Sensors Developed by Dr. Marvin Stone and Dr. John Solie

Hand-Held Sensors

Development of a field scale variable rate applicator is now ongoing and should be operational by the summer of 2002.

Our first variable rate applicator (4 independent sensors on the front integrated into 4 nozzle systems on the back) was shown to industry and producers in Oklahoma in March, 1996

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John Ringer and Shannon Taylor (now Osborne) utilize one of our first sensors for detecting biomass differences in bermudagrass.  John Ringer is now employed by John Deere and Dr. Shannon Osborne is a Research Scientist with USDA-ARS in South Dakota

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Curt Woolfolk and Jeremy Dennis operate the JD 318 Garden Tractor that is used for sensing and collecting information.  The sensor is mounted on the front, combined with an ultrasound device.

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Looking at the bottom of the sensor, you can see one wide slit where both red and near infrared readings are collected.  In addition, two fiber optic cables are mounted at the top of the sensor and which are pointed upward.  By using upward looking input, red and NIR readings can be adjusted for incoming light, and thus calibrated reflectance.  Combined a modified normalized difference vegetative index (NDVI) is determined from multi-spectral reflectance measurements under daytime lighting {NDVI=[(NIR down/NIR up)-(Red down/Red up)/(NIR down/NIR up)+(Red down/Red up)]}.

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