Wind tunnel and CFD study of dust dispersion from pesticide-treated maize seed

Drilling of treated seeds with vacuum-based precision drills can cause emissions of pesticide-laden dust, which have been linked with declines of pollinator populations. Predicting the drift pattern of this type of dust is challenging because the particles are very irregular in terms of size, shape, density, internal porosity and chemical composition. In this work, a 3D Computational Fluid Dynamics (CFD) model of seed treatment dust drift was developed and validated with wind tunnel data. In the wind tunnel experiment, dust abraded from pesticide-treated seed was separated in three size fractions and released from a point source at a height of 0.7 m at three air velocities. Dust deposition was measured at six distances on the wind tunnel floor. The physicochemical properties of the dust samples were measured and implemented in the CFD model. Lagrangian tracking was used to calculate the dust particle trajectories. The simulated dust deposition patterns agreed with those observed in the wind tunnel trials. It was demonstrated that an accurate, particle size-dependent description of the shape, chemical content and internal porosity of the dust particles was necessary to achieve good validation results. The CFD model can be used as a basis for the simulation of dust drift in the field during sowing.