Soil fumigants have been used to sterilize soils in preparation for planting many crops. Current methods of soil fumigation can result in unintended fumigant escape into the atmosphere. Inadequate sealing practices will reduce fumigant efficacy to control soil pests and may cause significant off-site emissions. Reduction of fumigant emissions into the atmosphere has become critical to ensure the continued availability of methyl bromide alternative fumigants. The use of virtually impermeable film (VIF) and semi-impermeable film (SIF) has shown to reduce emissions under laboratory conditions, but limited information is available on their permeability under field conditions. Application of thiosulfate fertilizers to the soil surface can potentially reduce volatilization losses of halogenated fumigants by transforming fumigant vapors to non-volatile products. Our research evaluated the use of VIF, SIF, and water plus potassium thiosulfate seal relative to standard polyethylene (PE) film to reduce volatilization losses of 1,3-dichloropropene (1,3-D) and chloropicrin after drip application of these fumigants to raised soil beds. Field experiments were conducted in two regions in California. Each experiment was conducted simultaneously on four adjacent fields. Volatilization flux measurements were obtained using air samplers positioned at eight locations around each field. The Industrial Source Complex Short Term (ISCST3) model was used to back-calculate the field emission rates. The percentage of mass loss of chloropicrin and 1,3-D relative to the amount applied under PE film was 20 and 31%, respectively. The use of PE film plus thiosulfate seal or VIF reduced chloropicrin emissions by more than 40% relative to PE film alone, and the use of VIF plus thiosulfate seal reduced chloropicrin emissions by more than 65%. Thiosulfate and SIF reduced atmospheric emissions of 1,3-D by 20% relative to PE film. Fumigant emissions computed by using three techniques will be presented.