Estimating Corn Yields Prior to Harvest
A numerical constant for kernel weight is figured into the equation in order to calculate grain yield. Since weight per kernel will very depending on hybrid and environment, the yield equation should only be use to estimate relative grain yield. For example, yield will be over estimated in a year with poor grain fill conditions, while it will be underestimated in a year with good grain fill conditions.
Step 1: At each estimation site, measure off a length of row equal to 1/1,000th acre. for 30-inch rows, this equals 17.4 feet.
Step 2: Count and record the number of harvestable ears in the 1/1,000th acre.
Step 3: On every fifth ear, count the number of complete kernel rows and the average number of kernels per row. Multiply the number of rows of each ear by the number of kernels per row to calculate the total number of kernels per ear.
Step 4: Calculate the average number of kernels per ear by adding the values for all the sampled ears and dividing by the number of ears.
Step 5: Estimate the yield for each site by multiplying the ear number by the average number of kernels per ear. Divide that number by 90.Yield (bu./A) equals:
(ear #)x(avg. row #)x(avg. kernel #) / 90
* Source: Purdue University Corn & Soybean Field Guide 2008 Edition