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Have to give credit to OCES
County Educators and Area
Agronomists’ who ran with the technology

2003
2003
2005
2003

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1991: Developed optical sensors and sprayer control systems to detect bindweed in fallow fields and to spot spray the weed
1993: Sensor used to measure total N uptake in wheat and to variably apply N fertilizer.
1994: Predicted forage biomass and total forage N uptake using NDVI (Feekes 5).
1994: First application of N fertilizer based on sensor readings. N rate was reduced with no decrease in grain yield.
1996: Worlds first optical sensing variable N rate applicator developed at OSU
1997: OSU optical sensor simultaneously measures incident and reflected light at two wavelengths, (670 ±6 nm and
780 ±6 nm) and incident light is cosine corrected enabling the use of calibrated reflectance.
1997: Variable rate technology used to sense and treat every 4 square
1998: Yields increased by treating spatial variability and OSU’s In-Season-Estimated-Yield (INSEY)
1998: INSEY refined to account for temporal variability
1999: Found that adjacent 4 square foot areas will not always have the same yield potential
1999: Entered into discussions with John Mayfield concerning the potential commercialization of a sensor-based N
2000: N fertilizer rate needed to maximize yields varied widely over years and was unpredictable; developed RI
2001: NDVI readings used for plant selection of triticales in Mexico.
2001: NFOA algorithm field tested in 2001, demonstrating that grain yields could be increased at lower N rates when N fertilizers were applied to each 4 square feet (using INSEY and RI)
2002: Ideal growth stage in corn identified for in-season N applications in corn via daily NDVI sampling in Mexico as V8.
2003: CV from NDVI readings collected in corn and wheat were first used within NFOA’s developed at OSU.
2003: When site CV’s were greater than 18, recovery of maximum yield from mid-season fertilizer N applications was not possible in wheat
2004: Calibration stamp technology jointly developed and extended within the farming community
2004: OSU-NFOA’s (wheat and corn) used in Argentina, and extended in China and India.
2005: USAID Grant allowed GreenSeeker Sensors to be delivered in China, India, Turkey, Mexico, Argentina,
Pakistan, Uzbekistan, and Australia.
2006: Delivery of 586 RAMPS and 1500 N Rich Strips (using RCS and SBNRC approaches respectively) in farmer fields across Oklahoma resulted in an estimated service area exceeding 200,000 acres and increased farmer revenue exceeding $2,000,000.
2010: Estimated that the N-Rich Strip was utilized on 400,000 acres in Oklahoma. Average increase in profit of
$10/ac

1993
Dr. Marvin Stone adjusts the fiber optics in a portable spectrometer used in early bermudagrass N rate studies with the Noble Foundation, 1994.
Sensor readings at ongoing bermudagrass, N rate * N timing experiments with the Noble Foundation in Ardmore, OK. Initial results were promising enough to continue this work in wheat.

Samples were collected from every 1 square foot.
These experiments helped to show that each 4ft 2 in agricultural fields need to be treated as separate farms.
1995
New ‘reflectance’ sensor developed.
Extensive field experiments looking at changes in sensor readings with changing, growth stage, variety, row spacing, and N rates were conducted.

1997
In 1997, our precision sensing team put together two web sites to communicate
TEAM-VRT results. Since that time, over
20,000 visitors have been to our sites.
(www.dasnr.okstate.edu/precision_ag) www.dasnr.okstate.edu/nitrogen_use
The first attempt to combine sensor readings over sites into a single equation for yield prediction A modification of this index would later become known as INSEY (inseason estimated yield), but was first called F45D.

1998
6
Cooperative research program with CIMMYT.
Kyle Freeman and Paul Hodgen have each spent 4 months in Ciudad Obregon, MX, working with CIMMYT on the applications of sensors for plant breeding and nutrient management.
5
4
3
2
1
Cooperative
Research
0
Program with
Virginia Tech
N*P Perkins, 1998
S*N Perkins, 1998
S*N Tipton, 1998
N*P Perkins, 1999
Experiment 222, 1999
Experiment 301, 1999
Efaw AA, 1999
Experiment 801, 1999
Experiment 502, 1999
N*P Perkins, 2000
Experiment 222, 2000
Experiment 301, 2000
Efaw AA, 2000
Experiment 801, 2000
Experiment 502, 2000
Hennessey, AA, 2000
VIRGINIA (7 Loc's)
0.001
0.002
0.003
0.004
0.005
0.006
INSEY (NDVI Feekes 4-6/days from planting to Feekes 4-6)
0.007
0.008

90
80
70
60
50
40
30
20
10
0
Fertilized N required to maximize yield (Lahoma, OK).
y = 0.65x + 27 (CV = 62)
Discovered that the N fertilizer rate needed to maximize yields varied widely over years and was unpredictable in several long-term experiments. This led to his development of the RESPONSE INDEX.
3
2.5
2
1.5
1
Year y = 1.06x + 0.18
R
2
= 0.56
0.5
0
0
RI Harvest
0.5
1 1.5
RI NDVI
2000
2
Predicted potential response to applied N using sensor measurements collected inseason. Approach allowed us to predict the magnitude of response to topdress fertilizer, and in time to adjust topdress N based on a projected
‘responsiveness.’
2.5
3

2001
N Fertilizer Optimization Algorithm (NFOA):
1. Predict potential grain yield or YP
0
(grain yield achievable with no additional N fertilization) from the grain yield-INSEY equation, where;
9
8
INSEY = NDVI (Feekes 4 to 6)/days from planting to sensing (days with
GDD>0)
7
6
5
4
3
2
1
0
0.3
y = 0.0438e
6.2862x
R
2
= 0.75
Feekes 10
0.5
0.7
0.9
YP
0
= 0.74076 + 0.10210 e 577.66(INSEY)
2. Predict the magnitude of response to N fertilization (In-Season-
Response-Index, or RI
NDVI
). RI
NDVI
, computed as; NDVI from Feekes 4 to
Feekes 6 in non-N-limiting fertilized plots divided by NDVI Feekes 4 to
Feekes 6 in the farmer check plots (common fertilization practice employed by the farmer). The non-N limiting (preplant fertilized) strip will be established in the center of each farmer field.
Red NDVI
9
8
7
6
3. Determine the predicted yield that can be attained with added N
(YP
N
) fertilization based both on the in-season response index (RI and the potential yield achievable with no added N fertilization, computed as follows:
NDVI
)
5
4
3
2
1
YP
N
= (YP
0
)/ (1/R
INDVI
) = YP0 * RI
NDVI
4. Predict %N in the grain (PNG) based on YP
N level)
(includes adjusted yield
Feekes 10
0 PNG = -0.1918YP
N
+ 2.7836
0 2 4
Visual Score
6 8
5. Calculate grain N uptake (predicted %N in the grain multiplied times
YP
N
)
Work with wheat and triticale plant breeders at CIMMYT, demonstrated that
5.468NDVI
N
/1000)
NDVI readings could be used for plant selection
7. Determine in-season topdress fertilizer N requirement (FNR)=
Engineering, plant, and, soil scientists at OSU release applicator capable of treating every 4 square feet at
20 mph

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From 2007 to 2011 Regular trainings for
OSU OCES and OK NRCS
NRCS EQIP supported the program.
A few key producers spoke often at meetings.

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About 8 hours per year to put out strips
About 8 hours per year to read strips.
80 hours of work over 5 year period
Saved in fertilizer and application costs over 5 years
$384,000
$4,800 per hour
 In 2013 Kinder reported total benefit of
$1.1Million

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Simplistic
Low Cost
Light weight
User Friendly

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Truly the most successful extension project.
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WHY
VISIBILITY
›
›
Hundreds of locations
And results are visual.

View from Blarney Castle. Fairview Oklahoma

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Crop Consultants and Custom
Applicators.

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Can there be more to Reference strips.
Ramps have been tried.

P0902XR
Hybrid
P1395XR
Hybrid
Cody Daft, Pioneer Agronomy Services

P0902XR Treatment
Comparison
100
80
60
40
20
0
P0902XR
Reference Hybrid
P1395XR
LSD(0.1)=28.0
*Difference of 34.5 lbs/a N applied
P1395XR Treatment
Comparison
100
80
60
40
20
0
LSD(0.1)=28.0
P1395XR
Reference Hybrid
P0902XR
*Difference of 44.5 lbs/a N applied
Cody Daft, Pioneer Agronomy Services

Income Comparison LSD(0.1)=NS
1160
1140
1120
1100
1080
1060
1040
1020
1000
Conventional
Sensor Based
P0902XR P1395XR
Nitrogen Management Program
• Across locations, use of crop sensors for corn N management on P0902XR (Trt 2) resulted in a $34/acre benefit compared to traditional N management (Trt 1), while there was a $17/acre benefit for P1395XR (Trt 5 vs. 6).
Cody Daft, Pioneer Agronomy Services

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Response Index values updated each time the applicator passes over the strip.

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N-Rich Strip provides indication of the
N-Cycle
For summer crops the NRS may be slow developing, especially in high OM soils.
Is there a model that could provide net winter and spring mineralization and immobilization values?

Brian Arnall
373 Ag Hall
405-744-1722 b.arnall@okstate.edu
Presentation available @ www.npk.okstate.edu
Twitter: @OSU_NPK
Blog: OSUNPK.com www.Facebook.com/OSUNPK
You Tube Channel: OSUNPK www.AglandLease.info