Application of pesticides to seeds is an effective way to control pests and a common agricultural practice in the overall plant protection process. During planting, abraded seed dust particles coated with pesticides can potentially become airborne and drift to non-target areas. Therefore, a method to quantify the potential level of exposure from such seed planting operations was investigated.<br/>While some field monitoring efforts have previously been undertaken to quantify seed dust transport, this can be resource intensive; therefore, a modeling initiative was implemented to assess seed dust transport during planting and to support current and future monitoring programs. The modeling work aimed to provide a robust mechanistic understanding of the exposure levels and illustrate the development of a field-scale dispersion model for a moving pneumatic planter using both Gaussian and Lagrangian modeling schemes. The model performance was evaluated against dust deposition samples collected at discrete distances from the edge of a planted field. Inputs to the model included laboratory data on particles mass distribution by size as well as meteorological data.<br/>The models depicted the plume transport spatially and temporally with respect to the planter movement along the field and were able to capture the magnitude (within a factor of approximately 7 times the observations) and variability of deposition samples (with maximum correlation of 55%). In general, the models over-predicted the measured dust deposit with a minimum bias of 1.3 and maximum bias of 6.5 times the observations.<br/>The vertical profiles at the dust sample locations showed maximum pesticide concentrations for 25 μm particles size fraction at the release height of 1.8 m. The plume reached a maximum height of 5 m above the ground as predicted by the Gaussian model. Particles sizes greater than 5 μm tend to overcome the atmospheric lofting due to high gravitational settling velocity and thereby vertical concentrations decreased after 20 m. The largest particle size (300-2000 μm) deposited before the 1 m sampling distance.

Modeling dispersion of dust emissions from pesticide treated seeds during agricultural seed planting operations

254th National Meeting (2017)

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