Increasing population rates will bump yield at harvest only if it produces a higher ear count. Yields might fall, however, if you get poor plant spacing with frequent doubles and triples, which rob productive plants of water and nutrients.
Where traditional wisdom steers us wrong
Remember your favorite school-teachers? They helped you learn by challenging your beliefs and presenting new angles. In corn production too, traditional wisdom isn’t always accurate. Even when it is, you’ll reach higher yields by looking beneath the surface.
Take time during the off-season to think about your corn production techniques. It’s often the little changes that reap the highest returns.
Does pushing population bump yield?
Not necessarily, says Farm Journal Field Agronomist Ken Ferrie. Increasing population will boost yield if it results in a higher ear count. "But if you push population and don’t produce more ears, you’ll go backward in yield," he says.
That can happen if you ramp up population without slowing down your planter. Ferrie sees that often, when farmers plant yield contest plots.
"That causes rough spacing, with doubles and triples," he says. "Those crowded plants abort their ears, so ear count goes down. They become weeds, stealing water and nutrients from plants that are producing ears. So yield goes down."
Pushing population successfully requires understanding each hybrid, Ferrie adds. "Our population test plots show that every hybrid, even with ideal spacing, reaches a point where yield plateaus and then goes down," he says.
"Some hybrids peak at 34,000 to 36,000 plants per acre, and some at 38,000 to 40,000," Ferrie says. "The point where yield will plateau changes with various management systems, such as different row spacing or nitrogen programs, but it always occurs.
"Few of today’s hybrids continue to increase yield beyond 40,000 plants per acre, although I think those hybrids are coming in the future," he says.
Equally important is matching population to environment. "In our variable-rate technology [VRT] studies, comparing 30,000 to 36,000 plants per acre, farmers get nervous about planting only 30,000," Ferrie says. "But it’s rare for the high population, planted across the field, to beat the VRT population, matched to soil conditions."
Does rain make grain?
It’s easy to blame poor yield on lack of rainfall, Ferrie says, but there might be other factors at work. "Even if you do everything right, lack of water can limit your yield. But if you do two or three things wrong, water might not add grain."
|Instead of automatically blaming poor yield on lack of rainfall, evaluate your planting and crop management strategies. If you do several things wrong, even abundant rainfall might not help you next year.
The 2011 growing season provided examples. "We saw 200-bu. corn and 120-bu. corn from the same amount of rainfall," Ferrie says. "Several times, I heard growers complain about poor yield, when I know fields on either side of them did much better. Many growers who eliminated planting issues and managed soil density, nitrogen and pests harvested a lot of grain, even though it got dry later."
If you weren’t satisfied with this past season’s yields, evaluate your management practices and make sure lack of water was the real cause. Then you’ll be ready to use every drop of rain that falls next season.
|If ears are completely filled, it might indicate you’re planting too low a population. It’s better to have a little tip showing.
Do fully filled ears maximize yield?
It’s better to have a little tip showing, says Farm Journal Associate Field Agronomist Missy Bauer. "If ears are completely filled, it probably means you’re planting too low a population," she says.
"Lots of second ears also indicate too low of a population," she adds. "You may brag about second ears in July but not at harvest, because they typically abort. Plant each hybrid at its ideal population."
Does poor pollination cause unfilled ears?
"Unfilled ears may result from poor pollination caused by hot weather, but there can be other causes," says Farm Journal Associate Field Agronomist Missy Bauer. "The ear may have pollinated, but the kernels aborted later."
To find the actual cause of poor ear-fill, "investigate what stresses the crop had to deal with," Bauer advises. "If it ran out of water, maybe you can do some vertical tillage to create a more uniform soil profile and help water move upward in July and August.
"If the problem was poor pollination, it doesn’t mean that it’s a bad hybrid. If it had been planted a few days earlier or later, it might have missed the heat. Don’t throw out a good hybrid until you learn whether the cause of poor ear-fill is something you can fix," she adds.
Does a rough surface indicate effective tillage?
"If the soil surface looks really rough, many farmers think they are tilling deep," says Farm Journal Associate Field Agronomist Missy Bauer. "Actually, it’s the opposite: the deeper you run, the more level the surface will be.
"A rough surface means your tillage tool is throwing up soil rather than shattering it uniformly underground, from shank to shank," Bauer says. "That leaves columns of dense, undisturbed soil.
"If you practice vertical tillage, using a vertical harrow in the spring [as opposed to a horizontal soil finisher], the columns of soil you created the previous fall will remain. They will be like speed bumps for your planter, resulting in an uneven stand."
If you’re not sure what your tool is accomplishing, grab a spade and investigate, Bauer concludes.
- January 2012