What is biochar?
Biochar is a special kind of eco-friendly charcoal that you add to soil to improve its function.
How is biochar made?
Biochar is made by burning wood and other organic biomass (natural plant and tree waste) in a kiln at low temperatures in a low oxygen environment, in a process called ‘pyrolysis’.
How is biochar different from the standard kind of charcoal that you put on your barbecue?
Although they are made in similar ways, biochar is designed to be biologically active. Due to its processing techniques, lots of nooks and crannies are created in its surface – making it much more porous and absorbent than common charcoal. The beneficial fungi, bacteria and other microorganisms that are essential to healthy and fertile soil flourish in these tiny spaces. Barbecue charcoal, on the other hand, has been made purely to burn. Adding it to your soil will not produce the same nourishing results.
Moreover, biochar is made from sustainable plant biomass. Over 90% of the charcoal sold in the UK is imported – and is the result of environmentally damaging deforestation in the tropics.
What does biochar do for soil?
There are numerous benefits arising from adding biochar to your soil. It can boost the fertility of your soil – and, as a result, plant health and crop yields. It does this by improving the nutritional content and fertility of the soil by creating the perfect environment for mycorrhizal fungi and beneficial bacteria to flourish. These do wonders for plant health. Through its roots, they feed the plant nutrients and protect it from disease.
Biochar also manages, seemingly paradoxically, to improve soil’s water holding capacity, at the same time as helping with drainage. It can do this because it’s so porous. It can soak up lots of water and hold onto it. This means your plants need less watering – and the beneficial fungi and bacteria in your soil won’t die off during a dry spell.
Why is it good for the environment?
Biochar can assist with two of the greatest environment problems we face.
First of all, it offers one way to help combat the widespread problem of soil degradation. The United Nations has pronounced a third of Earth’s soils ‘severely degraded’ – as a result of intensive farming, industrial fertilizers, pesticides and pollution. Biochar can restore degraded soils, by helping beneficial fungi, bacteria and microorganisms to flourish. It also offers a significant tool in the fight against soil acidification – a key factor in soil degradation – by maintaining soil’s natural pH levels.
Secondly, biochar can contribute to the issue of runaway carbon emissions, which drive global warming. It captures carbon (CO2) and fixes it in the soil.
What is the scientific proof that it works?
James Lovelock, the visionary scientist behind the Gaia Hypothesis, has advocated putting biochar into the soil as one way of cutting carbon levels and mitigating climate change. Chris Goodall, author of Ten Technologies to Save the Planet, also recommends biochar as one means to carbon level reduction.
Academic interest in biochar is at an all-time high. Research is ongoing, however, the results to date are highly promising. In the UK numerous universities are involved. Edinburgh University hosts the UK’s Biochar Research Centre. Professor Peter Smith of The University of Aberdeen, and also Director of Scotland’s Climate Change Centre of Expertise, has written a paper advocating biochar as part of the solution to runaway carbon emissions. Research into biochar is also being undertaken at Coventry University, Reading University and the University of Newcastle. Professor James Fairhead of the University of Sussex has conducted research into rural African farmers using biochar to make their agricultural practice more sustainable.
How long does it stay in the soil?
Ancient Amazonian peoples used biochar to create highly nutrient-rich ‘super soils’, called ‘Terra Preta’, to solve the problem of poor tropical soil fertility. Modern scientists have dated these soils back at least 2,500 years, but some are much older still – suggesting that biochar is stable and long-lasting.