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ARS Home » Southeast Area » Stoneville, Mississippi » Crop Production Systems Research » Research » Publications at this Location » Publication #254008
Title: Spray Deposition and Drift Characteristics of a Low Drift Nozzle for Aerial Application at Different Application Altitudes

Author
item Huang, Yanbo
item Thomson, Steven

Submitted to: Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE)
Publication Type: Proceedings
Publication Acceptance Date: 5/13/2010
Publication Date: 6/21/2010
Citation: Huang, Y., Thomson, S.J. 2010. Spray Deposition and Drift Characteristics of a Low Drift Nozzle for Aerial Application at Different Application Altitudes. Proceedings of the American Society of Agricultural and Biological Engineers International (ASABE), St. Joseph, MI. Paper No 10-08374.

Interpretive Summary: When agricultural chemicals are applied to crops using sprayers mounted on aircraft various factors can affect the performance of the spray and the drift on non-target crops. This study evaluated the droplet size and deposition characteristics of a low drift CP flat-fan nozzle at different application altitudes. In this study, CP flat-fan nozzles were set to a downward angle of 30 degrees applying a mixture of water, adjuvant, and Rubidium Chloride (RbCl) tracer at a 18.7 gal/acre delivered at altitudes of 12, 16 and 20 feet. Spray droplets were collected using water sensitive paper (WSP) cards placed in the spray swath. Relative amount of RbCl was measured using Mylar sheets placed in the swath and downwind for drift sampling. Statistical analysis indicated that droplet spectra collected on the WSP cards and RbCl tracer from Mylar sheets over the spray swath was not significantly influenced by application height. However, application height significantly influenced the spray deposition on drift samplers along with wind direction. These studies indicate that accurate setting and determination of spray release height can contribute significantly towards reducing off-target drift.

Technical Abstract: A complex interaction of controllable and uncontrollable factors is involved in aerial application of crop production and protection materials. Although it is difficult to completely characterize spray deposition and drift, these important factors can be estimated with appropriate sampling protocol and analysis. Application height is an important variable influencing off-target spray drift, but this variable has not been easily measured or logged. A custom-configured aircraft-mounted laser with logging capabilities makes this possible. This study was designed to investigate droplet size and deposition characteristics of a low drift CP flat-fan nozzle at application altitudes 3.7 m, 4.9 m, and 6.1 m. In the study, CP flat-fan nozzles were set to a downward angle of 30 degrees applying a mixture of water, Syl-Tac® adjuvant, and Rubidium Chloride (RbCl) tracer at a 28.5 L/ha application rate. Spray droplets were collected using water sensitive paper (WSP) cards placed in the spray swath. Mylar sheets were also placed in the swath and downwind for drift sampling. Statistical analysis indicated that median droplet diameter as determined by WSP in the spray swath was not significantly influenced by spray application height. Similarly, statistical analysis also indicated that concentration of RbCl tracer from Mylar samplers in the spray swath was not significantly influenced by application height. Application height had a significant effect on spray deposition from drift samplers, along with wind direction and relative humidity. Final results for drift samplers may have been influenced by shifts in wind direction that altered the relationship between orientation of samplers and wind.