A FIELD COMPARISON OF SEVERAL METHODS FOR MEASURING PESTICIDE EVAPORATION RATES FROM SOIL

Several methods for determining pesticide evaporative flux from fallow soil were evaluated in a side-by-side field study. Four compounds were applied to the surface as an emulsifiable concentrate. Statistical analysis of the results showed no significant difference at the 95% confidence level in flux values between the methods. The profile techniques used included the aerodynamic, eddy correlation, and energy balance methods and an integrated horizontal flux method. A theoretical profile shape method based on predictions of a trajectory simulation model was also used. The results indicate that each method yields comparable results when used over fallow soil under moderate wind conditions. The simpler theoretical profile shape method was shown to be reliable in determining evaporative fluxes, providing more rapid final results at an overall reduced expense, when compared with profile techniques. However, under low wind conditions, the eddy correlation and energy budget-Bowen ratio methods resulted in more reliable measurements. © 1990, American Chemical Society. All rights reserved.