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Dear EarthTalk: What effects do fertilizers, pesticides and herbicides used on residential lawns or on farms have on nearby water bodies like rivers, streams-or even the ocean for those of us who live near the shore? -- Linda Reddington, Manahawkin, NJ
 With
the advent of the so-called Green Revolution in the second
half of the 20th century—when farmers began to use technological
advances to boost yields—synthetic fertilizers, pesticides
and herbicides became commonplace around the world not only
on farms, but in backyard gardens and on front lawns as well.
These chemicals, many of which were developed in the lab
and are petroleum-based, have allowed farmers and gardeners
of every stripe to exercise greater control over the plants
they want to grow by enriching the immediate environment and
warding off pests. But such benefits haven’t come without
environmental costs—namely the wholesale pollution of
most of our streams, rivers, ponds, lakes and even coastal
areas, as these synthetic chemicals run-off into the nearby
waterways.
When the excess nutrients from all the fertilizer we use
runs off into our waterways, they cause algae blooms sometimes
big enough to make waterways impassable. When the algae die,
they sink to the bottom and decompose in a process that removes
oxygen from the water. Fish and other aquatic species can’t
survive in these so-called “dead zones” and so they
die or move on to greener underwater pastures.
A related issue is the poisoning of aquatic life. According
to the U.S. Centers for Disease Control (CDC), Americans alone
churn through 75 million pounds of pesticides each year to
keep the bugs off their peapods and petunias. When those chemicals
get into waterways, fish ingest them and become diseased.
Humans who eat diseased fish can themselves become ill, completing
the circle wrought by pollution.
A 2007 study of pollution in rivers around Portland, Oregon,
found that wild salmon there are swimming around with dozens
of synthetic chemicals in their systems. Another recent study
from Indiana found that a variety of corn genetically engineered
to produce the insecticide Bt is having toxic effects on non-target
aquatic insects, including caddis flies, a major food source
for fish and frogs.
The solution, of course, is to go organic, both at home and
on the farm. According to the Organic Trade Association, organic
farmers and gardeners use composted manure and other natural
materials, as well as crop rotation, to help improve soil
fertility, rather than synthetic fertilizers that can result
in an overabundance of nutrients. As a result, these practices
protect ground water supplies and avoid runoff of chemicals
that can cause dead zones and poisoned aquatic life.
There is now a large variety of organic fertilizer available
commercially, as well as many ways to keep pests at bay without
resorting to harsh synthetic chemicals. A wealth of information
on growing greener can be found online: Check out Organic
Gardening Guru.com and the U.S.
Department of Agriculture’s Alternative Farming System
Information Center, for starters. Those interested in
face-to-face advice should consult with a master gardener
at a local nursery that specializes in organic gardening.
FURTHER READING:
CDC
Organic
Gardening Guru
USDAs
Alternative Farming System Information Center
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