Relationships between SPADs, Aerial Images, and Yield

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Relationships between SPADs, Aerial Images, and
Yield

• Gaylia Ostermeier1, Larry Hendrickson1, John
  Sawyer2
• 1 John Deere Ag Management Solutions
• 2 Iowa State University

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Trial Design

• 8 fields with 12 or 16-row treatment strips
  typically applied the length of field
• Treatments were
• 0, 60, 120, and 240 lb N per acre for CS rotation
• 0, 90, 180, and 270 lb N per acre for CC rotation
• SPAD readings were taken at 89 to 126 locations
  in each field between V10 and V14
• Aerial image typically taken within 3 days of
  SPAD readings

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Data Analysis

• Extracted yield, GNDVI, and Relative Vigor (RV)
  using square regions of interest at each SPAD
  location

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Data Analysis

• Related yield to SPAD, GNDVI, RV
• Definition of 100 for Relative Levels
• SPADAverage of highest N rate for sensor and
  yields
• GNDVIAverage of highest N rate for sensor and
  yields
• RV Average GNDVI value for best representative
  area and average yield for those pixels

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Target Value Definitions
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R2 0.58
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R2 0.79
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R2 0.79
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Relationship between Yield and Relative Values
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Conclusions

• Generally, images were equivalent or superior to
  SPAD readings on both an individual field basis
  or as a whole
• RV can be obtained without reference strips and
  SPAD readings