Corn Sensing Research

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Corn Sensing Research

• John Shanahan

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Use of Chlorophyll Meter to Schedule N
Application

• 1991-present
• Corn/Soybean rotation
• 4 corn hybrids
• 6 N treatments
• 5 at planting rates
• 0, 50, 100, 150, 200 kg-N/ha
• 1 As needed treatment N was spoon fed as
  determined with chlorophyll meter

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Use of Chlorophyll Meter to Detect N Deficiency
in Corn
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Chlorophyll Meter and N Status
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Yield Response to N and Temporal Variability
1997
2003
1993
1994
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Average Yield Response to N
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Nitrogen Use Efficiency
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Genotype Response to Varying Water and N Levels
(1999-2002)

• Treatments
• Deficit and full irrigation
• 0 and 200 kg N ha-1
• 12 Hybrids
• 1970s era
• (B73 x Mo17)
• Early 1990s era
• (3 Pioneer hybrids)
• Late 1990s era
• (8 Pioneer hybrids)

Full Irr.
Deficit Irr.
FN
NS
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Evaluation of N Effect on Genotypes
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Premise of In-Season Strategy
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So Imagery Was Tried As Means of Remotely Sensing
N Status
Plot dimensions 50 x 30
N Rates (kg/ha) 0 56 112 168 224
Pioneer Hybrids 3162 3379 3394 3417
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Vegetation Indices and Equations

• NDVI (NIR-RED)/(NIR RED)
• GNDVI(NIR GREEN)/(NIR GREEN)

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Correlation of GNDVI With Yield
r0.21
r0.93
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Correlation Vs Growth Stage
Soil Background
R-2
V-T
V-6
Tassel Structure
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Imagery Problems Caused Us to Develop On-the Go
Sensor System
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In-Season Applicator
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Possible systems
Regionalsatelliteview

• With or without
• GPS
• sensors

-GPS
Multiple Applications
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Hardware and Labview Interface
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Red and Green Sensor Readings From N Plots Around
V-14 Growth Stage
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Field Research (2003)
V-14 Application, July 17
V-10 Application, June 30
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Field Research (2003)
Four N rates 0, 40, 80, 120 lb N/acre
May 21, 2003
V-14 Application, July 17
900 ft
40
120
80
0
V-10 Application, June 30
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Field Research (2003)
Four N rates 0, 40, 80, 120 lb N/acre
May 21, 2003
V-14 Application, July 17
V-10 Application, June 30
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Electrical Conductivity Survey
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Aerial Imagery For Two Dates
N Reference Strip
N Reference Strip
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Aerial Image on July 29, 2003
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Aerial Imagery and Yield Response
July 29 Image
Yield response (Bu/ac) to N by location for V14
application
Yield response (Bu/ac) to N by location for V10
application
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Association of N Response With Soil and Crop
Variables
Late Application
Early Application
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Field Work in 2004
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Summary and Conclusion

• Greengtred for detecting N stress during window we
  propose to apply N
• Corn is responsive to N application even as late
  as V-14 growth stage
• Both crop reflectance and soil-derived data may
  be useful in predicting yield response to N

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Thank You

• ?