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| Emission Reduction |
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Introduction
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Many soil-chemical processes affect the fate and transport of soil
fumigants. Containment, degradation and soil-gas concentration (i.e.,
effective dosage) must be controlled to reduce emissions while maintaining
adequate pest control. Unless each of these factors is controlled,
unacceptable emissions or inadequate pest control will likely occur. Two
important factors that may affect fumigant transformation and distribution
and its ultimate volatilization into the air are depth of placement and
the use of soil surface cover. These two factors have been frequently used
to alter a fumigant's distribution to reach adequate control in the
specified target zones. Depending on the target pest, the fumigant can be
applied at the soil surface under plastic film to as deep as 60-100 cm
below the soil surface. Deeper placement consistently results in deeper
penetration in the soil. Abdalla et al. (1974) found that MeBr application
at 76-81 cm without a soil cover resulted in gas distribution at
concentrations sufficient for nematode kill as deep as 244 cm. Kolbezen et
al. (1974) detected adequate dosages at 300-360 cm when MeBr was applied
at 90 cm. Though these early studies were mostly designed for achieving
better nematode control in deep soil layers, they demonstrate that
downward diffusion is encouraged by deep application. More recent research
has been directed at investigating other methods for controlling emissions.
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Last Modified: 10/21/2005
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