In 1542, the Spanish explorer, Francisco de Orellana ventured along the
Rio Negro, one of the Amazon Basin's great rivers. Hunting a hidden city
of gold, his expedition found a network of farms, villages and even
huge walled cities. At least that is what he told an eager audience on
his return to Spain.
The prospect of gold drew others to explore the region, but none could
find the people of whom Orellana had spoken. The missionaries who
followed a century later reported finding just isolated tribes of
hunter-gatherers. Orellana's story seemed to be no more than a fanciful
With no trace of such a vast civilization in an area so inhospitable to
agriculture, who would conclude differently? Without extensive
agriculture major population centers could not have existed, but in the
Amazon all attempts at intensive agriculture have led to disaster. That
is until researchers began to question the mysterious presence of terra
The Secret of the
The search for clues in the
Amazon takes place right at the grass roots level - in the soil itself.
Along Brazil's Tapajos River, archaeologist Bill Woods has mapped
numerous prehistoric sites, some with exquisite, 2,000 year old pottery.
There is a common thread: the earth where people have lived is much
darker than the surrounding yellow soil of the rainforest. Closer
investigation showed that the two soils are the same, but the dark loam
is enriched with biological matter. The Brazilians call this fertile
ground terra preta. It is renowned for its productivity and
even sold by local people.
Archaeologists have surveyed the distribution of terra preta
and found it correlates favorably with the places Orellana reported back
in the 16th century. The land area is immense – the size of California
(or twice the size of the Britain). It seems the long ago Amazonian
peoples transformed the earth beneath their feet. The terra preta
could have sustained permanent intensive agriculture, which in turn
would have fostered the development of advanced societies.
Archaeologists like Bill Petersen, from the University of Vermont, now
regard Orellana's account as highly plausible. But if the first
Conquistadors told the truth, what became of the people they described?
Tragically, the visitors brought diseases to which the Amerindians had
little resistance: smallpox, influenza, measles. Orellana and his men
were the first and last Europeans to set eyes on an Amazonian
civilization. They themselves may have been the ones to trigger its
Yet the Amazonians' greatest achievement lives on. Soil scientists
analyzing the terra preta have found its characteristics
astonishing, especially its ability to maintain nutrient levels over
hundreds of years. By comparison, traditional slash and burn practices
yield a type of nomadic farming that can sustain only a few. Even modern
techniques have simply led to ecological catastrophe with vast swathes
of forest being cleared, only for the land to be abandoned. With the
vegetation burned off, the high rainfall soon leaches all the nutrients
out of the soil. Research has shown that even chemical fertilizers
cannot maintain crop yields into a third consecutive growing season, yet
terra preta remains fertile year after year.
Local farmers testify, “The soil is easy to work and very fertile. We
plant papaya, we plant banana, corn, beans and manioc in terra preta.
Whatever you plant in terra preta does exceptionally well.” Terra
preta is so fertile that Brazilian farmers have prized it for
centuries. Somehow the prehistoric Amazonians transformed the world's
worst soil into some of the best.
Nature and Nurture
Again, Orellana's accounts
offer potential insight. He reported that the indigenous people used
fire to clear their fields. Bruno Glaser, from the University of
Bayreuth, has found that terra preta is rich in charcoal. He
believes it acts to hold the nutrients in the soil and sustain its
fertility from year to year. This is the great secret of the early
Amazonians: how to nurture the soil towards lasting productivity. In
experimental plots, adding a combination of charcoal and fertilizer into
the rainforest soil, Glaser recorded an 880% increase in yields
compared with fertilizer alone.
Yet terra preta may have a still more remarkable ability.
Almost as if alive, it appears to reproduce. Bill Woods has met local
farmers who mine the soil commercially. Farmer, “After digging the
soil,what is left will grow deeper. It's because it's being fed by the
leaves that fall on it.” Like the lump of dough once saved from a batch
of bread making to leaven the next batch, these farmers find that, as
long as they leave 20cm of terra preta undisturbed, the bed
will regenerate over a period of about 20 years. He suspects that a
combination of bacteria and fungi is causing this effect.
Today the Amazon rainforest is under threat as never before. Millions of
acres have been wiped out and every year farmers continue to slash and
burn their way across the jungle in a largely futile attempt to turn it
into farmland. Meanwhile, scientists are busy searching for the
biological cocktail that makes barren earth productive. Scientists are
now working to find out how terra preta does it. There are
literally tens of thousands of species of bacteria and fungi in the soil
and they suspect that somewhere among them must be unique
microorganisms that allow the terra preta to grow. If they can succeed
in recreating the Amerindians' terra preta, then a legacy more
precious than the legendary golden city of El Dorado could spare the
rainforest from destruction and help feed people across the developing
I see two ironies in the story of the hunt for El Dorado. There was once
a great civilization in the Amazon, one the Europeans destroyed even as
they discovered it. And, one has to wonder if that ancient civilization
had understood the healing virtues of charcoal for sick bodies as they
evidently did for sick soils, they may have survived their European
guests. Today, that black earth, the terra preta, and its
supernatural ingredient charcoal may offer the solution to more than
just our small vegetable gardens.
Who will benefit most if the bio/chemical secret of terra preta
is ultimately unlocked? It could have profound effects on tropical
agriculture, especially in light of a worldwide crisis in soil
fertility. Terra preta seems especially suitable for the
cultivation of fruit and vegetables, what we would call market
gardening. These crops have high economic and nutritional value for poor
farmers in the developing world, and they would be the main
beneficiaries if it could be recreated on a wide scale in local
To learn more how charcoal can serve you in your garden or on your farm
we recommend the book: CharcoalRemedies.com
The Complete Handbook of Medicinal Charcoal & Its Applications.