An Old Idea, Backed by Modern Science
Indigenous Amazonians created some of the world's most fertile soils using charred biomass over 2,500 years ago. Today, peer-reviewed research confirms what they discovered: biochar locks carbon away for millennia while improving the land it's applied to.
What Is Biochar?
Biochar is charcoal made for soil, not for burning. It's produced by heating organic material like wood, agricultural waste, or forestry residues in a low-oxygen environment. This process is called pyrolysis, and it typically happens at temperatures between 350°C and 700°C.
The result is a stable, carbon-rich material. The carbon in biochar is arranged in structures that resist breakdown by microbes, which is why it can persist in soil for centuries to millennia.
What makes biochar useful is its structure. It's full of tiny pores that hold water and nutrients, and provide habitat for beneficial soil organisms. A single gram of biochar can have a surface area larger than a tennis court.
What Biochar Does for Soil
Holds Water
The porous structure acts like a sponge, keeping water in the root zone where plants can use it during dry periods.
Up to 18% more plant-available waterSource: Zhou et al. (2018), 8-year field trial, sandy loam soil
Improves Yields
Studies show yield improvements that compound over time. Some tropical trials have seen gains of 20%, 30%, even 140% by year four.
13-20% average yield increaseSource: Liu et al. (2013); Biederman & Stanley (2013), meta-analyses of 100+ studies
Retains Nutrients
Biochar binds to nutrients and prevents them from washing away, keeping them available for plants to use.
Up to 37% less nitrate leachingSource: Jiang et al. (2022), sandy-loam soil study
Terra Preta: 2,500 Years of Evidence
In the Amazon Basin, scattered across thousands of hectares, there are patches of unusually dark, fertile soil. The Portuguese called it Terra Preta de Índio, meaning "black earth of the Indians."
These soils were created by Indigenous communities between 450 BCE and 950 CE. They mixed charcoal with organic waste, bones, and pottery shards. The result was soil that remains productive today, despite centuries of tropical rainfall that would strip nutrients from ordinary ground.
Modern analysis shows exactly why: the charcoal is still there, still holding nutrients, still supporting plant growth.
"The charcoal is stable and remains in the soil for thousands of years, binding and retaining minerals and nutrients."
Want to use biochar on your land?
Whether you're exploring biochar for your climate strategy or just curious about the science, we're happy to talk.