Uniform Plant Spacing in Corn = Greater Yield Potential!

Corn producers should evaluate their uniformity of plant spacing.  A well-tuned planter operating at a reasonable speed should optimize uniform plant spacing within a row. Planting at high speeds with a poorly maintained planter can result in a large number of doubles (two-plant hills) and skips (missing plants), both resulting in lost yield potential for the field.

There is a quick and easy way to determine yield potential  yield loss from non-uniform plant spacing.

#1. Take a 20-ft tape measure and lay next to the row of plants to be evaluated for uniformity of spacing (see figure below).


#2. Record the location within each row in inches of each corn plant (up to 20 ft).

#3. Enter the data into a spreadsheet where average plant spacing and standard deviation (SD) can be calculated.  See below for an example.  Yield loss due to non-uniform plant spacing is estimated using the following equation:

yield loss = (present plant spacing SD – 2.0) x (4 bushel per acre per inch of SD improvement)

Figure 2:  Example spreadsheet, including equations used, for calculating plant spacing uniformity.

 Column A Column B
  Measured location of each corn plant Spacing between each pair of plants measured Equation Used
3 0
4 2 2 =A4-A3
5 17 15 =A5-A4
6 33 16 =A6-A5
7 38 5 =A7-A6
8 39 1 =A8-A7
9 44 5 =A9-A8
10 52 8 =A10-A9
11 55 3 =A11=A10
12 60 5 =A12-A11
13 68 8 =A13-A12
Average 6.8 =AVERAGE(B4:B13)
Standard Deviation (SD) 5.1 =STDEV(B4:B13)
Estimated Yield Loss (bu/ac) 12.5 =(B15-2)*4


So what should producers be aiming for?  Doerge and Hall (2000) previously found a standard deviation of 2 inches is the best spacing uniformity that a commercial producer can typically expect to obtain under normal production planting conditions. They found that if the SD is greater than 3, then the planter needs calibration. If the SD is less than 3, then calibration is not required.

The entire article titled “Estimating Corn Yield Losses from Unevenly Spaced Planting” by Carlson, Doerge and Clay can be found at: http://nue.okstate.edu/CORN/Corn_YieldLoss.pdf

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist

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Determining Final Plant Stands in Corn

The corn crop in Manitoba is now planted and corn is emerging quickly!  Over the next few weeks is when producers should be evaluating their final plant stands as plants emerge and develop through early leaf stages.

Did You Hit Your Plant Stand Target or Miss it? 

To determine plant population or stand, count the number of corn plants in a row length equal to 1/1000 acre. Multiply that number by 1000 to get the number of plants per acre.  Do this several times in a field to get a representative sample.

  • In a 30-inch row spacing, count the plants in a 17’4″ row.
  • 20-inch row spacing, count the plants in a 26’1″ row.
  • 22-inch row spacing, count the plants in a 23’8″ row.

Now compare the final plant populations achieved to what you intended to plant, i.e. calculate your attrition losses.  If losses range up to 10% or more, investigate the reasons.  Was germination impacted by cold, wet soils? Did insects like wireworms or cutworms impact final plant stands?  Identifying the cause(s) behind the losses is important.  It can help determine whether changes in your planting operation or agronomic decisions may improve the odds of good stand establishment in the future.

Also keep in mind that corn that initially emerges and develops uniformly through early leaf stages can take a turn for the worse around the three- to four-leaf stage if the plant is damaged by insect or disease prior to the successful development of nodal roots from the crown area of the plant.

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist


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My winter wheat has been seeded for awhile and is showing no signs of emerging. Should I be concerned?

The continuing dry conditions across Manitoba have many producers concerned about their winter wheat crop.   In Fall of 2011, some areas of Manitoba experienced similiar dry conditions.  There were questions surrounding winter wheat not emerging and its impact to the crop, as well in the Spring of 2012 on spring germinating winter wheat.  The following articles were written to address those questions and can be found on MAFRD’s website using the following links.

What Happens if my Winter Wheat did not Emerge?http://www.gov.mb.ca/agriculture/crops/production/what-happens-if-my-winter-wheat-did-not-emerge-.html

Spring Germinating Winter Wheat:   http://www.gov.mb.ca/agriculture/crops/production/spring-germinating-winter-wheat.html

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, MAFRD


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