Evaluation of Totally Impermeable Film for Fumigant Emissions Reduction.

Emissions from soil fumigation are stringently regulated for environmental safety concerns. Low permeability films can be used to reduce fumigant and volatile organic compound (VOC) emissions and to allow for smaller buffer zones. A large-scale field trial was conducted in Ventura, CA, to determine the efficiency of totally impermeable film (TIF) for fumigant emissions reduction in comparison with standard polyethylene (PE) film. A 50/50 mixture of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) were applied to a sandy loam soil by shank injection at 30 cm depth. Volatilization losses were measured using dynamic flux chambers. About 43% of the applied 1,3-D and 12% of applied CP was lost from the PE covered field during the first six days, but the total mass loss of these fumigants was less than 2% of total applied from the TIF covered field. However, after the tarp was cut, the total mass loss of 1,3-D from both PE and TIF covered fields were 23% and 53% of total applied, respectively due to the surge of emissions from fumigants retained under the tarp. Chloropicrin emissions after tarp cutting were minimal because of its fast degradation in soil. The results suggest that the TIF has great potential to control 1,3-D emissions in large-scale fields while early cutting may result in significant volatilization losses. Proper tarping period for 1,3-D must be determined which would allow for fumigant degradation in soil to reduce potential exposure risks and to minimize the contribution of fumigants to atmospheric VOCs.