Nitrogen Use Efficiency, Nitrogen Fertilizers, NUE, Nitrogen and the Environment OSU Hand Held Greenseeker Sensor
OSU Pocket Sensor
More Information (OSU Hand Held, Trimble Greenseeker Sensor)
Trimble releases new handheld GreenSeekerSensor Specifics:  

Multi-spectral, Two-band, Optical reflectance sensor (Optical reflectance ratios (NDVI) at two wavelengths: 656 nm and 774 nm)

Active illumination, Remote sensing

Multi-spectral, Two-band, Optical transmittance sensor (Optical Density Difference at two wavelengths: 650 nm and 940 nm)

Active illumination, non-remote sensing

Ground based, Active, Two-band Optical sensors

YouTube Release on the new Pocket Sensor, Dr. Brian Arnall

Colorado State University - Greenseeker - GS2 - Pocket Sensor Calibration/Comparison

Greenseeker calibration

Comparison of the GreenSeeker (1 and 2) and Hand held sensors (PS) manufactured by Trimble. Co. Cali Colombia, February 2013


Trimble, Hand held sensor OSU Hand Held GreenSeeker Sensor

Bill Gates evaluates Trimble Pocket Sensor  Bill Gates, Carlos Slim Greenseeker
Bill Gates and Carlos Slim, Greenseeker Sensor, CIMMYT, Mexico


Trimble LINK for those looking to purchase;


purchase: (Enter “GreenSeeker” for product + Country/zip)

BRAZIL Proposal:  Guilherme Arruda

This commercially available sensor was the product of work from many at OSU, Mike Thralls with the Oklahoma Conservation Commission, the Soil Fertility Research and Education Advisory Board with oversight from Joe Neal Hampton, and the Oklahoma Agricultural Experiment Station.
May 23, 2013

Report from Dr. Eric Miller and Dr. Jake Bushong
Also report from Mariana del Corso
OSU Pocket Sensor Operating Manual (English) (Word file)
   Manual de Operación en  Español (OSU Pocket Sensor Manual in Spanish)
OSU Pocket Sensor Operating Manual (Spanish) 
OSU Pocket Sensor PowerPoint (Spanish)

Pocket Sensor Tips (English power point, from J. Crain) Pocket Sensor Tips (Spanish)
Pocket Sensor Suggestions (from various workshops/input from J. Crain)

Pocket Sensor Questions/Answers (Jared Crain, June 2011)

Nitrogen Rich Strips for Improved Nitrogen Fertilizer ManagementThe importance of N Rich Strips has never been more apparent as farmers drive across the country side and visualize N response.  Please read this brochure. 

On the cover is a producer in Ciudad Obregon, MX who has now used N Rich Strips and the GreenSeeker sensor for many years. 

Pocket Sensor Interests

Kansas State University
CIMMYT, Ivan Ortiz-Monasterio, Mexico
CIMMYT, Fred Kanampiu, Kenya
Colorado State University, Raj Khosla (China project)
Sasakawa Foundation,
Helena Chemical Company
Noble Foundation, Ardmore, OK
Monsanto, St Louis, MO
Mosaic, MN
Texas A&M University, Linda Cleboski (Rwanda project)
Tanika O'Connor-Dennie, AJ Foster
Ministry of Agriculture and Fisheries, Jamaica
CropQuest, Dodge City, KS
Boulder County Colorado NRCS
County OCES educators, OK
Many OK Junior Colleges
Oklahoma NRCS and Conservation Districts
Cotton Inc and Cotton Council
Producers in and around Oklahoma
Many private crop consultants
OSU Pocket NDVI Sensor developed by Dr. Marvin Stone OSU Pocket NDVI Sensor OSU NDVI Pocket sensor developed by Dr. Marvin Stone OSU NDVI Pocket sensor OSU NDVI Pocket Sensor
OSU NDVI pocket sensor Ethan Wyatt
Pictured are Dr. Marvin Stone (designer and inventor of the pocket sensor, Natasha Macnack, Jared Crain, and Millor Mondini.
 GreenSeeker NDVI, pocket Sensor, Jonathan Kelly GreenSeeker Pocket Sensor, NDVI, Jonathan Kelly, Natasha Macnack GreenSeeker Pocket Sensor, NDVI, Jonathan Kelly, Natasha Macnack GreenSeeker Pocket Sensor, NDVI, Jonathan Kelly, Natasha Macnack
GreenSeeker pocket sensor, NDVI GreenSeeker pocket sensor, NDVI

Jonathan Kelly, Natasha Macnack, Jeremiah Mullock, and Kevin Waldschmidt use the NDVI Pocket Sensor near Hennessey, OK

 OSU, LSU pocket sensor LSU, OSU pocket sensor

Pocket Sensor use, LSU, Dr. Brenda Tubana

pocket sensor
June 4, 2012
Pocket Sensor training, El Batan, CIMMYT, Mexico pocket sensor training, NDVI, CIMMYT Pocket Sensor use in Corn Jared Crain, pocket sensor testing pocket sensors Ciudad Obregon
GreenSeeker and Pocket Sensor Training, Ciudad Obregon, MX Dr. Ivan Ortiz Monasterio, pocket sensor training OSU Students collecting NDVI data CIMMYT Experiment Station, Sonora OSU Students, CIMMYT Experiment Station
Pocket sensor training conducted by Dr. Ivan Ortiz-Monasterio and Jared Crain, at CIMMYT headquarters in El Batan, Mexico, and Ciudad Obregon, Sonora, Mexico

Oklahoma State University

Pocket Sensor Guidelines

1)    The sensor comes pre-calibrated to a Greenseeker sensor. (the manual below would indirectly suggest that the sensor might not be calibrated)
2)    The sensor can be calibrated to an “NDVI “ sensor (not just a  Greenseeker)
3)    The existing “Greenseeker calibration must be turned to FALSE (G, F) before re-calibrating

One thing that needs to be enforced is charging the battery of the pocket sensor every night.
Also, before calibration, the sensors need to be fully charged.
This will ensure the sensor is operating at it's best.


·         Attach the provided USB cable attachment to the front side of the pocket sensor, then plug in the USB cable directly into a USB port on a computer.  Charge for 3-4 hours.

·         Battery life is approximately 6-10 hours, depending on operation

·         A “batt” symbol will appear in the upper left-hand corner of the LCD screen if a low-battery condition occurs.


·         Care must be taken to keep the pocket sensor level while sensing, at a height of 24” to 30” (60-75 cm) above the crop canopy.  The target is circular with a dimension shown in Figure 1.

·         To operate, place the pocket sensor at the appropriate height above the canopy, then  push and hold the red button.

·         While holding the red button, walk slowly down the treatment (or strip) that you want to sense.  You will notice the NDVI value being displayed on the screen changing once per second during operation.

·         When you are done sensing, release the red button and note the last number displayed on the screen.  This is the average of all readings that were taken while the button was depressed.

·         Write down or remember this number quickly, because it will only be displayed for a few seconds before it disappears.  Ensuing readings once the red button is pressed again start anew. 

·         The pocket sensor does not have the capability of storing data, so you must record the NDVI values that you need after each operation.

Figure 1.  Target dimension for different sensing distances


·         Store in the cardboard box provided.  Be very cautious about placing the pocket sensor face down on any surface, as this could scratch the LED lenses.

Error Messages

·         An error message may be displayed on the screen if something is wrong.  The following messages may appear, with the correct description:

o  E01 – calculated NDVI value is less than 0, which is invalid

o  E02 – calculated NDVI value is greater than 1, which is invalid

Hours of Operation

·         The pocket sensor should provide the same readings day or night, as this is an active sensor.  You will not want to use the sensor if it is raining or in extreme heat or cold.


This should already have been accomplished, but if not, re-calibration procedures follow


Calibration Procedure for Pocket Sensor:

1.      Before the Pocket Sensor can be calibrated, any existing calibration must be set to 0.  Do this by:

A.     Plug the pocket sensor into a USB port on a computer, and follow the Installation instructions to download the driver onto the pocket sensor.  The correct driver to download is the Silicon Labs CP210x USB to UART Bridge.  This can be downloaded from and select the correct computer operating system.

B.      A terminal program must be downloaded onto the computer to communicate with the pocket sensor.  Go to and download the terminal program available on that website.

C.       With the pocket sensor plugged into the computer, open the terminal program.  At the top of the page, make sure the settings are as follows:

a.      Baud rate:  19,200

b.      Data bits: 8

c.       Parity:  none

d.      Stop bits:  1

e.      Handshaking:  none

D.     Select the correct COM port by looking at the Device Manager on your computer to determine where the Silicon Labs CP210x USB to UART Bridge is located.

E.      Hit the “Connect” button at the top-left corner of the screen.

F.       In the bottom portion of the screen, press “p” to print calibration numbers and the menu options.

a.      --Caution!!!     DO NOT press “f” while on the menu page, as this will restore the memory to the default settings, and will render the sensor unusable until reset by an OSU Engineer!!!!

G.     Press “g” to set the coefficients for the calibration equation.

H.     Once “g” is entered, the terminal will display “Enter CalNum.u8Flag.(T/F)……press “f”.

I.        The formula is in the form of:  y = Ax² + Bx + C.  The values A, B, and C need to display 0 for calibration

-- “Enter CalNum.fpA….”    Enter 0 for A, then press Enter
-- “Enter CalNum.fpB….”    Enter 0 for B, then press Enter
-- “Enter CalNum.fpC….”    Enter 0 for C, then press Enter

J.        In the terminal program select “Disconnect” the sensor has now been set to its original calibration, and can be calibrate with the GreenSeeker.

2.      Calibration must be done with a Greenseeker.  Take at least 70-100 readings with both the Pocket Sensor and the Greenseeker over different types of surfaces (bare soil, different shades of vegetation, etc.).

Note:  Make sure that the areas sensed by both the Greenseeker and Pocket  sensor are exactly the same.  Pick an area about 24” (60 cm) square, that is flat and homogenous.

3.      Enter the NDVI values of both Greenseeker and Pocket sensor into Microsoft Excel.  Place the Pocket sensor values in the left column (for the independent, x-axis) and the Greenseeker values in the right column (for the dependent, y-axis). 

4.      Plot these values as a scatter plot.  Make sure that Pocket sensor values are on the x-axis and Greenseeker values are on the y-axis.

5.      On the scatter plot, right-click on the mouse over the points, and select “Add Trendline”.

6.      On the Trendline menu, select “Polynomial” on the Regression Type, and “2” on the Order.  Also check the boxes for “Display Equation on chart” and “Display R-squared value on chart”.

7.      The Excel chart will now display the calibration equation that needs to be entered into the pocket sensor for calibration.

Entering the Calibration Equation into the Pocket Sensor:

1.      Connect the Pocket Sensor to the computer and open the terminal program as outlined in previous section.

2.      Press “p” to print calibration numbers and menu options.

--Caution!!!     DO NOT press “f” while on the menu page, as this will restore the memory to the default settings, and will render the sensor unusable until reset by an OSU Engineer!!!!

3.      Press “g” to set the coefficients for the calibration equation.

4.      Once “g” is entered into the terminal, enter the values for the calibration equation.

5.      Press “t” for True when it states “Enter CalNum.u8Flag.(T/F)……

6.      The formula is in the form of:  y = Ax² + Bx + C.  The values A, B, and C will then be entered into the terminal program:
-- “Enter CalNum.fpA….”    Enter value for A, then press Enter
-- “Enter CalNum.fpB….”    Enter value for B, then press Enter
-- “Enter CalNum.fpC….”    Enter value for C, then press Enter

                       Be careful to note the sign (+ or -) for the Ax2 value.

7.      The Pocket Sensor is now calibrated and ready for use.  Press “Disconnect” in the upper-left corner of screen to disconnect the device.


Note:  While the Pocket sensor is plugged into the terminal program, it is possible to capture individual sensor readings.  To do this, plug the sensor into the computer and connect to the terminal program, and press “p” to display the sensor values.


Experiences with the PocketSensor:


           During calibration of the Pocket sensor at the CIMMYT Research Station in El Batan, Mexico, some considerations were:  Wheat is planted on raised beds, and at the time of sensing the wheat was headed out (Reproductive Stage).  The height of the wheat and the distance between beds allowed the GreenSeeker to read soil background while the Pocket sensor was only able to read the rows of wheat, the soil was to far away.  It is imperative that both the GreenSeeker footprint and Pocket sensor be over the same targeted area to get an accurate calibration.  Note:  This may not be an issue when the wheat is vegetative and the soil is still within range of the Pocket sensor.

OSU Hand Planter

Comprehensive information on Nitrogen Use Efficiency for cereal crop production