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DATA
COLLECTION METHODS
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Putting precision
agriculture methods into practice depends on the ability to collect
data at a high resolution. Traditional methods of collecting landscape,
plant, and soil data are labor intensive and can be quite costly. At
the Upper Midwest RESAC, we are using remote sensing, GPS technology,
and penetrometer technology to increase the efficiency and reduce the
cost of data collection for precision agriculture.
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Remote
Sensing
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Remote
sensing typically involves equating radiances (energy reflected
or emitted in specific wavelengths) measured from satellite or airborn
instruments to the types of information that would normally be collected
in situ: temperature, leaf area, soil moisture, insolation, etc.
The image to the left shows LandSat-derived fractional vegetation
cover around the Slapout, OK Mesonet Tower. The red spot near the
top corresponds to a center-pivot irrigated field - an area with
dense vegetation cover. Fraction cover is used in DisALEXI,
a method to determine evapotranspiration at the 30m scale. |
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GPS
Technology
A "constellation" of satellites
orbiting the earth provides signals that are converted to location
coordinates. This Geographic Positioning System (GPS) allows anyone
with a GPS receiver (right, top) to determine their location on
the planet to within 20 meters. Using a second receiver, surveyed
points can be located to within a few centimeters. We use differentially
corrected GPS data to rapidly survey fields for elevation and locate
measurements of soil electrical conductivity (right, bottom).
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Penetrometer
Technology
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Measuring soil texture,
color, and density below the surface often means digging holes
or pulling cores. We are developing techniques to avoid this labor
intensive process. The tip-and-sleeve penetrometer (left) measures
the resistance of soil to downward and tangential pressure. These
measures can be converted into soil textural classes. Another
penetrometer under development contains a tiny camera and light
source to record soil texture, color, and structure in-situ (below).
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