Which factor is NOT a primary determinant of spray drift risk?

• A. Wind direction is not a determinant of drift.
• B. Droplet size is a determinant of drift.
• C. Soil type is not a primary determinant of drift.
• D. Temperature is a determinant of drift.

Answer: (C)

Spray drift risk comes from how droplets behave in the air after application. The main factors are how large the droplets are, the wind speed and direction, the temperature and humidity, and the nozzle type and pressure that determine droplet size and spray characteristics. Smaller droplets are carried more easily by air; wind moves them away from the target; temperature and humidity influence evaporation and drying, which can change droplet size in flight. Nozzle height and formulation also affect how far droplets travel before settling.

Soil type does not influence the airborne transport of droplets. It matters after droplets land—how the chemical interacts with soil, how much sticks to soil particles, and how it might move through soil or become absorbed. Those deposition and soil–chemical interaction aspects are separate from drift in the air, which is why soil type is not a primary determinant of spray drift risk.