Three-year test plot hones in on sidedress solutions
The No. 1 nitrogen management advice from Farm Journal Field Agronomist Ken Ferrie is, "never let corn have a bad day."
Sidedressing is one way to keep a ready supply of nitrogen available to the corn plant, and there are multiple methods to give corn a midseason shot of nitrogen. The most common questions that farmers have about sidedress are: is there a difference in applying anhydrous ammonia or 28% nitrogen; and is there a difference between running a knife and/or a coulter?
In 2012, Ferrie sought out to answer those sidedress questions and wrap up a three-year Farm Journal Test Plot in central Illinois.
Logistics setup. The plot crew used a Great Plains Nutri-Pro toolbar to apply either anhydrous ammonia or 28% at one time. The toolbar was outfitted with a Raven controller, a Raven anhydrous cooler and a hydraulic Hypro pump for the 28%. The plumbing was set up with quick couplers so anhydrous could be run through an anhydrous knife and 28% could be run through an anhydrous knife or a Great Plains Vantage 1 coulter inject. When using the knife, the test plot crew set the depth to ensure a good seal for the anhydrous application. The 28% applied with the knife was run at the same depth. A Yetter All-Steer cart was used to carry the 28% product.
"Farmers are asking if running the knife, doing a little tillage and aerating the soil will increase yield. So, in one treatment, we applied 28% through the coulter with the knife present," Ferrie explains. We also took off the knife and ran the 28% through the coulter."
The plots were planted and sidedressed with an RTK correction signal. The crew tackled all of the similar sidedress treatments in batches with the treatments randomized across the large-scale plot.
Following his standard protocol to determine a crop’s demand for sidedress, Ferrie and his crew collected soil nitrate samples as well as factored in Illinois Soil Nitrogen Test (ISNT) scores, or the soil-supplied nitrogen power of the soils.
For example, in 2010, the nitrate tests indicated a 60-lb. nitrogen application. In 2011, the field received 14" of rain in June, and the nitrate tests indicated a 150-lb. rate for sidedressing. In 2012, it indicated a 60-lb. rate.
"We also applied above and below that suggested rate with each application treatment," Ferrie says. "But we have to meet the crop’s need with at least the rate our sampling suggested. Going above that did not add up in yield, and applying below that rate brought a stiff penalty."
However, as long as the proper rate was applied, it didn’t matter which nitrogen product was applied.
"In the three years, across soil types, we did not see a difference to applying anhydrous ammonia or 28%," Ferrie says. "But we did see advantages to how we applied the products."
Details done right. To prevent volatility when applying anhydrous ammonia, Ferrie reminds farmers that it’s paramount to ensure that you achieve a good seal.
"If the soil is not properly sealing, you will expose the nitrogen to vol-atility," he says.
A pattern emerged when applying 28% with the various attachments.
"Across three soil types, we saw that when we applied the 28% with the coulter and the knife engaged, there was a ding in yield," Ferrie explains. "We didn’t see that yield penalty when the 28% was applied through the same knife or when the coulter was run by itself—only when the two attachments were used together."
Ferrie doesn’t believe roots were pruned, but instead the knife aerated the soil enough that it dried out, and the nitrogen applied by the coulter was left in dry soil and unused by the crop.
"Running the two attachments together is unrealistic, but it shows that nitrogen has to be placed where the crop can use it," Ferrie says. "Moisture is a factor in nitrogen application if conditions are hot and dry. Understanding nitrogen placement is key to sidedress applications."
Looking at the past three years of data, Ferrie says there were valuable lessons learned.
"Applying 28% with the coulter yielded as well or slightly better in normal or wet soils, but in droughty soils yield decreased slightly. Overall, when the products were placed where the plant could get them, whether it was anhydrous or 28%, applied with a coulter or knife, it didn’t seem to make a difference," he says. "Remember, we want to sidedress happy green corn and supply the nitrogen necessary for ear fill."
Thank You to Our Test Plot Partners
Each Farm Journal Test Plot is a cooperative effort. Thanks go to: Yetter Corporation and Scott Cale; Great Plains Manufac-turing, Tom Evans and Doug Jennings; Case IH, Dan Klein, Kyle Russell and Ryan Schaefer; Central Illinois Ag and Kip Hoke; Kinze Manufacturing, Suzanne Veatch and Luc Van Herle; Unverferth Manufacturing and Jerry Ecklund; LeRoy Fertilizer and Bob Spratt; McLaughlin-Dooley Farms; Crop-Tech Con-sulting, Isaac Ferrie and Brad Beutke.
You can e-mail Margy Fischer at firstname.lastname@example.org.