What is in this article?:
- Combine specialist John Aubin shares common combine problems and solutions during alfalfa seed harvest.
- Combine functions - cutting and feeding, thrashing, separating, cleaning, grain handling, and residue management.
- Important to ensure combine elevator chains are working properly to deliver quality grain to the grain tank.
GATHERED for the Combine Clinic for alfalfa seed production held in El Centro, Calif. in July include from left: Sam Wang, University of California (UC) Desert Research and Extension Center, El Centro; Oli Bachie, UC Cooperative Extension, Holtville; Kevin Grizzle, alfalfa seed grower, El Centro; John Aubin (instructor), Combine Harvesting Solutions, Lewisville, Texas; and Jose Arias, Forage Genetics, Napa, Idaho.
#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.