Ancient Amazonian technology could save the world

Terra Preta—the charcoal-based “black earth” crafted by ancient Amazonians to create permanently fertile farmland in the rainforest—is attracting fresh attention as scientists look for ways to fight global warming and boost crop yields, reports Scientific American.

The soil is easy to distinguish from typical Amazon earth by its dark color and mineral richness. Researchers believe pre-Columbian peoples produced it by mixing charcoal and animal bones into ordinary soil, creating an exceptionally fertile medium for agriculture.

Charcoal is the key ingredient: its porous structure binds organic compounds, holds moisture and nutrients, and resists oxidation.

On its own, charcoal supplies few nutrients, so Indigenous farmers enriched the mix with organic waste—turtle shells, fish remains, bird bones—leaving Terra Preta far richer in calcium, nitrogen, phosphorus, and sulfur than surrounding soils.

Properly managed, it also resists the yield “fatigue” that plagues most tropical farmland.

Although the exact formula was lost with the destruction of many Amazon cultures, soil scientists are experimenting with pyrolysis—heating biomass at high temperatures in the absence of oxygen—to recreate the effect.

The process yields “agrichar” (a charcoal soil amendment) plus bio-oil, a mix of oxygenated hydrocarbons that can be burned for heat or electricity, writes Anne Casselman for Scientific American.

Because agrichar decomposes only slowly, it can lock away its carbon for centuries instead of releasing it quickly to the atmosphere as greenhouse CO₂. In the process it boosts farm productivity by retaining nutrients and moisture.

Additional benefits, Casselman notes, could include:

• Greater bio-oil output, reducing dependence on imported petroleum.
• Higher tropical soil productivity—multiple harvests per year—easing pressure to clear new forest and thus protecting biodiversity.
• New income streams for farmers, much as global ethanol demand has strengthened corn prices in rural areas.
• Potential relief for coastal “dead zones”: by holding nitrogen and phosphorus in place, agrichar could cut fertilizer runoff into waterways.
• A productive use for sewage sludge and animal manure that would otherwise pollute oceans.

Despite Terra Preta’s promise, large-scale adoption has lagged outside academic circles.

That may change: U.S. Senator Ken Salazar (D-CO) is drafting farm-bill language that could channel federal research and implementation funds to agrichar projects, Casselman reports.

Even so, some experts doubt modern science can fully reproduce Terra Preta.

“The secret isn’t just charcoal and chicken manure—you need much more,” says Bruno Glaser, a soil scientist at the University of Bayreuth, Germany.

Achieving the right blend of stable charcoal and composite material might take “50 or 100 years,” he cautions. Stanley Buol, emeritus professor of soil science at North Carolina State University, is similarly skeptical: “It will look black and nice, but will it supply enough plant-growth ions like phosphorus and nitrogen?”

Deforestation flares again under Bolsonaro
Successful conservation examples remain rare in Brazil.

After the far-right election of Jair Bolsonaro last year, his administration has rushed to open the Amazon to commercial interests.

Loggers and land burners have benefited first.

Deforestation, already high, has surged: August’s forest loss was 222 percent greater than in the same month a year earlier—an area roughly the size of a soccer field disappearing every minute.

“Around here, law enforcement stopped being taken seriously after Bolsonaro’s election,” said a ranger with Brazil’s National Park Service in the western state of Acre.

“People cut and burn because they know no one will stop them.”

Bolsonaro and his allies argue that the rainforest is a natural resource that should be exploited, especially in a nation where many citizens live at or near the poverty line.

They claim that international concern for the Amazon ignores Brazil’s development needs even as wealthy countries have already destroyed much of their own wilderness.

The president’s stance has sparked global outrage and revived debate over how best to manage the rainforest.

Scientists, entrepreneurs, and environmentalists increasingly believe that advances in science and technology—such as agrichar—could promote sustainable development while combating deforestation.

Source: brasil.mongabay.com

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