Chemical Application Rate (GPA)
The gallons per acre a sprayer applies, or the speed and nozzle flow that hit a target rate.
Example
You enter
- Nozzle GPM 0.4
- Nozzle spacing (in) 20
- Ground speed (mph) 5
- Target GPA (optional) 25
You get
- GPA 23.76 gal/acre
- Required GPM for target 0.421
Details, formula, and sources
GPA = (5940 * GPM) / (speed * spacing) and inverse for target GPA.
GPA = (5940 × GPM) / (speed_mph × spacing_in). The constant 5940 = 60 min/hr × 43 560 ft²/acre / (12 in/ft × ?)... derives from unit reconciliation.
ASABE EP367 (Guide for Preparing Field Sprayer Calibration Procedures) by name; manufacturer sprayer-calibration guides (John Deere, AGCO, Case IH) by name.
ASABE standards licensed; calibration principles free at most state-extension service pages (e.g., extension.psu.edu).
Read and follow the product label. The label is the law (FIFRA).
Field names used by the API: gpm, spacing_in, speed_mph, target_gpa, gpa, required_gpm
- Constant 5940 engineering-practice constant for GPM-to-GPA at 1 mph nozzle spacingASABE EP367