Did you know that certain kinds of charcoal can be used as a soil amendment to revitalize exhausted and polluted land? And that doing so on a global scale could seriously jumpstart efforts to claw back the atmospheric greenhouse gases that are driving global warming? And that one of the neat side effects would be massive increases in the otherwise dismal nutritional quality of the food we all consume?
Heterotrophs of Earth, prepare to reduce your intake of multivitamins and dietary supplements. We are standing at the precipice of a global revolution in human and ecological health, thanks to a very special new/old soil fertilizing technology. It’s called “biochar,” and it’s not just the latest soil additive. It has become the rising star in a larger movement toward sustainable agro-ecology and ‘carbon farming’ for the good of the planet.
Biochar is a special kind of charcoal produced from waste biomass, i.e. plant waste, food scraps, wood, and basically anything else that’s biodegradable. It is worked into the soil along with compost, mulches and other organic matter. You can add it to poor or stressed soils to help bring them back to life. Many farmers see increased yields right away. Over time, the carbonaceous particles nurture a strong, biodiverse soil food web and, in turn, vigorous food crops with much higher nutritional content than what now seems normal.
Biochar’s unique properties arise in the transformation of biomass into black (elemental) carbon through partial burning or “pyrolysis,” resulting in a transitional substance that effectively bridges the gap between organic and inorganic carbon. In the ground, each charred particle acts like an electric sponge, equipped with electrically active surfaces that stimulate communications and nutrient exchange in the surrounding soil. Open spongelike pores harbor surpluses of nutrients, water and air, ensuring growing plants can always access what they need to thrive.
Beyond enhancing fertility and increasing yields, biochar can also help decontaminate polluted soils, ‘lime’ acidic soils, and desalinize salty soils and waters. It can help protect growing plants and subterranean biodiversity from sadly common threats skulking about in the soil, such as pharmaceutical residues and toxic heavy metals.
Biochar can do a lot of cool things under the right conditions. But what’s really made it a hot buzztrend is its emerging potential for carbon sequestration in the fight against global warming.
The rise of biochar highlights a neglected truth: The flip side of too much carbon in the atmosphere is too little carbon in the ground. While the atmosphere abhors a carbon excess, carbon is what fuels a living pedosphere. Thus, the flip side of the current atmospheric warming crisis is the world’s catastrophically depleted soils.
Turns out, modern civilization has done little to sustainably manage its agricultural soils; consequently, now we are facing a worldwide soil crisis, verging on collapse in some regions. The problem is pervasive: minimally arable lands are becoming fewer with each passing year, even as agro-industrial projects continue to strip soils’ of their carbon wealth without giving any back. The UN has warned that humanity has something like six more decades of carbon-depleting agriculture before the crops won’t grow anymore, no matter how much fertilizer we add.
In contrast, biochar is like the opposite of coal: instead of mining and releasing carbon into the air, we can put it back in the ground where it belongs, where it’s actually needed to relieve the carbon scarcity that practically defines the soil fertility crisis. Hence, biochar’s popularity amongst practitioners of “climate farming” or “carbon farming.”
Carbon farming is a way anyone who grows plants can do their part to help re-balance the global carbon cycle. Climate farmers practice regenerative agriculture, which emphasizes the cyclical return of carbon-rich biomass to the soil. The key to successful carbon farming is persistently high levels of soil organic matter, and that’s where biochar can contribute – by promoting humification. Humus is a mature, complex and more stable form of soil associated with high fertility levels. Biochemically stabilized forms of black carbon like biochar seem to enable humus formation, although the precise mechanisms are not well understood.
The molecular stability of biochar is the foundation of its carbon sequestration potential. It is highly resistant to biodegradation, with an estimated 1,000 to almost 14,000 years of soil residence time. If these figures are true, biochar could be just the biotechnology humanity needs to transform carbon-depleted lands around the world into long-term carbon sinks, much more quickly and efficiently than with organic farming alone.
In 2010, researchers calculated that the world could safely sequester away as much as 12 percent of global carbon emissions by sustainably recycling waste biomass into agricultural chars. Probably, we won’t truly know its potential until we’ve seen its effects develop across a diversity of contexts over the long term. Legend has it that biochar really shines in the fullness of time.
In the age of gene-splicing high-biotech adventurism, biochar comes across as a modest, low-tech proposal. Perhaps suspiciously so. One might justifiably ask what specifically is new about biochar, apart from the neologism.
After all, it’s just charcoal…Well, sort of. It’s more of a cousin of charcoal. They are similar in some ways. Most obviously, both are made of black carbon, “BC.” BC is what gives charry soils their dark chocolate-to-midnight coloring – often a sign of fertility. (However, there are many ways to cook your carbon, and not all of them result in an allotrope you’d wanna use in the soil that grows your food. FYI: Cooking charcoals are not interchangeable with biochar!)
In fact, the char-as-fertilizer concept isn’t new to humans. Its global/modern incarnation, labeled “biochar,” was first inspired by ancient practices evidenced by extraordinary soil excavations in the Amazon rainforest of South America, home of the famous "Terra Preta” soils. These superior, evidently manmade soils – still ultrafertile thousands of years after deposition – somehow outgamed the typically nutrient-poor conditions of the ambient rainforest. How did Terra Preta’s human cultivators do it?
Researchers have since done a little more digging and found that charcraft has long been practiced by numerous indigenous cultures in order to sustain productive soils across human generations — for example in West Africa, where traditionally prepared African Dark Earths boast three times as much organic carbon as nearby unmanaged land. These priceless locally-crafted Dark Earths keep the communities that tend them well-fed and healthy – in a part of the world where the soil is extremely degraded and drought is common.
So, what’s really new about biochar is its belated “discovery” by modern civilization, and its 21st-century juxtaposition with the climate crisis (itself only grudgingly “discovered” by the same).
Another way to think of it: The “biochar” concept is a behavioral prescription in disguise — Stop neglecting the soil! It supplies a clever narrative, drawing on ancient knowledge and indigenous practices, that has successfully galvanized thousands of people around the world to take concrete action to fight global warming, while helping to heal injured soil systems and make everyone healthier in the process…Not bad for a bit of charcoal.