If the spray volume recommended for broadcast spraying is 20 GPA, what would be the actual volume applied on a per acre basis when applied in a 15-inch band over 30-inch rows?

• A. 20 GPA
• B. 10 GPA
• C. 40 GPA
• D. 15 GPA

Answer: (B)

To understand the correct application volume in this scenario, start by recognizing what GPA (gallons per acre) signifies. The spray volume of 20 GPA indicates that when applied in a broadcast manner, 20 gallons of spray mix would cover one acre. However, when applying in a banded format over specific row widths, the total effective coverage changes.

In this case, a 15-inch band is being utilized over 30-inch rows. This means that only half of the total area of the acre will receive the spray since the band is only covering 15 inches of every 30-inch row (15 inches covers half of 30 inches). As a result, the actual volume applied on the per acre basis must reflect this reduction in coverage.

To convert the broadcast application rate to a banded application, you can use the following calculation: Divide the broadcast spray volume by the fraction of the row width being sprayed. The fraction in this case is 15 inches (the width of the band) divided by 30 inches (the total row width).

Calculating this gives:

• Fraction of area treated = 15 inches / 30 inches = 0.5

Now apply this fraction to the broadcast spray volume:

• Actual volume applied =