Are you thinking about planting corn in 60-inch single or twin rows? Consider these five factors to help ensure success:
1. Adjust planter setting for seeding. A planter set at 33,000 plants per acre in 30-inch rows needs to be adjusted to an equivalent 66,000 plants per acre in 60-inch rows, says Bob Recker, a consultant with Cedar Valley Innovation in Waterloo, Iowa.
"With a precision planter, it's pretty easy," says Wendy Johnson, a Charles City, Iowa, farmer. "You just shut off every other planter row."
It's more difficult with mechanical drive planters.
"A lot of them won't go that high, as they run out of gas at around 50,000" plants per acre, Recker says. "Oftentimes, the double-digit yield losses [with 60-inch rows compared to 30-inch ones] are caused because planters cannot plant above this level. Some people will try two-pass planting where they come back and plant into their tire tracks, but this gets messy."
2. Manage weeds. "This is tricky while growing two crops at once," says Brent Wilson, who works on such projects with BW Agronomics. "A farmer is limited to contact herbicides applied before cover crop emergence."
After that, it's up to cover crop competition to control weeds.
"The key is to get the cover crop established and catch a rain so it starts growing and competes with the weeds," Johnson says. "With all the rain we received this year, this really worked well. But if you don't get rain, the weeds can take over."
Consider a field's history. "I would be concerned to do this in a field with known weed problems, or one that has had an issue with perennial weeds," Wilson says.
3. Plant a multispecies cover crop. A mix of grasses, brassicas and legumes lets the cover crop adapt to changing conditions.
"Some cover crop species grew, while others wilted this year as soil conditions changed from wet to dry," Wilson says. "One component of the cover crop might be favored [due to changing conditions], but you at least have something growing."
4. Reduce competition between crops. Two crops growing simultaneously can create competition. Although cover crops are important, it's still corn that pays most of the bills, Wilson says.
Certain cover crops fuel crop competition. "Cereal rye is a big challenge because it is so competitive with corn," Wilson says of the grass. It's better-suited for use outside of the growing season, he adds.
Farmers can use cover crop seeding date to manage competition issues.
"You have to find that window where corn is established and growing quickly enough to get ahead of the cover crop," Wilson says. Interseeding the cover crop around the V4 stage is a good place to start, he says.
"If you wait too long, the corn gets supercompetitive," he says. "If you plant too early, the covers can be detrimental to corn yield."
A 10- to 15-inch "crop zone" consisting of just corn and no cover crop also deters competition. "This provides some safety in preventing the cover crop from hurting the corn," Wilson says.
5. Place fertilizer close to corn row. Going as close as possible to the row helps ensure that corn receives the fertilizer it needs and not the cover crop.
"I have seen the cover crop get very robust immediately from a sidedressed N application in the row," Wilson says. "Strip-tillers might have the best advantage [for this system], as they tend to band the biggest percentage of total nutrients right with the corn row."
