DripFume: A Visual Basic program for simulating distribution and atmospheric volatilization of soil fumigants applied through drip irrigation

A Windows-based graphical user interface program (DripFume) was developed in MS Visual Basic (VB) to utilize a two-dimensional multi-phase finite element pesticide transport model to simulate distribution and emission of volatile fumigant chemicals when applied through drip irrigation or shank injection. The program provides an intuitive user interface by linking databases with default soil and chemical properties to predict subsurface distribution patterns and surface volatilization losses of soil fumigants under selected field configurations and application regimes. The interface program was configured to simulate up to three chemicals simultaneously to accommodate the need of fumigation with multiple chemicals. Physical and chemical properties of cis- and trans-isomers of 1,3-dichloropropene and chloropicrin for a typical medium-textured soil were given as default values in the model input. Properties of other soil fumigants can be easily substituted as input options during program initialization. A database containing transport properties of 12 soil groups (from clay to sand) were created in DripFume as selectable sets of input values. Substitution is also allowed if properties of an individual soil are known. The VB output includes a normalized run-time volatilization flux display and selections in post-processing using MS Excel linked by VB. Output options from the post-processing VB/Excel program include data and graphs of cumulative volatilization loss, volatilization flux density, concentration profile by time for a selected location or by location for selected lapsed times after fumigant application. Although there are still limitations in selectable field configurations, the program should be useful in helping pesticide specialists, farm managers, or policy makers to optimize the depth, rate, and duration of fumigant application to achieve the highest possible distribution uniformity and the lowest volatilization loss.