In method 2 of boom sprayer calibration, what distance is sprayed to determine gallons per acre (GPA)?

• A. 528 ft
• B. 1000 ft
• C. 660 ft
• D. 1320 ft

Answer: (C)

The idea is to relate the amount of chemical sprayed to the area covered so you get gallons per acre (GPA). In method 2, you spray a fixed distance, 660 feet, with the boom width known. The sprayed area is that distance times the boom width. Convert that area to acres with 1 acre = 43,560 square feet. So area in acres = (660 × boom width) / 43,560, which simplifies to boom width divided by 66. Therefore GPA = gallons sprayed ÷ (boom width/66) = gallons sprayed × 66 ÷ boom width (in feet). Using 660 feet is handy because it makes this calculation quick and clean. For example, with a 40-foot boom, spraying 100 gallons over 660 feet gives GPA = 100 × 66 / 40 = 165 gallons per acre. This method relies on a steady spray rate and a precisely known sweep width.