Question: I have seen some information you had that shows how to estimate corn yield potential. Can you provide that again?
Answer: Here’s the basic formula, and I’m also including a chart that shows how to estimate corn yield potential under various row spacings.
If you’re in 30-inch rows, use a tape measure to mark off 17 feet 5 inches in a row of corn.
Count the number of corn plants in the measured-off space. Subtract any corn plants that appear unlikely to produce a good, harvestable ear.
Once you determine the number of harvestable ears in the measured-off space, randomly select three to five ears to count rows around and kernels long and use the following formula to arrive at anticipated yields:
average ears x average rows around x average kernels long = Yield
I’ve inserted some actual ear, row and kernel numbers in the formula here to give you an example:
32 x 16 x 35 = 199 bu/acre
I would encourage you to implement this practice in four or five different locations within each field, and then average the numbers, to arrive at a fairly accurate result.
Keep in mind the formula does not take into consideration kernel depths. Based on weather conditions during kernel fill you may increase or decrease your yield by 5 to 10 percent.
As you evaluate plant stand numbers and ear counts, consider that you can benefit from getting those two numbers to more closely align with each other.
For example, if you have 30,000 plants/A and your ear count is only 27,000 ears/A, you have the potential to increase yields 15 to 21 bu/A by increasing your ear count to 30,000 ears per acre.
While the number difference between plant stands and ear counts cannot be eliminated, it can be minimized. In a corn-soybean rotation, the difference between the two would ideally be no more than 1,200. In corn-on-corn, with heavy residue conditions, the ideal difference between the two would be 2,000 or less.
Table 1. Length of row to equal 1/1000th of
an acre for various row widths
13 feet 1 inch
13 feet 6 inches
17 feet 5 inches
23 feet 9 inches
34 feet 10 inches
*Information provided courtesy of University of Minnesota Extension Service.