Back to top

Food

Biochar

Researchers and archeologists from Embrapa, a network of Brazil’s agricultural research stations, hover around an excavation showing how deep biochar (terra preta) is buried in Amazonian soils. In Manaus, the Embrapa staff has planted annual crops in terra preta–laden soils for forty years and has been unable to exhaust or ruin their fertility or productivity. Some scientists call the potential of terra preta nova the equivalent of a “black revolution” in agriculture.

In ancient Amazonia, the waste disposal method of choice was to bury and burn. Wastes were baked beneath a layer of soil. This process, known as pyrolysis, produced a charcoal soil amendment rich in carbon. The result was terra preta, literally “black earth” in Portuguese. Today, terra preta soils cover up to 10 percent of the Amazon basin, retaining extraordinary amounts of carbon.

These ancient roots of what is now called biochar have modern promise for agriculture and the atmosphere. Biochar is commonly made from waste material ranging from peanut shells to rice straw to wood scraps. During the slow baking of biomass in the near or total absence of oxygen, gas and oil separate from carbon-rich solids. The output is twofold: fuels that can be used for energy and biochar that can be used to enrich soil.

When biomass decomposes on the earth’s surface, carbon and methane escape into the atmosphere. Biochar retains most of the carbon present in biomass feedstock and buries it. Rendered stable, that carbon can be held for centuries in the soil—a much-delayed return to the atmosphere. Theoretically, experts argue, biochar could sequester billions of tons of carbon dioxide every year.

Technical summaries for each solution will be available May 1, 2017.

Back to top

Join Us

We would like to stay in touch with you. Please sign up for updates to discover ways you can participate in the work of Drawdown.


Contact

Click to expand
Please send me more information about ways that I can participate as: (check all that apply)