Assessment of Various Methods for Fumigant Emission Reduction Using Simulation Model.

Various methods have been developed to reduce atmospheric emissions from the agricultural use of highly volatile pesticides and to mitigate their adverse environmental effects. Experimental studies in the laboratory or field have been conducted to evaluate the efficiencies of these methods, including 1) deep injection, 2) less permeable films over the soil surface (e.g., tarps of density polyethylene (HDPE) or virtually impermeable film (VIF)), 3) organic matter addition, 4) fertilizer addition, 5) surface irrigation, and 6) drip vs. shank injection.  The objective of this study was to analyze the sensitivity of model parameters (i.e., Henry’s constant, diffusion coefficient, degradation rate, sorption coefficient, and boundary layer thickness) and to validate the model for simulating 1,3-dichloropropene (1,3-D) volatilization rates by comparing the simulated results with those experimentally determined. The simulation model couples water, heat, and solute transport processes and considers temperature-dependence of model parameters and an adjustable surface boundary condition representing practical management on the soil surface.  Overall, the trend and shape of the measured values as well as total emission fraction were reasonably reproduced by the model for most treatments. The results will contribute to the application of simulation models to provide accurate information for decision making in terms of protecting public and environmental health.