In the heartland of America, where vast fields of corn stretch to the horizon, a subtle but significant shift has taken place.
If you’ve grown up in Iowa, you may have noticed it. Running between rows of corn is a lot harder now because they’re a lot closer together.
“It’s just the changing of the times,” says Adam Heitman, Manager of Liqui-Grow in West Liberty, which has been in the ag industry for six decades and two generations.
Liqui-Grow specializes in liquid fertilizers by providing farmers with the right fertilizer, at the right rate, in the right place, at the right time.
“Research shows that 30-inch rows are better than the 36 or 38 inches that they used to be,” he says. “You get more plants per acre when you narrow the rows, so your yield goes up.”
Many farmers are always looking to up that yield, even if that means departing from traditional practices, though it has sparked some debate about the benefits.
However, the shift has been driven by a combination of technological advancements, agronomic research, and economic considerations.
“When you have narrow corn rows, it also helps with weed control,” says Heitman, “Because then you have more shading to stop them from growing.”
Back in the day, the spacing between corn rows was determined by the width needed for farm animals to pull equipment between them, including horses and oxen.
However, tractors have replaced animal power, so researchers began to explore the potential advantages of narrower row spacing.
Studies conducted in the 1960s and 1970s indicated that switching from 40-inch to 30-inch rows could result in yield increases of 5 to 7 percent.
Decades of subsequent research have further shown the positive impact of row spacing on corn yield and productivity.
To dig into the details, one reason for narrow row spacing is the belief that closer spacing within the row reduces competition among plants for water, nutrients, and light.
This theory is supported by the fact that narrow rows have consistently increased yield potential, particularly in environments with limited moisture or other yield-limiting factors.
However, the transition to narrow row spacing is not without its challenges.
Compaction, which is caused by heavy farm equipment repeatedly treading the same ground, is a concern, as it can negatively impact the soil and inhibit root growth.
Farmers must be careful to manage wheel traffic to minimize compaction and preserve potential yield gains from narrower rows.
Next, the adoption of narrow row spacing brings up new cost considerations.
Farmers must invest in new equipment capable of planting and harvesting in narrower rows, which can result a substantial upfront cost.
Studies have suggested that a yield advantage of 6 to 8 percent over 7 to 10 years may be necessary to recoup these expenses on larger acreages.
Despite these challenges, many farmers are still drawn to narrow row spacing by the promise of increased yield potential and improved weed control.
In fact, the ability to use the same equipment for both corn and soybean crops, as well as reduce deer damage due to less space, further incentivizes the transition.
“The most common row spacing for corn across the Corn Belt is 30-inches,” states Iowa State University Extension and Outreach writing on integrated crop management.”
“This is compared to 36- and 38-inch row spacing dating back to the 1960s. Over the last decade, there has been increasing interest in 20-inch row spacing,” it states.
Research by Iowa State University has examined the effects of 20-inch and 30-inch row spacing on corn yields and found that it varied from location to location and from year to year.
They state that farmers should consider row spacing based on field productivity.
In high yielding environments, greater than 235 bushels per acre, yield increased 8-10 bushels per acre when planted in 20-inch rows compared to 30-inch.
However, in environments with less than 180 bushels per acre, both 20- and 30-inch spacing had similar yields.
There are a few other variables as well according to a May, 2022, article entitled “Corn Yield Potential and Row Spacing,” by the Crop Science wing of Bayer and Bayer.
Shorter, earlier-maturing corn varieties with few or narrow leaves have been shown to respond positively to narrow rows and higher plant populations.
In contrast, taller, later-maturing varieties may be better suited to wider row spacing.
“Stalk breakage or standability is a concern for some farmers with increases in population,” is states.
“However, corn products can be selected for end of season standability and stalk strength to help mitigate these concerns. Typically, new corn products can withstand the higher plant density.”
In the end, it looks like the shift to narrow rows is here to stay. It’s a significant departure from the America of the 1960s, but farming is an evolving science.
The shift represents a significant evolution in corn planting practices, the benefits of narrow rows in terms of yield potential and weed control are clear.
However, farmers must carefully weigh the associated costs and challenges before making the transition.
“Potential yield increases due to narrow row spacing are higher and more consistent in the Northern Corn Belt,” states Bayer and Bayer.
“Farmers should recognize the potential year-to-year variability of yield response to narrow rows in the Central Corn Belt and Southern regions.”
Information from this article was taken from Bayer and Bayer Crop Sciences found at cropscience.bayer.us, and ISU Extension and Outreach at crops.extension.iastate.edu