Too much of a good thing is bad. Just
as too much food leads to obesity and tight pants, too much fertilizer
contaminates the land and water we depend upon for food even while aiding the
production of that food. The main
environmental problem associated with fertilizer abuse is contamination of
water with nitrates and phosphates, and the main
problem with stories like this is that the technical explanation often goes in
one ear and dribbles out the other. I’ll try to simplify the story here.
Only a fraction of nitrogen-based fertilizer is
absorbed into plant matter. The rest accumulates in the soil where it is
eventually converted by bacteria to nitrates, or is lost as run-off. Nitrates are highly water-soluble, and leach
into ground water or wash out of the soil into streams and rivers. High nitrate
levels in drinking water are dangerous to human health. Because nitrogen is odorless and colorless, only testing can determine
whether contamination has occurred. In January 2013, the California State Water
Resources Control Board reported that more than 400 private wells and more than
200 water systems in the state were contaminated with nitrates.
When babies and the elderly drink water with high
nitrogen levels, they can develop symptoms such as gastrointestinal swelling
and irritation, diarrhea, and protein digestion problems—a condition called
methemoglobinemia, or "blue baby syndrome." Infants whose skin
tissues are low in oxygen appear to be blue or purplish in color. This occurs
when nitrates mix with iron in red blood cells, leaving the blood unable to
transport oxygen to the body's cells. Nitrates are dangerous enough; now let’s
take a look at phosphates.
Although phosphorus itself is not washed out of
soil, it combines with soil particles and travels with them to shallow water. Phosphorus is not dangerous by itself, but in
slow-moving water, it stimulates the growth of algae. Algae is not dangerous either – until it dies and decomposes removing oxygen from the water.
This kills fish and many other organisms.
Scientists, never at a loss for unpronounceable obscure words, call this
process eutrophication.
The lethal combination of excess nitrates and
phosphates constitutes pollution that should be mitigated, but fertilizer is
not the sole culprit. Other sources of these pollutants include industrial
waste, sewage, detergents and manures. The problem of high nitrate levels in
groundwater was actually recorded as early as 1860, long before synthetic fertilizer
was invented.
A
Little History…
In
the 1910s and 1920s, Fritz Haber, a bespectacled German chemist, devised a way
to manufacture ammonia from methane gas (NH3) and molecular nitrogen (N2).
The ammonia from the Haber process, a process still used today, was then
converted into nitric acid which led to the development of synthetic
fertilizer—and significantly aided the German war effort. The synthetic supply
of nitric acid was explosively useful in the manufacture of munitions.
Even
more significantly than its destructive capabilities, The Haber process supported
global population growth. It has been estimated that almost half the
people on the planet are fed as a result of synthetic nitrogen fertilizer use. Ramped up to an
industrial scale, ammonia synthesis has enabled widespread fertilization of
croplands ever since. As a direct result, the world's population skyrocketed
from 1.6 billion to six billion during the 20th century.
But
Haber's nourishing discovery has a dark side. The surfeit of fertilizer has
come at a high price for the environment. And the story gets even better…
Dead zone along coast of Maryland
Fertilizer’s
Dark Side
Earth’s
surging population demands ever increasing amounts of energy, and the burning
of fossil fuels threatens the planet with catastrophic climate change as a
warming blanket of greenhouse gases warms the oceans and melts arctic ice. In
order to mitigate this problem, alternatives to fossil fuels are becoming more
attractive. Biofuels perhaps?
Biofuels production in the US consists of ethanol
manufactured from corn. Cornell University environmental biologist Robert
Horwath who also chairs the International Scope Biofuels Project says, “The
production of ethanol from corn in the US is a disaster in terms of fertilizer
flowing down the Mississippi River.”
He is undoubtedly concerned about the seasonal dead
zone spreading from the Louisiana coast to Texas—covering approximately 5,000
square miles, an area roughly the size of Connecticut. The eutrophication in
this dead zone is formed by nutrients that flush into the Gulf's waters --
largely agricultural fertilizer and wastewater from the Mississippi River. The
resulting algae blooms suck up the oxygen in deep water, according to NOAA and
the U.S. Geological Survey. Marine life struggles to find enough oxygen to
survive within the zone.
As if this scenario
weren’t scary enough already, fertilizers release significant quantities of
nitrous oxide, a greenhouse gas with 300 times the heat-trapping capacity of carbon
dioxide (CO2). Nobel laureate Paul Crutzen of the Max Planck Institute for
Chemistry in Mainz, Germany, and his colleagues worry that cultivation of current
biofuel crops, corn included, will wipe out any CO2 savings by releasing higher
emissions of nitrous oxide and nitrogen oxide. The latter destroys the so-called
“good” ozone, which shelters us from damaging ultraviolet radiation. It also contributes
to ground level ozone, the main constituent in smog, widely known to exacerbate
human respiratory ailments. According to the U.S. Environmental Protection
Agency, millions of Americans live in areas that exceed the national standards
for ozone exposure.
What
Can We Do?
Despite the dangers posed by over-use of
fertilizers, they enhance the growth of our food crops and beautify our
landscapes—so they have value. However,
there are things we can do to alleviate the effects of fertilizer pollution,
and small steps taken by many people can make a big difference.
- Before fertilizing, have your soil tested; then test every three years or so to determine the pH of your soil since crops require difference acidity levels.
- Follow package label instructions carefully and mix the fertilizer accurately.
- Do not allow excess water to run into streets or gutters, and leave a buffer zone when near a body of water.
- Apply fertilizer 4 to 6 inches into the soil using a coring device or a spike, and clean up all spilled fertilizer.
- Because plant clippings contain phosphorus, debris should be removed and not directed into the street.
- Allow soil to replenish its nutrients naturally by giving it a break from crop production and by rotating crops.
- Avoid using fertilizer during the rain, and never apply it to frozen ground.
- Use organic fertilizers that consist of manures and animal wastes when practical.
Discover Buzzle at http://www.buzzle.com/articles/how-do-fertilizers-affect-the-environment.html
Visit NOAA at http://oceanservice.noaa.gov/education/kits/estuaries/media/supp_estuar09b_eutro.html
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