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United States Department of Agriculture

Agricultural Research Service

Title: Meteorological Effects on Deposition and Drift of Aerially Applied Sprays

Author
item Fritz, Bradley

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 21, 2006
Publication Date: November 1, 2006
Citation: Fritz, B.K. 2006. Meteorological effects on deposition and drift of aerially applied sprays. Transactions of the ASABE. 49:1295-1301.

Interpretive Summary: Drift from aerial application of crop protection materials is influenced by controllable factors, such as nozzle type and spray pressure, and uncontrollable factors, such as wind speed and atmospheric stability. Applicators are responsible for considering atmospheric conditions and adjusting operational factors to maximize on-target deposition and minimize the potential for drift. Generally, greater drift has been demonstrated to be associated with greater atmospheric stability. Field trials were conducted over the course of several mornings with the objective of assessing the degree of ground deposition and downwind drift of aerially applied spray treatments under various meteorological and atmospheric stability conditions. Results indicated that wind speed was the primary factor influencing spray transport and fate, but that increased atmospheric stability had the effect of maintaining droplet suspension which could potentially increase downwind drift and deposition. These results will help applicators make informed decisions resulting in applications of crop protection materials with maximum on-target deposition and minimal off-target drift.

Technical Abstract: Drift from aerial application of crop protection materials is influenced by many factors, and the applicator is responsible for insuring that all are considered and that all possible efforts are made to reduce the potential for drift. Atmospheric conditions and stability must be considered and adjusted for on the basis of on real time observations and past experience. The objective of this research was to document the effects of atmospheric conditions and stability on the deposition and drift of aerially applied sprays. Two treatments, a FINE and a MEDIUM spray, were used. Ground deposition and airborne concentrations of spray were sampled at multiple downwind locations using mylar cards and monofilament line, respectively. Results indicated increased downwind ground deposition as a result of increased wind speed, and increased airborne concentrations as a result of smaller droplet sprays and increased wind speed. Airborne concentration data indicates that increased atmospheric stability increases the time that smaller droplets remain suspended in the air, which could lead to increased transport of aerially applied sprays. Overall, the results of this study indicated that wind speed was the dominant factor in the transport and fate of aerially applied sprays.

Last Modified: 10/30/2014