Reduce Fumigant Emissions using Impermeable Film and Water Seal.

Current methods of soil fumigation can result in unintended fumigant escape into the atmosphere.  Reducing fumigant emissions into the atmosphere has become critical to ensure the continued availability of methyl bromide and the alternative fumigants for agricultural soil disinfestation. This research evaluated the use of semi-impermeable film (SIF), virtually impermeable film (VIF) and sprinkler-applied water plus thiosulfate seal in furrows to reduce volatilization losses of 1,3-dichloropropene (1,3-D) and chloropicrin. InLine (1,3-D/chloropicrin, 61/33) was drip-applied under SIF and chloropicrin EC was drip-applied under VIF.  Potassium thiosulfate (KTS)/water seal was applied by sprinklers immediately after drip fumigation.  The soil sealing treatments were: 1) standard high barrier polyethylene tarp (HBPE, 1.5 mil), 2) standard HBPE tarp plus KTS/water seal, 3) VIF (1.28 mil) or SIF (2.0 mil), and 4) VIF or SIF tarp plus KTS/water seal.  This study found that the use of SIF can reduced 1,3-D and chloropicrin emission rates by up to 25% relative to standard HBPE tarp. Volatilization losses of fumigants relative to amounts applied were highest for fields covered with standard HBPE than those covered with SIF. The use of VIF reduced early chloropicrin emission rates by 68% relative to standard HBPE.  Application of KTS/water seal to fields covered with VIF reduced total emissions by about 40% relative to standard HBPE tarp. This presentation will discuss emissions results for chloropicrin and 1,3-D applied under various tarps . In addition, this presentation will compare fumigant emissions computed by various models.