Tips for harvesting edible beans
With edible dry beans, quality and cleanliness are paramount.
November 19, 2007 By Bruce Barker
Kevin Kehler with Green Valley Equipment in Altona, Manitoba, says edible dry
beans present special challenges in combine harvesting. Damaged beans reduce
quality and harvest losses mount in the high value crop. He provides these tips
on getting the most from a dry bean harvest with a John Deere STS combine.
Starting at the front of the machine, Kehler recommends an after-market pickup
from Elmer's Manufacturing. Available in 12, 14, 20, 22 and 30 foot widths,
Elmer's pick-up headers have a 26 inch drum that pulls in more beans, and floor
screens that allow dirt to fall off the pickup before entering the combine.
A nine bar pick-up means two rows of pickup teeth are always engaged with the
undercut dry beans to more gently pull in the crop.
If using a John Deere platform, Kehler recommends installing a 50 tooth sprocket
on the platform auger to gently handle the beans. Pick-up speed should be about
one-half of ground speed.
At the feeder house, the feeder drive chain should be set on the small sprocket
to run at the slowest speed. The front drum on the feeder house should be set
in the down (grain) position. A 'feed accelerator slow speed kit' should also
be installed to help achieve optimum quality. The feed accelerator should be
slowed down to 320rpm.
In the STS combine operator's manual, Kehler says round bar concaves are recommended
for dry beans. However, he says round bar concaves cause beans to stay in the
threshing area too long, which results in cracks and mashing of the beans. Round
bar concaves also wear out faster. Rather, Kehler recommends large wire concaves.
Kehler says to improve sample quality with large wire concaves, not all the
wires should be left installed. Rather, every other wire on the front and second
concaves should be removed, while leaving all of the wires out on the back concave.
He explains that removing the wires prevents wet, puffy green beans from going
into the hopper. As well, wire removal also helps prevent wet beans from smearing
and clogging up in the clean grain elevator.
"In good conditions like we had in 2006 with uniform maturity, it is not
necessary to remove concave wires," adds Kehler.
The separator grate covers should be removed and the concave should be levelled
proportionally to the STS rotor. The concave setting should be initially set
at 30mm, and then closed as needed to achieve complete threshing. The slowest
possible rotor speed should be used, but should run fast enough to achieve complete
threshing – about 200rpm to 350rpm.
A paddle/flight kit should be installed, replacing four tines at the rear of
the rotor, when harvesting edible beans. This moves material away from the rotor
to help prevent plugging. In the cleaning shoe, the chaffer should be set at
a 14mm to 18mm opening. The sieve opening should be set slightly larger than
seed size of six to 10 millimetres. To achieve the correct sieve opening, with
the combine shut down, Kehler suggests shutting the sieve completely, dropping
a harvest sample of beans on the sieve and then opening the sieve until all
the seeds drop through.
Fan speeds should be adjusted to the highest revolutions per minute setting
without grain loss over the shoe – about 1150rpm to 1250rpm. For John Deere
60 series, the fan speed should be set between 950rpm to 1050rpm.
Gently handle clean grain
A significant portion of damage and smearing of dry beans occurs after the threshing
and separating process. Kehler says that augers and elevator chains should be
inspected for wear and sharp edges, and be replaced as necessary. The clean
grain elevator chain should be adjusted to the correct tension. "Adjusting
the clean grain elevator is more important than many people realize. If the
chain is too loose, there is more smearing," explains Kehler.
There are also optional steel paddles for the clean grain elevator which keep
the elevator cleaner. Screens in the clean grain and tailings augers, elevator
doors and unloading augers also help eliminate dirt. A Horndean area manufacturer,
JJEB Industries, developed a new 'floor screen' option to fit the feeder house
floor. A clean grain elevator 'slow down kit' should also be installed to minimize
grain damage. It should be noted, though, that slowing down the clean grain
elevator will eliminate yield mapping ability.
On the grain tank cross augers, Kehler recommends installing large sprockets
to slow down the speed of travel in the hopper. Grain tank auger covers should
also be adjusted to reduce grain flow. Kehler says a four inch wide slot can
be cut in the grain tank load auger housing to reduce grain smearing as well.
The sump on the unloading auger should be frequently cleaned of dirt to prevent
smearing and staining.
Instead of the standard unloading auger, Kehler highly recommends a conveyor
attachment for unloading beans. He says the Schnell conveyor attachment retails
for up to $17,800 installed, depending on size and model. It is a high capacity
conveyor that unloads beans from the combine hopper without smearing. Once installed,
it can be switched back to grain mode in less than three hours. The Schnell
conveyor unloads at about 120 to 180 bushels per minute and can be used on-the-go.
"With a conveyor, you can start harvest two to four days earlier than
with an unloading auger because it reduces smearing from the wet immature beans.
It also has a lot more capacity, so you don't have to worry about plugging an
auger with wet beans – that's not pretty. It's almost like cement,"
Kehler says that because dry beans are a high value crop, investing in specialized
options can rapidly pay off. Finally, he says that constant adjustment with
combine settings, especially as harvest conditions change throughout the day
and evening, will help ensure the highest quality bean sample. -30-