Brittle, ashen, and pulverized, biochar may not be the sexiest thing on the landscape. But when it comes to carbon sequestration and organic farming, this blackened and partially decomposed product of biomass is truly provocative. A perfectly natural and stable substance, biochar is especially useful for mitigating climate change because it captures and stores significant amounts of carbon that would otherwise be drifting through the atmosphere. Adding biochar to the soil can trap the carbon for hundreds if not thousands of years, at the same time contributing to greater fertility and higher crop yields.
Biochar is a grayish-black, cinerary substance produced by burning biomass at a very high temperature in an oxygen-deprived environment. In most respects, biochar is almost the same thing as charcoal.
Both are created through a process of pyrolysis, which partially decomposes the organic material and leaves behind a lightweight residue that’s particularly high in carbon. But whereas charcoal is meant to be burned for cooking or heating, biochar is typically used in powder form as a soil amendment. It can also be mixed into livestock feed or used for industrial applications like cement or carbonized steel.
In terms of the processing, biochar is also produced at a higher temperature, between 650º to 1,000º C, compared to charcoal, which can be prepared at temperatures 200-300º C lower. Activated charcoal, another related product, commonly used to purify air or water, is produced at temperatures above 1,000º C.
Whether for charcoal or biochar, the best feedstock for this process tends to be a denser, woody biomass, like trees or thick shrubs. Although lightweight stuff like coffee bean shells, sawdust and rice husk can also work.
Bamboo is ideal feedstock for both biochar and charcoal because of its remarkably fast growth rate and renewability. As a grass, bamboo produces a fresh batch of culms (or poles) every year, and they reach their full height in a single growing season. Relying on this highly sustainable resource can dramatically reduce the need to cut down trees for a low-value product such as charcoal.
Like hardwoods, bamboo is also very dense and high in carbon. But at the same time, because most bamboo is hollow down the middle, rather than solid like a tree, it can undergo the pyrolysis (or thermal decomposition) more quickly and efficiently than most tree logs. Simple, low-tech kilns are perfectly adequate for converting bamboo biomass into biochar.
At Planboo, we are somewhat partial to bamboo, which we consider one of the very best sources of biomass feedstock for biochar. But we also engage projects that have a steady and sustainable supply of other woody biomasses, such as rubber trees, cinnamon sticks, mesquite, and rattan.
The benefits of biochar begin directly at the source. Carbon-rich biochar is derived from carbon-rich biomass, and that biomass gathers its carbon directly from the atmosphere by way of photosynthesis. As most of us learned in middle school, if not sooner, all plants and trees absorb carbon dioxide from the air and release oxygen in return. It’s basically just the opposite of animal or human respiration.
In terms of mitigating Climate Change and providing us with clean air to breathe, this vegetative process is absolutely essential. Ordinarily, the atmospheric carbon gets stored in the stems and roots of the plants. This is what we refer to as a carbon sink.
If the tree or bamboo is harvested and made into a building material, the carbon will be locked inside that structure for many decades, until the material gradually begins to decompose. In the case of a tree, however, much of the CO2 is released from the trunk and the roots when it gets cut down. That’s not the case with bamboo though, because even when the culms are harvested, the plant survives, with its life force (and significant quantities of the carbon) still held in the complex root system.
Now, if we convert that biomass into biochar, we have a substance that’s made up of about 80-90 percent carbon. And if we are applying biochar as a fertilizer, they we’ve literally drawn carbon out of the atmosphere – where it’s harmful – and sequestered it into the ground – where it’s extremely beneficial. And where it will remain for centuries.
There are a wide variety of applications for biochar, but we’re most enthusiastic about its use as a fertiliser. One reason is that it provides the longest-lasting method of carbon sequestration, storing carbon in the soil for up to a thousand years or more. The other reason is that we are huge proponents of regenerative agriculture, and biochar is a fabulous ingredient for that.
As we know, Carbon Dioxide levels in the atmosphere have recently been climbing to alarming levels, acting as a primary contributor to Climate Change. Abnormal CO2 levels play a major role in driving higher seawater temperatures and extreme weather events. But underground, in the soil, carbon is a vital nutrient that brings a long list of benefits.
High-quality biochar typically contains 80 to 90 percent carbon. In addition to imparting this fundamental element, biochar has a uniquely granular texture that creates an extraordinarily large surface area. This makes it a particularly effective tool for water filtration and air purification. Those nearly microscopic nooks and crannies are also quite inviting for the microorganisms that live in the soil and humus and bring fertility to fields and farmlands.
As these dusty grey, carbon-rich particles attract more living things into the rhizosphere, the microbiome begins to flourish, all leading to higher fertility and bigger crop yields. For organic farmers, and anyone interested in long-term soil health and in spending less money on commercial chemical fertilisers, the state of the microbiome is crucial. This is where the magic happens, at the very bottom of the food chain.
By itself, biochar is somewhat dull and inert. When added to the soil, it soaks up surrounding substances something like a sponge. This property also makes biochar effective at retaining moisture in the soil. Furthermore, it’s very valuable for phytoremediation, or drawing up inorganic chemicals and contaminants, helping to restore degraded landscapes. But it can also draw beneficial microbes away from your plants, at least in the short-term.
Therefore, it’s strongly recommended to mix the raw biochar with compost. In an ordinary compost heap, consisting of dry leaves, kitchen scraps, yard clippings, maybe some chicken manure, and so on, you have a healthy mix of carbon and nitrogen that can take several months to decompose.
Blending biochar into the mix — around 3 or 4 parts biochar to 1 part compost — will greatly speed up the processing of your compost and “charge” the biochar. Mixing biochar directly with animal manure is another great strategy. Within just a few weeks, you can apply to this charged biochar to your farm, garden or forest, and reap almost immediate benefits. For even faster results, you can mix biochar with a liquid nutrient, such as compost tea or worm tea.
Biochar, at least in its most natural form, left behind after a forest fire, has been present and available in the soil since the dawn of time. Slash-and-burn farming practices, which we vehemently oppose, also make use of biochar when struggling farmers intentionally burn down forests to plant their own subsistence crops.
But the directed use of man-made biochar in organic farming is something of a more recent development. Therefore, we don’t have a perfect consensus on exactly how much biochar to add to your soil and what the end results will look like.
And as with any other organic farming practice, the specifics are surely going to vary, depending on your climate, what type of soil you have to begin with, the historic use of the land, what you’re trying to grow, and so forth.
General recommendations are to add about two or three tons of biochar per hectare (or one to two tons per acre). But some biochar enthusiasts might tell you to add 15 or 20 tons per hectare. Again, this will depend heavily on the initial condition of your soil, as well as the quantities of biochar you have available.
Unlike typical fertilizers, whether organic or synthetic, biochar lingers in the soil for centuries, so you don’t need to add it regularly, every year. Although you’d have to add an outrageous amount, well above 20 tons per hectare, to overdo it. As long as you’re adding well-charged biochar, you’re just going to be improving the health of your soil.
Biochar is slightly alkaline, with a pH of about 8, so it can increase the pH of your soil, or make it less acidic. But, again, so long as the biochar is mixed with other organic matter, manure or compost, you need not worry about raising the soil pH too high.
As if ridding the atmosphere of CO2 and ramping up the health and wellness of your rhizosphere weren’t enough to convince you to convert your agriculture waste into biochar, there’s more.
By measuring the quantities of carbon collected in your biochar, you can actually generate valuable carbon credits on top of your valuable soil additive. Unlike other types of carbon sequestration, like through forestry, which can be quite difficult to quantity, repeatedly measuring soil, roots, above ground biomass, and more, biochar is relatively straightforward. Completely tangible, you can easily look at a cubic meter of biochar, you can measure it to be 88 percent carbon, and you can physically bury that carbon in the ground (after mixing it with organic compost). So it’s reasonably easy to know and verify how much CO2 you are removing from the sky.
Although the carbon credit marketplace has its critics, this system does create financial incentives both for gross polluters to reduce their emissions and for private enterprises of all kinds to develop projects that will remove more CO2 from the air. And because biochar production is such an effective means of carbon removal and sequestration, it is possible to earn Carbon Dioxide Removal Credits (CDRCs) when you are producing significant quantities for sustainable biomass and ag waste into biochar.
At Planboo, we don’t think of CDRCs as get-out-of-jail cards for big corporations and major polluters. Instead, we see the system as a means to support and finance our climate positive projects in the tropics while passing the bill on to those in the Global North who have historically contributed the most to this problem in the first place.
Sure, like any system or marketplace, there will be those who try to take advantage or abuse it, but Planboo has developed a stringent set of MRV (Measuring, Reporting and Verifying) tools and technologies to ensure the highest levels of compliance and the support the most socially and environmentally responsible projects.
By applying biochar to your soil, you are effectively taking carbon out of the atmosphere and burying it in the ground to improve crop fertility.
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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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.
