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United States Department of Agriculture

Agricultural Research Service

Research Project: Pesticide Application Technologies for Spray-drift Management, Maximizing In-field Deposition, and Targeted Spraying

Location: Crop Production Systems Research Unit

Title: Optimizing selection of controllable variables to minimize downwind drift from aerially applied sprays

Authors
item Huang, Yanbo
item Zhan, Wei -
item Fritz, Bradley
item Thomson, Steven

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 20, 2012
Publication Date: July 1, 2012
Citation: Huang, Y., Zhan, W., Fritz, B.K., Thomson, S.J. 2012. Optimizing selection of controllable variables to minimize downwind drift from aerially applied sprays. Applied Engineering in Agriculture. 28(3):307-314.

Interpretive Summary: Control of off-target drift of aerially applied crop protection and production materials is of primary concern in agricultural operations. In order to develop an effective method to control the off-target drift, studies have been conducted in fields to clarify the relationship between the drift and the impact factors. The field studies are costly and laborious, and the results were often biased by unexpected weather condition. Computer simulation provides an approach to modeling the drift with impact factors to narrow down the ranges of the factor changes for field studies. AGDISP is such a software which provides such a capability to simulate the spray drift. This research studies the spray drift using a novel simulation-based approach. This new approach first studies many factors that can potentially contribute to downwind deposition from aerial spray application to narrow down the major contributing factors. An optimization process is then applied to reduce the negative impact from one of the main factors, wind speed. With the focus on major contributing factors such as wind speed, release height, and droplet size, the optimization process is carried out in AGDISP and MATLAB, another scientific computing software. The new method can provide some guidance to the applicators. For instance, in order to achieve a certain application efficiency value, some constraints on wind speed, release height, and droplet size must be satisfied.

Technical Abstract: Drift of aerially applied crop protection and production materials is studied using a novel simulation-based approach. This new approach first studies many factors that can potentially contribute to downwind deposition from aerial spray application to narrow down the major contributing factors. An optimization process is then applied to reduce the negative impact from one of the main factors, wind speed. With the focus on major contributing factors such as wind speed, release height, and droplet size, the optimization process is carried out in AGDISP and MATLAB. This results in a sub-optimal offset of the flight trajectory in the direction perpendicular to the swath lines to compensate for the wind speed. The effect of the sub-optimal offset, i.e., the swath displacement, is then validated using the Monte Carlo analysis: random values for all the factors are generated; the sub-optimal swath displacement values are used in comparison to the default one half swath width offset; the difference between the default and the sub-optimal offset is analyzed. Statistical analysis of the results shows that using the sub-optimal offset values can greatly reduce downwind drift as compared to the default offset value. The sub-optimal offset values achieve results that are very close to the optimal ones. For the comparison of the results, the application efficiency, the cumulative downwind deposition between 30.48 m (100 ft) and 45.72 m (150 ft), and the deposition at 30.48 m (100 ft), 76.2 m (250 ft), and 152.4 m (500 ft) are used as the performance metrics. The new method can provide some guidance to the applicators. For instance, in order to achieve a certain application efficiency value, some constraints on wind speed, release height, and droplet size must be satisfied.

Last Modified: 12/19/2014