Tools For Managing Nitrogen - Dr. Newell Kitchen, USDA Agricultural Research Service (ARS), from the 2018 Conservation Tillage and Technology Conference, March 6 - 7, Ada, OH, USA. More presentations at https://www.youtube.com/channel/UCZBwPfKdlk4SB63zZy16kyA

1. Tests, Models, and
Sensing Tools:
Which is Best for Corn
Nitrogen Decisions?
Newell R. Kitchen
USDA-ARS
Cropping Systems and
Water Quality Research Unit
Columbia, Missouri

2. What is in a Decision?
• The average number of remotely
conscious decisions an adult
makes each day is ~35,000
• Grower surveys often list N
fertilizer management among
the more challenging
decisions of modern corn
production

3. Nitrogen Cycle in Agriculture Fields

4. How much N this year?

5. What happens if we are not close
to the right rate?
N Rate – EONR (lb N/a)
• When applications are >30 lbs N/ac over
EONR, every lb N applied = N lb lost
• 20-40% of US corn acres have N over-
application >30 lbs N/ac
• 90 m US corn ac/year
• Mean over-application of 60 lbs N/ac
• 405,000 tons of N lost/yr
Chris Bandura
University of Wisconsin

6. 585 barges of urea-N

7. PPNT Pre-Plant Soil Nitrate Test
SDNT Side-Dress Soil Nitrate Test
Crop Growth Models
Empirical-Based Models
Canopy Sensing Soil Tests
Encirca N Service
Maize-N
Climate: Nitrogen Advisor
Adapt-N
Which is the Most
Reliable Corn Nitrogen
Recommendation Tool?

8. Maximum Return to Nitrogen (MRTN)

9. 9
30
0
50
100
150
200
250
300
350
0 50 100 150 200 250 300
Yield,bu/acre
N rate, lb N/acre
35 on-farm trials Soy-Corn 2015
Optima MRTN
Courtesy of Emerson Nafziger, UI

10. PPNT Pre-Plant Soil Nitrate Test
SDNT Side-Dress Soil Nitrate Test
Crop Growth Models
Empirical-Based Models
Soil Tests
Encirca N Service
Maize-N
Climate: Nitrogen Advisor
Adapt-N
Side-by-Side
Comparison
Canopy Sensing

12. Public-Private Partnering for
Improving Performance of
Corn Nitrogen Fertilization Tools
James Camberato
Purdue University
Emerson Nafziger
University of Illinois
Carrie Laboski
University of Wisconsin
Fabián Fernández
University of Minnesota
David Franzen
North Dakota St. University
John Sawyer
Iowa State University
Richard Ferguson
University of Nebraska
Newell Kitchen
USDA-ARS
University of Missouri
Paul R. Carter

13. Project
Data
Evaluate
DuPont Pioneer
proprietary
products and
decision aids
Evaluate public-domain
decision aid tools, develop
agronomic science for
improved crop N
management, train new
scientists, and publish results
University

14. Research Locations 16 Locations/Year Total 49
Temperature
Precipitation

15. …. a wide array of weather
and soils conditions.

16. N Treatments (lbs/acre)
Measurements
Crop
Plant N (VT & R6)
Canopy reflectance (V9)
Grain yield and moisture
Soil
EC mapping (VerisTM)
Soil sampling (3x)
Soil moisture ( TRT 3+16)
Climate
Precipitation
Temperature
Solar radiation
Standardized Design
Planting Split (plt+V9)
0 40+40
40 40+80
80 40+120
120 40+160
160 40+200
200 40+240
240 80+80
280 80+160

17. What was the correct N rate?
Best-fit model for Economic Optimal N Rate (EONR)

18. Variation in Economic Optimal N Rate
2014 2015 2016

19. Economic Optimal Nitrogen Rate (EONR)

20. Tools Tested
• At Planting
– State-Specific Yield Goal
– Pre-plant Soil Nitrogen Test (PPNT)
– Maximum Return to Nitrogen (MRTN)
– Crop model (Maize-N)
• Split (40lbs/a at planting + top dress)
– State-Specific Yield Goal
– Side-dress Soil Nitrogen Test (PSNT)
– Maximum Return to Nitrogen (MRTN)
– Crop model (Maize-N)
– Canopy Reflectance - MU algorithm

21. r2 = 0.01r2 = 0.01 r2 = 0.16
r2 = 0.23

22. Yield Goal Tools

23. PPNT Tools

24. 0 lbs N/A 40 lbs N/A
PSNT Tools

25. Other Tools

26. Canopy Sensing

27. Algorithm Performance

28. Courtesy of Iowa State Extension

31. 31
Encirca™ Nitrogen Management Service.
Cronus Crop Model
Target N
Level
Current and
forecast
(Soil N to date)
Multi-year
historical (Potential
N outcomes)
Local Weather
Cronus
Crop
Model
N Recommendation
Planned Application
Date
N Source/application
method
Current Soil N per DZ
Target N RequiredERU -Soil
Yield Goal
O.M.
Soil Criteria
Productivity
Soil Water
Hybrid
Seeding
Rate
Initial N
Manure
N
applications
Inhibitor
Residue
Credit
Tillage
Tile
Irrigation
Management
Decision Zone

32. 32
Environmental Response Units
(ERU)
ERU’s Improve Correlation
to Measured Yield 300%!
• ERU’s developed using high
resolution digital elevation
models (e.g. LIDAR) Watershed
Information, SSURGO Data
• Are key input to defining field
management zones
• Process continues to be
improved as new data sources
emerge

33. 33
Cronus Crop Model – soil nitrogen dynamics
V
T
V
T
Models are a potential tool to improve nitrogen management
Good agreement between model
and measured soil NO3 But models alone are not perfect!
Representative response graphs (of graphs from 360+ sampled blocks ) – PRNT sites

34. An Objective, Science-based Assessment & Education
Program for Nutrient-Use Efficiency Tools & Products
Courtesy of Dr. James Schepers

35. 2015 Encirca Nitrogen Innovation Trials
124 Locations
Application Timing
2015 EncircaSM Nitrogen Innovation Trials

36. Managing Variability
with EncircaSM Nitrogen Service
Good
Mineralization /
High N Loss
Good
Mineralization /
Low N Loss

37. $100
$50
$0
$50
$100
$150
$200
$250
1 11 21 31 41 51 61 71 81 91 101 111
PartialProfitability($/A)
Field Trials
Adapt – N . . . Partial Profitability
2011-2014
~5 bu/A

38. Which tool should I use?
• Many of the current publicly-available N recommendation tools don’t
work well when EONR is low (< 100 lbs N/ac) or high (> 220 lbs N/ac).
• Tools that use soil and/or crop measurements on the fields of interest
generally work better (e.g., PPNT/PSNT, canopy reflectance).
• Fields that historically show variation in greenness on wet years (look
at Google Earth), deserve a tool that can address spatial soil variation.
• Tool development and validation are needed that are adaptive to
weather and soil interactions (e.g., modeling, canopy reflectance).
• Using on-farm strip trials over several years is an excellent ways to
judge your current tool (e.g., strips with ± 30 lbs N/ac + current).
• If both ± strips are within 5 bu/ac of the current tool, then you are
close to EONR and your tool is working fairly well
• If you don’t see a yield increase with +30 and don’t see a yield
decrease with -30, then you’re likely over-applying (tool failure)
• If you see a yield increase with +30, then you are under-applying
(tool failure)

39. N Application >> Corn Crop Need
From Benton/Tama Nutrient Reduction Project

40. Acknowledgements

41. Questions?
Newell R. Kitchen
573-882-1114
KitchenN@Missouri.edu
or Newell.Kitchen@ars.usda.gov

42. PPNT Pre-Plant Soil Nitrate Test
SDNT Side-Dress Soil Nitrate Test
Crop Growth Models
Empirical-Based Models
Proximal Canopy Sensing Soil Tests
Encirca N Services
Maize-N
Climate: Nitrogen Advisor
Adapt-N
Fusion