How to Make Biochar (3 DIY Methods + An Easier Alternative)


Want to learn how to make biochar at home?

You can make your own biochar using trenches, drums, or kilns to burn organic material in the absence of oxygen.

In this article, we’ll explore how to make biochar at home using 3 DIY methods, including the materials you can use and a few safety notes. We’ll also show you an easier alternative for acquiring high-quality biochar.

 Further reading

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      How To Make Biochar For Your Garden

      Biochar is a black carbon material made from the pyrolysis of biomass in the absence of oxygen. 

      Its use as a soil amendment was first discovered in terra preta, a highly fertile soil used over 2000 years ago in the Amazon basin. Biochar was a key component of terra preta soil, which helped improve the soil quality of poor soil for a higher crop yield.

      Wait, how does it improve the soil?
      Biochar’s surface area and porosity allow it to house soil microbes and retain soil nutrients, helping improve soil fertility and plant growth over time.  

      But that’s not all. 

      According to the International Biochar Initiative, biochar production is a carbon negative technology as it helps reduce greenhouse gas emissions.

      It reduces atmospheric carbon dioxide by taking the decaying organic material, which would release carbon dioxide, and storing it as pure carbon in the soil (carbon sequestration).

      What Materials Do You Need to Make Biochar?

      You can make biochar from dry organic waste (feedstock), like crop residues and wood. But remember, the feedstock you use impacts your biochar's nutrient composition and yield.

      Usually, you’ll require around 4 lbs (~2 kgs) of woody biomass to produce 1 lb (~0.5 kgs) of biochar.

      You’ll also need: 

      • A drum, pit, or biochar kiln. 
      • A rake or shovel.
      • A hose.
      • Water.

      Once biochar is produced, you should activate it to improve its nutrient levels. 

      For this, you create a 50-50 biochar mix of raw biochar with organic material like compost, manure, etc. — which takes a week to become enriched biochar.

      Note: Biochar’s activation process is different from activated carbon or activated charcoal. 

      3 DIY Methods To Make Biochar

      Making biochar at home is relatively simple. 

      The methods we’ll discuss here have a lower carbon footprint than traditional biochar production methods like using a retort kiln — which releases more pyrolysis gases.

      Here are three simple biochar production methods to use at home:

      1. Cone Pit

      You can use the cone pit method with dry plant material, like twigs and wood. 

      Here’s how it works:

      • Create a cone-shaped pit (surface diameter around 1 meter) by digging into the soil. 
      • Start a fire at the base of the cone using small twigs. Once it burns strongly, add slightly larger wood pieces.
      • After the initial wood starts developing a layer of white ash, add more wood. Repeat this process till you reach the top of the cone, using larger pieces of wood each time.
      • Once the top layer starts turning white, quench the fire with water. The charred remnants are your biochar, which could be inconsistently sized depending on your feedstock. 

      In this method, the flames deprive the material of oxygen, creating a smokeless burn.  

      2. Trench or Drum

      The drum or trench method uses dried leaves and woody biomass to produce biochar. 

      You’ll need a cylindrical metal drum (ideally a 44 gallon or 200-liter drum), or you can dig a trench. 

      Then, follow these steps:

      • Pile the organic material into the drum or trench and light it from the top down.
      • Once the smoke turns grayish blue, add a layer of soil over it and leave it to burn slowly.
      • After the organic matter is charred, put out the fire with water. The material left behind is your bio charcoal (biochar).

      This method traps around 50% of the carbon from the organic matter in the biochar. Additionally, there are fewer emissions as the biomass burns without oxygen.

      3. Cone Stove

      The simplest biochar production method involves using a cone stove or biochar kiln, which you can buy at a store.

      Here’s what you need to do:

      • Add your dry organic matter to the bottom of the cone stove and light the top on fire.
      • When the top layer is coated with ash, put off the fire using water.
      • The charred material left behind is your biochar.

      This method creates a flame curtain on the top and prevents oxygen from entering the lower regions. However, it’s a less efficient method than the cone pit method, as it has a higher product emission rate.

      Safety Concerns When Making Your Own Biochar

      As biochar production requires constant supervision, here are some things to keep in mind:

      • The fire burns at extremely high temperatures — don’t leave it unattended and keep children and pets away. 
      • Keep the production site far from buildings, plants, and trees to prevent the fire from spreading.
      • Always keep an immediate supply of water available.
      • Avoid producing biochar from mixed waste since certain products, like printed paper and painted wood, may have chemicals that increase soil pH and deteriorate healthy soil.

      Clearly, producing biochar isn’t without risks. 

      But it’s also less efficient than commercial production methods.

      Commercial methods use clean and consistent feedstock to produce high-quality and more stable biochar, which improves soil health and carbon sequestration in the long run. 

      They also use industrial-grade equipment to produce a higher quantity of biochar and have much lower greenhouse gas emissions. Additionally, you get renewable energy as by-products, which can be used as an alternative to fossil fuels. 

      This further lowers its carbon footprint and contribution to climate change than homemade biochar. 

      That’s why, although homemade biochar is cheaper, its potential low quality can affect soil microbes and soil pH. Moreover, its higher environmental impact is a major concern.

      Instead, it’s better to go for commercially produced, eco-friendly biochar like Rosy Biochar.

      An Easier Alternative: Rosy Biochar’s Potting Mix

      Rosy Biochar produces the most easy-to-use Potting Mix for home gardens.

      The product is a single-source, chemical-free soil amendment that’s highly beneficial for plant growth.

      Rosy Biochar’s Potting Mix comes pre-activated with plant-based compost and beneficial microbes for improving soil health and nourishing your plants.

      So you don’t have to waste time producing homemade biochar and then activating it.
      Just apply Rosy’s biochar mix into your garden soil to improve soil fertility and create a lush yard in no time!

      Wrapping Up

      Homemade biochar can be an effective tool for waste management, and it comes at almost no cost. Plus, it's a quick fix for rejuvenating your garden soil. 

      But if you’re worried about the safety and environmental element, as well as the quality of homemade biochar, you could choose to buy eco-friendly and sustainable biochar, like Rosy Biochar.

      Try a bag of Rosy’s Potting Mix to give your garden a biochar boost today!