ISSUE 14 August 3, 2000
With silking finished on corn that is progressing in a timely fashion in order to mature before the average frost date, estimates of the relative grain yield can be done. First, count the number of harvestable ears per 1/1000th of an acre. With 30-inch rows that is a row length of 17 feet, 5 inches and with 22-inch rows count the number of ears down 23 feet, 9 inches of a row to determine the estimate. Within this ear count area, also count the number of kernel rows on the ears of every fifth plant. Also, count the number of kernels per row on these same ears. Remember to only count kernels that are developing well (do not count kernels on the tip that are less than half the size of those mid-way up the ear). Average the total number of ear rows counted within the area, then separately average the total number of kernels per row within the area. If possible, move to various areas of the field and repeat the above estimations and average your findings. Next use the following formula to determine yield:
Remember, this estimate of relative grain yield will be underestimated in a year with good grain fill conditions.
Extension Crop Production Specialist