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EC SoDak | For corn, scouts walk into the field, past the end rows. The Pro Farmer editors recommend walking 35 paces past the end rows. They measure the row width and hook a 30' length of rope on a corn stalk. Next, scouts count the number of ears in two rows along the rope, and pull the 5th, 8th and 11th ears from one of the rows.
Then scouts find their way back to the car and husk the ears. They measure the length of the grain on each ear and count the number of kernel rows around. Often, scouts break an ear in half to look at kernel depth and the milk like, but this isn't an official part of the formula.
Now, to the math. Scouts average their ear counts. For instance, one 30' row has 51 ears and the other has 54. They use 52.5 ears in the formula.
Next, scouts average the grain length. If the 5th ear is 7 inches, the 8th ear is 6.5 inches and 11th is 6 inches, scouts will use 6.5 inches. Then they figure the average number of kernel rows, and for the purpose of this example, we'll say all ears have 16 rows of kernels.
They plug it into the formula:
Ear count (52.5) x grain length (6.5) x kernel rows (16) = 5460/row width (30') = 182 bushels per acre.
The soybean calculations, on their face, are simpler than corn. However, two people must work together to take corn yield estimates and on soybeans they take two separate counts and average them together.
Scouts get past the field's end rows and use a measuring tape to determine row width and define a 3' section of a row. They count all of the plants in the row and then pull three random plants from it.
Once they're back at the car, they count pods on each plant and figure an average pod-per-plant count. Then scouts plug their numbers into this formula (I inserted numbers for this example):
Number of plants in 3' (14) x Average number of pods per plant (35) = Pods in 3' (490) x 36 (makes it a square) = 17,640/row spacing (15) = 1176 pods in a 3' by 3' square.
I know it's hard to visualize what those pod counts really mean, especially when you're used to thinking about crops in terms of bushels per acre. One mathematical wizard I know once told me that if you divide the pod count by 27, you get something that approximates yield. In this case, 1176 pods work out to be about 43.5 bpa. I'm neither an agronomist nor mathematician, but if it helps you visualize the tour's findings, feel free to use this trick. I just wouldn't put too much stock in that yield estimate's accuracy
Found in a DTN article.
Edited by SoDak Farms 8/24/2017 15:04
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method used for Farm Journal crop yield
