When applying herbicides a more accurate, efficient and cost-effective treatment can be made if the sprayer’s application rate is determined. Determining a sprayer’s application rate in Gallons Per Acre will allow an applicator to mix herbicides to maximize effectiveness.
Hand Gun, Backpack and Hand Sprayer Calibration
Spraying an area 18.5 ft by 18.5 ft, the ounces of carrier used will be equal to the application rate in gallons per acre.
Measure an area 18.5’ X 18.5’
Fill sprayer with clean water
Time yourself as you spray the area
Try not to apply excessively
Try to replicate how you plan to apply herbicide in the field
When using a hand gun, application rates will vary slightly from person to person
Spray into a bucket for the same duration it took to cover the 18.5’ X 18.5’ area
Measure the volume of collected water in ounces.
The ounces collected represent the sprayer’s application rate in gallons per acre
Example: If it takes 26 seconds to spray an 18.5’ X 18.5’ area, and 170 ounces are applied in 26 seconds, then the sprayer is calibrated at 170 gallons per acre.
Boom Sprayer Calibration
Measure volume sprayed in one minute (gallons per minute)
Measure swath width (feet)
Measure the speed at which you will be spraying (1MPH = 88feet/minute)
Measure square footage covered per minute (swath width X ground speed in feet/minute)
Divide gallons per minute by square feet covered per minute and multiply by 43,560 (square feet per acre)
Example: GPM=1.58, Swath Width=12 feet, Ground Speed=88 feet per minute
12 X 88=1056 square feet per minute
(1.58 GPM / 1056 square feet per minute) X 43,560 square feet per acre = 65.17 gallons per acre