Spray drift assessment of different application techniques using a drift test bench and comparison with other assessment methods

As an alternative method to simplify the measurement of spray drift, the University of Turin (Department of Agricultural, Forestry and Environmental Economics and Engineering (DEIAFA)) developed a drift test bench to assess the spray drift risk generated by field crop sprayers. The method is based on the principle that the potential spray drift is directly related to the amount of initial spray that remains suspended in the air after the sprayer has passed. In this study the drift potential of 16 spray boom application techniques was assessed using the drift test bench under indoor conditions using a fully automated spray track and mineral chelate tracers. By comparison with the results from a reference spraying, the resulting drift reduction potentials were compared with the results from three other drift assessment methods (field, wind tunnel, Phase Doppler particle analyser (PDPA) laser measurements). The drift test bench trials confirmed the already known effects of nozzle type, spray pressure and boom height on drift potential but not of nozzle size and application speed. In general, the drift test bench showed similar trends as the other drift assessment methods, although large variations were present and some contradictory results were observed. The test bench is therefore considered a possible alternative for measuring potential spray drift of horizontal boom sprayers, albeit future studies should focus on reducing the sources of variation and evaluating if the methodology is able to test the effects of sprayer speed.