What is Biochar – How do you use it?
What is biochar?
Biochar is a carbon-rich material created by heating organic plant matter in the absence of oxygen — a process known as pyrolysis. Modern biochar is made using sustainable, low-emission methods that capture carbon and help fight climate change.
When added to soil, biochar enhances soil health, improves plant growth, and locks carbon away for centuries. Its production and use are defined by the European Biochar Certificate (EBC) and International Biochar Initiative (IBI) standards.
What Is the Best Biochar?
The best biochar depends on its purpose and the materials used to make it. For soil improvement, the most effective biochar is made from hardwood using medium-temperature pyrolysis.
Qualities of premium soil biochar
- Improves plant and crop growth
- Made from renewable, sustainable materials
- Long-lasting and stable in soil for hundreds of years
- Produced through a carbon-neutral or carbon-negative process
Not all biochars perform equally — only those produced from quality feedstocks using clean, efficient systems consistently benefit plant growth.
Buy certified SoilFixer biochar from our online store
Why Use Biochar?
When used correctly, biochar can transform soil performance. It:
- Increases water retention and root access to moisture
- Reduces nutrient run-off and wastage
- Boosts nutrient availability for plants
- Encourages beneficial microbes and mycorrhizal fungi
- Improves soil texture, structure, and long-term fertility
Environmental benefits
- Captures and stores carbon (CO₂ offset)
- Reduces greenhouse gas emissions (methane and NOx)
- Supports circular, sustainable resource use
Is Biochar Suitable for All Soils and Plants?
In general, yes — biochar benefits most sandy, clay and loam soils and suits the majority of plants.
Because most biochars are slightly alkaline (pH 8.5–10.5), care is needed with acid-loving plants such as blueberries or azaleas. Keep soil pH between 5 and 6.5 for these species.
Where to Use Biochar
Biochar can be used across almost all soil types and growing systems:
- Gardens and raised beds
- Planters and containers
- Allotments and lawns
- Tree planting holes and borders
- Compost mixes and soil improvers
How to Use Biochar
The biggest benefits occur in the root zone, where plant roots and soil microbes interact.
Recommended application
- Mix into soil during planting or cultivation
- Use as a top dressing and lightly hoe into the surface
- Blend with compost or soak in liquid fertiliser before applying
Raw biochar takes time (3–6 months) to “charge” with nutrients and microbes. To skip this waiting phase, use activated biochar or our ready-to-use SF60 Biochar Super Compost.
Activating Biochar
“Activation” or “inoculation” means pre-loading biochar with nutrients and microbial life.
You can activate biochar by:
- Adding it to compost as it matures
- Soaking it in an organic fertiliser or compost tea
Activated biochar delivers immediate soil benefits and avoids early nutrient lock-up.
How Much Biochar to Apply
A typical application rate is 1 kg per square metre (around 5% by volume).
For larger areas, focus on planting holes and seed rows to make your budget go further. Biochar lasts for centuries, so smaller annual top-ups are ideal.
How Biochar Works
Biochar acts as a sponge and habitat within the soil:
- It holds water and nutrients, releasing them gradually to roots.
- Its porous structure provides a home for microbes and fungi.
- These microbes form symbiotic relationships with plants, exchanging nutrients for sugars and boosting growth naturally.
In summary
- Chemical action: stores nutrients and reduces leaching
- Physical action: improves soil texture and moisture control
- Biological action: supports beneficial microbial life
Types of Biochar and How It’s Made
Biochar can be made from a wide range of plant materials including wood, straw, nutshells and miscanthus.
Each feedstock and production process creates different physical and chemical properties.
Typical production temperatures
- Low temperature: 300–500 °C
- Medium temperature: 500–800 °C
- High temperature: 800–900 °C
SoilFixer biochar is produced using advanced pyrolysis with heat recovery, meeting EBC certification for sustainability and efficiency.
Biochar as a Carbon Sink
Biochar is one of the most effective ways to lock carbon in the ground.
Each kilogram of biochar stores the equivalent of 2–2.5 kg of CO₂, depending on how it’s made.
Not all systems achieve this — older ring-kiln production methods fail to meet EBC standards due to higher emissions.
SoilFixer’s process is fully carbon-neutral and certified.
Biochar vs Compost
Biochar and compost work best together.
- Compost provides nutrients and organic matter.
- Biochar improves structure, moisture and microbial balance.
When combined, they form a long-lasting, fertile soil ecosystem that boosts plant health and yield.
Is Biochar an Organic Fertiliser?
Technically, yes — biochar is organic (plant-derived) and improves soil fertility.
However, under regulatory definitions, it is not classed as a fertiliser unless it contains defined levels of nitrogen, phosphorus and potassium (NPK).
Even so, biochar is recognised by many organic and sustainable farming systems as a valuable soil amendment.
Why Choose SoilFixer Biochar
- Certified under the European Biochar Certificate (EBC)
- Proven to enhance plant growth in UK soils
- Sustainably sourced from managed hardwood forests
- Optimised particle size (0–13 mm) for microbial and structural balance
- Avoid using fine powders or oversized pieces — they offer fewer benefits.
Can You Add Too Much Biochar?
Yes — moderation is key.
| Soil Type | Recommended Max Volume |
| Heavy clay | up to 20% |
| Loam | around 10% |
| Sandy | around 5% |
Excess biochar can make soil too coarse, reducing water retention. For sandy soils, combining biochar with colloidal humus (as found in SF60) provides better moisture and nutrient balance.
Custom Biochar Formulations
SoilFixer offers bespoke biochar blends for professional and research use:
- Inoculated biochar with nutrients, minerals or microbes
- Compost-biochar mixtures (PAS100 compliant)
- Available in fresh/dry or aged/wet forms
Contact us for tailored formulations to suit your growing system.
Our Biochar Production Journey
Our research started with small-scale Kon-Tiki kilns and has evolved into large-scale, energy-efficient pyrolysis systems with full heat recovery.
This allows us to deliver consistent, certified, sustainable biochar for gardeners, growers and farmers alike.
We continue to innovate with technology partners and investors to make biochar more accessible, affordable and impactful.