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OptRx™ Crop Sensors: A Tech Support Perspective

by Jun 21, 2011DirectCommand®

More farmers are beginning to take notice of OptRx crop sensors.  I know this because tech support seems to be taking more and more calls from growers who are interested in learning more about OptRx, and it seems as if everyone is asking very similar questions.

Many farmers are finding that they hadn't realized just how simple the system really is to use. Sure, when you tell someone we can calculate a nitrogen rate on the fly based on light reflectance, people tend to have the same response: HUH?  The main thing to understand is when the OptRx sensors detect healthy plants, the system will call for less N to be applied.  When the OptRx sensors see plants that need some help, the system will recommend more N.

I have compiled the list below to provide a perspective from the tech support department on the common questions we receive regarding OptRx crop sensors and to help you gain a better understanding of how they can work for your operation.

OptRx Crop Sensors

How do the sensors work?
OptRx sensors shine a light on the crop and measure the reflectance of a few specific wavelengths of light.  The light reflectance measured indicates plant biomass and chlorophyll content in the plants.  This allows the sensors to calculate vegetative index.

What is vegetative index (VI)?
Vegetative index is a number between 0 and 1 the OptRx system uses to quantify crop vigor.  A higher VI value indicates better crop vigor while a lower VI value indicates a lower crop vigor.  This gives the grower a snapshot of the overall crop quality when scanned with the OptRx sensors.

What kind of control do I have in the field?
I have spoken with several growers who have concerns over the recommended rate of N from OptRx.  The OptRx system allows the user to have control of the N recommendations. First, there is a minimum and maximum rate, which is defined by the user.  These settings prevent the system from applying too much or too little N.  The system also has a rate offset, which allows the user to add or subtract lbs of N from what OptRx recommends.  For example, you could add an extra 10 lbs of N on top of what the OptRx system is calling for.

How does a Virtual Reference Strip work?
The OptRx does not require an overdose of N on a single pass in every field to calibrate.  Instead, OptRx uses a Virtual Reference strip to determine the best crop vigor in the field.  The way to establish a Virtual Reference Strip is to run through a part of the field where you know you are likely to have better crops for at least five minutes.  During that time, OptRx will determine the best crop vigor. It will then calculate N recommendations and apply more N in areas of low crop vigor and less N in areas of high crop vigor.

While there is a small learning curve to OptRx, most growers I have spoken with have told me that after a few hours of running the system, they feel they have a firm grasp on how it works.  Once they learn not to get lost in the details and realize how to take control of their N application with the OptRx, it becomes an essential precision farming tool.

For additional information, read our previous series of blog posts about OptRx here or visit the OptRx page on our website.

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