Hello addie-ga,
This is a great question. As a corn lover, I’ve wondered how they do
this, but I never looked into. Thanks for giving me a good excuse.
They are able to do this so quickly because, the corn kernels are
removed from the cob (thrashed) on the field as they are picked, by a
combine.
A good discussion, including pictures, can be found at CyberSpace
Farm, a website Sponsored by Kansas Women Involved in Farm Economics
(WIFE):
Harvesting Fall Crops: Corn, Milo & Soybeans, By Ina, Golden Waves
WIFE
http://www.cyberspaceag.com/photoessays/harvestingfallcrops.htm
This article states the following:
“This combine has a "corn-head" attached to the front. With each trip
through the field, this combine will pick and thrash eight rows of
corn, planted in rows 30 inches apart. The combine has a grain tank
for holding the thrashed grain. When that tank is full, it must be
dumped (unloaded) before the combine can go back to thrashing. The
combine operator is unloading the grain tank into a waiting truck,
which will carry the corn to a storage facility.”
The process of removing the corn from the cob with a combine is also
called shelling.
According to Thomas H. Herdt, College of Veterinary Medicine, Michigan
State University (http://cvm.msu.edu/courses/Lcs643/conc/sld007.htm):
“Harvesting corn with a combine is often referred to shelling corn,
i.e. removing the corn grain from the cob.”
This type of combine is also called a “picker-sheller”.
According to IndianCommodity.com
(http://www.indiancommodity.com/grain/corn.htm):
“Harvest usually starts in early October, once the kernels have dried
(optimally to between 15 to 22 percent range). A special combine known
as a "picker-sheller" is used, which removes the ear from the plant,
removes the husks from the ear and shells the grain by removing the
kernels from the cob. Most of the corn usually is harvested by mid
November. “
Detailed pictures of a combine can be seen at the website of Gorden
Harvesting Equipment (http://www.harvesting.com/).
According to an essay titled “Farming Methods and Practices” at the
website of David Kusel
(http://www.davidkusel.com/centennial/237farming.htm)
“Mechanical corn pickers and combines have drastically changed the
time involved to harvest a corn crop. It is now common to have a
combine harvest 6,000 to 8,000 bushels per day, and this includes
getting the corn off the cob. No longer are winter days spent feeding
corn into a sheller to separate the corn from the cob. The U.S. Dept.
of Agriculture estimates that if the average corn crop in 1981 were
husked by hand, it would take a crew of 937,500 men working 100 days
to get the job done.”
Just a bit of trivia, Joseph Briggs invented the first corn sheller in
1845 (AmericanArtifacts.com,
http://www.americanartifacts.com/smma/sheller/sp44.htm)
I hope you have found this information helpful. If you have any
questions, please request clarification prior to rating the answer.
Good luck with your studies and eat lots of corn!
Googlenut
Google Search Terms:
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"picker-sheller"
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shelling corn
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combine corn cob
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Clarification of Answer by
googlenut-ga
on
20 Jan 2003 11:30 PST
Hello addie-ga,
Thanks to sparky4ca-ga and efn-ga for their very good comments.
On the question of sweet corn being threshed in the field or at a
later point in processing, the references to sweet corn being packed
on the ear may be referring to sweet corn that is sold on the ear
(corn on the cob).
However, sweet corn is threshed in the field as confirmed by the
following references:
Performance of Processing Sweet Corn Cultivars at Selected Spacings,
Plateau Experiment Station, 2000, Charles A. Mullins University of
Tenessee, Biosystems Engineering & Environmental Science
(http://bioengr.ag.utk.edu/Extension/ExtProg/Vegetable/year/VegInitReport00/5performance_of_processing_sweet_.htm)
“Processing sweet corn has increased in acreage in west Tennessee in
recent years. The crop is fully mechanized and kernels are cut from
the ear in the field. High production levels are needed, and closer
plant spacing generally have been effective in increasing yields of
sweet corn. Ear size is not a major concern in processing sweet corn
as long as the harvesters can be efficient in removing kernels from
the ear. The harvesters are set at 30 inch row spacing so in-row
spacing is the only factor that can be used effectively to manipulate
plant population.”
Nebraska Farm Bureau News, http://www.fb.com/nefb/ag-ed/corn.html
“Sometime between late September and November the corn will be dry
enough to be picked, or harvested. Corn is harvested by a large
machine called a combine. The combine cuts off the plant, removes the
ear of corn and separates the kernels from the corn cob. The corn
stalks and corncobs are left in the field to protect the soil for the
next year.”
---
“After harvest, the corn kernels will go to a processing plant to be
made into food. Corn makes oil, syrup, cereal, starch and more than
1,000 other products you can buy at the grocery store.”
Regarding how the combine works, it seems that the kernels are
“rubbed” off the cob.
The Purdue University class notes, Combine Components: Functions and
Adjustments, ASM 222 Classnotes, Prepared by Doug Biehl (October 7,
1994), (http://pasture.ecn.purdue.edu/~gem/class/asm222/combcomp.pdf),
state the following:
“Threshing is the action that removes the seed from the cobs, pods, or
heads of the crop. The threshing operation takes place between the
traditionally stationary concave and a rotating cylinder.”
The notes go on to say:
“The action of the cylinder rubbing the crop against the concave
causes the crop to be threshed.”
On the question of the “fine point” on the end of the corn and the
size of the kernels, I believe that the separating and cleaning
processes are where this is handled.
The Purdue University document provides the following descriptions:
“Separation is the act of separating any threshed grain from straw,
stalks, and some chaff. In conventional type systems separation takes
place in the cylinder and on the straw walkers. Separation only takes
place in the cylinder-concave area in rotor type combines.”
---
“Cleaning is the final step in the harvesting process other than the
handling of the grain. The cleaning unit takes the threshed, separated
grain and cleans it from any chaff present. The cleaning function
takes place in the shoe section of the combine. The shoe consists of
three main parts: chaffer sieve, shoe sieve, and fan.”
---
“The chaffer openings control how much material can pass through onto
the shoe
sieve. Most combines today provide adjustable chaffer openings. Larger
pieces of
straw and chaff pass over the chaffer sieve while grain and smaller
chaff pass through to the shoe sieve. For corn and soybeans, most
companies suggest a chaffer opening of 1/2" to 5/8". If the chaffer
opening is too large too much material will pass on to the shoe sieve
overloading it. The opening is the open distance from one row of
louvers to the other.”
Other references that you may find interesting”
Rootsweb.com, How a Combine Harvester Works
http://www.rootsweb.com/~pollubel/rural/comhow.htm
Doesn’t specifically address corn.
U.S. Patent and Trademark Office, Crop Threshing Or Separating
http://www.uspto.gov/go/classification/uspc460/defs460.htm
I also recommend a review of sparky4ca-ga's references for some
detailed information about combines.
This is the most detailed information that I was able to find. I hope
it satisfies your needs.
Googlenut
Google Search Terms:
processing "sweet corn" cob machine
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processing "sweet corn" cob
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combine kernel corn thresh
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"how" combine works corn harvest OR thresh
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"how" combine works corn harvest OR thresh cylinder
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