Calibrating Turfgrass Chemical Application Equipment

Bulletin 817-00

Useful Formulas

• To convert ounces per minute (OPM) to gallons per minute (GPM):

  OPM/128 = GPM

• To convert gallons per acre (GPA) to gallons per 1,000 square feet:

  0.023 x GPA = Gal per 1,000 square feet

• To convert gallons per 1,000 square feet to gallons per acre (GPA):
  
  

  (Gallons per 1,000 sq ft)	= GPA
  0.023

  
  
• To convert GPA to ounces per 1,000 square feet:

  2.94 x GPA = Ounces per 1,000 square feet

• To determine travel speed:
  
  

  Distance (feet)	x 0.68 = Travel speed (mph)
  Travel time (seconds)

  
  
• For any change in travel speed (mph), calculate the resulting GPA using:
  
  

  GPA2 =	GPA1 x MPH1
  	MPH2

  
  
  
• To determine the desired travel speed (mph) when changing application rate (GPA):
  
  

  MPH2 =	GPA1 x MPH1
  	GPA2

  
  
• To determine the resulting application rate (GPA) when changing nozzle pressure (psi):
  
  

  GPA2 = GPA1 x	PSI2
  	PSI1

  
  
• To determine the desired pressure (psi) that will produce a desired application rate (GPA):
  
  

  PSI2 = PSI1 x	(	GPA2	)2
  		GPA1

GPA₂, GPA₁: Desired and measured application rates, respectively (gal/A).

MPH₂, MPH₁: Desired and measured travel speeds, respectively (miles/hour).

PSI₂, PSI₁: Desired and measured spraying pressures, respectively (lb/sq in).