This is the VOA Special English Agriculture Report , from
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South America's
Amazon is the largest tropical rainforest and river system on Earth. But the
Amazon is disappearing at the rate of about eight hundred thousand hectares a
year. This deforestation is caused by an increase in agriculture and cattle
ranching and the building of roads and dams. Another cause is the illegal
cutting of trees for logging companies. Now, a new study says ancient Amazonian
farming methods could offer valuable lessons for today. The study looks at the
pre-Columbian period. Christopher Columbus and other European explorers began
arriving in the Americas in the late fourteen hundreds. The researchers studied
a coastal wetland area where ancient farm beds and canals remain unchanged. The
site is in French Guyana. A widely held belief is that pre-Columbian farmers
used a great deal of fire to manage Amazonian ecosystems. But the scientists say
their study calls this idea into question. It shows that raised-field farmers
limited their burning to improve agricultural production.Jose Iriarte from the
University of Exeter in England was lead author of the study. Mr. Iriarte says
fire results in the loss of important nutrients for crops. When land is not
being used for farming, periods without fire are most effective in rebuilding
soil organic matter and preserving soil structure. "So in this sense," he says,
"we interpreted that they were limiting fires because it was better to grow
crops in these raised field systems." He says this fire-free method by the
pre-Columbian farmers helped change the seasonally flooded savanna, or
grassland, into productive cropland. Raised fields provide better drainage and
soil aeration and also hold moisture during the dry season. This fire-free
method of agriculture would have been labor intensive. It ended when up to
ninety-five percent of the native people died from diseases brought by the
Europeans. Mitchell Power from the Natural History Museum at the University of
Utah says, "Once the Columbian encounter happens ... we start to see increased
burning and a shift towards dry-land farming." People were then clearing forests
and making their raised beds in the forests. The European colonizers brought
slash-and-burn methods that remain a threat to the rainforest. Experts say at
current rates, more than half of the Amazon's tropical rainforest could be gone
by twenty-thirty. The study is in the Proceedings of the National Academy of
Sciences. For VOA Special English, I'm Carolyn Presutti. (Adapted from a radio
program broadcast 17Apr2012)
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