New Lab Methods Speed Testing of Fumigant
Emissions By Sharon Durham October 4, 2007
A simpler, quicker way to track pesticide emissions from agricultural
fields has been devised by Agricultural Research Service (ARS) scientists. Using low-cost laboratory
tests and mathematical models, research leader
Yates and colleagues at the
Salinity Laboratory in Riverside, Calif., are able to evaluateand
even predictfumigant emissions.
With a ban looming on methyl bromide, a pre-plant soil fumigant widely
used by fruit and vegetable growers, Environmental Protection Agency (EPA) regulators are evaluating various
emissions-lowering fumigation alternatives. Each potential methyl bromide
replacement will require its own set of regulations, based on findings from
complex field studies.
According to Yates, such studies can take up to a year to complete,
cost hundreds of thousands of dollars and, in the process, bring research teams
in contact with toxic chemicals. Since a variety of factors must be considered
in each EPA evaluation, such as variations in soil and environmental
conditions, as many as 60 costly, long-term field experiments may be necessary.
Yates team has shown that lab tests can yield some of the same
results as those painstakingly obtained from outdoor field studies. To collect
their data, the ARS scientists designed elaborate soil columns and soil cell
equipment with which to observe pesticide movement through soil. They combine
data collected this way with numerous mathematically driven models.
These laboratory studies are ideally suited for helping pinpoint
information such as the total fraction of a given fumigant that ends up leaving
the soil after it's applied. This measurement, known as "cumulative emissions,"
is one of the EPAs critical data requirements for obtaining approval for
Yates is quick to acknowledge that field studies will always be needed
to tie lab-based findings to real-world agricultural landscapes. Thats
because laboratory methods cannot provide certain emissions data that are
linked to prevailing weather conditions, agricultural practices and other
more about this research in the October 2007 issue of Agricultural
ARS is the U.S. Department of
Agriculture's chief scientific research agency.