With the dry heat wave we are currently experiencing across the state, non-irrigated corn is declining in quality daily.
Where corn must be harvested for grain, getting some idea of yield potential makes sense. Not sure it will help folks sleep better at night, but at least we can get a ballpark idea of yield potential.
If you checked yield potential a week or two ago, you may want to check again. Some kernels that looked promising may not have made the cut.
Corn yield estimates can be made as early as R3 (roasting ear) stage although in a dry year please note that estimates can vary widely from the end result due to late season kernel loss.
The following is a basic formula for estimating corn yield with conversions for the amount of stress occurring during the season.
1.) Ears/Acre: Estimate harvestable ears in 1/1000th of an acre by counting plants with viable ears in a specific row length (30 in rows is 17.4 ft; 15 in rows is 34.8 ft; 36 in rows is 14.5 ft; 38 in rows is 13.75 ft).
Do this in four or five locations representative of the field to obtain an average. Some folks pick the worst spots and figure the rest of the field will always average a better yield, but that is up to you.
2.) Ear Size: Randomly pull 3 to 5 ears per location and count rows of kernels around the cob and kernel numbers long and get an average number of kernels per ear.
To count ear length, count only full rings of kernels and be careful to not over count those tip end kernels which are least likely to fill in a drought year.
I would suggest starting 1 row up from the bottom and ending where kernels start to look shrunken in size (Example: average 14 rows X 24 kernels= 364 ear size). This year ears may be tipped back 25 to 33 percent or more depending on field conditions.
3.) Correct for Stress: (Average Ears/acre) X (Average Ear Size)/Stress Factor= Bu/A Estimate
(Example: (30 average ears) X (364 ear size) / 95= 115 bu/A.