As harvest draws near, the anticipation of crop yield grows. Ohio State University offers two methods for estimating corn yield before harvest: yield component method and ear weight method.
The yield component method was developed at University of Illinois and can be used as early as milk stage of kernel development. This method should be used only to estimate relative grain yields; a ballpark. There are five steps to estimating yield using yield component method:
Step 1. Count the number of harvestable ears in a length of row equivalent to 1/1000th acre. For 30‑inch rows, this would be 17 ft. 5 in.
Step 2. On every fifth ear, count the number of kernel rows per ear and determine the average.
Step 3. On each of these ears count the number of kernels per row and determine the average. (Do not count kernels on either the butt or tip of the ear that are less than half the size of normal size kernels.)
Step 4. Yield (bushels per acre) equals (ear #) x (avg. row #) x (avg. kernel #) divided by 85.
Step 5. Repeat the procedure for at least four additional sites across the field. Keep in mind that uniformity of plant development affects the accuracy of the estimation technique.
The more variable crop development is across a field, the more samples should be taken for estimation.
Ear weight method
The ear weight method of corn yield measurement should be used only after corn has reached black layer because it’s based on actual ear weight. While sampling several sites in the field, measure a row length of 1/1000th of an acre. Count harvestable ears in that length. Weigh every fifth ear and calculate the average ear weight for the site. Hand shell the ears, mix the grain and determine an average grain moisture percent with a portable tester. To calculate estimate yield, follow these steps:
Step A) Multiply ear number by average ear weight.
Step B) Multiply average grain moisture by 1.411.
Step C) Add 46.2 to the result from step B.
Step D) Divide the result from step A by the result from step C.
Step E) Multiply the result from step D by 1,000.
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