight. Check the owner’s manual for recommendations.

#5 - Grain handling – It is important to ensure the combine’s elevator chains are working properly to deliver good quality grain to the grain tank.

Loose elevator chains, augers with sharp edges, and a pinch point located between the edge of the auger flighting and the auger trough can result in seed damage.

The combine specialist said, “Make sure the elevator chains are precisely taut, according to the manufacturer, to keep the seed from getting pinched between the elevator chain and the sprocket.”

In addition, inspect the edges on the flighting as sharp edges can crack or break the seed.

“Auger flighting located too close to the auger trough can grind the seed as it moves into the trough.”

The most common specification is a one-half-inch clearance between the auger and the auger

#6 - Residue management – This is the final function of a combine. This system reduces residue to the preferred size before release behind the combine. Rotating knives located between the stationary knives cut the stalk into the operator’s desired piece length for release for tillage later into the soil.

The residue size should meet the grower’s requirements for tillage back into the soil.

Adjust the stationary knives to obtain the proper residue length based on the grower’s farming practices. The failure to do so can unnecessarily use too much engine power; power which could be more effectively used in the rotor or other areas.

“This is common,” Aubin said. “Many times the chopper does not operate fast enough which impacts the spread pattern of the chopped residue, or the stationary knives are not in the proper position for the size of the residue.”

The rotating knives can be adjusted from a low-to-high speed. Aubin recommends the high-speed setting.

More to consider

Beyond the harvest functions, other combine issues should also be considered.

Growers sometimes switch combine manufacturers. While most combines work similarly, specific functions may operate differently; for example, different-sized concaves and thrashing elements on the rotor. Review the operator’s manual for specific configuration of the combine for the alfalfa seed harvest.

If a grower plans to hire a custom harvester, Aubin offers these suggestions. Choose a custom harvester with a good reputation and is willing to work with the grower to maximize seed quality and minimize seed loss.

Also, consider the quality of the custom harvester’s equipment to move the harvested seed from the field to the local elevator, Aubin says.

Well maintained equipment can reduce seed damage. A rule of thumb is up to 1 percent seed damage can occur each time the seed is moved if grain-handling equipment is not properly maintained.

Aubin also stresses the importance of safety during the harvest. Make sure all combine operators are aware of the safety measures outlined in the operator’s manual.

For more information, contact Aubin at (214) 578-8320 or [email protected].

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