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Terra Preta

The Magical Soils of El Dorado

I wanted to share information from an article I read in the Winter 2006 #50 edition of the UK’s Permaculture Magazine. On page 41 writer Karen Carmichael-Timson shows us how Terra Preta, also known as Indian Black Earth, may help revolutionize the way we revitalize depleted soils.

In 1542 Spanish Conquistador, Francisco de Orellana, claimed to have discovered a huge civilazation that stretched many miles along river bluffs with roadways and settlements. 100 years later, missionaries found no evidence of them ever existing in the Amazon Basin where he claimed he visited them. The soil there is typically thin, nutrient starved, subjected to intense rain and contains a high concentration of aluminum making it unable to grow food for tens of thousands of people. So the missionaries wrote off his stories claiming that this civilization could not have existed.

Recent investigations have discovered man-made structures, causeways and canals that can compete in their size and complexity with the ruins of Egypt. Along with these discoveries they found man-made soils that are extremely fertile and maintain their fertility for hundreds of years. It is so fertile that local farmers mine the original Terra Preta soil and sell it as a starter to generate new Terra Preta soil. It contains high levels of nutrients, soil bacteria, charcoal and arbuscular mycorrhizal fungi unique to the region. The villagers in the long lost civilazation had thrown fish and animal bone, shells, and human and animal manure into the soil then used a slash and char technique which adds black charcoal to the mix retaining 50% more of the biomass that the slash and burn technique. The charcoal acted as a sponge absorbing the nutrients and holding onto them during the intense rainfalls. When tested at the University of Bayreuth in Germany, the addition of this charcoal was found to raise the soils fertility by 880%! Terra Preta is considered an Anthrosol or anthropogenic soil, one that had been highly modified through human activity and the addition of organic resources. These are located only where humans have practiced agriculture for very long periods of time. What makes Terra Preta so different from other anthrosol soils is the addition of the black carbon. Cornell University is leading the study into these soils. The mycorrhizal fungi have been found to play a major role in the soils regeneration process.

Ms. Carmichael suggests that we may use the slash and char technique with a planned cycle of resting to allow the same area of land to be used indefinitely. She claims that, to help renew our soil, it is not the Terra Preta that we need to export but the techniques used to create it. She also suggests that the future of humanity may rest on us relearning what our ancestors once knew.