Application Equipment and Calibration
Calibration is the heart of accurate application: it matches output to the labeled rate so the target receives the intended dose without over- or under-application. Candidates must know the variables that affect output - nozzle type and size, pressure, speed, and spray pattern - and how changing one shifts the others. Nozzle selection follows the job: flat-fan for broadcast, cone for directed/foliar, and drift-reducing (air-induction) tips where drift risk is high. Worn or clogged nozzles skew the pattern and the rate; inspect and replace them.
Know the standard calibration relationships and be ready for a worked problem. A common method: measure output (gallons per minute per nozzle), then use speed and swath width to find gallons per acre. Traps in questions: mixing units (ounces vs. gallons, feet vs. acres); forgetting that doubling speed roughly halves the per-acre output; and calibrating with water but then changing product or adjuvant (which can change viscosity and flow). Always recalibrate after changing nozzles, pressure, or speed. Keep equipment clean and rinse between products to prevent cross-contamination.
Rule of thumb: if you change speed, pressure, or nozzle, recalibrate - output per acre is not fixed once you touch those variables.
Worked example: If a sprayer delivers a known gallons-per-acre at 4 mph and the operator speeds to 8 mph, per-acre output roughly halves, so the rate falls below label - the operator must recalibrate (or adjust pressure/nozzle) to restore the labeled rate.