The following procedure describes a calibration technique for application of granules in a band or directed applications in row crops. Calibration must be done with the same granules you intend to use during actual application. If the amount collected is not within 10% of the labeled rate or ounces required, make the appropriate adjustment to the gauge setting and repeat the calibration until you have collected the required amount.
Steps in calibrating equipment for band application when label rate is expressed in ounces per 1,000 feet of row.
Step 1. — Measure a 250 foot test course. The area should be similar in terrain to the area to be treated.
Step 2. — Adjust the applicator gate opening to the desired setting as suggested in the equipment operator’s manual or pesticide label.
Step 3. — Fill hoppers at least half full, turn on applicators and operate until granules discharge at a uniform rate.
Step 4. — Disconnect the drop tubes under the hopper, and securely attach a container to catch all granules discharged.
Step 5. — Drive the measured distance using a constant, suitable speed.
Step 6. — Weigh the amount of granules (in ounces) caught from each hopper.
Step 7. — Multiply the ounces of granules collected from each hopper by 4 (250 feet × 4 = 1,000 feet) to get the rate per 1,000 linear feet.
Calibrating equipment for band application when label rate is expressed in pounds per acre (broadcast rate).
Use the following formula to determine the required number of ounces to be discharged over a measured course:
2,722 is a constant obtained by dividing the number of square feet in one acre (43,560) by the number of ounces in one pound (16)
The label of an herbicide indicates a broadcast rate of 20 pounds per acre. You want to apply granules in a 10-inch band over each row (10 inches = 0.833 feet). How many ounces should you collect from each applicator after operating your equipment over a 500-foot calibration course?
Area treated = 500 ft × 0.833 ft = 416.5 sq ft
After traveling the 500-foot course, you should have collected 3.1 ounces ± 10% (2.7 oz. to 3.3 oz.) from each applicator unit to apply the correct amount of herbicide.
Calibrating equipment for in-the-row or in-furrow applications when the label rate is expressed in pounds per acre.
The number of ounces per 1,000 feet of row is usually listed on the label. If the label indicates the rate only in pounds per acre, it is generally associated with a standard row width, such as 40 inches, 36 inches, 20 inches, etc. For a specified row width, use the following formula to convert to ounces per 1,000 feet of row:
A soil insecticide label indicates a rate of 13 pounds per acre when applied in 36-inch rows (36 inches = 3 feet). How many ounces per 1,000 feet of row are required for accurate treatment?
After traveling a 1,000-foot calibration course, you should have collected 14.3 ounces ± 10% (12.9 oz. to 15.7 oz.) from each applicator to apply the correct amount of insecticide.
Compiled by Wayne Buhler, PhD.