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Nudge yields with narrow rows

Growing corn in northern areas has drawbacks such as late planting dates and short growing seasons. Then there’s the gut-churning that those corn growers endure in September (when an early fall frost looms.) 

There’s one plus, though. It’s a place where corn rows narrower than 30 inches shine. 

That’s what Darren Faurschou, who farms and has a short-line machinery business at Portage la Prairie, Manitoba, Canada, discovered. In 2016, he worked with University of Manitoba department of biosystems engineering researchers to study corn row spacings of: 

  • 7½ inches
  • 15 inches
  • 30 inches
  • 7½ inches paired-row on 30-inch centers 

He used two seeding systems: a precision twin-row Monosem planter and a Salford 522 air drill. Top yields occurred with the 15-inch-row spacings. With the precision planter, average 15-inch-row yields tallied 173 bushels per acre, 165 bushels per acre with the air drill. In each row-spacing comparison, the 30-inch-row option had the lowest yield. 

“I was really surprised by that,” he says. Faurschou believes the planter will glean more corn than an air drill, and 15-inch and 7½-inch rows return more corn than 30-inch rows. 

will it work in the states?

If you farm in areas buffering Canada, yes. “Typically, there is a northern advantage for corn planted in 20-inch rows, because it does better in shorter-season conditions,” says Jason Webster, a Precision Planting agronomist. 

An analysis of farm financial records from farmers indicates that average yields were greater in 19- to 25-inch rows than in 26- to 32-inch rows in west-central and northwest Minnesota. Meanwhile, inconsistent results occurred in southern Minnesota. That’s according to a report compiled by University of Minnesota researchers.

Narrow rows enable corn plants to better intercept sunlight. Higher sunlight levels help plants generate more photosynthesis and, ultimately, higher yields. 

In southern areas, though, sunlight is not as limiting as it is up north. Short-season hybrids tend to be short, and they don’t soak up as much sunlight as taller ones. 

“I’m 6 feet, 6 inches tall and many 80- and 90-day hybrids aren’t much taller than I am,” says Ryan Van Roekel, a DuPont Pioneer agronomist.

Planting date is another challenge. “We can plant corn in Iowa mid-April in most years,” Van Roekel says. 

That date won’t cut it in more northern areas. Even when corn is planted in later April or early May, cooler temperatures can create emergence and development difficulties.

A later planting date also translates into later silking and tasseling dates well into July. That’s often a month past the peak sunlight day of June 21. 

Go south   

Still, favorable returns have occurred in the central Corn Belt in Beck’s Hybrids tests. 

From 2009 to 2013, tests showed no advantage to 20-inch rows over 30-inch ones in Beck’s Hybrids tests in Illinois. 

For the first year in 2014, though, 20-inch rows returned $18 per acre more, on average, than 30-inch rows. Then in 2015, the revenue-per-acre edge for 20-inch rows grew to $51 per acre more than 30-inch rows. 

These results get farmers thinking whether they want to leave $50 per acre on the table, says Webster.  

This aligns with central Corn Belt research that Stine Seeds has done with twin-row 20-inch corn row spacings. The company has boosted yields an average 3% to 9% above 30-inch-row corn. 

Narrow rows are a way to push higher populations, too. At 60,000 plants per acre (ppa), plants in 30-inch rows would have just 3½ inches of room between them. 

In twin-row 20s, they’d have 8.7 inches. This alleviates the in-row stress that 30-inch-row plants would endure. Matching the right high-population hybrid with the right field could pick up another 5% to 12% in yields, according to Stine tests.

so why not do it?

Switching your machinery line from 30-inch rows to more narrow ones is spendy. Besides a narrow-row planter, there are other equipment considerations:

  • Determining narrow-row tire configurations.
  • Fitting a combine with a narrow-row corn head.
  • Revamping sidedressing equipment for applying nitrogen.

The corn head can be a challenge. “Narrow corn can be a jungle at harvesttime,” says Webster. Investing in a multi-directional corn head is recommended, he says.

On the planter side, though, better news exists. 

“Typically, a lot of farmers will plant soybeans in 15-inch rows with a split-row planter and corn in 30-inch rows,” says Webster. A compromise could entail use of a 15- or 20-inch planter for both corn and soybeans in narrow-row spacing.

While the yield advantage for narrow-row corn is sketchy outside of northern areas, University of Illinois research consistently shows a 2-bushel-per-acre soybean yield edge when rows are narrowed from 30 to 15 inches. (An exception is fields plagued by white mold.) 

seed solution

The major factor, though, in making all this fly is seed. 

“We need germplasm and hybrids where we can access the yield potential of narrow-row corn,” says Webster. 

DuPont Pioneer has full breeding programs for selecting hybrids that benefit from narrow-row spacing, says Van Roekel. So far, DuPont Pioneer has found that 80% of the time, the best hybrid is still the best hybrid, regardless of which row spacing it is grown in. 

Yields can also move to a higher plateau with higher populations, but it won’t happen in 30-inch rows. 

“Increased plant-to-plant competition in 30-inch rows would lead to increased stress levels,” says Webster.

Narrow rows allow more room within the row for plants. Even so, it takes a special type of hybrid to thrive at levels of 45,000 to 60,000 ppa. Shorter-stature hybrids that are more upright in leaf architecture do well, says Webster. 

So what should you do? Webster has two ideas. 

  • Think of today as practice time for narrow-row corn. After rounding up necessary equipment, Webster advises trying it on a field or two. Enlist the expertise of other farmers and trusted advisers to assist, he says. 
  • Don’t rush into ultra-high populations if you’re new to narrow rows. “This is where many producers fail from the start,” says Webster. 

Optimal narrow-row seeding rates for first-time growers should generally be near 36,000 to 38,000 ppa. Master this system before pushing seeding rates higher. 

If you do push populations further, adjust potassium and nitrogen levels to ensure they support higher plant populations. Meanwhile, assess hybrids for root and stalk strength that’s needed for hybrids that are seeded thicker, says Van Roekel. 

If hybrids trend toward this direction, though, you’ll be ready. 

“Growers will want to quickly take advantage of this and not suddenly be trying to figure out how to put the system in place,” says Webster.

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