Fumigant Emissions Affected by Bed Design and Other Factors From Low Permeability Tarped Fields.

Raised-bed agricultural system is used for production of some annual high value fruit and vegetable crops such as strawberry in CA and tomato in FL. Fumigation is an important tool to control soil-borne disease in the raised-beds prior to planting. However, fumigant emissions have inevitable environmental consequences. This presentation examines emission reduction using low permeability tarp technology in raised-bed fields and associated factors. A trial was recently conducted in Florida and fumigant emission from raised-beds tarped with totally-impermeable film (TIF) and from furrow was monitored for 10-d. Carbonated-fumigant Telone C35 was shank applied at 151 kg ha-1 to 25 cm deep. The bed dimension was 22 cm height and 76 cm width. Right after fumigant application, the beds were tarped with TIF immediately. Results showed that TIF reduced fumigant emission significantly with emission of only 0.1% of totally applied from the beds. However, significantly high emissions (27% of applied 1,3-D) was determined from the furrows. The results were very different from findings in California trials when InLine was drip-applied to raised beds at a much higher rate near the surface under low permeability tarp of VIF with a bed dimension of 30 cm height and 107 cm width (~30% of applied 1,3-D from beds and negligible from furrows). These results indicate that the fumigant emissions depend highly on the bed designs and other associated factors. Proper bed design for certain soil conditions and fumigant application rates and methods are needed to minimize emissions when using low permeability tarps.