Estimating Corn Yield

There are multiple ways to estimate yield some take a little more work than others. The most common one is the Yield Component Method where the number of harvestable ears in 1000^th of an acre (17’ 5” for 30” row width) are counted. Within this measurement, the number of rows and kernels per row on the 5^th ear are counted. This should be done in several areas in the field to get a good average.

To do this method follow these steps:

1. Measure 1000^th of an acre (Table 1).

2. Count and record the number of harvestable ears in the 1000^th acre measurement. Don’t count nubbins.

3. Count and record the number of complete kernel rows and number of kernels per row on a set number of ear, for example, every 5^th ear per sample. Then multiply the number of rows by the number of kernels to get the number of kernels per ear.

4. Repeat steps 1-3 in various areas of the field for a representative field average.

5. After completing step 4, add the kernels per ear numbers together then divide by the number of ears counted. This provides the field average for the number of kernels per ear.

6. Now you are ready to calculate the estimated yield. Standard practice is to assume there are 90,000 kernels per bushel of corn. Since every region and year is different, use a couple of factors to give a yield range. I use 100,000 for light test weight corn and 70,000 for heavy test weight corn. With 80,000 and 90,000 for average test weight. To calculate yield, (average number of kernels per ear X average number of harvestable ears) ÷ number of kernels per bushel (remember you are using 1000^th acre, so use 90 for 90,000).

For example, after counting, you average 34 harvestable ears per 1000^th acre and 540 kernels per ear (18 rows X 30 kernels/row). Using the formula above, 540 kernel average X 34 average number of harvestable ears = 18,360 kernels ÷ 90 (90,000 kernels/bu) = 204 bu/acre estimate. If you use 80,000 kernels, the average bu/acre is 229.

Other methods for calculating yield estimates can be found in Methods for Calculating Corn Yields – University of Wisconsin Extension.¹ Keep in mind, any method, other than over the scale, is just an estimate.

Nathan Falk
CHANNEL Agronomist

Source:

¹Lauer, J. 2002. Methods for calculating corn yield. Agronomy Advice. University of Wisconsin Agronomy. https://green.extension.wisc.edu/files/2010/05/Corn-Yields.pdf

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