Corn Characteristic Response to Nitrogen

Corn Characteristic Response to Nitrogen - 2021

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 what nitrogen application strategy the corn product is most responsive to.

  • 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 applications can help farmers improve their N management system for individual corn products.

  • The objective of this study was to evaluate corn characteristics for a second year and compare results from year 1: (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

Location Gothenburg, NE     
Soil Type  Hord silt loam   

Previous
Crop
Soybean    
Tillage
Type
Strip-trip  


 
Planting Date 4/26/21    
Harvest Date 10/21/21  

Potential Yield
 (bu/acre)
290    
Seeding Rate
(seeds/acre)
36,000

 

 

 

  • A soil test report on April 1, 2021 indicated 189 lb N/acre was recommended (31 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. 
  • The trial was sprinkler irrigated.
    • Fertilizer Treatments: 
      • Up-front Nitrogen (N) – Strip-tilled 29 lb N/acre on 4/13/2021, and applied 160 lb N/acre with 360 Yield Center Y-Drops on 5/12/2021 when corn was at the V1 growth stage. 
      • Split N - Strip-tilled 29 lb N/acre on 4/13/2021 and applied 40 lb N/acre with the Y-Drops on 5/12/2021, followed by 120 lb N/acre applied by fertigation. The fertigation was split into 4 to 30 lb N/acre increments with applications on 6/29, 7/9, 7/27, and 8/6. 
    • 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 
  • The study area also received 60 lb P/acre, 25 lb S/acre, and 0.25 lb Zn/acre with the 4/13/2021 strip-till application. 
  • Weeds were uniformly controlled with herbicides and no other pesticides were applied. 
  • Test weight, moisture, and total shelled weight were collected to calculate yield. 
  • Yield was corrected to a standard of 15% moisture content. 

 

UNDERSTANDING THE RESULTS

Late Season Plant Health
 
  • The difference in how corn that was classified as either ‘high’ or ‘low’ for late season plant health responded to a split nitrogen (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.
    • These results are similar to those observed in 2020.

 

image Figure 1. Response of late season plant health to nitrogen strategy. (Bars represent the split N application average yield minus the up-front N application average yield)
Ear Flex
 
  • Corn rated either ‘high’ or ‘low’ for ear flex had a positive response to the split N application treatment with a significant difference observed for corn classified as ‘high’ ear flex. Corn rated with ‘low’ ear flex also had a positive response to the split N application but not to the same extent as corn rated with “high” ear flex (Figure 2).   

  • The differences were more pronounced than what was observed in 2020; however, the 2020 results with ‘high’ ear flex corn had a trend for higher yields with a split N application.  

image Figure 2. Response of corn ear flex to nitrogen strategy. (Bars represent the split N application average yield minus the up-front N application average yield)

KEY LEARNINGS

  • Late season plant health - ‘High’ late season plant health had a consistent positive response to split N applications, whereas ‘Low’ late season plant health did not respond to split N applications in either 2020 or 2021.

  • Ear Flex - Results varied between 2020 and 2021 on the impact that nitrogen strategy had on ‘high’ or ‘low’ ear flex. However, no negative response was observed from a split N application across either ‘high’ or ‘low’ ear flex products in either year.

  • Testing to evaluate the response of corn characteristics to nitrogen strategy will continue in 2022.   

 

1011_R6_21

Corn Response to Nitrogen Rates - 2020

TRIAL OBJECTIVE

  • The optimum nitrogen (N) rate for corn can be difficult to determine. Inadequate N can cause a noticeable reduction in yield while excess, unused N reduces the return on N investment and can have negative environmental impacts.
  • The objective of this study was to evaluate the response of corn products to different N rates.

 

RESEARCH SITE DETAILS

Location Gothenburg, NE     
Soil Type  Hord silt loam   

Previous
Crop
Corn     
Tillage
Type
 
No tillage


 
Planting Date 4/3/20    
Harvest Date 11/4/20  

Potential Yield
 (bu/acre)
250    
Seeding Rate
(seeds/acre)

36K


 
  • The study was set up as a split-plot design with four replications.
  • Four different relative maturity (RM) corn products (109RM, 111RM, 112RM, and 114RM) were evaluated under six different N rates (0, 60, 120, 180, 240, and 300 lb N/acre). Nitrogen was applied with 360 Y-DROP® fertilizer tube attachments at the V6 growth stage on 6/18/20.
  • Weeds were uniformly controlled, and no insecticides or fungicides were applied.
  • Grain weight and grain moisture were collected to calculate yield.
image Figure 1. The yellow coloration of the corn leaves on the left (0 lb N/acre) indicate the beginning of a N deficiency compared to the dark green of the leaves to the right (60 lb N/acre).

UNDERSTANDING THE RESULTS

image
image Figure 2. Average yield response to N application rates.
image Figure 3. Pounds of N to produce one bushel of grain based on total available N per acre (including residual soil N).
image

 

  • There was no N rate by corn product interaction, so data were averaged across corn products.
  • The previous crop was corn which depleted the soil profile of N and other nutrients. The residual N in the top two feet of soil is shown in Table 1.
  • As N rate increased, yield increased until it reached a maximum at 240 lb N/acre (Figure 2).
  • The amount of N to produce on bushel of grain increased as the applied N rate increased. More N was needed to produce one bushel of grain at the higher N rates compared to the lower N rates (Figure 3).
  • As N fertilizer cost increased, the return on N investment decreased. For this trial, the largest return on N investment was at the 60 lb N/acre rate and the lowest return was at the 300 lb N/acre rate (Table 2).

 

KEY LEARNINGS

  • The law of diminishing returns is illustrated in this study with more value observed from the first 60 lb N/acre applied compared to the last 60 lb N/acre. 
  • Nitrogen application rates are a key factor in maximizing yield. Determining residual N in the soil in combination with an N application rate that maximizes the return on N investment should be taken into consideration when developing a cost-effective fertility program.
 

1011_R6_20 

Corn Response to Nitrogen Rates - 2019

 

Trial Objective
        

       
Location Gothenburg, NE Planting Date 5/15/19
Soil Type Hord Silt Loam Harvest Date 10/25/19
Previous Crop Corn Potential Yield
(bu/acre)
220
Tillage Type Strip Tillage Seeding Rate
seeds/acre
34K
  • The study was set up as a split-plot design with four replications.   

  • The previous crop was corn, which depleted the soil profile of N and other nutrients. The residual N in the top two feet was 26 lb N/acre. 

  • Nitrogen rate was the whole plot factor with six rates of N: 0, 60, 120, 180, 240, and 300 lb/acre, which was applied with 360 Y-DROP® fertilizer tube attachments at the V5 corn growth stage on June 26th, 2019. No additional nutrients were applied to the plots. 

  • Corn product was the subplot with the three products evaluated ranging in maturity from 100 to 117 relative maturity. 

  • Weeds were uniformly controlled; no other pests were controlled in the study.  

  • Shelled corn weight and grain moisture were collected, and bushels per acre calculated. 

 

UNDERSTANDING THE RESULTS 

 

 

Figure 1. Yield response to N application rates. The positive yield response to additional N leveled off at the 240 lb N/acre rate with 91% of the yield potential achieved with the 180 lb N/acre rate. Figure 1. Yield response to N application rates. The positive yield response to additional N leveled off at the 240 lb N/acre rate with 91% of the yield potential achieved with the 180 lb N/acre rate.
Figure 2. Pounds of N to make one bushel of grain based on total available N per acre (including soil residual N). Figure 2. Pounds of N to make one bushel of grain based on total available N per acre (including soil residual N).
  • There was no N rate by corn product interaction, so data were averaged across corn products. 

  • The amount of N to produce one bushel of grain increased as the applied N rate increased. Compared to the first increments of applied N, more N was needed to make one bushel of grain at the greater rates of applied N (Figure 2).  

  • Application of 180 lb N/acre calculated 1.08 lb of N to make one bushel. This result coincides with the application recommendation of 1.0 to 1.2 lb N/acre calculated from fertility formulas based on the yield goal of a field.1,2   

Figure 3. Total available N per bushel of yield gained over the previous treatment. Figure 3. Total available N per bushel of yield gained over the previous treatment.
  • Approximately 14 lb of N was needed to produce one bushel of grain with the greatest rate of applied N (300 lb/acre). In comparison, it took 1.6 lb of N to produce one bushel of grain with the lowest rate of applied N (60 lb/acre) (Figure 3). 

     

KEY LEARNINGS

 

  • The law of diminishing returns is illustrated in this research with more value observed from the first 60 lb N/acre applied than the last 60 lb N/acre increment.  

  • Nitrogen application rates are a key factor in driving yield, but residual N should be considered to tailor the N rate for a specific field.  

  • While maximum yield potential is the goal of many operations, the value of the input in increasing crop yield needs to be carefully considered as farmers put together their fertility plans. 

 

Sources: 

1 Nielsen, R.L. 2001. Optimizing fertilizer decisions. Corny News Network. Purdue University. https://www.agry.purdue.edu/ext/corn/news/articles.01/N_Use_Efficiency_0221.html.

2 University of Maryland Cooperative Extension. 2009. Nutrient recommendations by crop. Maryland Nutrient Management Crop Recommendations | University of Maryland Extension (umd.edu)

Web sources verified 11/9/19.  1011_R1 

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