History of Biochar

In Amazonia, a great agricultural civilization fertilized poor forest soils with terra preta, the first biochar, to feed tens of thousands of people.

Today, we are rediscovering the value of biochar as the world staggers under climate change, environmental degradation and human poverty.


What is Biochar?

Biochar is a super charcoal made by heating any biomass – for example, corncob, husk or stalk, potato or soy hay, rice or wheat straw – without oxygen. All of the cellulose, lignin and other, non-carbon materials gasify and are burned away. What remains is pure carbon – 40% of the carbon originally contained in the biomass.

Why is it so valuable?

Climate change is threatening food security around the world. When farmers use Biochar as a soil amendment they will benefit from:

• Bigger yields   • Healthier soil   • Lower acidity   • Better water retention 
• Stronger plants   • Richer soil life   • Less contamination   • Higher fertility 
 • Promotes seed germination 

​Biochar seems to have no end of uses that derive from a handful of key characteristics.

Tiny holes, huge surface area – retaining water for a dry day

If you look at biochar under an electron microscope, you see an extraordinary moonscape of holes upon holes. What’s this mean? Biochar is an amazing sponge that will hold (absorb) huge amounts of water. All those little holes also provide very convenient condos for soil microbes; we’ll revisit this below.

pH of 8 – unlocking even poor soil’s nutrients

Plants like soil that has a nice, neutral pH of say 6.5 to 7, but most soils in the developing world are acid to very acid – 4 to 5.5. In soils this acidic, most plants cannot take up nutrients, even if they are present in the soil. Stick some biochar in this soil, however, and you can push the pH as much as a whole point higher. As the pH rises, more and more nutrients become available to crops.


Electrically charged surface – very attractive to chemicals

Biochar is attractive to chemicals of all types. Stick a bit of pure carbon biochar in the soil and six months later it is covered with scales of calcium, iron, magnesium, phosphorous, potassium, and sulphur. It’s become a little mineral ball. Sprinkle fertilizer on the soil and instead of seeing 50% of it leach away with the rain, that fertilizer, too, will glom onto the biochar, providing long-lasting, slow-release nutrition. Stick biochar in a heavy metal contaminated field and soon the cadmium, lead or mercury are chemically bound to it (adsorbed) where plants can no longer take them up and water can no longer wash them away.

Bug friendly – encouraging soil life

Plants can’t eat their elements raw. No matter how much they need nitrogen, they can’t just suck it up; they need microbes to digest it first and pee it out as nitrates or nitrites. If you look at the root systems of plants, you find all sorts of similar, collaborative relationships. To put it differently, if you don’t see such relationships, chances are, you can’t grow anything. 

How do you make Biochar?

Biochar production is a simple process that anyone can do. Warm Heart has designed cheap and easy methods for converting biomass waste into biochar. The simplest and cheapest method is to dig a hole in the ground. You can also build a cheap biochar oven using an old oil drum, or build a trough.

Whichever method is used, the process is the same, biomass is burned with a lack of oxygen, turning the biomass in biochar, smoke free.

Benefits of making Biochar

If you live in the developed world, field fires are a thing of the past. If you live in the developing world, smoke from agricultural field fires can obscure the sun for days.

Field fires are often smoky, slow smolders burning the residue of crops containing fertilizers fortified with nitrogen and sulphur. These generate large quantities of greenhouse gases (GHGs) such as methane and the NOxs (nitrous oxides) that are many times more warming than CO2. (Methane has a global warming potential (GWP) of 25, NOx 298!)

They also produce large quantities of smog precursors such as ammonia and the SOx (sulphur oxides) that react with sunlight to form smog. Finally, that smoke that blocks the sun is PM2.5 – particulate matter so small that it passes through the walls of the lungs into the bloodstream to wreak havoc throughout the body.


Crop waste eliminated through the process of making biochar produces no smoke.

Every year, farmers in the developing world burn more than 10 billion tonnes of crop wastes in their fields. This releases 16.6 billion tonnes of CO2, 11.2 billion tonnes of CO2e, 1.1 billion tonnes of smog precursors and 65.7 million tonnes of PM2.5 into the atmosphere. The combined annual CO2 and CO2e emissions from crop waste burning are equivalent to the annual emissions of 714 coal fired power plants.

The alternative – converting the waste into biochar instead of burning it removes three tons CO2 from the atmosphere for every ton produced; when added to fields as a soil amendment, that carbon is permanently sequestered.

The long term benefits of making biochar is a huge reduction of greenhouse gases that contribute to global warming.

Solution for a healthier planet

Biochar production is not limited to just replacing agricultural field burning in the developing world, anywhere there is a need to remove biomass there is an opportunity to make biochar.

Globally we all need recognize it as a powerful solution to reducing global warming. Even your hometown can participate and reap the benefits of biochar, learn more about how your town can help save the world!

The many uses of Biochar

While it may be invaluable for farmers, it has many other practical uses too. The absorption qualities of biochar make it a perfect solution for odor control, useful for eliminating unwanted odors: in cars, homes, compost piles, pet odors, closets, bathrooms, even in stinky old sneakers!

The powerful moisture adsorption quality makes it extremely helpful in cutting down mildew in damp areas.

Household plants? Biochar potting soil will boost growth and give you healthy plants.

Look for ways to enrich your life with biochar, and help build a market to encourage widespread manufacturing of this simple, yet amazing natural product. It could help save the world!

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