Test Plots track how flexed and fixed hybrids respond
The first step in maximizing yield is choosing the right hybrids for your fields. It’s how you manage those hybrids, though, that propels you to the finish line with more bushels in the bin.
Every hybrid responds differently to stress—plant densities, nitrogen management, disease, insects and all the other variables during the season. To better understand how stress impacts yields, Farm Journal Field Agronomist Ken Ferrie has led efforts in the Farm Journal Test Plots to learn more.
"First and foremost, farmers do and should pick hybrids based on the best yield potential for their fields," Ferrie says. "Then, with those selections, it’s important to know how to manage each hybrid for its maximum yield."
Five years ago, Farm Journal started a partnership with AgriGold Hybrids to see how hybrids respond to nitrogen timing and rates. For the past two years, the test plot crew studied how fixed and flex hybrids respond to nitrogen and population.
"In our plots, we have learned fixed hybrids can be pushed to add up to 10 bu. to the yield just by increasing populations," Ferrie says. "We’ve learned that while flex hybrids have a tremendous capacity to flex up in yield, they carry a risk when put under stress with too much population or nitrogen deficiencies."
In 2011, four hybrids were placed in two different fields, one fixed number and one flex number in each plot. The planted populations were 32,000, 34,000 and 36,000 plants per acre. At sidedress, three nitrogen rates were applied.
"We started looking at the effect that row spacing has as well," Ferrie says. "One of our fields was planted to 30" rows, and the other was planted with a Great Plains Yield-Pro twin-row planter."
In the field planted to 30" rows, 90 lb. of nitrogen was applied before emergence, and sidedress rates included 60 lb., 90 lb. and 120 lb.
"In this plot, pushing populations haunts the flex hybrid but not the fixed hybrid," Ferrie says. "From our previous studies, we know it’s important to support higher populations of the flex hybrid by following up with increased nitrogen, but at 36,000 plants per acre, the highest nitrogen rate could not bring this hybrid back to the same yield as the lowest population. We know nitrogen is important, and we know we caused nitrogen stress. We tried to cause both population and nitrogen stress. In the fixed hybrid, the higher population didn’t stress it as much as the lowest nitrogen rate."
In 30" rows, many of the trends were similar, with the addition of an emerging trend based on years of data.
"All hybrids have some flex to them—and I’m learning that even when hybrids are labeled as fixed, they probably have more ability to flex than we give them credit for in depth of kernel," Ferrie says.
Hybrids flex their ear production by length, girth or kernel depth. Based on the test plot, Ferrie says the more flex a hybrid has, the more the yield seems to be negatively affected by stress.
"The flex hybrids used in our plots definitely had more flex on the bottom side of a population. If you ignore a flex hybrid and push it too hard, it doesn’t have the ability to withstand high amounts of stress compared with the fixed hybrids," Ferrie explains.
With the knowledge that all hybrids flex, twin rows were added to the test plot. The second field was planted to 30" and twin rows.
"A large part of ear fill, of course, will be turning sunlight into food, and population and row spacing all play into that. There’s a point when all the light gets intercepted, 95% to 97%, and that’s when we are maximizing photosynthesis," Ferrie says. In studying twin rows for more than two decades, the test plot crew has seen improved light interception early in the season because of plant spacing.
The Farm Journal Test Plots are made possible with dozens of industry partnerships. In the field, data is
verified with scale carts.
"We’re trying to see if capturing more sunlight early in the season with narrow rows affects early ear selection differently in fixed or flex hybrids," Ferrie says.
In the first year of results, the maximum yield for the flex hybrid occurred at the lowest population (see charts).
"It looks like there can be an interaction between fixed and flex ears and row spacing," Ferrie says.
The key lessons from these plots are to choose for yield first and manage for maximum potential in the season.
"If you choose a fixed hybrid, you have a little more room to work with and aren’t quite as worried about population because that hybrid won’t back up under stress as easily," Ferrie says.
"When planting a full flex hybrid, you need to be more attentive to population, nitrogen and compaction. Stresses need to be managed more actively."
Thank You to Our Test Plot Partners
Each Farm Journal Test Plot is a cooperative effort. Thanks
go to: AgriGold Hybrids, Mike Kavanaugh, John Kermicle,
Justin Warren and Phil McCutchan; Great Plains Manufacturing,
Tom Evans and Doug Jennings; Kinze Manufacturing and
Susanne Veatch; Unverferth Manufacturing and Jerry Ecklund;
Case IH, Tony McClelland, Tom Dean and Pete Bailey; Cross
Brothers and Brad Cross; Don Schlessinger; Bob Kuntz and
Mike Craig; Crop-Tech, Isaac Ferrie and Jason Kienast.