Narrowing the gap
A few years ago, after listening to Harry Stine talk about his ultra-narrow-row corn system on a plot tour at Stine Seed Co. near Adel, one farmer said to another, “This is a Henry Wallace, hybrid corn type of idea.” Indeed, corn planted in 12-inch rows at high populations is a game-changer if you have the right genetics and enough nitrogen.
In the 1920s corn breeder Henry A. Wallace had a hard time persuading farmers to switch from open-pollinated to hybrid corn. He wrote a lot about hybrid corn in Wallaces Farmer. Still, farmers were skeptical. It took a couple of decades for hybrid corn to be widely planted, but gradually more farmers tried it, saw the benefits and planted hybrid seed.
Today, farmers are quicker to adopt a new method if it proves to be more profitable. At that 2012 field day, Stine proposed planting corn in rows only 12 inches apart instead of the usual 30 inches. Row width by itself isn’t the key to achieving higher corn yields. The goal is to boost yields by planting high populations per acre. To do that, you have to go to narrow rows.
Higher population is key
For example, at 51,000 plants per acre, plants in 12-inch rows are 12.3 inches apart within the row. In 30-inch rows, plant spacing would be every 3.5 to 4 inches at that same population, which is too close to avoid competition from crowding. In 12-inch rows with seed spaced farther apart, plants can better access soil moisture, nutrients and sunlight. It’s equidistant planting, or close to it. In theory anyway, this should boost yields.
USDA data show average U.S. corn plant populations and yields have been edging upward at roughly the same rate over the past 80 years. Analysis of the data also shows that corn plants in both the 1930s and today produced about the same amount of grain per plant (0.33 pound). Thus, yield gains are largely due to much higher seeding rates, says David Thompson, national marketing and sales director for Stine Seed.
“Corn yields have increased by a factor of almost five over the past 80 years, and plant populations are up by the same factor of four or five,” he says. This correlation persuaded Stine to begin pushing the concept in its breeding program by selecting for corn genetics specifically suited for populations well above today’s standards.
Choose hybrids fit for job
Stine corn breeders eliminated hybrids prone to lodging in the thickly planted plots, and over the past 20 years the company has developed genetics adapted to high populations planted in narrow rows. These corn plants tend to be shorter than most hybrids, and the leaf architecture is more upright, allowing the plant to catch more sunlight. Strong roots also enable the plants to withstand high populations. In the Stine lineup, these hybrids are designated as high population, or HP, hybrids.
A drawback with 12-inch rows is the need for special planting and harvesting equipment. To more easily transition to narrow-row, high-population corn, Stine has shifted from planting corn in 12-inch rows to a twin-row, 20-inch width. This system spaces twin corn rows 8 inches apart, with a 12-inch gap between the sets of twin rows, for a total span of 20 inches. The average row width in this configuration across the field is 10 inches.
Stine Seed made the shift to twin-row 20s last year on its 15,000-acre farming operation in central Iowa and in its marketing program for farmers planting Stine HP hybrids. The recommended seeding rates vary, depending on row spacing, genetics and soil type, says Thompson. Adding more plants per acre also requires more nitrogen and management. Both John Deere and Great Plains have produced specialized planters for Stine that plant in this configuration.
This article published in the May, 2015 edition of WALLACES FARMER.
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