Black Earth and BioChar
It is possible that we know less about soil biology than we know about the ocean, both invisible below the surface; vast, deep or shallow, amazingly diverse with life. And like the sea, we have only begun to learn a few of soil's creatures by name or how they have lived together in that dark community since water and wind first eroded soil's precursors from planet-plates of bedrock.
When far fewer of our kind lived on Earth and before humans shifted from nomadic to agrarian lifestyles, the soils were deep and rich. The only persistent threat to sustainable soil was weather extremes that carried soil to sea on swollen, brown torrents of stormwater.
TERRA PRETA: BLACK EARTH
The early farming tribes learned that better soil grew better crops, and over time, they discovered ways to improve yield. One of those ways is evidenced by the existence of terra preta—dark earth—at locations around the planet. It was first described in the Amazon and written about to any degree starting around 2000.
The black soils were often many feet deep and covered many acres, where villages added old bones, pottery shards and especially charcoal from their campfires. Some probably made charcoal intentionally towards sweetening the soil that grew their tended crops. Tropical soil is generally poor, but the black earth soils were noticeably more productive.
From those discoveries of terra preta and its role in producing sustainable soils came the term biochar. I was fascinated at the time, and read whatever I could find on this new OLD method of making soils better for plants.
And it turns out that biochar is also the end of the line for carbon that would otherwise find its way back into the atmosphere (through decomposition or incineration) as carbon dioxide. Biochar is essentially elemental carbon only, the end of the line for the carbon in chicken feathers, human sludge, wood chips, beet pulp or crop residue of any kind when burned (by pyrolysis not incineration) with low oxygen at high heat.
One third of the excess CO2 in the atmosphere comes from agricultural soils.
Putting carbon back in the ground where it came from (as fossil fuels or as plant material) is urgently necessary. Biochar seems to provide a double-dividend solution, improving soil quality and sequestering carbon in one go.
So see me leaning forward in my chair less than a year ago when I learned of local interest in biochar production in our county. I returned to the topic to see what had been learned and what was planned for biochar’s incorporation into modern farming soils. (There are also proposed uses for construction, filtration, odor reduction and much more.)
UP TO SPEED ON BIOCHAR TODAY
I learned all biochars are not created equal. The feedstock from which it is produced determines the physical properties like porosity and determines how well it might provide housing for essential soil microbiomes, for water, necessary soil charged particles and minerals.
I learned that not all biochars are created from the organic waste stream. As you can imagine, commercial timber interests are happy to turn standing even-aged pine trees into something other than wood pulp, if the money’s right.
I learned that not all soils or all crops benefit equally or immediately from the addition of biochar, and that biochar works better if pre-innoculated with a microbial population supplied by mixing with moist compost.
I’ve been disappointed by the fact that my Google Alerts for the term biochar return mostly reports of MARKET GROWTH and financial speculation for turning nature into profit. It does look like some folks are going to get rich from this technology, so follow the money. And mind the green-washing.
Modern soils tend to be yellow, red or white because they are low in carbon. Think about the soil in the deepest woods nearest you. The “natural” soil smells sweet and is black with carbon that binds to essential minerals and nutrients.
Overly-harvested, pale agricultural soils have become decarbonized. Nutrients have been lost from these overworked soils for a hundred years. So, for good growth in grains or row crops, N, P and K (and other minerals) have to be replaced by commercial fertilizer—at great cost to the environment. And perhaps more on fertilizer in a future post.
SUMMARY: BIOCHAR IS “the solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment”. It reduces organic matter from the waste stream into its carbon skeleton only. The resulting product has properties that make it useful in agriculture and industry and it can serve to sequester carbon in the soil to prevent it from re-entering the atmosphere as the greenhouse gasses, carbon dioxide and methane.
So now and henceforth, when you see this “new word” in your vocabulary cropping up more and more often, you will have heard the term biochar, and maybe listen with greater attention and curiosity. Let me know what you learn! And if you have questions, I might can tell you what I know. Won’t take long. ¯\_(ツ)_/¯
Or you can make your own biochar at home!
I can’t help it, even knowing how very few readers click links I add towards locating the source material. Here’s a short list of relevant links, even so:
Terra Preta - Origin of Biochar
The Nutrient-Rich Legacy in the Amazon’s Dark Earths
The Many Benefits of Biochar | EcoFarming Daily
Biochar as a Soil Ameliorant: How Biochar Properties Benefit Soil Fertility—A Review
Sustainability & Climate Change - biochar-international
Biochar Market Size, Trends 2030: Industry Forecast
Biochar Teams Sweep 4 of 15 XPRIZE $1 Million Climate Innovation Awards
Good topic and you presented it well ! Thanks 🌏