Don't fret late planting yet
April and early May is typically accepted as the ideal window for planting corn. This year, Mother Nature's doing everything she can to stretch that window later, and it's got a lot of farmers starting to worry that they're starting the 2013 corn crop off on an ugly foot.
Ask a lot of agronomists and they'll tell you once you get much past mid-May, you'll likely start to incur some yield penalties. That's true.
"It is true that corn grain yield potential declines with delayed planting after about May 1. Estimated yield loss per day with delayed planting varies from about 0.3% per day early in May to about 1% per day by the end of May," says Purdue University Extension agronomist Bob Nielsen.
But, it's not the only factor. "Yield potential goes down with delayed planting because of a number of factors, including a shorter growing season, greater insect & disease pressure, and higher risk of hot, dry conditions during pollination," he adds.
So, what's it mean? Don't get tunnel-vision and consider planting date in a vacuum. There's a lot more that goes into a a good corn yield, and trying to get your crop planted in conditions like the ones facing most Corn Belt farmers right now could do you more harm than good.
"The good news is that planting date is only one of many yield-influencing factors (YIFs) for corn. What is important to understand is that yield loss due to delayed planting is relative to the maximum possible yield in a given year. In other words, if all the other YIFs work together to determine that the maximum possible yield this year for the optimum planting date is 220 bushels/acre, then the consequence of a 10-day planting delay beyond April 30 (at 0.3% decrease per day) would be a yield potential of about 213 bushels/acre," Nielsen adds. "However, if all the other YIFs work together to determine that the maximum possible yield this year for the optimum planting date is only 150 bushels/acre, then the consequence of a 10-day planting delay beyond May 1 would be a yield potential of about 146 bushels/acre."
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When you consider all the YIFs in play in a given crop year, the one that's most likely to offset potential yield cuts from late planting is weather conditions during the latter half of the growing season, says University of Missouri plant sciences specialist Brent Myers. But, even though the factors are clearly linked, it's still very much a moving target.
"Differences occur among years for response of corn yield to planting date. Weather conditions in July and early August affect corn yield far more than planting date and weather during those weeks can mask the effect of planting date," Myers says in a university report. "For this reason, it is difficult to predict in any specific year what will happen to corn yield if planting is delayed. However, on average, corn yield potential declines during May, first slowly, but then at an increasing rate toward the end of the month."
Ultimately, though it may not be the perfect time, planting corn in mid- to late May isn't that bad of an idea. Myers says it's usually better to stick to your guns rather than change acreage decisions at the last minute.
"The costs and benefits of switching corn acreage to another crop such as soybean vary among farmers and fields. Each farmer must make the decisions for which he/she is comfortable. But, our data indicate that switching out of corn may not be wise even if planting is delayed until the end of May," he says. "Our data provide some optimism that reasonably high yield can be obtained when corn is planted in mid to late May. However, yield potential is very strongly dependent on weather conditions in summer."
And remember this, Nielsen says: You've likely got the tools to catch up when the window finally does open up and let you charge through your fields with your planter.
"Let's not succumb quite yet to fearmongering triggered by the prospects of a delayed start to corn planting in 2013. 'Mudding in' a crop early to avoid planting late will almost always end up being an unwise decision. While important, planting date is only one of many yield-influencing factors for corn," Nielsen says. "Another reason that it is probably too early to fearmonger about the anticipated late start to planting is that growers have the machinery capacity to 'catch up' quickly once the weather and soil conditions become favorable for planting."