More Than Planting Date Impacts Corn Yield Potential

Mudding corn in just to beat May 10 is a dangerous practice.

Published on: May 2, 2011

Many farmers report that their best yields come from early-planted corn. Often, that's corn planted in April. However, that is a rare club to be a part of this year. Only 2% of the corn was planted statewide as of May 1. For those not in the 2% club, Purdue University Extension agronomist and corn specialist Bob Nielsen says you should take heart. A lot of factors besides early planting plays into corn yield potential in any given year.

In fact, Nielsen and Emerson Nafziger, University of Illinois Extension corn specialist, have both looked at corn yields, based on averages, vs. planting date for several years, going back nearly 20 years. There is a relationship there, but it is far weaker than most people would think, Nielsen notes.

In fact, the correlation is only about 12% at best. What that means, Nielsen says, is there are a while lot of other factors that affect yield besides planting date. Planting early may favor high yields, but it certainly doesn't guarantee it. Conversely, planting in near-mud conditions just to get crop in once soils begin to dry out almost guarantees problems from the very start for that corn crop.

What's so difficult to determine, Nielsen notes, is that not only are there so many other factors that affect yield over time, they can all be different in nay given year. It's often impossible to tell ahead of time what those factors might be in most cases.

What Nielsen is saying is that if your yield potential was 200 and you have a late planting date but many other factors fall in the crop's favor, the yield might wind up at 190 bushels per acre vs. 200 bushels per acre due to delayed planting into mid-May or later.

However, if other factors combine to drop potential to 160 bushels per acre before planting date is considered, then the yield might drop from 160 maximum to 150 bushels per acre.

His bottom line is not to panic and give up hope, or be tempted to mud things in yet. Don't go into a frenzy trying to find shorter-season hybrids to plant, either, he says. Time for those decisions may come, but we're not ready for them yet. After all, it's only the first week of May, and on a historical basis it's tough to justify big yield cuts yet just because seeds were planted late.