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Battle for the Belt: Episode 24

Episode 24 of Battle for the Belt is now available:

In Episode 24, we go to each research location with Taylor Dill and conduct yield estimates on corn. Taylor is a graduate student in the department of Horticulture and Crop science at Ohio State University.

Yield Estimation

Every summer throughout the state, agronomists, extension educators, extension specialists, and farmers do yield estimates on their corn crop. Yield estimations for corn can be accurate to about 20 bushels per acre difference. There are two ways to estimate corn yield, the yield component method and the ear weight method. The ear component method can be used as early as R3, the milk stage. We will only be covering the yield component method in this article.

The yield component method has four simple steps to follow.

  1. First, we count the number of plants (we assume that there is one good ear per plant). Measure out 17ft and 5 inches (one thousandth of an acre when the crop is grown in 30-inch row width) and count plants or ears in one crop row. If we multiply this by 1,000, we get the number of plants per acre.
  2. Next, count the number of kernel rows per ear and kernels per row for every fifth ear. Do not sample ears that are abnormal unless that is uniform to the rest of the row. The kernel rows are always an even number because of cell division. When counting kernels per row, do not count the butt or the tip of the ear, instead, begin where there are “complete rings” of kernels (Nielsen, 2021). After counting each component for every fifth ear, average the kernel row number per ear and kernels per row.
  3. Now, multiply the ear/plant population x kernel row average x kernel per row average and divide by 85. The number we divide by is known as the “fudge factor”. This number accounts for kernel weight. When this method was originally developed a factor of 90 was used but with plant breeding and management practices improving over the years, the updated recommended fudge factor is 85. However, if you notice that the kernels are smaller than usual, then increasing the fudge factor to 90 is warranted.

Example: 33 (plant population or number of harvestable ears) x 16 (average kernel rows) x 38 (kernels per row) ÷ 85 (fudge factor) = 236 bushels per acre.

  1. Finally, for an accurate estimation for a field, repeat this process four or five times.

A reminder that this is a tool for estimation and kernel size and weight can change depending on the environment, which affects overall yield. In drought years and environments causing poor pollination, yields can be overestimated. In environments with outstanding grain fill, the yield can be underestimated.

Battle For the Belt Location Updates

Last week, we did yield estimations for each location specifically looking at planting date one and planting date three. All locations had a noticeable yield difference between the two planting dates. After harvest, we will dig into the data and try to explain yield differences among the five planting dates.

Figure 1. Planting date three (left) planting date one (right) at the Wooster location.

For planting date one at the Wooster location the population was 29,000 plants per acre with an average of 14 kernel rows and 31 kernels per row, coming out to an estimated yield of 140 bushels per acre. Planting date three had a more optimistic outlook. The population was 33,000 plants per acre, with an average of 16 kernel rows and 38 kernels per row. The estimated yield comes out to 223 bu/acre. This location was wet and cold during the planting of planting date one and has had more disease than other planting dates at R1. Planting date three also has a significant height difference (taller plants) in comparison to planting date one.

At the Western location planting date one had a population of 33,000. The yield components were an average of 14 kernels per row and an average of 28 kernels per row. The estimated yield comes out to be 152 bu/acre. In this planting date, there have been many short and small ears, which may be causing the lower estimation. For planting date three the population was 30,000 plants per acre. The average kernel rows were 16 and the average kernels per row was 31. The estimated yield for this planting date is 175 bu/acre. At this location, at the R1 stage, there was low disease pressure but over time there has been an increase in Gray Leaf Spot to about a 10% severity on the ear leaf. This disease is more severe at Western than at Northwest or Wooster.

Figure 2. Planting date one (left) planting date three (right) at the Western location

The Norwest location planting date one had a population of 32,000 plants per acre. The yield components were 14 kernel rows and 32 kernels per row. This comes out to an estimated yield of 169 bu/acre. Planting date three had a population of 31,000 plants per acre. The average kernel rows were 16 and the average kernels per row was 36. The estimated yield was 210 bu/acre. This location has had the least disease pressure across planting dates thus far, but has had tar spot come in late for our early planting dates and at R1 for planting date four and five.

Overall, planting date three is expected to out yield planting date one in corn at each location by 85, 25, and 40 bushels per acre, respectively. It is also interesting to note the consistent difference in kernel rows. Planting date one at each location averaged 14 kernel rows per ear and planting date three averaged 16. This trait is determined by V12 and is also influenced by genetics. The environment of the early season has the potential to affect this yield component.

Table 1. Planting dates one, two, three, four and five in the trial at all three locations with day of planting, soil, air temperature averages, and Growing Degree Days (GDDS). Information from CFAES Weather System,

Table 1

Keep following the ‘Battle for the Belt’ this growing season to learn more and get further updates! You can  find the full video playlist of Battle for the Belt on the Ohio State Agronomy YouTube channel.


R.L. Nielsen. 2021. Estimating Corn Grain Yield Prior to Harvest. Agronomy Dept, Purdue Univserity.

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.