Biochar: a Slow-Burn Success
Posted by Unknown in Biochar, Budget and Funding, FAO and UN, Gardening, Organic, Soil Management on Tuesday, 14 May 2013
Biochar could help you get more from your plants and save the planet at the same time. What's the secret?
By Lia Leendertz
Telegraph
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| Growth area: Daylesford Organic gardener Jez Taylor extols the virtues of biochar, which has improved his germination rates his germination rates Photo: Christopher Jones |
Farmers in
Belize are excited about it, as are carbon capture scientists, the
United Nations Development Programme (UNDP), and multinationals such as
Kraft and Nestlé. It may provide a carbon sink, it may save degraded
soils, it may alleviate rural poverty.
"It" is
biochar. For Jez Taylor, the head gardener at Daylesford Organic, the
attraction is more simple: "The environmental benefits and its ability
to capture carbon are delightful, of course. But I just get fantastic
propagation results when I'm using it. That's what I'm interested in."
Biochar is "the
oldest new thing you've never heard of", to quote a phrase coined by
Wae Nelson, a US biochar expert, and its applications are wide ranging.
It is essentially charcoal, but burnt at a lower temperature and with a
more restricted flow of oxygen. Its proponents believe it was the force
behind ancient cities in the depths of the Amazon, where poor, acidic,
tropical soils would not otherwise have been able to sustain large
populations. In such sites up to 2m (6ft 6in) of terra preta (Portuguese
for "black earth") can be found: rich, dark and fertile pockets that
occur naturally among the yellow surrounding earth.
Jez Taylor is
one of a number of head gardeners who are pioneering the use of biochar
in Britain. He manages 20 acres and six polytunnels of crops that supply
Daylesford's own upmarket farm shops in the Cotswolds and London, and
his main interest is in propagating the many plants that will fill those
fields. Each starts off in a tiny plug of compost, desperately
vulnerable to drying out.
"I don't claim
to be an expert propagator, and often we have apprentices watering who
may be even less expert," he explains. "The compost needs to be
bombproof or young plants will be lost, particularly those in tiny
modules, such as spring onions."
Conservationists call on Government to back ban on 'bee-killing' pesticides 13 Mar 2013
Jez tried a mix
of coir and biochar and found that the water-holding action of the
biochar improved his results dramatically. "I now know I can water on a
Friday and come back in on Monday to find that everything is OK. I can
be certain that seeds are still moist at the crucial moment when the
root emerges from the seed, and last year this improved germination
rates from around 80 per cent to closer to 95 or 100 per cent."
Jez also uses a biochar-based compost for larger vegetables that go into the shops for sale as plants.
"It is great in
the potting mix and I'm convinced it gives it more guts. Plants seem to
be supported for longer and there is less yellowing of leaves. When we
feed, the feed isn't given in one go but locked away by the biochar and
released slowly to the plant, and it really shows."
Dr Saran Sohi,
of the UK Biochar Research Centre, started his career researching soils
and soil additives. He says the effect biochar has on soil is different
from that of any other additive.
"Biochar brings
a physical and permanent change to the soil. Every other additive
decomposes but biochar remains, and its effects increase over time."
Biochar works
in several ways. Though it is not filled with nutrients itself, it is
able to attract and hold on to nutrients, so preventing them from
leaching away, and holding them just where plants can reach them. Its
porous nature provides refuges for mycorrhizal fungi, which in effect
enlarge the plant's root system while also increasing its resistance to
diseases. It makes soil far more attractive and stable for beneficial
microbial activity. Essentially it does everything organic matter does
to the soil, but better, and permanently.
All this goes
some way to explaining the impressive results seen in Belize. Craig
Sams, founder of Green & Black's chocolate, has a strong interest in
biochar, having founded a company, Carbon Gold, that sells biochar
mixes and kilns.
"I've been in organic food most of my life, so I've seen the difference that good soil management can make," he says.
He wanted to
bring the two parts of his work together and see what impact biochar
could have on cacao growers' crops. Two Belize farmers were taken to
Cornell University and "pumped on biochar", as Sams puts it. On their
return they were given kilns and asked to put what they had learnt into
practice. The results surprised everyone. Cacao plants planted into soil
rich in biochar started producing fruits when about three-and-a-half
years old; they usually take seven years to reach this maturity.
This caught the
eye of the UNDP, which has now provided $50,000 (£32,900) for more
kilns, and there are several non government organisations working to
create biochar gardens throughout Africa and the Third World. Large food
companies have also started getting in on the act: a sure sign that the
enthusiasts are onto something. Unlike charcoal – which is made from
hardwood at high temperatures – biochar is made at low temperatures and
from any waste, including animal dung, twiggy waste, softwoods and rice
husks, making it a realistic proposition for farmers in developing
countries.
"When diseases
hit plants grown in biochar-rich soils they have to fight their way
through a shield of beneficial fungi and bacteria, and we think this is
why the Belize plants produced so much earlier than usual. They could
grow unhindered," says Sams. In Britain he is working with Bartlett Tree
Experts on a trial with ash trees infected with ash dieback, to see if
biochar might give them a similar increase in armoury.
Elsewhere, Ed
Ikin at National Trust property Nymans is the first head gardener to
install a biochar kiln to deal with his garden's waste and improve its
soils, and Great Dixter head gardener Fergus Garrett uses biochar in his
compost mixes.
"It's an excellent peat substitute," says Garrett. "Better than green waste. I would use it as part of a John Innes mix."
While biochar's
effect on soils and plants is exciting, there are also great
environmental benefits to its manufacture and use, and these stem from
its capacity to lock up carbon. Soil is naturally a carbon sink – it
locks away carbon and prevents it from entering the atmosphere – but a
chunk of our troublesome greenhouse gases arises from ploughing soil and
releasing this carbon. Although normal composting and mulching takes
carbon in the form of organic matter and puts it into the soil, this
quickly breaks down as matter rots, and the carbon is released again.
Every time we dig or disturb the soil we speed up this process. Peat
mining is an extreme example of this: when we disturb peat bogs we
release carbon that was locked away thousands of years ago. But at least
50 per cent of the carbon in any piece of waste turned into biochar
becomes permanently stable.
Gardeners digging biochar into their soils are taking a small step in undoing the environmental damage caused by peat users.
While Dr Saran
is particularly enthused about the use of biochar in tropical climates,
he thinks it could have applications in British gardens.
"In the average
back garden you can make a big impact," he says. "A little can have a
big effect on the soil. The way biochar interacts with water, nutrients,
microbes and fungi will improve growing conditions and make soils more
stable and fertile."
