Start And Finish Faster

Corn yield isn’t the only consideration when applying starter fertilizer.

By Jason Jenkins

Just as a nutritious breakfast starts the day off right, corn growers can give their crop a boost of early nourishment in the form of starter fertilizer. Placing fertilizer—phosphorus either alone or with nitrogen—near or with the seed at planting offers several agronomic advantages.

“I think corn is so responsive to starter fertilizer because it’s a Central American plant that’s being grown in northern climates. Whenever you put that plant in cold soils, it needs some help,” says David Franzen, Extension soil specialist at North Dakota State University.

“Here, the largest response to starter fertilizer application was done in a study at a research station near Carrington, which is about 100 miles northwest of Fargo. They got almost a 50-bushel-an-acre yield response from 6 gallons of 10-34-0 compared to none. So that was huge.”

However, the benefits of starter fertilizer aren’t equal throughout the Corn Belt. While a North Dakota grower may consistently reap greater yields by applying starter, that may not be the case in southern Illinois or Indiana.

“We’re still scratching our heads trying to understand why we sometimes see yield responses and sometimes we don’t,” says Bob Nielsen, professor of agronomy at Purdue University. “We don’t see a good correlation with soil temperatures in our trials.”

Franzen, who previously worked in Illinois, agrees. “In southern Illinois, researchers recorded a starter response maybe one [out of] every three years, and it was only about 10 bushels an acre,” he says. “In central Illinois, response was around 50-50. By the time you got up around DeKalb, most of the time they got a response, and it was often greater than 20 bushels an acre. I tell growers in North Dakota: ‘I think we’re north of DeKalb.’”

Earlier growth and drydown

While yield response may be inconsistent geographically, applying starter fertilizer where it can be accessed quickly by the seedling’s seminal and crown roots does lead consistently to increased early-season growth and other benefits.

“We almost always see the visual effects in early season, and sometimes the plants can be quite dramatic in terms of height and color,” Nielsen says. “When they’re under stress early in the season, the presence of that starter band allows them to tolerate that stress better. They tend to develop a little earlier, flower a little earlier, go through grain fill and finish a little earlier.

“As a result, we see a consistent reduction in grain moisture with starter,” he continues. “It’s common to see between one and two points drier grain at harvest, even if there’s no yield response. If I’m going to save one or two points on moisture every year, I can start doing the math on what that’s going to save on drying costs.”

Placement options

There are a number of options when placing starter fertilizer with corn seed. In-furrow, or “pop-up,” places the starter directly with the seed, whereas “2×2” placement directs a band of fertilizer 2 inches below and 2 inches to the side of the seed. Relay starter fertilizer combines pop-up and 2×2, while one of the newer application technologies, the FurrowJet planter fertilizer attachment from Precision Planting, places starter fertilizer in three locations—in the furrow and in two bands directed three-fourths of an inch on each side of the seed.

Caution should be taken when placing pop-up starter, as there is potential for injury to the seedling. Penn State Extension recommends that the rate be kept below 10 pounds total of nitrogen and potash per acre.

“Definitely no more than 10 pounds N plus K2O,” Franzen says of the recommendation. “And I get a little bit nervous about that, because if it does turn dry after you put it on, the salt tends to concentrate, and you risk injury.”

He adds that 2×2 placement offers more flexibility and gives the option of increasing starter rates to as much as 50 pounds of nitrogen in the 2×2 band.

Bryce Baker, integrated marketing manager for Precision Planting, says placing starter fertilizer near the seedling allows for more efficient uptake. As a result, growers can reduce their overall fertilizer inputs and still increase yields. In 2015 and 2016, for example, trials with FurrowJet found that while fertilizer rates were decreased 30%, the resulting yields increased by an average of 5 to 16 bushels with banded starter over broadcast fertilizer. Use of the technology resulted in a net return of $11.50 to $50 per acre.

At Purdue, Nielsen believes that when he does see yield response in his Indiana field trials, it is likely due to the nitrogen component of the starter. He urges growers to consider that nitrogen as part of the plant’s total nitrogen need and reduce their sidedress application by the same amount.

“When starter nitrogen doesn’t represent additional cost, it becomes very low-cost insurance for the plant,” he says. “In years when you don’t get a starter response, you haven’t lost any money because you’re spending the same amount on total nitrogen. Then, in those years when you get a 5- to 10-bushel response, well that’s just frosting on the cake.”