One of the most popular stops at the 2013 Farm Progress Show was to see a 30-row, 12-inch planter from Marion Calmer. Long an advocate of narrower row spacing for corn, Calmer strives to meet the harvest needs of the most forward-thinking producers. And yes, there are experiments on 12-inch rows. In fact, 11-inch rows are being studied, too.

It’s all about trying to achieve equidistant spacing to maximize the solar energy the corn crop receives, and to obtain that magic 300-bushel-per-acre yield, plant population has to go up, too. While the 12-inch row won’t be everyone’s choice, chances are that narrower rows — to 20 or 15 inches — may be in the cards. But you have to run the numbers to see why you need narrower rows.

Fred Below, plant physiologist at the University of Illinois, runs the numbers as part of his Seven Wonders of the Corn World. Below has been trying to consistently hit 300 bushels per acre in his field-size plots, and he’s getting closer, but what must happen to achieve those yields?

He lays it out pretty simply on a per-acre basis:

For 200 bushels per acre, the average stand would have to be 32,000 plants per acre, and each ear would need 550 kernels. Dry weight for each kernel should be 250 milligrams.

For 250 bushels per acre, you’ll need a stand of 36,000 plants per acre, on average, and every ear should have 600 kernels. You get a break on the dry weight, at 255 milligrams per kernel. If farmers are hitting those levels now with lower stand counts, they’re getting bigger ears with heavier kernels.

As for the mythical 300 bushels per acre? You’ll want 45,000 plants per acre, and each ear should have 565 kernels with a weight of 260 milligrams per kernel.

If higher plant population is your ticket to higher yields, pushing those rows closer together is key to the high-yield math you’ll perform for your farm.