Some people forced to plant corn in June, particularly in the Eastern Corn Belt and other isolated areas, found it yielded better than earlier-planted corn this season. In those cases- earlier was relative, say the third week of May. But others found that their latest planted corn didn't yield as well. In all cases, moisture was typically higher on corn planted after June 1 when it was harvested this fall. In some cases, that meant harvest just wrapped up, or might still be in the last stages on a few farms.
In the Farm Progress/Precision Planting plots conducted on the Purdue University Throckmorton Farm near Romney in north-central to northwest Indiana, there was a May 20 planting and a June 10 planting. They were scheduled to be late April and mid -May plantings, but Mother Nature didn't cooperate. The plots were actually part of a replicated study designed to determine if seed depth of placement, planting speed, and amount of downforce applied on the planter unit make a difference in plant stands and, ultimately, in corn yields.
Jeff Phillips, Tippecanoe County, Ind., Extension ag educator who assisted with the plots, oversaw harvest recently. Average yield for the May 20 planting was about 40 bushel per acre higher than for the June 120 planting. If you use the standard of 1.5 bushels per day and assumes it grows even larger as loss per day for delayed planting, that's about on track for a 21 day delay. In other words, you would expect about a 35 to 40 bushel reduction per acre in corn yield for a 20-day delay that late in the season, on average. Of course, the 2011 growing season was anything but average.
Phillips observed that even though the field was relatively uniform, some areas were more productive than others. That's why plots are replicated. The higher areas didn't do as well this year. Where water from a large late May rain didn't interfere, black ground tended to produce better yields.