What is biochar?

How biochar is made: pyrolysis

Give wood plenty of air and it burns to grey ash. Give it almost none and it stops halfway, leaving black carbon. That is the whole idea.

Dry biomass is heated to roughly 450–700°C with the oxygen largely excluded. The volatile fraction leaves as gas and vapour — often burned to sustain the process or recovered as heat and power — and what remains is a porous solid that is typically 65–90% carbon.

Temperature and residence time decide the quality. They set the hydrogen-to-organic-carbon ratio (H:Corg), which is the measurement standards use to estimate how long the carbon will stay locked away. Char made too cool or too fast is less stable and worth less.

1. 1

   Dry the biomass

   Wet feedstock wastes energy boiling water and makes smoke and tar instead of char.

2. 2

   Size it consistently

   Even pieces pyrolyse evenly, which is what gives consistent quality.

3. 3

   Heat with little air

   Flame-curtain kiln, retort or continuous reactor — all exclude oxygen from the char.

4. 4

   Quench before ash

   Stop the process while the bed is black. Grey means the carbon has burned away.

5. 5

   Charge before use

   Compost it or soak it in slurry so it releases nutrients rather than absorbing them.

Scale runs from a farmer with a single cone kiln to a continuous industrial reactor. See how to choose between artisanal, batch and continuous pyrolysis, or the step-by-step guide to making biochar if you want the practical version.

What biochar is used for

Soil dominates, but the end-use matters for carbon accounting as well as agronomy.

• Soil improvement

  The largest use by far. Biochar holds water and nutrients in the root zone, gives soil microbes somewhere to live, and raises pH on acidic soils. Most useful on degraded, sandy or acidic land — least useful on soil that is already fertile and well structured.

• Carbon removal

  Because the carbon in biochar resists decomposition for centuries, putting it in the ground is a measurable way of removing CO₂ from the atmosphere. This is what makes it saleable as a durable carbon-removal credit.

• Livestock feed and bedding

  Small quantities are used as a feed supplement and in bedding, where it reduces odour and absorbs nutrients. The manure that results is itself a good way of charging biochar before it reaches the field.

• Water filtration

  The same porous structure that holds nutrients in soil also adsorbs contaminants from water — a smaller but growing application, and a step towards activated carbon.

• Construction materials

  Biochar can be blended into concrete and asphalt, locking the carbon into the built environment rather than the soil. Still early, but it is one of the end-uses recognised under carbon methodologies.

Biochar in agriculture: what it does to soil

Biochar is a soil conditioner, not a fertiliser. It carries few plant-available nutrients itself. What it changes is the soil’s ability to hold what you put in: water retention on sandy soils, cation exchange capacity, pH on acidic ground, and habitat for microbial life.

That means the benefit is conditional. The strongest, most consistent responses come on degraded, acidic, sandy or low-organic-matter soils — which describes a great deal of Indian farmland. On soil that is already fertile and well structured, the yield response is often small or absent. Anyone promising a uniform yield increase across all soils is overselling it.

The most common mistake is applying it raw. Fresh biochar is highly porous and will initially absorb nitrogen from the soil — the nitrogen the crop wanted — which is why growers who skip charging sometimes see a worse first season and conclude it does not work. Compost it, soak it in dung slurry, or run it through animal bedding first.

On application rate: research trials commonly use 5–20 t/ha, but most smallholders realistically apply 1–5 t/ha, or place smaller targeted doses in the furrow or planting pit where the effect per rupee is highest. Our agronomic and soil advisory covers this in a field context, and the paddy-soil research comparison looks at the evidence for rice systems specifically.

What biochar is made from in India

India generates on the order of 500 million tonnes of crop residue a year, a large share of it surplus. Feedstock choice drives both char quality and whether a carbon project stands up.

For carbon purposes the rule is simple: the biomass must be genuinely surplus or waste. Residue that would otherwise be burned in the field qualifies; material diverted from fodder, fuel or soil cover does not, and neither does anything that drives land-use change. See biochar from crop residue in India for the full picture.

What biochar costs in India

Bulk agricultural biochar commonly sells in an indicative range of roughly ₹10–30 per kg as of 2026. Retail, horticultural and packaged grades sell for considerably more; industrial charcoal grades for less. Treat every figure here as an estimate to verify locally, not a quotation — this is a thin, fragmented market and prices move.

What actually moves the price:

• Carbon content and consistency. A buyer paying for soil performance or carbon wants a known specification, not a variable one.
• Particle size and moisture. Screened, dry, dust-controlled material commands a premium and ships better.
• Distance. Biochar is bulky and light. Freight destroys margin quickly, which is why production usually sits close to both feedstock and buyer.
• Whether the carbon is sold separately. A tonne of biochar can earn twice — once as a product, once as a verified removal — but only if it was made and measured to a registry’s rules from the start.

Why biochar earns carbon credits

Plants pull CO₂ out of the air as they grow. Left to rot or burn, they give it straight back. Pyrolysis interrupts that cycle: a large share of the carbon is fixed into a form that decomposes over centuries rather than seasons. Store it, and you have removed CO₂ from the atmosphere — measurably, and with a physical product you can weigh.

As an indicative figure, a tonne of certified biochar corresponds to roughly 2–2.8 tonnes of CO₂e of durable removal, depending on carbon content and the methodology applied. That is what buyers of durable carbon dioxide removal (CDR) pay for, and why biochar trades well above avoidance-type offsets.

Turning that into revenue means a registry, a methodology, laboratory testing, independent verification and a buyer — costs that fall before any credit is issued. It works at repeatable volume, not for a one-off batch. Start with the complete guide to biochar carbon credits in India, or see how a project comes together end to end.

Four things people get wrong

• “Biochar is just charcoal.”

  Chemically they are close relatives. The difference is intent and control: biochar is made to defined conditions so its stability can be measured and its carbon counted, then it is buried rather than burned.

• “Adding biochar always increases yield.”

  It does not. Gains are largest on degraded, acidic or sandy soils and can be negligible on already-fertile ground. Applied raw, it can reduce the first season’s yield by tying up nitrogen.

• “You can make it in an open fire.”

  You can make something black in an open fire, but most of the carbon burns away to ash and the smoke is genuinely harmful. Controlled low-oxygen pyrolysis is what produces stable, saleable char.

• “Any biomass qualifies for carbon credits.”

  Only genuinely surplus or waste biomass. Cutting healthy trees to make biochar moves carbon rather than removing it, and will not survive an audit.

Frequently asked questions