Deutche Bahn (German Railways) has
commissioned a study-the Evaluation and Development of Methods of Control
of Railway Vegetation-from the Eco-Institute of Freiburg.
German Railways relies on herbicides to clear vegetation on
72,000km of railway lines, and is the country's biggest single user of
herbicides on uncultivated land, overseeing the use of 250 tonnes of chemicals
per year.
The report cites monitoring evidence indicating that
herbicides such as bromacil and diuron used on the railways cause significant
contamination of water resources-especially ground water. In the 1980s German
Railways used a wide range of chemical herbicides. But now, the use of the
foliar-acting herbicide glyphosate predominates, after the soil-acting diuron
was first withdrawn and, finally banned for use on railways last year.
Researchers are experimenting with an 'optoelectronic
sensor' that applies selective herbicides in sequence. The first calculations
suggest a 50% reduction in the quantities of chemical used.
The Frauenhofer Institute for Environmental Chemistry and
Eco-toxology (IUTC) is working on a parallel project assessing the environmental
risks of herbicide use and is looking for radical improvement by developing and
eventually introducing new products.
The IUTC has tested trains with sprays but the models have
indicated no appreciable reduction in the application of herbicides.
German Railways claims, on the evidence of (unpublished)
freelance studies, that herbicide pollution of groundwater can occur directly
through cracks in the soil or through fissures in vertical structures that are
opened up by trains passing over at speed.
The Eco-Institute recommends a mixture of methods. Protecting
groundwater must take priority and therefore the use of herbicides should, as
far as possible, be avoided or, at the very least, significantly reduced. For
areas of high-speed track there are at present no alternatives to herbicide use
in prospect.
The attitude of German Railways makes it unlikely that there
will be a total withdrawal of herbicides in the future as it merely hopes for a
wider spectrum of effective chemicals to become available.
Currently DM 9.5 million (US $17.1 million) is available for
the project Integrated Management of Vegetation and also DM 60 million is
for more intensive upkeep of railway embankments, headlined as Green on the
Line. There is some suspicion that the project aims to gain greater
acceptance of the use of herbicides, but German environmentalists hope that
non-chemical procedures will be applied more frequently in future. The publicity
created by the success of recent conferences could be built on by making
research findings and data on vegetation control easily available to interested
bodies. The Eco-Institute's study, which is finished and has been submitted to
German Railways, should also be made public.
Pestizid Brief, May 1997.
[This
article first appeared in Pesticides News No. 37,
September 1997, page 9]