Monday, 14 September 2009


When plants grow they absorb carbon dioxide from the atmosphere. Under the normal carbon cycle when plants die they either rot or are burnt and the carbon they absorbed is returned to the atmosphere but although this is better than using fossil fuels for compost or heating/light, the process does not remove carbon from the atmosphere. The same applies to Bio fuel. The crops from which bio fuels are made take carbon dioxide out of the atmosphere while they are growing, but as soon as that bio fuel is used, the carbon is returned to the atmosphere through emissions. If, instead, waste biomass is turned into Biochar, it can be buried in the ground, locking in the carbon for hundreds or even thousands of years and have a positive impact on crop outputs.

I recently went to see a pilot system of making Biochar. The Biochar in this case was small branches that would normally be burnt or used for wood chippings. The project I looked at uses a sealed system so the gasses from the wood actually burn the wood, and 90% of the carbon is still locked in the Biochar.

But what then do we do with this material?

Scientists have known for years that adding Biochar could improve soil fertility. The early Amazonian Indians introduced Biochar to their soil over 3,000 years ago, forming the Terra Preta, black soil which remains fertile to this day. It is only recently that the reasons why this happened have been understood. Biochar is extremely porous; the surface is like a sponge. This encourages the growth of micro-organisms which produce enzymes that release the mineral ions trapped by the heat stabilized plant resins in the charcoal and make it available to the root hairs of the plant as nutrients. Furthermore, the resins within the charcoal act like an ion exchange resin, absorbing traces of mineral ions onto the charcoal particle surfaces from the rain water, and trapping it within the charcoal’s molecular structure. The trace minerals always present in rainwater actually act as a fertilizer - providing the nutrients needed by the crops, year after year.

Or as Johannes Lehmann - Department of Crop and Soil Sciences, Cornell University, Ithaca, New York, U.S.A said, “Important lessons can be learned from Terra Preta about development of civilization in the Amazon, basic functioning of soils, carbon sequestration, and sustainable land use”. I especially liked that last point, ‘sustainable land use’.

So we have a win-win situation, we create Biochar, locking the C02 away, and also create a proven fertiliser.

The systems to enable this are totally unsophisticated, as you can see. The materials are cheap and easy to obtain, a few building blocks, a sheet of metal and some oil drums. In the retort you can see in my photo’s the gas tight seal was obtained by a liberal application of Sussex clay, obtained from underfoot, while the trees that provided the wood grew around us. If you would like to know more about the Carbon-Gold project, please see HERE.

Genesis 1:12 The land produced vegetation: plants bearing seed according to their kinds and trees bearing fruit with seed in it according to their kinds. And God saw that it was good.

And not just good for beauty and food either it seems.

1 comment:

Erich J. Knight said...

Dear Fr Peter,

There are dozens soil researchers on the subject now at USDA-ARS.
and many studies at The up coming ASA-CSSA-SSSA joint meeting;

Also got to the Economist!
The virtues of biochar: A new growth industry? | The Economist

Biotic Carbon, the carbon transformed by life, should never be combusted, oxidized and destroyed. It deserves more respect, reverence even, and understanding to use it back to the soil where 2/3 of excess atmospheric carbon originally came from.

We all know we are carbon-centered life, we seldom think about the complex web of recycled bio-carbon which is the true center of life. A cradle to cradle, mutually co-evolved biosphere reaching into every crack and crevice on Earth.

It's hard for most to revere microbes and fungus, but from our toes to our gums (onward), their balanced ecology is our health. The greater earth and soils are just as dependent, at much longer time scales. Our farming for over 10,000 years has been responsible for 2/3rds of our excess greenhouse gases. This soil carbon, converted to carbon dioxide, Methane & Nitrous oxide began a slow stable warming that now accelerates with burning of fossil fuel. Agriculture allowed our cultural accent and Agriculture will now prevent our descent.

Wise Land management; Organic farming and afforestation can build back our soil carbon,

Biochar allows the soil food web to build much more recalcitrant organic carbon, ( living biomass & Glomalins) in addition to the carbon in the biochar.

Every 1 ton of Biomass yields 1/3 ton Charcoal for soil Sequestration (= to 1 Ton CO2e) + Bio-Gas & Bio-oil fuels = to 1MWh exported electricity, so is a totally virtuous, carbon negative energy cycle.

Biochar viewed as soil Infrastructure; The old saw;
"Feed the Soil Not the Plants" becomes;
"Feed, Cloth and House the Soil, utilities included !".
Free Carbon Condominiums with carboxyl group fats in the pantry and hydroxyl alcohol in the mini bar.
Build it and the Wee-Beasties will come.
Microbes like to sit down when they eat.
By setting this table we expand husbandry to whole new orders & Kingdoms of life.

This is what I try to get across to Farmers, as to how I feel about the act of returning carbon to the soil. An act of penitence and thankfulness for the civilization we have created. Farmers are the Soil Sink Bankers, once carbon has a price, they will be laughing all the way to it.

Let us all Please incant ritual supplications for a smooth transition to these new agricultural protocols.

Just for fun (If you can indulge my blasphemous paraphrase of our lords prayer) I leave you with My Terra Preta Prayer;

The Terra Preta Prayer

Our Carbon who art in heaven,
Hallowed be thy name
By kingdom come, thy will be done, IN the Earth to make it Heaven.
It will give us each day our daily bread and forgive us our atmospheric trespasses
As we forgive those who trespass against the Kyoto protocols
And lead us not into fossil fuel temptation, but diliver us from it's evil
low as we walk through the valley of the shadow of Global Warming,
I will feel no evil, your Bio-fuels and fertile microbes will comfort me,
For thine is the fungal kingdom,
and the microbe power,
and the Sequestration Glory,
For ever and ever (well at least 2000 years)