The benefits of bamboo biochar: Renewable and regenerative

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The funny thing that bamboo and biochar have in common, they’ve both been around since, basically, forever. And yet it feels like they’ve suddenly been discovered for the first time. Bamboo has been used for food, tools, musical instruments, and construction material for thousands of years. But just in the last few years, the interest in farming bamboo has exploded – in Africa, North America, and even Europe. Likewise, farmers started using biochar to enhance their soil quality millennia ago, long before the dawn of industrialization. And today it’s being revered like a radical new innovation and an exotic strain of black gold.

When it comes to regenerative agriculture, bamboo is something of a wonder crop. It has minimal nutrient needs, it’s relatively quick to get established, and once established, it grows with unmatched vigor, using its tenacious roots to raise the water table and curb erosion. Meanwhile, biochar is a bit of a miracle worker in its own right. Made up of about 80% carbon, with a coarse, complex texture that produces an astronomical surface area, biochar can attract beneficial microbes and boost soil health like nothing else. 

Bamboo is an optimal source of biochar because it grows faster than any other woody plant. And biochar’s high carbon content is a direct result of a plant’s metabolic activity, namely photosynthesis, the process through which plants ingest CO2 and release oxygen. With its unsurpassed growth rate, bamboo yields more biomass and captures more atmospheric carbon per acre than anything. So if your goal is to remove carbon from the sky and add it to the soil, the collaboration between bamboo and biochar is hard to beat.

But first, what is biochar?

Biochar is a type of charcoal that is made by heating organic materials, such as wood, agricultural waste, and even municipal sludge, in the absence of oxygen through a process called pyrolysis. This process converts the organic material into a stable, carbon-rich form of charcoal that can have a host of applications. But we’re most interested in its use as a soil amendment.

Biochar has a wide range of benefits for both the environment and agriculture. When added to soil, it can improve soil health, increase water retention, and reduce nutrient leaching. The vast and porous surface area attracts and encourages the proliferation of beneficial microorganisms in the ground, which can improve plant growth and nutrient uptake. Its positive effects are especially notable in promoting healthy root development. Additionally, biochar can sequester carbon, helping to mitigate climate change.

The use of biochar dates back thousands of years, with evidence of its use found in soils of the Amazon Basin, known as Terra Preta. These soils are highly fertile and contain significant amounts of biochar. The ancient Amazonians used biochar as a soil amendment to improve soil fertility and elevate crop yields.

In recent years, biochar has gained renewed interest as a sustainable and environmentally friendly way to improve the soil and sequester carbon. More specifically, the process of pyrolysis fixes the carbon that is built up in the plant biomass, having been absorbed from the air through photosynthesis (the process in which plants ingest CO2 and release oxygen). When added to the soil, the majority of that carbon will stay put for many centuries.   

Bamboo farming captures carbon
A mature plantation of timber bamboo can easily generate 35% more oxygen than an equal area of trees.

Renewability and versatility

As the reality of Climate Change has intensified over the last couple of decades, environmentalists have increasingly recognized bamboo for its remarkable renewability and its great capacity for carbon sequestration. Indeed, as the fastest-growing plant on earth, bamboo photosynthesizes with great speed and efficiency. 

Impressively, a mature grove of bamboo generates about 35% more oxygen than an equal area of trees. And in doing so, the stems, roots and leaves of bamboo must absorb a wealth of carbon dioxide from the atmosphere. In the sky, this CO2 is more of a liability, but when buried in the ground — which is exactly what we do with biochar — the carbon becomes a long-lasting asset, ensuring a rich and lively soil composition for decades and centuries to come. 

Even more important is the harvesting of bamboo compared to trees. When felling a tree, the organism dies, and as it decays, the carbon that had been stored in the roots is released. Not so, however, with bamboo. Because it’s a rhizomatous grass, you can chop down poles o’ plenty, but the bamboo endures. The life source is centered in the roots, and those roots continue to serve as a carbon sink, even after the above-ground biomass has been removed. 

In fact, harvesting bamboo — when done skillfully and sustainably — actually increases its effectiveness as a carbon sink. When they’re left on the plant, the oldest culms will gradually age, decay, and begin to release CO2 and other greenhouse gasses. Harvesting mature bamboo poles ensures that the CO2 is locked in place, in both the roots and the woody material, before nature has a chance to run her course.

Converting this woody biomass into biochar is an extremely useful and effective way to further fix the carbon. Good quality biochar can contain up to 90% carbon. It’s also interesting to note that 1 kg of solid carbon is actually equivalent to about 3.6 kg of CO2. That’s some serious carbon removal right there. (Technically, the factor 44/12 (i.e., 3.6) is the ratio between the molar mass of carbon dioxide and the molar mass of carbon. This factor converts an amount of carbon to its corresponding amount of carbon dioxide.)

 

Agricultural waste and lesser-quality biomass

As you can see, we are big fans of bamboo and all its many uses. Of course, that includes biochar. But when it comes to making biochar, there’s really nothing better than agricultural waste. There are thousands of products you can make from bamboo, and many of them are more valuable than biochar, at least in terms of their market price. And these are great alternatives to similar products made from trees, steel, or plastic. 

With agricultural waste, like coconut shells, discarded rubber trees, and other leftovers, there’s frequently no other practical use. So farmers often just leave this waste material to rot on the side of a field, or they burn it all in an open fire. In these cases, there’s no doubt that converting into biochar is a superior strategy, both financially and environmentally. 

I would have to concede that ag waste is a better feedstock for biochar than bamboo, in most cases. But it’s important to remember that woody bamboo has a higher concentration of carbon than most waste material, especially soft stuff like rice husks. Woody biomass is also easier to process without the need for more sophisticated machinery. 

And, remember, not all bamboo is created equally. Some species of bamboo are more commercially useful than others, and bamboo waste is still another option. Ideally, the prime pieces of bamboo should be processed into the highest-value products, like flooring and building material. But there’s usually plenty of remnants left behind, all the offcuts, as well as the thinner branches and flimsy tops of the bamboo culms that are less useful. 

In many parts of the tropics, the elaborate machinery to turn woody poles into beams and panels is simply not available. In the absence of such equipment to commoditize the bamboo, biochar is an easy product to make, a lower-hanging fruit, if you will. Furthermore, there are many species of bamboo that just don’t lend themselves to high value addition. Tall, thick, straight culms of Moso, Asper, and Guadua are well suited for building materials. But something like Bambusa vulgaris, widespread throughout the tropical world, with thinner culm walls and not such straight stalks, may fare better as biochar. 

Bamboo biomass for biochar
Farmworkers in Malawi gather bamboo to produce high-quality biochar.

Land restoration, regeneration and remediation

One of the primary purposes of biochar is to restore and improve the soil conditions. As a “hotel for microorganisms”, biochar brings life into the topsoil and allows the rhizosphere to flourish. This results in significantly healthier plants without the need for conventional fertilizers. 

If land restoration is your goal, then it’s impossible to overlook the value of bamboo. This tenacious grass requires little in the way of nutrients and is able to gain a foothold quickly. As it does so, bamboo binds the soil and prevents erosion. In addition, the fallen leaves and healthy roots contribute to the humus and bolster the topsoil. 

As such, biochar and bamboo really go hand in hand. Not to say that you should uproot your garden or clear the forest and replace it with bamboo. But in areas degraded by flooding, clearcutting, mining, and other disasters — either natural or manmade — bamboo and biochar both have the special ability to restore life.

The two are also especially effective for soil remediation. In areas of heavy pollution, where the landscape is tainted with petroleum or chemical runoff, biochar and bamboo have been shown to extract these toxins and make the soil more hospitable for farming. 

 

 

Higher quality biochar

On the question of whether bamboo produces a better quality of biochar than other feedstocks, the verdict is still out. I’ve spoken with a few bamboo enthusiasts who insist that bamboo biochar is the best, and I’d like to believe them. But at this point, I’ve not seen any solid scientific evidence to support this theory.

On the one hand, bamboo is woody and dense, with relatively high levels of carbon. And compared to other woody biomass like trees, bamboo burns more quickly, because the poles are generally hollow. This makes the pyrolysis process more efficient. 

On the other hand, some claim that bamboo makes better biochar on account of other traits like its porosity. It’s important for biochar to be porous, but it’s not clear whether that characteristic carries over and results in any difference with the finished product. 

I have also heard it said that bamboo’s high silica content gives the biochar a higher cation-exchange capacity. More negatively charged soil particles will attract more nutrients that are positively charged, thereby increasing the soil fertility. Again, I’ve not seen any hard evidence to confirm this conjecture. Supposedly, the high silica profile also leads to better quality wood vinegar, one of the numerous co-products that can be collected during pyrolysis. This is according to Michael Wittman of Blue Sky Biochar.

 

Conclusions

The most important reasons to advocate for bamboo as a biochar feedstock are pretty similar to the reasons we endorse bamboo in general. For carbon sequestration and renewability, nothing quite compares to bamboo. And since carbon removal is one of the key benefits of biochar, it makes a certain amount of sense to pair the two together. 

But is bamboo biochar going to make a bigger impact on your soil quality and your crop yields than other biochar? Probably not. In the end, as long as you’re adding biochar, the difference to not using biochar at all is going to be the most striking comparison. Still more scientific documentation is required in this area as well, but we’ve seen more than enough evidence with our own eyes to be thoroughly convinced. 

And at the end of the day, when it comes to making biochar, it’s not a competition. The point is to do what makes sense with the available resources in any given environment. It’s all about regenerating agricultural land and converting waste into something of far greater value. So use what you have, and do your best to leave the land better than you found it.

 
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Fred

Fred Hornaday, founder of Bambu Batu, is a leading voice in the bamboo industry. He's been working in the industry since 2006 with a network that spans all six continents.

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Carbon Removal

To keep the world within 1.5 degrees of global warming and to avoid global catastrophe – we now need to not only drastically reduce our emissions but also rapidly remove them too.

However, there is very little carbon removal today with less than 50,000 tonnes of CO2 removed in 2021. It’s estimated we need to remove 10% of Global GHG emissions by 2030, which is equal to 5 billion tonnes per year. Carbon removal needs to grow 100,000 times bigger. 

Planboo is a nature-based carbon removal company, using bamboo-the fastest growing plant in the world. Like all plants, through photosynthesis bamboo absorbs CO2 and releases oxygen into the atmosphere. Because it grows so fast, it’s carbon removal potential is huge. We develop projects in Sri Lanka with local partners and supply high quality and high integrity carbon removal credits for the carbon market.