Discovery of Black Earth plots in Amazon area uncovers facts about the benefits of Charcoal as a soil additive

Floris56 By Floris56, 26th Sep 2011 | Follow this author | RSS Feed | Short URL
Posted in Wikinut>News>Environment

Research continues to point toward ancient amazonian Indians as the creators of many plots of very fertile black soil, in the midst of very poor, leached and eroded native soil. Charcoal is the main additive to the soil , along with shards from hundreds of clay pots. Further research shows that charcoal added to soil has many benefits such as stabilizing the soil, defending it from leaching and erosion, better nutrient retention and promoting growth of needed microbes in the soil.

Read further to learn the possible ramification of this important discovery

The discovery of scattered plots of extremely fertile black soil in The Amazon river basin of Brazil has prompted intense scientific investigation and spawned new energy technologies in some parts of the world. Generally the soils in this rainforest area of Brazil are devoid of nutrients due to intense tropic rainfall and resulting leaching and erosion. Why all the excitement over a bit of black dirt?

Scientists have solid evidence that hundreds of years ago Indians used a method of jungle clearing called “slash and char”. This method differs from “slash and burn” in one very important respect. Using “slash and burn”, trees were felled and burned in the open air. Smoke rose into the atmosphere, carrying with it CO2 and other unburned gases. Using the “slash and char” method the early farmers felled the trees and “cooked” the logs using one of two possible methods. They could pile the logs up and cover the pile with dirt and straw. Or they could have dug massive pits, into which they threw the logs, again, covering them with sod and straw. When the logs were set on fire they would produce trapped combustible gases which would burn very slowly deep within the covered pile. Since the wood is oxygen deprived by being covered with dirt the carbon in the wood could not combine with oxygen to form CO2. The carbon simply sat there in the form of charcoal. The pile probably smouldered for many days before it was cool enough to uncover. The farmers could then harvest the charcoal. So what would a farmer of primitive methods do with a few tons of charcoal? After all, about half of the weight of each tree was made up of carbon, so there was a lot.

Scientists theorize that the charcoal was spread over the future fields. They attribute the spreading of carbon over these fields to human beings because, along with the charcoal, they found shards of pottery. The assumption is that these farmers knew not only the merits of spreading carbon over their fields, but they knew something about aeration also. They used the pottery shards to aerate the soil. In addition to Charcoal and pottery researchers found evidence of household waste strewed about, presumably to enrich the soil that was normally lacking such nutrients.

So what are these much ballyhooed merits of spreading charcoal on farm fields? Leaching and erosion are big problems in rain forest country. Carbon in the soil acts to absorb moisture and stabilize the soil. Nutrients cannot as easily soak down through the large and abrasive charcoal structures. The charcoal holds them into the upper layers of soil . . . for centuries. Scientists are learning still more about the benefits of carbon in the soil. Experiments that test the stability of carbon rich soils compared to carbon poor soils are still in progress. Water flowing over carbon rich soils loses much of its erosive power. Water that does percolate through the carbon rich soil is cleaner when it finally flows from a well or spring. Further, carbon rich soil is also rich in microbial fungi. These beneficial microbes help break down nutrients, rendering them usable for new plant life.

Charcoal production is certainly not new, but engineers in Japan are experimenting with producing electricity by cooking wood and using excess heat to run steam powered, electricity generating turbines. The charcoal produced by the process can then be sold to farmers in areas where leaching and erosion is a problem. Even ordinary farm fields can benefit from carbon since any fertilizers (natural or chemical) used on carbon rich fields will retain the nutrients longer when used on carbon rich soil. Less fertilizer is needed.

James Orton, a geologist and explorer from Vassar College first described the Black Earth of Brazil (know also as Terra Preta de Indio) In 1870 in his book, The Andes and the Amazon.

Most research activity generated by interest in the black Earth discoveries has taken place overseas. Two American professors, Cornell University’s Johannes Lehmann and University of Wisconsin’s William Woods, have done most of the work in the United States.

Given the legislative power of the chemical companies, that produce and sell chemical fertilizers, we are not likely to see much funding of research in anything that might threaten the chemical company’s lock on the agriculture business. The status quo has been very kind to them. They will kindly teach us that progress is not necessary.


Amazon, Black Earth Black Soil, Boiler, Brazil, Carbon, Carbon Dioxide, Charcoal, Co2, Discover, Energy, Environment, Jungle, Pottery, Retort, Scientist, Shards, Slash And Burn, Soil, Steam, Terra, Terra Preta

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author avatar Floris56
I am a retired science librarian and data archivist. I usually write science articles or fiction.
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author avatar amberdextrous
26th Sep 2011 (#)

A wonderful account of an early -and apparently sucessful- carbon capture and storage system. Thank You for this interesting information, Amos.

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author avatar Ptrikha
15th Mar 2013 (#)

Incredible science! This shows that we must try to engage local tribal communities and provide them supporting environment. In turn, their traditional knowledge and wisdom can help us also.

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