Comparisons of the mechanistic AGDISP ground boom model with experimental data

Since work reported in 2008, developments on the AGDISP ground boom model have improved results against New Zealand field trial drift data and also compare better with ground boom drift data sets from Belgium and Canada. The model still predicts more drift than the experimental data in most cases, especially for smaller droplet sizes, but does predict less drift for larger droplets at large distances downwind. The original AGDISP ground model was calibrated from Spray Drift Task Force data from the United States. The experimental methods need to be developed to improve collection efficiency and mass balance. The physics behind the model are discussed and proposed methods for improvement are suggested, including air velocities in the spray jet below the nozzle, the dispersion of the spray plume cloud at ground level due to atmospheric turbulence and wakes from the spraying equipment.