Boom sprayer calibration tips
NOTE: If the tank is not completely empty when refilling, use the amount of water required to refill the tank, not the capacity of the tank itself when determining acres treated per tank. For example: If you have a 300 gallon tank but you have 75 gallons of spray left in it when you refill, you will use 225 gallons in your calculations instead of the total tank capacity.
225 gal. refill/15 gal./A. = 15 A./refill
15 A./refill x 2 pts/A. = 30 pts./refill
You must add 30 pints of chemical to the tank.
Sometimes, chemical manufacturers give recommended rates in terms of active ingredient (A.I.) to be used per acre rather than the amount of total product per acre. In these cases, calculate the amount of material to be applied as shown in examples 2 and 3 for dry chemicals and liquid chemicals, respectively.
The application rate of the chemical is 2 pounds A.I. applied per acre. The material to be used is a wettable powder containing 50 percent A.I. Determine the quantity of chemical to add to the tank:
Lbs. of material per A. = 2 lbs X 100/50 = 4 lbs./A.
4 lbs/A. x 20 A./tank = 80 lbs./tank
The chemical you are using is liquid. The recommendation calls for 1 pound A.I. per acre. You have purchased a formulation that contains 4 pounds A.I. per gallon. Determine the amount of product needed per acre.
Gal.of product needed per A.= 1 lb.A.I./A. /4 lb.A.I.gal = 0.25gal./A.
Next, calculate the amount of chemical to add to each tankful:
0.25 gal./A. X 20 A./tank = 5 gal./tank
(Band Spraying) You want to apply a herbicide on a 12-inch band on rows spaced 36 inches apart. The herbicide label recommends 3 pounds of material per acre on a broadcast basis. The sprayer has a 300 gallon tank, and the application rate measured with the calibration method explained previously for band application is 5 GPA. Determine the amount of chemical needed per tank:
- First, determine how much chemical will be used when applied on 12-inch bands.
12-in. band/36-in row X 3 lbs./A. = 1 lb./A.
The rest of the procedure to determine the chemical required per tank is the same as explained earlier for broadcast applications.
300 gal. per tank/ 5 gal. per tank = 60 A./tank
60 A./tank X 1 lb./A. = 60 lbs./tank
Thus, you will need to add 60 pounds of chemical product to the 300 gallon tank.
Mixing the pesticide thoroughly and carefully is an important step in good sprayer operation. Incomplete mixing results in varied application rates - too heavy at times, too low otherwise. Some chemicals, when mixed improperly with others, form a thick, mayonnaise-like mixture that will not spray properly and is difficult to clean out of the sprayer. Always read the label for proper mixing sequence and test the compatibility of chemicals in a small container before mixing.