Monday, 22 August 2011


I am following a wide range of blogs and was pleased to discover Emma Coopers: her recent blog about biochar was really interesting and set me thinking.

'Biochar' seems to be a conflation of biological and charcoal and refers to charcoal that is used in the soil to lock in carbon and increase fertility. As Emma says:
'One of the hot topics in permaculture and organic gardening at the moment is biochar, an idea that is being developed after the discovery of charcoal-rich dark soils in the Amazon region (also known as Terra preta), which date back to before the arrival of the Conquistadors. These dark soils are surprisingly rich, even now, holding onto nutrients and improving soil fertility'.

Claims for biochar go beyond an ability to hold nutrients in the soil for centuries: they are said to be 'carbon negative' - removing carbon from the environment.

Our soil is little better than sand and soil improvement is a major priority if we are to develop healthy plants. So, biochar has the potential to be very useful for us. In fact, biochar could have value for many gardeners and farmers if the claims made for it are true.

And this leads on to a possible opportunity for us... Our site has large quantities of timber that must be removed over the next five or more years as the garden is developed for wildlife and the trees are thinned to give remaining trees more room. We are considering the use of wood burning stoves and may be able to make timber available for others to burn too. There will be, however, lots of branches and waste left over ...... and turning these into biochar could be a useful use of this waste material.

Conventional charcoal production uses hardwoods with cordwood split and stacked inside a large charcoal burner. The Centre for Alternative Technology did have information about much simpler biochar burners that take branches but the updated site only gives a general introduction to biochar.

There is a lot I need to learn about! Here's a few questions to get me going...
  • Most of our timber will be softwood - does this still produce biochar that can benefit the garden?
  • Is there an optimum quantity of biochar that should be integrated into the soil?
  • Do all plant groups benefit from biochar equally?
  • Does biochar hold all nutrients well or are some more or less available to plants from 'black soil'?
Much more reading is necessary!!!

The Biochar Research Centre is supported by our government and provides much information on this subject.

Take part in The Big Biochar Experiment!!

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