Ready Your Crop for a Strong Finish

March 19, 2016 02:20 AM
Planter planting

Test Plots show yield impacts to making your back-end nitrogen count

With tight margins in play, Farm Journal Field Agronomists Ken Ferrie and Missy Bauer encourage farmers to not discount the role nitrogen (N) plays in a successful crop. N is by far the most studied nutrient in the Farm Journal Test Plots 25-year program. All studies link big yields to an efficient, well-rounded N program.


“If farmers plan to cut costs, N is not a place to start,” Ferrie says. “Instead, start with the 4R approach: right product, right rate, right time, right place. Alter your program to match this method in order to use each pound of N as efficiently as possible.”

With several tools available to apply late-season N, the window of opportunity has greatly widened to help take care of mid- and late-season N deficiencies. For the past few growing seasons, the Farm Journal Test Plots have taken a closer look at the available tools and their potential yield impacts. Ferrie and Bauer find the impact to yields depends on the exact timing and placement of late-season N.

What Ken Ferrie and Missy Bauer Think You Need to Know

Although available tools allow you to hold off on applying N late-season, you need to make sure the crop is taken care of on the front end.

Consider placement of late-season N and the role timing plays in overall yield. 

Take time to learn your soils’ N-supplying power to make better informed N decisions. 

“Late-season N is crucial to provide the crop a strong finish,” Ferrie says. “From early milk to black layer, the corn crop requires 2 lb. of N per day.”

In 2015, the Illinois plot locations received 16" of rain in June, allowing the test plots crew to monitor the midseason effects of N loss. This boots-on-the-ground experience allowed the crew to make timely decisions and adjust late-season N applications. 

In a vertical-till, corn-on-corn field the test plots crew evaluated a 90-lb. strip-till application and 130-lb. side- dress application compared with a 90-lb. strip-till application and 130-lb. late-season application. From planting until midseason, the corn progressed similarly. Before the late-season application, the 90-lb. strip-till application was showing signs of deficiency. With excessive rain in June and early July, the crew could not apply N until July 6. This late-season application would ideally have happened 2.5 weeks earlier, Ferrie notes.
The corn did visually respond and turn green by Aug. 1 but the damage was already done (see photos below.)

“At this point, the late-season application could not make up for yield that was lost midseason,” Ferrie says. “It is essential to pay close attention midseason to your N levels because if not taken care of in time, the yield cannot be recovered.” 

This scenario also showed the importance of taking care of N on the front end of the crop to ensure you weatherproof your N program. 

Illinois Plot Locations 

Led by Ferrie, the test plots crew evaluated the placement and timing aspects of sidedressing in Illinois fields. 

The field had a base N program of 31 lb. applied in the fall and 110 lb.  applied broadcast. To apply N, the crew used a 360 Y-drop attachment mounted on an AirScout Hagie Edition and a standard sidedress toolbar with knives. The 360 Y-drop fertilizer attachment applies N 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. This placement provides N availability to the crown roots. The standard sidedress toolbar knives N into the middle of the row, approximately 15" from the corn plant. 

The test plots crew used the 360 Y-drop attachment and sidedress toolbar individually at different timings and then combined them to track the efficiency when used as a pair. The entire field was planted using three placements of variable-rate N ranging from 60 lb. to 120 lb., all replicated up to four times. The treatments included: a full-rate sidedress application on June 5; a full-rate late-season N application using 360 Y-drop on July 6; a half-rate sidedress application on June 5 followed by a half-rate late-season N applied using 360 Y-drop on July 6. 

The variable-rate N was altered to best meet crop needs based on certain zones’ Illinois Soil Nitrogen Test (ISNT) values. The test plots crew pulls 2' samples approximately every five years to get a better reading on the soil’s N-supplying power. This allows them to make a well-rounded N management program and proper adjustments in-season.  

“From a 2' sample, we typically suggest if your ISNT value is 350 and below, your soil is N thirsty,” Ferrie says. “If it is 350 and above, your soils are N friendly.”

On July 7 the test plots crew applied 130-lb. of late-season N to the 90-lb. strip-till treatment, which showed visual signs of response on Aug. 1, but it was too late to make up yield compared with the 90-lb. strip-till and 130-lb. sidedress applications.

In zones with a low ISNT value, the 60-lb. sidedress application on June 5 followed by a 60-lb. late-season application on July 6 resulted in a 12-bu. gain compared with the 120-lb. standard sidedress application on June 5. With the broadcast application taking care of the front end, this late-season application proved to be the most ideal by splitting the application to take care of the middle and back end of the crop. 

To apply late-season N, the Illinois plots location used 360 Y-drop attachments mounted on a Hagie AirScout Edition sprayer to apply fertilizer. 

“We’ve found in zones with low ISNT values (N thirsty) the corn responded best to the split timings and placements,” Ferrie says. “This application allows the crown roots to access N at different timings, providing a longer window of uptake.” 

Not only did the split-application result in more bushels, but it also had the most N cost savings, according to Ferrie. Even with the additional pass across the field, the half sidedress, half late-season applications resulted in $866 less N costs. This is a $33 difference compared with the standard sidedress application.

In southern Michigan, all replications applied late-season N using a 360 Y-drop fertilizer attachment, applying N directly above the root zone. 

In the high ISNT zones, the 30-lb. sidedress application on June 5 followed by a 30-lb. late-season application on July 6 resulted in a 2 bu. gain compared with the 60-lb. standard sidedress application on June 5. Therefore, the two sidedressing methods yielded equally. However, due to the extra pass in the split-application, the standard sidedress application cost $846 less compared with the $832 for the split-application. 

At a second plots location near Melvin, Ill., the crew conducted a study to evaluate the placement aspect of sidedressing. A portion of the toolbar included the 360 Y-drop attachment and another portion included a coulter toolbar with knives. From an application standpoint, both were equal. At the time of sidedressing, the corn was knee-high and green with no apparent water damage. 

In one management zone, both placements yielded similar. Since N was taken care of on the front end, with no visual deficiencies at sidedressing, the two placements will likely always perform similar. In another management zone in the same field, the 360 Y-drop application yielded higher, ranging from 1 bu. to 6 bu. gains. The yield response shows the corn was starting to need N shortly after the sidedress application. In Michigan, Bauer saw similar to slightly lower yields with the 360 Y-drop compared with the coulter knife at the V4 to V5 growth stage. 

Ferrie reminds farmers to keep in mind a few tips when considering the two types of applications. For example, using a coulter with knives in corn that is not N deficient: 

  • provides the plant with more N to use later, resulting in higher yields. 
  • risks pruning roots in tall corn. 
  • risks potential weed escapes in the knife tracks.
  • risks hitting rocks and causing damage to the machine.  
  • risks erosion in knife tracks on sloped fields.

Using an attachment such as 360 Y-drop in N deficient corn: 

  • offers a faster, quicker response to N resulting in higher yields.   
  • is helpful in wet years if unable to run in a timely manner.
  • risks potential leaf burn in small corn if run at later growth stages. 

“If this means waiting until V8 to apply N, you need to make sure you have enough clearance and early season N to get you to this stage without any problems,” Ferrie says.

The low ISNT zones in Illinois received 120 lb. of N at sidedress. The split-application of 60-lb. sidedress followed by a 60-lb. late-season application gained 12 bu. compared with the normal sidedress placement.

Michigan Plot Locations 

Bauer joined the efforts to study the effects of late-season N timing and placement in fields in southern Michigan. She reminds farmers in order to receive yield advantages to applying late-season N, you have to first be sure the corn crop is taken care of on the front end. 

Bauer conducted the studies in three separate plot locations with base N programs of 81 lb., 96 lb. and 30 lb., respectively. The test plots crew used the following two N placements across the plots: the 360 Y-drop attachment for late-season N and a standard sidedress toolbar with a coulter-mounted knife for the sidedress. All of the late-season N used Agrotain Ultra to help reduce volatilization of the surface applied N. See yield comparisons in the chart below. 

In southern Michigan, the plots showed similar trends across all three plot locations. In two of the three plot locations, the late-season applications yielded similar to the standard sidedress applications.

In two of the three plot locations, the late-season applications yielded similar to the variable-rate sidedress applications. In the second plot, yields decreased by 26 bu. per acre. Though the field received 96 lb. of N as its base program, the corn turned yellow prior to the V11 late-season application and was not able to recover. This midseason N deficiency hurt ear size.

Bauer found similar trends at all plot locations, where the crew applied 20 lb. less N late-season compared with the late-season application alone. The N was applied on the same day using the same placement. The yield results show a consistent decline in yield. See the differences in ear size below. 

At a southern Michigan plot location, using 20 lb. less N late-season resulted in up to a 5 bu. per acre loss compared with the full rate. The late-season N was applied the same day using the same attachment. 

“We were hoping to gain some efficiency with the late-season N timing [June 24 to July 1] since the N was not susceptible to the rains in June,” Bauer says. “But yields were not able to hold on when reducing the rate of N by 20 lb. per acre. Yields decreased 6 bu. to 14 bu. per acre.”

The split application of sidedress and late-season N was also consistent with the variable-rate sidedress at two of the three locations. 

“The split-timing of in-season N, half at sidedress and half late-season, did not improve yields compared with standard sidedresing,” Bauer says.  

To ensure high levels of accuracy, all Farm Journal Test Plots weigh each pass with grain carts using scales and are harvested with calibrated yield monitors. 

Note the variable-rate sidedress averaged the same total N as standard sidedress. This solely moved the N dollars around in the field based on management zones. At the third plot location, the variable-rate treatment had an 8 bu. gain compared with the standard sidedress, but yields were similar at the other two locations. 

“Typically variable-rate applications in southern Michigan move some of the N from the low ground to the high ground,” Bauer says. “However, with the excessive rainfall in 2015, the low ground actually needed more N fertilizer due to denitrification in two of the three locations.” 

Overall, the plots in central Illinois and southern Michigan show the synergistic effect of late-season N timing and placement. In order to achieve full yield potential, Ferrie and Bauer recommend staying in tune with your crop during the growing season. No one knows your crop better than you. Ground truth fields and pull frequent nitrate samples. Use this knowledge to stay ahead of N deficiencies.  

Thank You to Our Test Plot Partners

Case IH, Jay Barth, Bill Hoeg, and CJ Parker; New Holland, Daniel Valen, Ken Paul, Mike Kizis and Sheldon Gerspacher; Burnips Equipment and Carl VanderKolk; Versatile and Adam Reid; Central Illinois Ag and Kip Hoke; Kinze Manufacturing, Susanne Veatch and Phil Jennings; Unverferth Manufacturing and Jerry Ecklund; Wells Equipment; Apache Sprayers; Trimble, Frank Fidanza and John Pointon; AirScout and Brian Sutton; Ag Leader and Luke James; Yetter Manufacturing, Pat Whalen and Scott Cale; Blu-Jet and Nick Jensen; LeRoy Fertilizer and Bob Spratt; Weldon Fertilizer, Doug Sosamon and Ty Osterbur; Koch Agronomic Services and Steve Parrish; Schertz Aerial Service Inc. and Scott Schertz; Yamaha; Don Schlesinger; Lawrence “Shorty” Olson; McLaughlin-Dooley Farms; Crop-Tech Consulting, Isaac Ferrie, Brandon Myers and Eric Douglas; LDK Farms and Leon Knirk; North Concord Farms; Simington Farms; B&M Crop Consulting, Bill Bauer, Amanda Anderson, Jared Haylett

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