Leaving eight or nine kernels per square foot behind the combine tranlsates into 1 bu. of corn lost per acre. Actual grain loss calculations depend on the size of the head.
Understand how combine components interact to minimize grain loss
An odd thing happens when a farmer activates a combine system to match groundspeed to optimal grain threshing and separation: The combine generally slows down.
"Combine operators often have a certain groundspeed in mind," says Jeff Gray, senior product specialist, Claas Lexion. "I’ve noticed that once our Cruise Pilot auto-throughput control system settings are optimized, it may not drive the combine at the groundspeed the farmer desires. Farmers tend to think in terms of acres per hour harvested. With high grain prices, it’s more profitable to go a little slower, adjust the combine for minimum grain loss and maximize bushels per acre."
Gray and other combine performance experts say mandating a specific groundspeed can disrupt the critical balance among combine settings that optimize performance. Understanding how the machine responds is key to maximizing yield and minimizing loss.
A domino effect. "A combine is a system," says Kelly Kravig, Case IH product marketing manager. "No single aspect of a combine stands alone. The performance of the concave and rotor is related to how material is cut and fed into the machine by the header. How well the header feeds is tied to groundspeed, which is related to engine revolutions per minute, which influences sieve shake speed. You can’t change one setting without considering how it affects all the other settings."
Kravig starts his analysis of combine performance at the front of the machine.
"My first goal is smooth, even feeding," he says. "Don’t blame concave and rotor settings or your sieve and cleaning fan settings for trash in the tank if the header is set wrong and ‘wad feeding’ the combine."
Wad feeding, slug feeding, bunch feeding—whatever you choose to call it—temporarily overloads the threshing and separating components in combines and produces bursts of trash in the grain tank, along with temporary high grain losses out the rear of the combine. Operators often adjust concaves and rotors, or fans and sieves, to compensate for uneven feeding, when the cure is adjusting the header to feed crop smoothly into the machine.
"One of the best ways to check a combine’s performance is to move the [straw] chopper out of the way and temporarily windrow the material coming out the back of the machine," Gray says. "You want that windrow consistent—no bunches, no thin spots. Every time a dense slug or wad of
material goes through, the potential for grain loss and damage increases. If you’re dropping ‘beaver huts’ in the windrow, a good place to start correcting the problem is at the header."
Even if bunch feeding isn’t a problem, Gray likes to check for grain loss with the straw chopper in windrow position.
"Choppers mask a lot of losses," he says. "They grind and spread any grain coming off the sieves or rotor and spread it so it’s harder to get a grip on how much you’re losing. When you put everything in the windrow, you can use our grain loss tables in the owner’s manual to count kernels or beans per square foot and calculate your actual losses, based on the size of the header."
Kravig says his grain loss goal when setting combines is 1% or less of total yield. Careful adjustments often allow him to trim losses to much less.
"The best way to adjust a combine is to do a kill-stall when you’re in average-yielding crop, traveling at average groundspeed," Kravig says. He recommends reviewing instructions in the owner’s manual on how to kill-stall a particular combine and assures operators that a properly conducted kill-stall will not plug or harm the machine.
- September 2011