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In theory, calibration
is a simple process. Essentially, the
goal of calibrating a sprayer is to accurately determine sprayer output. Sprayer output is
measured as gallons per acre. Gallons
per acre is a function of gallons per minute and acres per minute sprayed: And, each of these elements can be further broken
down. |
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Best
Management Practices for Orchard Spraying |
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Accurate calibration can result in more efficient spray applications
through better coverage, greater efficacy, reduced chemical and labor costs, and better packouts. |
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Hood River Grower-Shipper Association -- Best Management Practices Project |
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acres per minute is a function of: · ground
speed · tree
row spacing |
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gallons per minute is a function of : · number
of nozzle · size
of nozzles · operating
pressure |
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In practice, sprayer
calibration is not an exact science and will require some trial and
error. Here is an outline of how to proceed. 1) Determine
tractor speed (gear & RPM) that results in good coverage. For PTO sprayers, you run the engine at the
manufacturer specified RPM and adjust ground speed by selecting different
gears. Of course, good coverage is
affected by all of the other factors.
So to start, you need to have an idea of your rate for a given
application i.e. 50, 100, 200, 400 gallons per acre. This will depend on the material, target
pest, and time of year. For example,
dormant and delayed dormant applications may require higher volumes to soak
into bark crevices (and to reduce potential for drift with larger droplet
size). 2) Determine actual speed in MPH. You need to
measure this. One way to do this is to
time how long it takes to drive 88 feet in the selected gear and RPM and use the following formula: |
