use of by-plot cv’s for refining mid-season fertilizer n rates daryl brian arnall plant and soil...
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Use of By-Plot CV’s for Use of By-Plot CV’s for Refining Mid-Season Fertilizer Refining Mid-Season Fertilizer
N RatesN Rates
Daryl Brian ArnallDaryl Brian ArnallPlant and Soil Sciences DepartmentPlant and Soil Sciences Department
Oklahoma State UniversityOklahoma State University
IntroductionIntroductionScrutiny of Nitrogen Application Scrutiny of Nitrogen Application
Rise in Nitrogen costRise in Nitrogen cost
Environmental impactEnvironmental impact
Precision Nitrogen ApplicationPrecision Nitrogen ApplicationGreat PotentialGreat Potential
Reduce Application LevelsReduce Application Levels
Use of Statistical Analysis for ImprovingUse of Statistical Analysis for Improving
Application Not Completely Examined Application Not Completely Examined
ObjectiveObjective
Determine the relationship between Determine the relationship between the CV measured using spectral radiance the CV measured using spectral radiance measurements, and plant population at measurements, and plant population at early growth stages. early growth stages.
Sensing direction in relation to the Sensing direction in relation to the crop row direction impact on NDVI.crop row direction impact on NDVI.
MethodMethod
25 plots at 3 locations:25 plots at 3 locations:
Plots measured 1.48m by 4.88mPlots measured 1.48m by 4.88m
3 nitrogen treatments implemented with 3 nitrogen treatments implemented with each plot.each plot.
0 N, 120kg/ha Fall App., 80 kg/ha Top-0 N, 120kg/ha Fall App., 80 kg/ha Top-dressdress
Method cont.Method cont.
At Feekes 1 (At Feekes 1 (EmergenceEmergence))::
Plots were established.Plots were established.
Fall nitrogen applied.Fall nitrogen applied.
Plant counts taken on 4 randomly selected Plant counts taken on 4 randomly selected rows.rows.
At Feekes 6 (At Feekes 6 (Stem ElongationStem Elongation))::
Topdress nitrogen appliedTopdress nitrogen applied
Method cont.Method cont.Sensing Sensing
Began in January.Began in January.Concluded at physiological maturity.Concluded at physiological maturity.
Sensor held 75cm to 100 cm over the crop Sensor held 75cm to 100 cm over the crop canopy.canopy.
3 seconds allowed for each reading.3 seconds allowed for each reading.
Sensing PlanSensing Plan
1 2 3 4 5 6 7 8
1
2
3
4
Row
5
1 2 3 4 5 6 7 8
1
2
3
4
Row
5
5 Readings per trt: 2 with row, 2 across row, 5 Readings per trt: 2 with row, 2 across row, and 1 at a 45 degree to the seed row.and 1 at a 45 degree to the seed row.
Method cont.Method cont.At Physiological Maturity:At Physiological Maturity:
A 1mA 1m22 area hand harvested from each area hand harvested from each plot.plot.
Thrashed with a mechanical thrasher.Thrashed with a mechanical thrasher.
Grain weighed for yield.Grain weighed for yield.Processed and analyzed for N content.Processed and analyzed for N content.
CV and PopulationCV and Population
Feekes 5
0
100
200
300
400
500
600
0 10 20 30 40 50CV, %
Pla
nts
/m2
Perkins
Efaw
LCB
LCB03
Perkins03
Henn03
EFAW03
y = -12.94x + 321Intercept; CV = 20 Population = 52
Feekes 5
0
100
200
300
400
500
600
0 10 20 30 40 50CV, %
Pla
nts
/m2
Perkins
Efaw
LCB
LCB03
Perkins03
Henn03
EFAW03
Feekes 5
0
100
200
300
400
500
600
0 10 20 30 40 50CV, %
Pla
nts
/m2
Perkins
Efaw
LCB
LCB03
Perkins03
Henn03
EFAW03
y = -12.94x + 321Intercept; CV = 20 Population = 52
CV over TimeCV over Time
0
5
10
15
20
25
30
5-Jan 19-Jan 2-Feb 16-Feb 1-Mar 15-Mar 29-Mar 12-Apr
CV
Check
120 Fall App.
80 Top-dress
Top-dress N applied
F3 F9F7F5
Top-dress N appliedTop-dress N applied
F3 F9F7F5
0
5
10
15
20
25
30
5-Jan 19-Jan 2-Feb 16-Feb 1-Mar 15-Mar 29-Mar 12-Apr
CV
Check
120 Fall App.
80 Top-dress
Top-dress N applied
F10.5F3 F7F5
Top-dress N appliedTop-dress N applied
F10.5F3 F7F5
RI HybridRI HybridRI = Response Index
RIharvest = Yield of N-rich plot / Yield of the check
RIndvi = NDVI of N-rich plot / NDVI of check plot
y = 0.52x + 0.73
R2 = 0.17
0.0
0.5
1.0
1.5
2.0
2.5
0.0 0.5 1.0 1.5 2.0 2.5RIndvi
RIh
arve
st
RIhybrid = NDVI of N-rich /
(NDVI of check plot /
SqRt of the check plot CV)
y = 1.9x + 0.70
R2 = 0.36
0.0
0.5
1.0
1.5
2.0
2.5
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7RIhybrid
RIh
arve
st
Sensor DirectionSensor Direction
0.00
0.20
0.40
0.60
0.80
0.00 0.20 0.40 0.60 0.80
With Row NDVI
Acr
oss
Row
ND
VI
PERKINS04
EFAW04
LCB04
EFAW03
LCB03
Perk03
Henn03
n = 3660y = 0.98x + 0.01R2 = 0.97
0.00
0.20
0.40
0.60
0.80
0.00 0.20 0.40 0.60 0.80
With row NDVI
45 D
egre
e N
DV
I
PERKINS
EFAW
LCBn = 2325y = 1.01x + 0.00R2 = 0.97
Directional CVDirectional CV
R2 = 0.71
R2 = 0.72
R2 = 0.78
0.0
5.0
10.0
15.0
20.0
25.0
30.0
0 20 40 60 80 100 120 140 160
GDD>0
CV
With Row
Across Row
45 Degree
ConclusionConclusionHigh CV’s from sensor NDVI readings can High CV’s from sensor NDVI readings can
be used as an indicator of poor plant be used as an indicator of poor plant stands.stands.
CV can be used to improve determination of CV can be used to improve determination of RI.RI.
Seed row direction had no effect on NDVI Seed row direction had no effect on NDVI Readings.Readings.