Does Biochar hold the key to natural carbon sequestration?

By Laura Porter-Jacobs on 10th September 2014.

Biochar technology is a novel approach to reducing atmospheric carbon dioxide (CO2) concentrations by retaining carbon in soils. Biochar is a manmade substance, an organic matter that is transformed into a charcoal by pyrolysis, the thermal decomposition of organic material, in a low oxygen (O2) environment. This process occurs at a relatively low temperature, below 700°C.

The product of this pyrolysis has a high chemical stability with a carbon content that can reside in soils for decades as evidenced in the discovery of Amazonian Dark Earth. This Amazonian Dark Earth otherwise known as 'terra preta do índio' is a soil that was developed by Amazonian civilisations hundreds of years ago in order to improve the fertility of the poor and acidic tropical soils in the region. A key component of the soil is its biochar.

This soil, and the biochar it holds, have remained stable for hundreds of years with sizeable deposits still found today, as shown in the below photo. Current research is analysing the persistence of biochar in a range of soils and ecosystems. To date, biochar has been determined as significantly more persistent in soil than any other organic matter.

Pre-Columbian biochar found in Kuelap, Amazonas, Peru, picture by Laura Porter-Jacobs

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