Crop Expert: Future of Corn Is Narrow Rows

University of Illinois Professor Fred Below: “Twenty-inch rows is the future. Better fertility is the future.”


Fred Below, the spirited Professor of Crop Physiology at the University of Illinois, watched from the front row as growers in many states planted late this excessively wet spring season.

“I can’t tell you the challenge that this year (was) as far as getting our trials established,” Below said June 25 at the Leaders in Farming Technology (LIFT) field day in Champaign, IL. “The thinking is, if you plant corn after the first of June, you’re going to get 80% to 85% of maximum yield. We planted a lot of corn in June, which we would never do. The weather rules.”

As helpless as growers might feel against the elements, they can dictate other crop success factors, Below said. His first of several recommendations — more narrow rows. “If you planted late, you should have planted more plants, just because more plants are going to intercept more light,” Below said. “That would have been a decent management practice. Plants per acre — that is the yield component most under the grower’s control.”

What is the maximum density that corn plants can tolerate in standard 30-inch row spacing? The answer, according to Below’s department, is 38,000 plants per acre. The current average is 32,000, with an average increase of 400 plants per year. “That means that in 15 years the U.S. will be at the maximum density for a 30-inch row,” Below said. “And that means something is going to have to change. We believe that the future of corn has to be narrow rows.”

Transitioning to 20-inch rows — with 7.1 inches between plants rather than the 4.8 inches of 30-inch rows — would offer two advantages, according to Below: 1) an increase in light interception and 2) the ability to manage a higher density of plants. This, he said, will result in a 10- to 15-bushel increase in corn.

Another noteworthy factor in corn yield — the fastest-growing and hardest to predict, Below noted — revolves around plant growth regulators (PGRs) and biologicals. “Boy, this is the wild west of ag,” he said. “I can’t tell you the number of products that are available and the things that they do.”

What intrigues Below is that the PGR/biologicals category, which adds 10 bushels of corn per product, is the only factor that can be compounded. “I might put something in furrow and get (10 bushels), and then I’d come back with a foliar and get another 10. This is the only category that you can do that with, and that makes it darn interesting to us,” Below said.

Below promotes positive interaction among all crop management factors. For instance, a PGR might help make nitrogen. A biological might protect the plant from stress. “Those are positive interactions,” Below said.

Because the size of root systems diminishes as plant population increases, growers need to do a better job of fertilizing, particularly in terms of source and placement, Below said.

“Instead of fertilizing the whole surface of the soil, why don’t we fertilize 10 inches of it. Why don’t we put the fertilizer where the root is going to be? Just a wild idea,” he says. “We’ve done this for the last 10 years, and every single time we’ve seen a screaming improvement in the early growth of the crop.”

At the heart of Below and his team’s research is a study now in Year Six that revolves around an enhanced production system. The five factors tested in this “high-tech” system, which is then compared to a standard system, are:

  • Fertility — N, P, S, Zn (30 N, 100 P2O5, 25 S, 2.5 Zn) banded under the row and broadcast K and B (75 K20, 0.6 B).
  • Nitrogen — Base rate of 180 pounds of nitrogen per acre plus an extra 60 pounds of side dress nitrogen at V5.
  • Population — Up to 44,000 plants per acre
  • Fungicide — Strobilurin fungicide at R1.
  • Row space — 30- vs. 20-inch row spacing.

On average, the enhanced system has netted 51 more bushels per year than the standard system.

While analogizing the five factors to a “basketball team of management,” Below noted that his team’s ultimate goal has been to determine which factor was the “superstar of the team” and which one was the “slacker?” “That’s a very difficult statistical question,” he said. “If I have five factors that give me a 51-bushel increase in yield, are they all worth 10 bushels, or are some factors worth more than the others?”

Using an addition/omission plot to answer that question, Below’s team determined that the “MVPs” were fertility, 20-inch rows, and plant population. “Twenty-inch rows is the future. Better fertility is the future,” Below said.

The professor also noted that the cost of omitting a factor has always been greater than the gain of adding it. “Boy, it’s not what you do, it’s what you decided not to do that kills you,” he said. “That’s the synergy of those five factors working together as a team.”

The LIFT initiative is sponsored by West Central Distribution, Corteva Agriscience, Nufarm, Valent USA, and Vive Crop Protection. The group’s goal is to increase crop yields by incorporating the newest farming technology.

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