The questions that come up first, answered plainly. Anything more specific belongs on the contact page.
Is biochar just barbecue charcoal?
Same chemistry, different specification. Fuel charcoal is made for energy density and may contain binders or accelerants. Biochar is made and certified for soil: controlled feedstock, verified carbon and hydrogen ratios, tested limits on heavy metals and PAHs. Charcoal briquettes sold for grilling meet none of that, so keep them out of the garden.
Doesn’t making it release CO2?
Some, yes. Roughly half the feedstock carbon leaves as gas and oil, and burning that syngas releases it. But that carbon came out of the air within the last few decades, so it is a return, not an addition. The stable half that stays in the char is a net withdrawal, which is how the accounting lands at around two to three tonnes of CO2e per tonne of biochar.
How long does it really last?
It depends on the char. Low-temperature char with a high hydrogen-to-carbon ratio can largely disappear within a century. High-temperature char with a molar H/C below about 0.4 is credited with a half-life measured in centuries to over a thousand years. This is the single most important quality number in the industry.
Will it increase my yields?
Possibly not. If your soil is fertile, well-structured and adequately watered, the honest expectation is little to no yield gain: the benefit is carbon storage and long-term resilience. If your soil is sandy, acidic or degraded, the response can be large.
How much do I apply, and how?
Field rates are usually quoted in tonnes per hectare, incorporated into the topsoil. Charge it first: compost it, soak it in slurry, or mix it into manure, because raw char adsorbs nutrients and can suppress the first crop if applied dry and hungry. Spread it on a still day: dry char is dusty, and dusty carbon is flammable in bulk.
Who checks that a tonne is a tonne?
Independent standards (the European Biochar Certificate, the IBI guidelines, and carbon registries such as Puro.earth and Verra) set production, contaminant and accounting rules. Credits are issued against measured, sampled output, not against a promise about the future.
How to make biochar yourself
Small-scale kilns and steel-drum retorts are within reach for a garden or a smallholding, and are a reasonable way to learn the process. Anything sold as biochar, fed to livestock, or claimed as carbon removal needs to be tested against the same feedstock, contaminant and H/C standards a commercial producer works to homemade char that has not been tested is charcoal, not certified biochar.
Is it safe? What about contamination?
The pyrolysis temperatures involved destroy pathogens and most organic contaminants in the feedstock. The two things worth checking on a lab report are heavy metals, which concentrate rather than disappear if they were present in the feedstock, and PAHs, which can form during a poorly controlled burn. Certified biochar is tested for both against published limits.