What Is Biochar? Uses, Production and More (A Definitive Guide)

Want to learn about biochar and its uses?
Biochar is a carbon compound that can improve soil health, filter water, and even reduce atmospheric carbon dioxide

In this article, we’ll explore everything about biochar.

From what biochar is to how it’s made and its five promising applications. We’ll also discuss how biochar helps mitigate climate change and its economic feasibility.

Finally, we’ll reveal the best biochar product that’ll help nourish your gardens. 

This Article Contains:

(Click on a link below to jump to a specific section)

Let’s go. 

What Is Biochar?

Biochar is an ancient, all-natural black carbon compound that can do wonders for soil. It’s created via pyrolysis, which involves burning biomass or organic feedstock like wood chips, crop residues, agricultural residues, etc., in the absence of oxygen. 

The first use of biochar was documented nearly 2000 years ago in terra preta, a highly fertile soil made using biochar. Local Amazonian farmers used the terra preta soil to transform depleted soils into highly fertile soils.

Biochar is similar to charcoal, but they differ in their ingredients and uses. Charcoal is produced from pyrolyzed wood and is typically used as a heat source, while biochar has many applications.

(We’ll dive into the uses of biochar later in this article.)

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Let’s now understand what makes biochar so special.  

The Physical and Chemical Properties of Biochar 

Biochar is a porous carbon compound with a substantial surface area. 

As a result, it can adsorb (hold on its external surface) a lot of soil nutrients and water molecules.

However, not all biochar is created equal.

The characteristics of biochar differ based on the pyrolysis method used during biochar production.

Here’s a quick summary of how the pyrolysis method used can impact the biochar properties:

Heating Process

Heat Exposure

Biochar Particle Qualities

Biochar pH

Fast pyrolysis at 1200°F (650 C)

Short (seconds)

Fine and porous with a greater surface area

Higher (more alkaline)

Slow pyrolysis at 840-1200°F (450-650°C) 

Long (minutes or hours) 

Large particles with a smaller surface area

Lower (more acidic)


Essentially, the biochar produced quickly at higher temperatures has smaller particle sizes. 

And what does that translate to?

It’s more porous, with a greater surface area and cation exchange capacity (the ability to retain plant nutrients).

On the other hand, the slow pyrolysis of biomass at lower temperatures gives you a higher biochar yield. However, this biochar has a larger particle size with a reduced surface area for adsorption.

Additionally, biochar can have different nutrient characteristics based on the biomass feedstock used during pyrolysis. 

What’s feedstock?
It’s the organic material you burn to create biochar.

Here’s a handy table about this:

Source Used for Biochar Production

Macronutrient (Essential Plant Nutrients)

Biosolids and organic waste (compost)

P (Phosphorus) 

Corn and rice straw

P and K (Potassium)

Rice hulls

P and K

Hardwood

K

Pelleted agricultural residues (crop residue)

P and K

Switchgrass

P and K

Timber residues (wood chips)

P and Mg (Magnesium)


So what does this tell us?
Knowing the biomass feedstock source can give you an idea of how effective your biochar will be for the soil!

Feedstock can influence biochar’s capacity for adsorption, with wood and agricultural biomass having high adsorption capacities. This happens because the source material creates biochar with greater porosity and pre-concentration of minerals. 

So it’s quite important to vet your biochar and find out more about its source.

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We’ve now talked about biochar properties and how the production process can affect them. 

Let’s now dig into biochar production.  

How Is Biochar Made?

Biochar is made via pyrolysis.

The process involves the thermal decomposition of biomass of organic material, like wood chips, crop residue, rice hulls, etc., converting it into a stable biochar carbon that can’t escape into the atmosphere. 

This stable form is highly beneficial for soil amendment, among many other things.

Here are the traditional pyrolysis methods used for the production of biochar:

A. Conservation Burning

Conservation burning aims to burn organic matter quickly to produce biochar. It’s a simple process that can be carried out without much equipment.

Here’s how it’s done:

  • The feedstock (wood) is stacked like a cone with dry organic matter and coal placed in the center to help the stack burn faster. 
  • The fire is then ignited at the top. And as it spreads downwards, the flames at the top consume all the oxygen - resulting in fast, high-temperature pyrolysis of the organic material lower down, creating biochar
  • The organic material consumes most of the carbon dioxide emissions released during the pyrolysis process.
  • The fire is then put out using a pressurized water source before the feedstock turns to ash.

B. Flame Cap Kilns

The flame cap kiln method uses a metal cylinder or box to convert biomass into biochar. This method allows for increased production of biochar and organic waste elimination. 

Here’s what the process involves:

  • A fire is started in the kiln (metal box) using kindling (small dry sticks or twigs) or fuel. Similar sized biomass feedstock is added for a faster burn rate.
  • More biomass is consistently added until the kiln is full of char.
  • The flames at the top eliminate oxygen to facilitate the pyrolysis of the biomass, giving you biochar
  • Finally, the fire is put out using water or a metal lid.

C. Commercial Production

Commercial production of biochar usually happens in centralized systems or plants outside of agricultural lands. 

It involves transporting feedstock to these plants and using industrial-grade pyrolysis reactors to produce biochar. Usually, these plants will also have a system to extract the byproducts of biochar production, such as syngas — which can be used as an alternative to fossil fuels.   

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Now that you know how biochar is made, let’s look at its uses.

5 Promising Applications of Biochar

Biochar’s diverse physical and chemical properties make it extremely useful for various purposes.

Here are five promising applications of biochar:

1. Soil Amendment 

The International Biochar Initiative highlights biochar as a valuable soil amendment that helps improve soil health and plant growth in healthy soil or poor soil.

However, when you add raw biochar to the soil, it temporarily absorbs soil nutrients, affecting plant growth in the short run. 

To avoid this, you need to activate biochar. 

What’s biochar activation?
Biochar activation involves mixing raw biochar with nutrient loaded organic matter like compost and manure and setting it aside for around two weeks. When you apply the activated biochar to soils, it improves the soil properties, like increasing soil carbon, soil fertility, and the growth of beneficial microbes.

Additionally, biochar’s porous structure improves the soil’s water and nutrient retention capacity, making it highly beneficial for sandy soil and degraded soils. 

And due to increased nutrient retention in the soil, biochar reduces the need for chemical fertilizers

Why does that matter?
Chemical fertilizers increase soil acidity (reduce soil pH) and negatively affect soil microbes and natural soil fertility. They can also pollute the soil and water resources and even have a high carbon footprint

On the other hand, biochar as a soil amendment improves soil pH, natural soil health, and crop yield, helping rejuvenate depleted soils. And most importantly, it’s carbon negative.

Wondering how to use biochar to amend your garden soil?
Read our step-by-step guide here.

2. Carbon Sink

Biochar’s properties make it a useful carbon capture system, allowing it to capture atmospheric carbon dioxide (carbon sequestration) and create a carbon sink in gardens and agricultural soils where it’s applied. 

What’s a carbon sink?

A carbon sink is any structure that absorbs more carbon from the atmosphere than it releases.

How does biochar do this?
During biochar production, the decaying organic material is converted into a stable form of carbon. This organic matter would otherwise release higher amounts of carbon dioxide and methane if it were to decompose naturally. 

So, soil with biochar can capture and store the CO₂ greenhouse gas for hundreds to thousands of years in stable forms. 

And since this stable biochar carbon isn’t released into the atmosphere, it doesn’t trap heat or raise global temperatures, helping us reduce the effects of climate change

Moreover, this captured soil carbon stimulates the growth of microbes and improves soil properties, like soil quality, structure, and fertility.

3. Water Filtration

Another great application of biochar is filtering water.

Biochar’s porosity and large surface area promote water flow while helping it adsorb and filter chemical, biological, and physical contaminants. 

Additionally, the larger pores support the growth of beneficial bacteria that aid water filtration.

Some of these bacteria include: 

  • Aerobic nitrifying bacteria that convert toxic ammonia into non-toxic nitrates. 
  • Aerobic composting bacteria that consume organic matter from water.
  • Anaerobic bacteria that break down sewage sludge and convert it into biogas (an alternative energy source).

As a result, biochar systems can be highly effective for water filtration, in addition to their soil amendment benefits.

4. Livestock Feed

Biochar addition to livestock feed improves animal health by:

  • Increasing nutrient intake efficiency.
  • Aiding digestion.
  • Removing toxic substances from the digestive tract.

But that isn’t all.

When the livestock consumes the feed, the biochar is enriched with nitrogen compounds during the digestion process.

As a result, it can become a valuable, low-cost fertilizer when eventually expelled by livestock. 

When applied to soils, this nitrogen-amended biochar can decrease greenhouse gas emissions, such as nitrous oxide emission — compared to chemical fertilizers.

5. Building Material

Traditional construction materials like concrete and asphalt have a high carbon footprint. 

In fact, concrete accounts for at least 8% of global carbon dioxide emissions!

Why are we mentioning this?
Studies have found that biochar can be mixed into concrete and asphalt to help offset the carbon footprint of these widely used materials.

Biochar transforms these materials into carbon sinks, making them carbon-negative systems.

But that’s not all. 

Here are some other uses of biochar as a building material:

  • The high water absorption capacity of biochar is useful in reducing dampness and air condensation on walls, allowing it to regulate humidity and prevent mold from developing.
  • According to a study, biochar also aids the adsorption of odors and toxins in the air, making it viable for buildings like libraries, schools, warehouses, and factories.
  • Biochar can also be used with plaster or mud to coat exterior walls. It acts as a thermal insulator, reducing heat transfer into living spaces and promoting a healthier indoor environment.

For more information on biochar benefits, check out our comprehensive article here.

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Clearly, biochar offers amazing benefits for us and the environment. 
Let’s now take a closer look at how it can help us fight climate change. 

How Biochar Helps Mitigate Climate Change 

Biochar has been a hot topic in the field of environmental science for its use in carbon sequestration and reducing other greenhouse gas emissions like nitrous oxide. 

Wait, what’s carbon sequestration?

It’s the process of capturing and storing atmospheric carbon, thereby reducing the amount of carbon lying around in our atmosphere.

Experts believe biochar can sequester carbon at the rate of billion tons of carbon annually and slow the increase of greenhouse gas levels in the atmosphere.

According to a study, biochar applied in a field can reduce carbon dioxide emissions by 33% and carbon dioxide equivalent emissions of nitrous oxide and methane by 37% over two years! 

Another research found that biochar could mitigate around 300-600 million tonnes of CO₂ by 2050. 

These findings highlight biochar’s potential to mitigate climate change. 

Reducing greenhouse gas emissions is also important for soil fertility as global warming can decrease soil moisture content. Low soil moisture content leads to more irrigation requirements, lower crop yields, and even land desertification — which we can mitigate by using biochar.  

And don’t forget that biochar addition to soil facilitates plant growth.
This indirectly increases carbon consumption as plants utilize carbon dioxide during photosynthesis. 

Moreover, biochar production also produces clean and renewable energy (bio-oil and syngas) as a byproduct. These byproducts can be an alternative to fossil fuels — for example, you can use syngas to replace fossil fuels like gasoline.   

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The benefits are clearly great, but how cost-effective is biochar production and application? Let’s find out.

Is Biochar Economical?

Yes! 

This soil amendment is a cost-effective solution for gardening, agriculture, as well as for some of our planet’s most troubling problems.

According to the International Biochar Initiative, biochar can last for a long time in the soil, so you don’t have to apply it repeatedly. Moreover, the benefits of biochar become more apparent as time goes by.

Some of these benefits include: 

  • Improving phosphorus and potassium fertilizer efficiency. 
  • Reducing irrigation requirements and plant cultivation costs. 
  • Increasing crop yield.

That said, the initial cost of high-quality biochar can be considerably high compared to other soil amendments (like peat moss and vermicompost) due to factors like transportation and large-scale biomass pyrolysis.

However, its potential to improve the quality of our environment in the long run is undeniable. 

Since biochar can help save the planet by reducing greenhouse gas emissions, the price of biochar is also expected to decrease as it becomes more readily available for use.

Fortunately, you don’t have to wait until then to get your hands on quality biochar that’s accessible. 

Meet Willow Biochar.  

The Best Biochar Product In 2022: Willow Biochar’s Potting Mix

Willow offers a ready-to-use Potting Mix made from biochar that isn’t blended or mixed with fillers, synthetic fertilizers, or peat moss. 

It’s a clean, single source, and organic product that is safe to use and gives you consistent results.

The best part? 
Willow’s Potting Mix comes pre-activated with plant-based compost and endomycorrhizal fungi that conserve water and promote plant growth. 

As a result, you won’t have to waste time activating biochar. 

You can get started right away

Just add the Potting Mix directly into your soil or add it to the base of each plant, and voila! 

You’ll witness happier and healthier plants in no time. 

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Wrapping Up

Biochar is one of the best soil carbon sequestration resources available today. 

It’s also incredibly beneficial as a gardening and agriculture resource, helping you improve soil quality and plant health. 

To enjoy all these benefits, all you need to do is find the perfect biochar product for your garden. 

And that’s where Willow comes in. 

Try a bag of Willow’s eco-friendly Potting Mix to breathe life into your garden today!