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ND | From the quick reference card. Sorry that I am just copy and pasting but the info should be sufficient.
The GreenSeeker handheld crop sensor is an active light
source optical sensor that is used to measure plant
biomass and display as NDVI (Normalized Difference
Vegetation Index). When you pull the trigger, the
measured NDVI reading appears on the LCD display
immediately.
How the sensor works
Upon pulling the trigger, the sensor turns on and emits
brief bursts of red and infrared light, and then measures
the amount of each that is reflected back. While the
trigger remains engaged, the sensor continues to sample
the scanned area by generating continuous bursts of light
pulses and updating the display.
Green plants absorb most of the red light and reflect most
of the infrared light. The relative strength of the detected
light is a direct indicator of the density of the foliage in the
sensor’s view. The denser and more vigorous the plant,
the greater the difference is between the reflected light
signals.
The sensor displays the measured value on its LCD. NDVI
can range from 0.00 to 0.99.
Using the sensor to estimate a fertilizer rate
A key use of this sensor is to estimate fertilizer application
rates. Sensor measurements combined with agronomic
information such as type of crop, may be used to estimate
a fertilizer rate. The steps that follow show one procedure
to get readings for a field that includes a reference
area. These values are then referenced on the chart and
table to determine a rate per the example. The current
algorithm is available as a separate document (Fertilizer
Estimation Chart).
An N-Rich strip is a small area within the field to which
more than enough fertilizer has been applied at or before
planting. This area will be a gauge of the crop not limited
in vigor due to insufficient fertilizer. Including a reference
area or “N-rich strip” provides an accurate method to
determine how much additional fertilizer is necessary to
maximize the crop yield in a particular field. Use the peak
value within the N-rich strip and a value typical of other
areas of the field as two inputs to the Fertilizer Estimation
Chart to determine an application rate. For more
information on the N-rich strip practice, go to
www.trimble.com/agriculture/greenseeker.aspx | |
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Anyone use Trimbles hand held green seeker?
