Forget all those fancy ideas about pumpng CO2 into holes in the ground. A millenia-old technique could hold the key to our greenhouse gas problems and declining soil fertility .
Terra Preta is the name given to the areas of fertile ‘dark earth’ scattered throughout the Amazon basin, which explain how Indian peoples were able to sustain high agricultural outputs on generally low-fertility soils. Biomass-derived carbon (“bio-char”) was dug into the earth in huge quantities. Recent research shows that bio-char can persist in the soil for thousands of years, improving soil structure and fertility.
Millions of tons of agricultural wastes are discarded annually which can be used to produce bio-char and applied to soil. In the modern version of this age-old process, agricultural wastes and bio-energy crops can be used to produce energy by charring them in specialised power plants yielding bio-char as a by-product. The bulk of the energy would be extracted as hydrogen or bio-diesel at potentially very high levels of efficiency.
For a second opinion, go to:
Generally favourable, with the additional interesting information that bio-char may not be suitable on all soil types as it increases alkalinity.
And a link to a Nature article with details of the processes involved here.