In-Field Nitrogen Management Tools

In-Field Nitrogen Management Tools

Consider timing and placement efficiencies when applying late-season nitrogen

No other nutrient has received more attention than nitrogen in the Farm Journal Test Plots program. For more than two decades, Farm Journal Field Agronomist Ken Ferrie has studied nitrogen timing and placement. In 2014, with tighter margins in play, Ferrie took a closer look at sidedress timing and placement. The field trials dialed in to nitrogen’s role in late-season corn and adding inhibitors to protect the nitrogen applications.

Farm Site #1 
This second-year nitrogen timing and placement study near Heyworth, Ill., evaluated the placement aspect of 
sidedressing. The tools included the 360 Y-drop attachment, a traditional drop nozzle design using VeriFlow nozzles and a standard sidedress toolbar with knives. The 360 Y-drop fertilizer attachment applies nitrogen at the base of the plant. Water from morning dew travels down the plant and creates a moist ring around the base of the plant, known as stem water. Placing nitrogen in the stem water zone provides nitrogen availability to the crown roots. The traditional drop nozzles apply nitrogen on top of the surface down the middle of the rows, and the sidedress toolbar knives nitrogen into the middle of the row. Both placements are about 15" from the corn plant. 

Using a high clearance sprayer, farm site #1 applied nitrogen at the V6 and V9 growth stages using the 360 Y-drop. The ability to apply nitrogen after V6, keeps the corn plant happy on the back end of the crop and avoids late-season nitrogen deficiencies. 

At farm site #1, all three placements were applied at the same time, so the test plots crew could track yield based on placement. In its first year of study in 2013, the 360 Y-drop and the side- dress toolbar yielded similarly (see “On-Site, On Demand,” March 2014). In 2014, at farm site #1, the field trial again evaluated the placement of the three sidedress applications but at different timings to see how timing plays a role in plant health and yield on the back end of the crop. 

The early application on June 6 included four treatments: standard side- dress toolbar, 360 Y-drop, standard sidedress toolbar with Nutrisphere inhibitor and the 360 Y-drop with Nutrisphere inhibitor. The later application, on June 14 (which didn’t receive an earlier nitrogen application) included two treatments: traditional drop and 360 Y-drop. 

The June 6 nitrogen application not only evaluated the two sidedressing methods but also compared the role of an inhibitor with a standard sidedress application and 360 Y-drop. The inhibitors were added to help protect the nitrogen from leaching, volatilization and denitrification. The next day the field received 1.25" of rain, followed by 0.4" on June 10. Results from pulling nitrates after the rain called for a nitrogen application to avoid stress in the strips where nitrogen had not yet been applied. The later application on June 14 included the traditional drop nozzle and 360 Y-drop.

In the Catlin silt loam soil on farm site #1, the standard sidedress toolbar yielded 225 bu., and the 360 Y-drop yielded just 1 bu. less. As the results prove, the two sidedressing methods yielded equally. In the strips where nitrogen was applied nine days later, the yield jumped to 231 bu., indicating a strong response to nitrogen later in the season. This proves the June 14 application was in time to prevent early season yield loss and lingered in the season to increase yield.

In the Catlin silt loam, the corn benefited more from the June 14 nitrogen application. Using traditional drop nozzles, the corn yielded 231 bu., and the later Y-drop application yielded slightly less at 230 bu. 

After the later nitrogen application, the field received adequate rain from mid-June through July. The stronger yield response to the later nitrogen application demonstrates the ability to weatherproof the field and manage nitrogen on the back end of the crop. 

At farm site #1, an early application using the standard sidedress toolbar and Nutrisphere and the later Y-drop application without an inhibitor both yielded 231 bu. per acre.

The sidedress timings were within nine days of each other, which shows the benefit of adding Nutrisphere to the sidedress application. Most inhibitors provide two weeks delayed response by slowing nitrate production. 

“I have many farmers ask if adding an inhibitor to their sidedress application will keep up with the 360 Y-drop,” Ferrie says. “Data from this farm site shows this is possible.”

Ferrie reminds farmers to evaluate their inhibitor options and application timing if they plan to apply nitrogen at tassel or if the application window spans a longer time frame.

Farm Site #2 
In its first year of study, farm site #2 evaluated how to apply nitrogen efficiently by using the 360 Y-drop attachment on every row versus every other row. Regardless of method, the plant received the same amount of nitrogen. For example, when applying nitrogen at a 90-lb. rate on every row, 45 lb. is applied on both sides of the plant. If applying on every other row, 90 lb. of nitrogen is applied on one side in one pass (see photos below). 

The field was divided into eight management zones based on soil type to compare three nitrogen rates ranging from 60 lb. to 120 lb. The test plot crew analyzed yield by management zone and by rate to help classify the differences across the field. Each rate was replicated up to four times in each management zone. For example, in the Catlin silt loam, four passes received the 90-lb. nitrogen rate every row and four passes every other row. 

The plot shows similar yields by applying variable-rate nitrogen with the 360 Y-drop every other row versus every row. If nitrogen is not a limiting factor, you can achieve the same response sidedressing every other row.

In the Catlin and Ipava silt loams on farm site #2, the zones show there was no yield difference between every row versus every other row. In this field, nitrogen was not the limiting factor, which opens the door to apply nitrogen on every other row. This allows the ability to reduce weight on the sprayer and protect the booms. 

Ferrie says the same results can be seen when using sidedress toolbars and knifing in the nitrogen late season.  
“On a 24-row toolbar, some farmers may only put 12 coulters on to eliminate weight and reduce horsepower requirements,” Ferrie says. “In our studies, we have found by applying nitrogen every other row, yield is the same as long as the rate of nitrogen is not the limiting factor. When we reduce nitrogen rates, causing a nitrogen deficiency, then every row responds better than every other row.” 

Ferrie plans to continue studying nitrogen timing and placement in the Farm Journal Test Plots in Illinois to hone rates while minding yield. The Farm Journal Test Plots program in Michigan plans to incorporate nitrogen timing and placement plots as well. 

Efficient Nitrogen Placement Matters

Using the 360 Y-drop, nitrogen was applied on every row (left photo) and every other row (right photo). The corn plant still received the same amount of nitrogen, 90 lb., in both scenarios.  

Test Plot Details

Farm Site #1

Farmers: Rod Wilson and Brad Beutke, Heyworth, Ill.

Field size: 80 acres

Field specifics: Corn following soybeans, no-till, 30" rows

Soil types: Sable silty clay loam, Catlin silty clay loam and Ipava silt loam

Planting date: April 23

Hybrid: Stone 5914RIB 

Plant population: VRT by soil type, 30,000 to 34,000

Applications: 42-0-90 fall, 80 lb. weed and feed

Sidedress timing: June 6 and June 14 

Starter blend: 7 gal. 7-22-5-1Zn

Farm Site #2

Farmers: Rod Wilson and Brad Beutke, Birkbeck, Ill.

Field size: 60 acres

Field specifics: Corn following soybeans, no-till, 30" rows

Soil types: Sable silty clay loam, Catlin silt loam and Ipava silt loam

Planting date: May 5

Hybrid: NK N75H GTA 

Plant population: VRT by soil type, 28,000 to 34,000

Application timing: 48-69-90-24S fall, 75 lb. weed and feed 

Sidedress timing: June 6

Starter blend: 5 gal. 7-22-5-1Zn


What Ken Ferrie Thinks You Need to Know

  • Whether using drop nozzles, a sidedress toolbar or 360 Y-drop, consider placement of nitrogen and the role timing plays in overall yield.
  • You have the ability to add up to 10 days to sidedressing applications with inhibitors.
  • If nitrogen is not a limiting factor, you might receive the same yield response sidedressing every other row. 

Thank You to Our Test Plot Partners
Our thanks go to: Y-Drop and Dan Muff; AirScout and Brian Sutton; Just a Mere Farm, Rod Wilson, Brad Beutke and Ethan Heidenreich; Crop-Tech Consulting, Isaac Ferrie.

Farm Journal Test Plots Pledge
You can count on our test plots to be conducted on real farms with real equipment using a high-touch set of protocols. The information will be com-pletely independent and actionable. Our hands will always be in the dirt researching the production practices and technology that are best for you. 

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