Comparison of NDVI, Response Index, and CV, in Corn, Sorghum, and
Wheat from GreenSeeker and Crop Circle Hand-Held Active Sensors
Drew Tucker
GRA Agronomy Department, Kansas State University
Overview of GreenSeeker and Crop Circle Hand Held Active Sensors
•
•
•
•
GreenSeeker sensor wavelengths are approximately 660 and 770 nm.
The field of view at 1 meter from the target is approximately 1 cm by 61
cm wide.
Crop Circle sensor wavelengths are approximately 550 and 880 nm.
The field of view at 1 meter from the target is approximately 11 cm by 54
cm wide.
Research Objectives
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To see how NDVI, Response Index, and CV correlates in Corn,
Sorghum, and Wheat between the GreenSeeker and Crop Circle
hand held active sensors throughout the growing season.
Materials and Methods
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Several Nitrogen field experiments were conducted during the 20062008 growing seasons on Corn, Sorghum, and Wheat.
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NDVI, Response Index, and CV from each treatment was collected and
averaged.
•
The sensors always sensed the same sampling area at the same
height above the target at close sensing time intervals to give as true
as a comparison as possible.
Comparison of GS NDVI and CC NDVI in Corn.
1
y = 1.2185x - 0.0438
R2 = 0.79
0.9
0.8
GS NDVI
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.1
0.2
0.3
0.4
0.5
CC NDVI
0.6
0.7
0.8
0.9
1
Comparison of GS RI and CC RI in Corn.
1.4
1.35
y = 1.2694x - 0.2656
R2 = 0.57
1.3
1.25
GS RI
1.2
1.15
1.1
1.05
1
0.95
0.9
0.9
0.95
1
1.05
1.1
1.15
CC RI
1.2
1.25
1.3
1.35
1.4
Comparison of GS CV and CC CV in Corn.
35
y = 2.0024x - 3.4394
R2 = 0.77
30
GS CV
25
20
15
10
5
0
0
5
10
15
20
CC CV
25
30
35
Field of
view
CV
readings
Avg. NDVI
Sensor
noise?
CV in 1 m of row
CV per plot
CV in 1 m of row
CV per plot
Comparison of GS NDVI and CC NDVI in Sorghum.
1
y = 1.484x - 0.2317
R2 = 0.95
0.9
0.8
0.7
GS NDVI
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.1
0.2
0.3
0.4
0.5
CC NDVI
0.6
0.7
0.8
0.9
1
Comparison of GS RI and CC RI in Sorghum.
1.4
y = 1.4243x - 0.4314
R2 = 0.85
1.35
1.3
1.25
GS RI
1.2
1.15
1.1
1.05
1
0.95
0.9
0.9
0.95
1
1.05
1.1
1.15
CC RI
1.2
1.25
1.3
1.35
1.4
Comparison of GS CV and CC CV in Sorghum.
35
30
y = 2.4398x - 6.8625
R2 = 0.87
GS CV
25
20
15
10
5
0
0
5
10
15
20
CC CV
25
30
35
Comparison of GS NDVI and CC NDVI in Wheat.
1
y = 1.6436x - 0.333
R2 = 0.97
0.9
0.8
0.7
GS NDVI
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.1
0.2
0.3
0.4
0.5
CC NDVI
0.6
0.7
0.8
0.9
1
Comparison of GS RI and CC RI in Wheat.
1.8
1.7
y = 1.3698x - 0.3678
R2 = 0.79
1.6
GS RI
1.5
1.4
1.3
1.2
1.1
1
0.9
0.9
1
1.1
1.2
1.3
1.4
CC RI
1.5
1.6
1.7
1.8
Comparison of GS CV and CC CV in Wheat.
35
30
y = 1.6062x - 0.0817
R2 = 0.48
GS CV
25
20
15
10
5
0
0
5
10
15
20
CC CV
25
30
35
Conclusions
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NDVI was very strong correlated in sorghum and wheat, while still
maintaining a relationship in corn.
Response Index was very strongly correlated in sorghum and wheat,
however, in corn this relationship was not very good.
CV correlations were very good in sorghum and corn, however, in wheat
this relationship was not very good.
The GreenSeeker sensor seems to have a wider working range and more
sensitivity in detecting nitrogen stress especially early in the growing
season.
The Crop Circle sensor and the GreenSeeker sensor both seem to saturate
at the same time.
Due to the observed differences, separate sensor recommendations need
to be developed.