Master of Science (MS)
Geography and Anthropology
Drift of pesticides can be a significant health hazard, particularly in areas where agricultural land is adjacent to a school, retirement home, or other populated area. Off-target drift of pesticides depends on many atmospheric variables, both mechanical and thermal. While non-atmospheric variables, such as applicator nozzle size, height of application, and particle size, can be controlled by the applicator to reduce drift potential, understanding how atmospheric conditions set a framework for drift potential enables applicators to choose to spray when the weather conditions would minimize drift. Specifically, atmospheric stability plays an important role in the near-ground concentration of sprays downwind of the spray site; stable conditions confine spray near the surface if the application occurs near the surface. This project investigates the efficacy of using Pasquill stability classes as a simple way to estimate surface boundary layer stability conditions in the field. Wind speed and a qualitative insolation estimate (strong, moderate, or slight) are used to determine the Pasquill stability class. A series of case studies conducted under varying Pasquill stability classes near Winnsboro, Louisiana, provides data to test the efficacy of Pasquill stability classes as drift predictors. Results suggest that the Pasquill stability estimates give applicators a useful method for estimating downwind dispersion and drift under a wide range of atmospheric conditions, thereby improving their ability to make informed decisions to reduce the risk of off-target drift.
Document Availability at the Time of Submission
Release the entire work immediately for access worldwide.
Tollefson, William, "Effect of atmospheric boundary layer conditions on agricultural spray drift" (2013). LSU Master's Theses. 2667.