Evaluation of Spray Drift Reductions Technologies and Practices
Fritz, B., Hoffmann, W. C., Bagley, B. E., Thornburg, J. W., Birchfield, N. B., Ellenberger, J.
Contact: Bradley K. Fritz
Aerial Application Technology Group
2771 F&B Road
College Station, TX 77845
Drift continues to be one of the major concerns of the spray application industry. A testing program for measuring the performance of drift reduction technologies (DRTs) was initiated by the U.S. EPA in 2004. Drift reduction technologies can be spray nozzles, sprayer modifications, spray delivery assistance, spray property modifiers (adjuvants), and/or landscape modifications. A protocol for testing DRTs in high speed wind tunnels has been previously reported and was expanded to test spray nozzles. The work in this manuscript will report on the initial implementation of the DRT program for conducting DRT evaluations of three spray nozzles under high speed conditions (i.e. 100-140 mph), which are relevant to the aerial application of crop production and protection materials. The spray nozzles were evaluated in the USDA-ARS High Speed Wind Tunnel facility. Droplet size of each of the nozzles with different airspeeds, spray pressures, and orientation were measured with a Sympatec Helos laser diffraction instrument. The droplet size spectra for each test was input in a spray dispersion model (AGDISP), which calculates the downwind drift expected from a typical aerial application scenario. As compared to the reference nozzle, the three spray nozzles reduced spray drift by 12-26% from 0 to 350 m downwind from the spray block. The nozzles generated spray droplets with volume median diameters 60-80 µm larger than the reference nozzle. One of the aerial application industry’s Best Management Practices (BMP) is to not spray directly on the downwind edge of a field. The spray swath near this edge is moved up wind (i.e. offset) by ˝ to 1 swath width. When this BMP was combined with the drift reductions from the spray nozzles, the amount of drift reduction was increased to 56-76%. These results demonstrate the possibility of combining multiple drift reduction techniques/technologies to greatly reduce spray drift.
Select for Presentation Slides
Select for Manuscript