You're headed to the field to check your corn yields before harvest. You've heard all the talk about aborted kernels on tips fo ears due to heat during pollination, and kernel set problems, and even talk of small ears in thick stands. Form the road, the ears hanging on your plants in almost every field looks like 200 bushels per acre or more. And if you ran the formula on the outside rows, it might be possible to find numbers that high.
Some who have seen that from the outside, then walked in several rows, tell us their heart sinks only a few rows in. Ears are much smaller inside the field, Some have found kernel tip abortion as well. In affect, tip abortion results in a smaller ear. It doesn't really matter to the yield estimation formula if it's a short ear filled to the tip or a longer ear with a couple inches of aborted kernels near the tip. It's kernels per row and number of rows that determines kernels per ear, which in turn helps determine yield.
Here are three examples. First, suppose you check the outside row. You find 32,000 plants in 17 feet and 5 inches, in 30-inch rows. That represents one/one-thousandth of an acre. Then you check every fifth ear at random and find 18 kernel rows and 38 kernels per ear. Plug in the numbers.
So it's 32 ears times 684 kernels per ear= 21,888, divided by a constant factor for average conditions. In this case, use the factor of 90. Wow! You get 242 bushels per acre. That's impressive.
Go in 8 rows. If you're on end rows, you may want to do this on a side of the field where you didn't have the turn rows. Now you find 32,000 plants with 18 rows, but only 30 kernels per ear. This time the math results in 542 kernels per ear. It's a significant drop, and the only thing that changed was length of the ear. This time the projected yield in average conditions is: 192. Far less than on the outside, but still a good yield.
Now let's get to the heart of what some say they're finding. Go in 24 rows, moving toward the heart of the field with less air movement. This time you only find 29,000 ears- at some point a signal told the plant it couldn't produce 32,000 ears. And there are only 16 rows of kernels per ear. Some claim they're only finding 14. We'll drop the kernels per ear due to tip dieback to 28.
So you have only 448 kernels per ear, Suddenly the yield estimate is 145 bushels per acre. That's nearly a full 100-bushel per acre drop from the outside rows.
Is this example too extreme? Perhaps- the idea was to make a point. Check your fields, and tell us what you find. Email firstname.lastname@example.org.