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 Did
you know 10 percent of the crops irrigated around the world are
watered with sewage? Crops as diverse as lettuce and mangoes are
being watered with raw, untreated sewage directly from pipes into
fields near major world cities, according to a recent survey.
What's even more surprising: Farmers like to irrigate their
crops that way, because the smelly, pathogen-rich sewage is rich
in phosphates and nitrates and serves as a free fertilizer. And,
governing agricultural bodies outlaw the practice; even though they
are well aware farmers do it anyway.
Almost 50 million acres of farmland around the world are irrigated
with sewage. In fact, sewage is probably the largest source of water
for urban farming that provides 20 percent of the world's food.
Other interesting facts about growing food worldwide with sewage:
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A fourth of the vegetables grown in Pakistan, including salad
crops, are irrigated in sewage. In fact, land watered by sewage
is twice as valuable as those that use clean water
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One African farmer grows 12 crops of lettuce each year in his
sewage farm
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Some countries (Mexico, Israel, Tunisia and Jordan) treat sewage
to remove pathogens for safer irrigation but in others (Indian,
China and Pakistan) treatment is rare
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In one Indian city (Hyderabad), virtually all the crops grown
there are watered with sewage
To say the least, many people probably wouldn't buy vegetables
at stores if they were aware how they were grown which is why many
farmers ship produce to distant markets. Unfortunately, the survey
found banning the use of sewage to water crops just isn't workable.
That's why some experts are urging governments to recognize
sewage can be a good resource after all and to show farmers how
to better utilize it.
New
Scientist August 18, 2004
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