The Effect of Nitrogen Application Strategy on Corn Yield

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The Effect of Nitrogen Application Strategy on Corn Yield - 2022

TRIAL OBJECTIVE

  • New corn products are introduced every year with an aim to improve the corn portfolio and farmer choice, resulting in a short time for farmers to become familiar with what nitrogen (N) strategy the corn product is most responsive to.
  • Corn product characteristics such as late season plant health and ear flex require different management recommendations, and corn products can respond to different N application strategies depending on their characteristics.
  • The objective of this study was to evaluate the effects of different N application strategies on the yield potential of corn products with different late season plant health and ear flex characteristics. 

RESEARCH SITE DETAILS

LocationGothenburg, NE 
Soil Type Hord silt loam 
Previous
Crop
Soybeans
Tillage
Type
Strip-tillage
Planting Date04/28/22
Harvest Date10/09/22
Potential Yield
 (bu/acre)
250
Seeding Rate
(seeds/acre)
36K

 

  • With a yield goal of 250 bu/acre, a total of 207 lbs of N/acre was applied either up-front or split applied throughout the growing season.
  • The study design was a split plot with fertilizer as the whole plot and corn characteristics as the subplot with four replications.
    • Fertility
      • The study was strip-tilled on 4/14/2022 with a strip-till mix containing 29 lbs of N/acre, 60 lbs of Phosphorus (P)/acre, 25 lbs of Sulfur (S)/acre, and 0.25 lbs Zinc (Zn) /acre.
      • Up-front N: 178 lbs of N/acre were applied with 360 Y-DROP® applicators on 6/17/2022.
      • Split N: 58 lbs of N/acre were applied with 360 Y-DROP® applicators on 6/17/2022.
        • The remaining 120 lbs of N/acre were applied through fertigation at 30 lbs/acre increments on 7/05, 7/20, 8/02, and 8/22.
    • Characteristics and Relative Maturity (RM) of Corn Products
      • Late season plant health defined by the stay-green rating of the corn product.
        • High (+) – 105RM, 111RM (2), 112RM, 113RM, 114RM, and 115RM
        • Low (-) – 101RM, 109RM (2), 110RM, 111RM (2), and 113RM
      • Ear flex defined by advice from agronomists that indicate the ability to modify ear size in response to the environment.
        • High (+)– 104RM, 107RM, 110RM, and 113RM (3)
        • Low (-)– 106RM, 108RM, 109RM, 111RM, 112RM, and 114RM
  • Weeds were controlled uniformly across the study. No additional insecticides or fungicides were included.
  • Study was irrigated through a sub-surface drip irrigation system to meet the evapotranspiration demands of the crop and received 9.74 inches of rain through the growing season.
  • Stay-green ratings were conducted in September to assess the late season vigor of corn plants on a scale of 1 to 9, with 1 being the greenest and 9 being the least green overall.
  • Plots were harvested with a plot combine and total plot weight, percent moisture content, and test weight were collected.  

 

UNDERSTANDING THE RESULTS

  • In this study, corn treated with split-applied N throughout the growing season outyielded the up-front N corn by over 18 bu/acre (Figure 1).
    • Average corn yield for the split-applied N was 222.38 bu/acre.
    • Average corn yield for the up-front N was 203.82 bu/acre.
image Figure 1. Average corn yields as impacted by N strategy and corn characteristic at the Bayer Water Utilization Learning Center, Gothenburg, NE (2022).
  • Within the split application N treatment, the corn characteristics of strong late season plant health (late season +) yielded the highest and were significantly greater than the high ear flex (ear flex +) corn products.
  • Similarly, within the up-front N treatment, the average corn yields from late season + corn products were the highest compared to the other corn characteristics, although not significantly higher.
  • Overall, all corn characteristics within split-applied N, aside from ear flex +, had significantly greater average yields compared to the same corn characteristics within the up-front N treatment.
  • A comparison of stay-green ratings within corn characteristics revealed that the late season + plants had a significantly lower average stay-green on a scale of 1 to 9 with 1 being the best (Figure 2).
  • The yield advantage of the split application could be exaggerated by the abnormally dry growing season and the irrigation being from sub surface drip tape. There is the possibility that the up-front application did not have enough moisture for some of the N to move down into the root zone. 
image Figure 2. Stay-green potential as impacted by corn characteristic at the Bayer Water Utilization Learning Center, Gothenburg, NE (2022).
image Figure 3. Comparison of late season stay-green appearance of corn plants by N treatment and corn characteristic. The pictures were taken on 9/22/2022 at the Bayer Water Utilization Learning Center, Gothenburg, NE (2022).

KEY LEARNINGS

  • Split-applying N resulted in greater average corn yields compared to an up-front N strategy, regardless of corn product and associated corn characteristics.
    •  The goal of N management is to have the greatest amount of N available to the crop when nutrient demands are high and split-applying N throughout the growing season as the crop requires is a good management practice.
  • Corn product characteristics affected average corn yields significantly, with the late season + products staying green later into the growing season resulting in higher average yields.
    • Ear flex + corn products had lower average corn yields compared to the other corn characteristics, possibly due to drier than average conditions and a high seeding rate.
  • Nitrogen management strategy and corn product characteristics can have significant effects on yield potential, with split-applied N and late season + corn products performing well under these conditions.
  • In 2020 and 2021, corn products with higher late season plant health or stay-green ratings responded with increased yield to the fertigation strategy while corn products with late poor season plant health did not. The results in 2022 where all product classes responded to fertigation appears to be a result of the abnormally low in-season rainfall.
  • Farmers should work with their local seeds sales team member to help identify the best adapted corn product for their production systems.

 

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Yield Response to Corn Characteristics and Nitrogen Strategy - 2020

TRIAL OBJECTIVE

  • Many new corn products are developed each year as research and development pipelines aim to improve the corn portfolio and farmer choice. Farmers have a short time to become familiar with the nitrogen (N) efficiency of new corn products. 

  • Flex-ear corn products can adjust yield components and set more rows around on the cob, more kernels per row, or increase kernel depth if conditions are favorable. Increasing seeding rates to increase yield are recommended for fixed-ear corn products as the yield components do not change much. 

  • Agronomists make recommendations for corn products with high or low late-season plant health and ear flexibility. These corn characteristics may affect N uptake and allocation and impact corn yield potential. Additional information about N application can help farmers improve their N management system for individual corn products.

  • The objective of this study was to evaluate corn characteristics: (1) late season plant health and (2) corn ear flex and their influence on corn yield potential with different N application strategies.   

 

RESEARCH SITE DETAILS

LocationGothenburg, NE 
Soil Type Hord silt loam 
Previous
Crop
Soybeans
Tillage
Type
Strip-tillage 
Planting Date04/28/20
Harvest Date10/23/2020
Potential Yield
 (bu/acre)
270
Seeding Rate
(seeds/acre)
36K

 

  • A soil test report on April 14, 2020 indicated 187 lb N/acre was recommended (33 lb N/acre in the top 2 ft of soil plus 40 lb N/acre legume credit) for a yield goal of 270 bu/acre.
  • The study design was a split-plot with fertilizer as the whole plot and corn characteristics as the subplot with four replications.
    • Fertilizer Treatments:
      • Up-front N – Strip-tilled 27.5 lb N/acre on 4/8/2020 and applied 160 lb N/acre with a streamer bar (nozzles attached to a regular 30-ft sprayer) on 4/29/2020.
      • Split N - Strip-tilled 27.5 lb N/acre on 4/8/2020 and applied 40 lb N/acre with the streamer bar on 4/29/2020, followed by 120 lb N/acre applied by fertigation. The fertigation was split into 8 to 15 lb N/acre increments with applications on 7/11, 7/17, 7/21, 7/26, 7/30, 8/2, 8/6, and 8/10.
      • The study area also received 70 lb P/acre and 15 lb S/acre.
    • Corn Characteristic Treatments:
      • Late-season plant health 
        • High – 105-day relative maturity (RM), 111RM, and 113RM
        • Low – 110RM, 111RM, and 113RM
      • Ear Flex
        • High – 104RM, 113RM, and 113RM
        • Low – 108RM, 109RM, and 113RM
  • Weeds were uniformly controlled and no insecticides or fungicides were applied.
  • A sub-surface drip irrigation system was used to meet the evapotranspiration demands of the crop.
  • Plots were harvested with a small plot combine and total plot weight, percent moisture, and test weight were recorded.  
  • Average corn yields were calculated and bushel difference between split N and up-front N treatments were also reported. The average corn yield was 256 bu/acre across all treatments.

 

UNDERSTANDING THE RESULTS

  • The difference in how corn that was classified as either ‘high’ or ‘low’ for late season plant health responded to a split N or the up-front N treatments is detailed in Figure 1.  
    • Corn products with “high” late-season plant health had greater yields from the split N treatment compared to the up-front N treatment. Corn products with “low” late-season plant health had no yield difference between the two N strategies.
image Figure 1. Response to nitrogen strategy and late season plant health: split N average yield minus up-front average yield.
  • Corn was classified as a ‘high’ or ‘low’ ear flex based on its response to the split N or the up-front N treatments (Figure 2).  

  • Corn rated either high or low for ear flex responded similarly to N strategy with both groups having greater yields with the split N application treatment. 

image Figure 2. Response to nitrogen strategy and ear flex: split N average yield minus up-front average yield.
  • On average, corn had higher average yields with split N application strategy compared to the up-front N application strategy.

 

KEY LEARNINGS

 

  • Corn tended to yield greater with a split N application strategy compared to N applied up-front at planting.
  • This is the first year of this study so more research is needed to confirm how corn characteristics influenced yield. In the meantime, farmers may consider the following-
    • Corn with a ‘high’ late-season plant health score may have greater yield potential from a split N strategy compared to an up-front N strategy while there was no difference in how corn responded to N strategy with a ‘low’ late- season plant health score.
    • Corn yielding high with split N application had the same N strategy response regardless of ear flex rating.
 
 
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