We like to hold contests. Perhaps we should have held one on this question. What is the highest possible yield you can expect from corn in Indiana planted on June 15?
Don't over think it. Yes, it is affected by the weather afterwards and by the season. Yes, it is affected by the nutrition that is in the field. Instead, just answer it – what does your logic tell you?
If you use common guiding principle for loss per day of yield for planting late, you would likely subtract 40 or 50 bushels from 200 bushels per acre and say 150 bushels per acre. You would only be off by 100 bushels per acre.
Betsy Bower, an agronomist with Ceres Solutions in west-central Indiana, reports that Del Unger, Carlisle, planted corn June 15 and harvested it about two weeks ago. The corn made 250.3 dry bushels per acre!
Impossible? A yield monitor error? An FSA acres screw-up on the field? No, Del and son Lance and their families are straight shooters – it made 250.3 bushels per acre.
What's more, it endured about 10 inches of rain in the first two weeks after planting. Even Bower says it looked "puny" for a while.
So how did it produce the corn? Obviously the growing season had a lot to do with it. The weather remained relatively cool, especially at night, through key pollination and grain fill periods. The field was also irrigated, so water wasn't an issue late in the season.
The other answer is soil fertility. Unger added nutrition through irrigation water when it was growing, even if it didn't need water, Bower says. It obviously paid off.
There is one catch with late-planted corn. It was 28% moisture at harvest. But a late fall let it get physiologically mature before frost.
Will this work every year? Probably not – other years have different weather patterns. The point is it worked this year. If someone asked how much corn you could possibly grow planting on June 15, the answer in 2013 was 250 bushels per acre!