Calibrate Your Sprayer Before Hitting the Field

The NWTF has compiled some easy, do-it-yourself instructions for calibrating your sprayer before heading to the field this spring. By following the instructions below, you will not only save yourself time and money, you can ensure you get the desired effect from your herbicide.

128th Acre Calibration Method

128th Acre = 340 sq. ft.
340/nozzle spacing in ft. = Calibration Distance

Example:
Calculate the calibration distance:

17 inch nozzle spacing = 17/12 = 1.41 ft. 340/1.41 sq. ft. = 240 ft.

Then:

Measure and mark a 240 ft course over the field you intend to spray At normal driving speed time several trips over the distance and determine an average. For example, suppose it takes your spray rig an average of 30 seconds to cover the distance, then 30 seconds is the collection time.

Next:

With the sprayer operating, using plain water, collect the spray from 1 nozzle for 30 seconds (the calculated collection time). The volume collected in ounces will be equivalent to the volume in gallons per acre delivered by the spray rig. For example, if 20 ounces of water are collected during the 30 second collection period, then the spray rate is 20 gallons per acre.

Application:

Suppose the herbicide label calls for 1 quart of herbicide per acre and you've determined that the spray rate is 20 gallons per acre. This means that you add 1 quart of herbicide for every 20 gallons of water in the tank. For example, to properly cover a 5 acre field at the rate of 1 quart of herbicide per acre, you will mix 5 quarts of herbicide in 100 gallons of water, and be assured that the delivery rate will be accurate.