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Frequently Asked Questions
Can I buy biochar?
Biochar can be purchased from a small number of online suppliers but be aware, not all biochar is manufactured sustainably.
Some biochar sold is made as a byproduct of charcoal production, which can be created in a smokey, methane polluting process. This would make the biochar product carbon positive, (releasing more greenhouse gas than it sequesters).
Some biochar sold is produced using a smoke-free process but can come from unsustainable forest monoculture plantations which can have negative impacts on ecology.
Earthly Biochar are responsible manufacturers and only use ‘waste’ organic material to create our biochar. This ‘waste’ material would otherwise be incinerated (releasing carbon) or left to decay. Fruit pulp, wood shavings and grain husk are turned into biochar in a smoke-free process which generates carbon neutral heat for use in drying the next batch of feedstock.
In summary, you can buy biochar online but make sure you know the feedstock and production method to ensure it is carbon negative and safe for soil use.
Can I make biochar at home?
It is possible to make biochar at home, but it can be easy to get it wrong.
For those without specialist tools or skills, offering a safe and sustainable alternative to traditional at-home production methods, Earthly Biochar are the first on the market to design and manufacture a purpose-built smokeless biochar kiln.
Our clean burning technology makes it safe and easy for domestic gardeners to make biochar at home in just one hour. The process is optimised for sustainability while the product is designed to be user-friendly and long-lasting.
Read more about our biochar kiln for easy production of biochar at home.
For those wanting to try a DIY production approach, we suggest you read our blog “The top 3 most important things to get right when making biochar” to avoid doing more harm than good. It’s important to note that these processes can be dangerous, as well as damaging to the environment releasing harmful gases into the atmosphere.
Is biochar a fertiliser?
Biochar performs the same function as a fertiliser as it increases soil fertility. However it does so by increasing water and nutrient efficiency rather than providing nutrients directly to plants.
Having biochar in your soil allows you to use less water and fertiliser as the biochar acts as a sponge to prevent the nutrients washing away in the rain.
Freshly made biochar contains almost nothing but pure carbon. This carbon isn’t available as a nutrient which is why it cannot be broken down and turned into CO2. What the carbon does do however is create a structure that acts as a sponge in your soil. Having biochar in your soil allows you to use less water and fertiliser as the biochar acts as a sponge to prevent the nutrients washing away in the rain.
How long does biochar last in the soil?
Biochar can last in the soil for hundreds, possibly thousands of years. Scientists have even found charcoal calculated to be 4,800 years old [Source: University of Exeter]
Because biochar doesn't break down easily, once your soil is roughly 10% biochar by volume, you don’t need to apply anymore to get the desired effects, and you won’t need to re-apply.
The reason why it lasts so long in the soil is because the production process heats the carbon to a temperature which converts the chemical structure from one that is easily broken down by microbes to one that is nearly impossible to break down. The carbon forms what is called a crystalline structure, similar to a diamond, making it an unattractive food option for soil microbes.
Does biochar affect pH?
The pH of biochar depends on the production process and the material the biochar is made from.
Our biochar is slightly alkaline, at pH 9, however this does not mean your soil pH will be significantly affected.
Biochar has been used successfully in acidic soils as a substitute for lime to neutralise the pH. Research trials have shown where biochar is used for this purpose, crop yields boom.
On the other hand, if your soil is already alkaline and you would like to reap the benefits of biochar to increase soil fertility (through increased nutrient use efficiency, increased water use efficiency and increased microbial activity), you can add biochar to your soil after mixing it with compost. The pH of biochar is neutralised after it is mixed with compost and left to absorb nutrients, moisture and become colonised with the beneficial bacteria and fungi. This can be achieved on a small scale in your garden compost bin, but also on a larger scale in compost rows. The addition of biochar to compost improves the compost quality and speeds up the process, we have more information on this here.
Does biochar absorb CO2?
Biochar does not absorb CO2, rather it sequesters carbon.
Waste organic material will inevitably be broken down by microbes into CO2. Turning this material into biochar will release 50% of the CO2 stored in the organic material when it goes through the production process. Then it will turn the remaining 50% into a non-biodegradable form, meaning it will not turn into CO2 unless burnt. This makes biochar carbon negative, because it is actively preventing total CO2 release.
What biochar does absorb is methane. Mixing biochar into your compost bin will cut methane emission by 40%. This is because it acts like a filter, meaning methane is trapped inside the maze of pores inside the biochar. This adds to biochar's already awesome ability to reduce greenhouse gas emissions - something which is not always fully quantified when talking about biochar’s carbon sequestration ability.
Can biochar improve crop yields?
The amendment of soil with biochar in agriculture can increase crop yields.
Academic literature has shown biochar amended soils tend to have more productive plants which are more drought tolerant, and the end result to the farmer is an increase in yield.
The mechanisms behind this have been researched and the current consensus is that biochar becomes a host for beneficial bacteria and fungi (including mycorrhizae). In parallel, the negative charge of biochar forms bonds with water molecules and nutrient ions.
Having a higher concentration of water and nutrients around a plant’s root system increases symbiotic relationships with beneficial microbes, which play a key role in the exchange of nutrients between the soil and the plants. The community of microbes have also been shown to increase a plant’s resistance to pathogens.
Research has been conducted in the northern hemisphere as well as closer to the equator where the climate is more arid, as well as on different soil types. However our research in the UK has shown biochar to be effective at speeding up plant growth when mixed into commercial compost.
At present, we know biochar brings the most benefits and greatest increase in crop yields in sandy, dry soils and in compacted, clay soils. If drought is a concern, biochar has been shown to increase drought tolerance because it increases the soils’ water holding capacity and water use efficiency. If you would like to know more or ask a question specific to your farm, or soil type, please contact us using the form at the top of this page.
Can biochar be used in vertical farming?Biochar has been found to significantly improve multiple aspects of vertical farming. If your vertical farm uses soil then biochar can be mixed into the soil and provide benefits such as:
- Water retention
- Feed retention
- Microbial stimulation
- Increased aeration
- Improved drainage
- Increased water holding capacity
If your vertical farm is soil free, biochar can be used to replace 50% of the expanded clay balls or perlite with effects such as, increase leafy biomass and reduced algal buildup. It helps reduce algae production due to its ability to absorb excess nutrients in water making it harder to reach for the algae.
In summary, biochar is a great addition to vertical farming and should be applied according to the specifics of your set up. Contact us using the form at the top of this page if you have any questions.