The Farm Journal Test Plots set out to understand the differences in nitrogen and phosphorus starter rates applied at planting.
Starter test plots dial in early season nutrient needs
In the quest for higher yields, identifying the limiting factors helps to guide your steps along the path. Starter fertilizer is a tool that provides young corn with key nutrients, particularly phosphorus and nitrogen.
Farm Journal Field Agronomist Ken Ferrie reminds farmers that the keys to nutrient management are the three R’s: right place, right time and right rate. Supplying the necessary amount of phosphorus and nitrogen at planting can boost your corn yields to a higher plateau. (See "Strategic Placement," February 2012, for more on applying starter in the right place.)
"Never let corn have a bad day, and that starts at the beginning," Ferrie says. "Let corn talk to you and tell you what it needs."
To investigate starter blends, Ferrie led a crew to conduct test plots in central Illinois and Farm Journal Associate Field Agronomist Missy Bauer did the same in southern Michigan.
"We’ve looked at starter fertilizer in test plots for two decades," Ferrie says. "On average, applying starter fertilizer with the planter can boost yields 7 bu. to 10 bu. However, this past year in a number of our starter plots we saw higher than typical responses to starter because we
advanced the plants’ maturity into a safer reproductive stage during the extreme heat."
What does your corn crave? Farmers have different goals for applying fertilizer with the planter. Some focus on early-season nitrogen needs, others target early phosphorus needs and some try to tackle both.
"When I think about how corn responds, I separate nitrogen responses from traditional starter responses caused by phosphorus," Ferrie explains. "If a farmer is getting as big of a response from straight 28 as starter, the corn is telling him he isn’t supplying enough early nitrogen."
Ferrie conducted his test plots in two fields: one corn after soybeans, the other corn on corn. The test plots were planted with an eight-row Kinze EdgeVac planter, and mixes of 7-22-5 plus zinc, 28% nitrogen, 50/50 mixes of the two, and 60/40 mixes of the two, all applied on a per-acre basis.
The starter attachments included the Huckstep shoe and the Yetter 2959 coulter injector. Starter was also dribbled above the row.
In the corn/soybean field, the dry fertilizer program included 30 lb. of nitrogen broadcast in the fall and 90 lb. broadcast preplant; the rest was sidedressed. The field showed the greatest response to the 7-22-5 starter blend applied with a Huckstep shoe, which mounts between the disk openers.
"Farmers should consider how they apply nitrogen, how much nitrogen is in the starter and if they are meeting early nitrogen needs," Ferrie says. "This farmer managed his nitrogen upfront and in-season with sidedress. The corn plants responded most to the highest level of phosphorus because it was the limiting factor, not nitrogen."
In the corn-on-corn field, there was more residue and a higher carbon penalty. The farmer applied 30 lb. of nitrogen in the fall and 150 lb. of nitrogen preplant (he originally planned to apply 90 lb. but increased the rate to help pay the carbon penalty and compensate for a wet spring).
"Then, the farm received 9" of rain in April, and the heavy rain moved that nitrogen further down in the soil profile," Ferrie says.
The greatest yield increase came from applying the highest rate of nitrogen and phosphorus using the Yetter 2959 coulter injector.
"Even when we broadcast 150 lb. of nitrogen, we couldn’t meet the early nitrogen needs of the crop because of the weather conditions," Ferrie says. "Particularly in corn on corn, farmers should pay attention to their weather. Depending on their fertilizer attachment, they can make the call right before planting to move nitrogen into their starter program."
Base your decision on the starter response in corn on corn during previous seasons.
"When corn fields yellow early in the season, that is a result of insufficient nitrogen to pay the carbon penalty," Ferrie explains. "The corn is telling you to kick up the nitrogen rate at planting. This has to be done outside the furrow so you don’t burn the seed."
Another advantage to starter fertilizer is its efficiency, he adds.
"Any time you band a nutrient, it’s significantly more efficient," he says. "We have nitrogen applied with the planter at two times the factor when dealing with early nitrogen needs. When you improve nitrogen uptake, you improve phosphorus uptake, so that also works in your favor."
Bauer’s test plots were run with different starter blends than Ferrie’s.
"In the eastern Corn Belt, we run higher nitrogen rates in our starter combinations of 10-34-0 and 28% nitrogen," she says. "Even so, with increasing phosphorus prices, farmers are looking to make their starter application the most economical while not losing yield potential."
In corn-after-soybean plots, Bauer says, yields did drop when only nitrogen was applied compared with starter blends of 32-29-0 and 36-20-0 on a per-acre analysis.
"Our results show some phosphorus needs to be applied at planting," she says. "Farmers should be cautious of taking phosphorus levels too low if soil test levels are low. We saw in tissue samples that we could maintain phosphorus levels in the plant, even reducing the applied rates from 30 lb. to 20 lb. per acre with adequate nitrogen applied as well."
Ferrie and Bauer also studied starter rates in twin-row corn plots.
"To get the same response in twins, we have to think of fertilizer per foot of row," Bauer says. If planting twin rows, you can double the starter rate without increasing the risk of starter burn. For example, in twins, you can run 10 gal. to the acre in furrow because it’s 5 gal. in each row. In sandy soils, farmers can apply a 6-gal. rate in twins compared with the 3-gal. rate in 30" rows.
"It’s no higher risk to apply per foot of row. In fact, from an overall fertility perspective, it allows you to band more starter than in 30" rows," Ferrie says. "Farmers can look at applying starter on twin rows two ways: as double the cost or double the opportunity."
When considering the outcome of the starter test plots, Ferrie and Bauer point out that the rate and success of starter is linked to crop rotation and environment.
"The highest yield responses to starter are in corn-on-corn fields and zones with low phosphorus availability. Adding nitrogen to your blend will help if nitrogen, not phosphorus, is your limiting factor," Ferrie says.
Thank You to Our Test Plot Partners
Each Farm Journal Test Plot is a cooperative effort. Our thanks go to: Yetter Manufacturing, Pat Whalen, Susan Wherley and Scott Cale; Kinze Manufacturing, Susanne Veatch and Mike Feldman; AGCO, Mike Alvin and Reid Hamre; Farm Depot and Mark Laethem; Precision Planting and Gregg Sauder; Great Plains Manufacturing, Tom Evans, Doug Jennings and John Sites; Versatile and Adam Reid; McCormick USA, Doug Rehor and Kurt Schneick; Unverferth Manufacturing and Jerry Ecklund; Orthman Manufacturing, Adam Souder and John Bell; Case IH and Tom Dean; Archhold Equipment and Bill Roth; Jensen Electronics and Stephen Jensen; Trimble, Sid Siefkin and Brian Stark; OmniStar and John Pointon; The Andersons, Jan Finch and Jeff Balsley; LeRoy Fertilizer and Bob Spratt; Van Horn Fertilizer and Terry Daugherty; Marco N.P.K. Inc.; Mike and Steve McLaughlin; Cole Dooley; Don Schlesinger; Bob Kuntz; Terry Finegan; Bob and Mary Kochendorfer; Crop-Tech Consulting, Brad Beutke, Isaac Ferrie, Jason Kienast and Justin Zeeb; B&M Crop Consulting, Vicki Williams and Gary Cooper.
- Mid-February 2012