Modeling pesticide volatilization from turf

Area of Science:

• Environmental Chemistry
• Agricultural Science
• Ecotoxicology

Background:

• Traditional pesticide volatilization models rely on soil equilibrium partitioning, which is unsuitable for turf systems.
• Direct vaporization from vegetation surfaces is a significant but complex source of pesticide loss in turf.
• Equilibrium methods face challenges in plant material due to uncertainties in solid-liquid-gas partitioning.

Purpose of the Study:

• To develop and validate an alternative model for pesticide volatilization from turfgrass.
• To adapt principles of water evaporation for predicting chemical vaporization from vegetation.
• To assess the model's accuracy in estimating pesticide losses under field conditions.

Main Methods:

• A novel model was developed, adjusting evapotranspiration values (Penman equation) for chemical vaporization.
• The model incorporates ratios of water and chemical vapor pressures and latent heats of vaporization.
• First-order degradation kinetics of pesticides on turf vegetation were assumed and integrated.

Main Results:

• Field experiments measured volatilization fluxes ranging from 0.1% to 22% of applied pesticide.
• The model provided conservative estimates, with predicted mean losses exceeding observations by 20%.
• The model successfully explained 67% of the observed variation in pesticide volatilization fluxes.

Conclusions:

• The developed model offers a viable alternative for estimating pesticide volatilization from turf.
• Model accuracy was highest for pesticides with greater volatilization losses.
• The findings support using water evaporation principles to predict pesticide behavior in turf systems.