Narrow Row Corn
Marion with Francis
Myths of 15 and 20-inch Row Corn

  • More bushels per acre
  • Less weeds
  • Less erosion
  • Plant and harvest faster
  • More bottom line profit!

In 15" and 20" rows, plant spacing becomes more uniform. This reduces in-row competition
between plants and improves sunlight interception (see chart below).
                                                                                                                                      Copyright © Calmer Corn Heads. All Rights Reserved.
Calmer Corn Heads
Corn Heads, Inc.
3056 700th Avenue
Lynn Center, Illinois  61262
Phone : (309) 629-9000
Fax : (309) 629-9001
Email : mcalmer@
Research data from Texas actually shows a higher yield
advantage to 15-inch corn rows over 30-inch than does
University of Illinois research data.  Argentina and Brasil are way
ahead of the United States in the adoption of narrow row corn.
Research data from Texas actually shows a higher yield.
It takes a special hybrid to grow narrow row corn.
Premier hybrids in wide rows tend to be Premier hybrids in
15 and 20-inch rows.
Narrow row corn requires narrow tires.
Research from Ohio State indicates wider tires have a bigger
footprint thus reducing compaction and increasing yields.
"The poorer the soil the bigger the yield kick to 15
or 20-inch row corn!"
George Roberts - Trovoli, Illinois
Switched to 20-inch rows in 1989

"When we finished harvesting our 15-inch rows and
pulled into the field of 30-inch rows, it looked like
there was one row missing and so much wasted
 Dave Sweeden, Farmer - Streator, Illinois
Seed costs increase in 15 and 20-inch rows due to higher
Significant yield advantages have been documented even
when both row spacings are compared at the same
The yield advantage of 15 and 20-inch row corn is minimal.
In 394 side-by-side farmer field trials, 15-inch row corn
outyielded 30-inch row corn by an average of 12.3 bushels
per acre.
Row Width
Plant Spacing
30"  at
=  7.5"
20"  at
=  11"
15"  at
=  15"
Based on farmer run research and experience, correct implantation of these row spacings
will provide significantly higher yields (see chart below).
No. Yield
30" Yield
15" Yield
At $2 Bushel
"Narrow rows will not penalize in dry years"
John Bradley, researcher - Milan, TX
Now with Monsanto
1. In selecting the number of row units for planters and corn heads farmers prefer an even
number of rows and a 1:1 or 2:1 ratio.  Example: 24 Row Planter and a 12 Row Corn Head.
2.  Rows in 15 and 20 inches allow for slower meter
speeds, which should result in better spacing
performance.  Some Kinze owners say that in 15
and 20-inch rows the meter speed is too slow and
a round seed when released by the finger
sometimes bounces back through the window like
a basketball causing skips and low populations.  
Some farmers remove every other finger for
15-inch rows.  Also there are some new
experimental backing plates with smaller windows
that reduce seed bounce and skips.  
(Kinze part #GD 11788) Case IH planters use a 36-hole drum for 30 and 36-inch rows but
need a 24 hole drum for 15 and 20-inch rows to maintain optimum drum rpm.  Raising air
pressure or vacuum can help reduce skips.
3.  Setting planter maker 5 inches wider than the row spacing will help avoid knocking down
rows at harvest.
4.  If you have an odd numbered row planter, planting the center row into a deep marker
trench could result in yield reductions within that row.
5.  Planting into compacted tire tracks may cuse some yield reduction.  Reduced tractor
weight, coulters, track eliminators, tracks, big tires, and low air pressure in radial tires will help
alleviate compaction and tread patterns created at planting time.
6.  John Deere 15-inch planters drive over the splitter row before it's planted.  Kinze 15-inch
planters drive over the row after it's planted.  Kinze sells a tire that has no center ribs on it to
help alleviate compaction directly above the seed.
7.  Tall, wide tires with big footprints decrease soil compaction.  Tall skinny tires with small
footprints increase soil compaction.
8.  Genetics - top yielding hybrids in 30-inch rows tend to be the top yielding hybrids in 15 and
20-inch rows.  It takes longer to burn the fog out of a 15-inch row in the summer and there is
more soil moisture, so select hybrids with good resistance to stalk, rot, and leaf diseases.
9.  Some farmers growing ultra-narrow row corn mix liquid insecticide with starter fertilizer and
inject the mixture into the seed trench.  Other farmers broadcast liquid (Furadan) insecticide in
the plant spike to 5-inch stage of growth.
10. Most farmers in the Central and Southern Corn Belt think optimum planting populations are
from 28,000 to 32,000 plants per acre.  Higher population increase your risk of lodging.
11. Most farmers in the Northern Corn Belt think optimum planting populations are from 30,000
to 36,000 plants per acre.
12. Populations - optimum populations in 30-inch rows tend to be the optimum populations in
15 and 20-inch rows.  Recalibration of the corn meter is necessary for 15 and 20-inch rows.
13. Farmers claim they can plant faster with no yield reductions and sometimes get a yield
increase because the corn meters are running too slow when planting 15 and 20-inch rows at
5 mph.
14. In any row spacing, a good job of planting 30,000 plants per acre will have a higher ear
count at harvest than a poor job of planting 30,000 plants per acre.
15. Vertical placement of the seed is probably more important than horizontal placement in 15
and 20-inch rows.
Benefits of 15 and 20-inch Row Corn
Planting - Narrow Row Corn
Farmer Split Planter / Side-by-Side Comparisons
Growing Season - Narrow Row Corn
Harvesting - Narrow Row Corn
1. It's best to harvest 15-inch rows with a 15-inch row corn head especially in research plots.  If
a 15-inch corn head is not available, you can use a 30-inch row head, which pulls two 15-inch
rows together, but there is greater potential for ear loss.  Avoid this potential ear loss by
cutting ground speed. harvesting early, and using BT hybrids.
2.  Farmers claim they can harvest "downed corn" easier with 15 and 20-inch row headers
than with 30 and 36-inch row headers.
3.  Finding the rows at harvest can be chalenging in severely wind blown 15 and 20-inch corn.  
White corn head divider snouts, a guidance system and auto header height ar helpful.
4.  Farmers say 15 and 20-inch corn heads can pick in any direction.
5.  Shorter divider snouts are available for use on contours.
6.  Farmers claim they can harvest faster in 15 and 20-inch rows.
7.  The yield advantage for narrower rows occurs every year but at different levels.
8. 100 percent of farmers with single chain corn heads stated they performed as well if not
better than 2 chain corn heads.
9. Since machinery cost can be higher the yield advantage must be large enough to cover the
cost and still have some money left over to make it profitable.  At our farm we feel it takes 5
bushels per acre to make it profitable.
10. The economics of 15  or 20-inch rows is determined by a math equation considering
multipe factors such as: acres, one planter/two crops, one corn head/two row spacings, cost to
modify equipment and savings in weed and erosion control.
Researching 15 & 20-inch Row Corn
Allen Berry looking over Calmer's Corn Head
                              1. Some research has indicated that uniform plant spacing may                   
                               explain why the average stalk diameter has increased in 15 and                   
                               20-inch rows.
                         2.  Narrow rows provide more even distribution of roots during the                     
                          growing season.  This should make the plant more efficient in                           
                          absorbing nutrients and water.  This also helps reduce erosion.
                         3.  Narrow rows canapy faster and provide better weed control.                         
                          (Weeds don't grow where the sun doesn't shine.)
                         4.  In 15-inch rows you'll normally see only one flush of weeds due to t              
                          he quicker canopy, so spray early.
                         5.  When spraying with the rows, use the correct wheel spacing and                  
                          tire size.  12.4 - 54 tires on tractors or spray coupes work nicely in                    
                          15-inch rows.
                         6.  If correct wheel spacing and tire size is not an option, spray at 90                 
                          degrees to the row, expecially in research plots.
                         7.  A one-pass post emerge Roundup herbicide program does work in              
                          15-inch rows.
                         8. There's the possibility of an increase in leaf desease pressure                      
                          because of the quicker/denser canopy, which holds more moisture between
the rows.  Scout hybrids with low resistance to leafe didease, expecially during a wet growing
season and treat accordingly.
9. Farmers with experience growing 15-inch corn believe the yield advantage is greater on
poorer soils than on better soils.
1. Doubling back with a 30-inch planter to create 15-inch rows creates twice as much
compaction, which can nullify the yield advantage of 15-inch rows.  Doubling back may be
acceptable in demonstration plots but is not acceptable in reasearch plots.
2.  All field operations should be performed in a different direction than planting.  Example:
Plant north and south...spray, fertilize, or till east and west.
3.  Ideally, row spacings should be compared at the same planting populations.
4.  Ideally, row spacing should be compared with the same planter and should be equipped
and calibrated so that meters operate at the same speed for both row spacings.
5.  Both 23 and 31 row 15-inch Kinze and 31 row 15-inc John Deere Planters provide a good
way to test 15 versus 30-inch.  They have two transmissions which allows planting of both row
spacings at the same time.
6.  When calculating yield data in 15-inch rows, remember that 15 - 15 inch rows = 225 inches
which is only 18 feet 9 inches and not 20 feet.
7.  At our farm, test plots with long row length have less yield variability than test plots with
short row lengths.
8. We don't do everything correctly on every acre or every research plot.  We are still learning
and do not know what ultra-narrow corn's full potential is, but we know the yield advantage
does increase with experience.
New practices, new equipment could usher in a new type of corn production
The move from 40- and 38-inch row corn down to 30-inch rows is credited
as one of the major factors contributing to the steady increase of corn yields
over the past several decades, along with improved hybrids, and better
herbicides and fertilizers.
The next major breakthrough may be just over the horizon, if 15-inch
"ultra-narrow row" corn fulfills its early promises of improved yields and
weed control advantages, similar to the gains 15-inch soybeans have
There's a generally accepted rule of thumb among corn rsearchers that says
you'll average a 1-bushel-per-acre yield increase with every inch of row
spacing you decrease.  While quite a few studies have focused on 20-inch
corn, researchers involved with 15-inch corn see no reason to consider 20
inches as a self-imposed lower limit .  15-inch row corn, they say, offers the
best balance of yield potential, weed control and harvesting ease.
Marion Calmer is an Alpha, Illinois, farmer who operates his own 1,300 acre
independent research center based on "real world" field trials.  He is an
enthusiastic proponent of ultra-narrow row.
"We have been doing extensive work with ultra-narrow row corn and believe
beyond the shadow of a doubt that 15-inch rows offer a yield advantage,"
says Calmer, who has grown 15-inch corn in field conditions for several
Gord Scheifele, a research scientist at the Ridgetown College of Agricultural
Technology in Ridgetown, Ontario, agrees.  He says test plot evaluations
show "significant incremental increases in yields" compared to 20-inch corn.
Purdue studies acknowledge the potential for yield gains in the "bushel per
row inch"  range, although noting the more consistent yield responses to
ultra-narrow row corn appera to ocur in the Northern Corn Belt.
Farm Forum - Spring 1997

corn heads
trash reduction
moving to 15" & 20" rows
agronomic research
about us
Francis Childs
Manchester, Iowa
World Record Corn yield!
441 bu/ac - 20" rows
New 2008 15" Advantage report
Four Oaks Sinele Farms -Southern Illinois
Harvest Date      10-Nov-08
Seed type           Row spacing         Bu        Acres        Bu/Acre         15"
Pioneer 32T84          15                  115         0.4            287.5                 22.5
Pioneer 32T84           30                 106         0.4            265

Pioneer 32T84          15                  119.4      0.4            298.5                 34.5
Pioneer 32T84          30                  105.6      0.4            264
Pioneer 32T84          15                  117         0.4            292.5                 28.5
Plot planting date, May 5                         Average advantage           28.5
"All indications are that I should have
switched to 20"rows sooner!"
 Click here         to
Marion Calmer
in a great  
agronomics video  
link brings you to U-Tube
Great Residue!
20 row 12 inch Calmer Corn Head