Jiggi project at forefront of biochar revolution

BURNING ISSUE: The new kiln at the Jiggi bamboo plantation. INSET: Finished product.
BURNING ISSUE: The new kiln at the Jiggi bamboo plantation. INSET: Finished product.

A BAMBOO plantation at Jiggi is the home of an experimental biochar kiln, the brainchild of soil carbon advocates Dr Paul Taylor and Prof Stephen Joseph.

Landowner Kerrie O'Neill is currently commissioning the furnace, which can hold two cubic metres of feedstock - in this case rapid growing, perennial bamboo.

Last Saturday she showed it off to a small gathering of keen gardeners intent on improving their own backyard soil.

For Tweed Valley resident Dr. Taylor, author of the book 'The Biochar Revolution', the newly-created kiln will help make a regular supply of this valuable organic charcoal and at the same time reduce carbon in the atmosphere by storing it underground where it will last for hundreds of years.

Last week Dr Taylor hosted a visit to the area by Prof Joseph of the University of NSW. The pair visited the kiln they designed at Jiggi and demonstrated its efficiency to a workshop group. They are also finding time to create a smaller version, which when finished will be suitable for home use. They plan to make both designs available in a bid to increase home and small farm biochar production.

The Jiggi kiln is designed to create an enhanced biochar soil additive, based on the research of Prof Joseph, using a blend of chicken manure, straw and clay as well as woody fibre (in this case bamboo) in an attempt to recreate the remarkable Terra Preta soils found in the Amazon basin.

Terra Preta, Portuguese for 'black earth' is found in pockets of rich, fertile dirt under the Amazon rainforest, otherwise known for its poor, thin soils.

Dutch scientist Wim Sombroek recognised in the 1950s that Terra Preta was human created since it contained charcoal and other refuse and artefacts of human culture.

The charcoal in Terra Preta soils had been there for up to 3000 years.

Simply sprinkling straight charcoal on the ground may not always have the desired effect on plant life because it may initially lock up nutrients, rather than make them available.

Enhanced 'Terra Preta' biochars, on the other hand have been used in field trials with just a few hundred kilograms per hectare, rather than 10 times that much using plain charcoal.

Dr Taylor, an astrophysicist who has turned his attentions to the issues of climate change and renewable energy, pointed out that the term 'biochar' was only coined in 2005 and today it is regarded as a potential 'magic bullet' in the race to pull C02 out of the atmosphere.

What makes Dr Taylor and Prof Joseph so excited about this black, granular material is the fact that - like the Amazon Indians - everyday people using simple techniques can take weeds, waste and woody materials and store their accumulated carbon in the ground for a very long time.

"We can take a waste material, process it and lock it up in the soil and at the same time benefit that soil and make it and food production more resilient," he said.

"It can enhance water and nutrient holding capacities of the soil and act as a catalyst for micro organisms and plant growth."

Charcoal is a substance that has been made by humans around the world for thousands of years, but often in very polluting ways. The secret to making environmentally correct biochar is to roast woody material slowly, in an oxygen-free environment, and then flare off polluting gases at a higher temperature, rendering them climate neutral.

When charcoal is used as a fuel (to cook food or melt metals) it is oxidised and the carbon returns to the atmosphere.

Charcoal made at higher temperatures is 'activated' by creating lots of tiny holes in the char. This material is excellent for purifying water or air, but it is not necessarily the best for growing plants.

When wood is turned into biochar, it is cooked at 400-500 degrees Celsius, about half the temperature used to create 'activated charcoal'.

In the case of the Jiggi kiln, a blend of fibre, manure, clay and straw is pre-mixed to provide an enhanced biochar rich in minerals and ripe for microbial colonisation.

In other methods, already in production elsewhere, biochar is sometimes mixed with compost and other ingredients after it has been made.

But Mr Taylor says the technique adopted at Jiggi is expected to produce results more akin to the ancient Terra Preta.

And the newly designed kiln is suitable for burning a wide variety of plant material, including macadamia shells and sawmill waste. Kerrie O'Neill hopes that other people with various waste products may commission her to convert them into advanced biochars.

Prof Joseph is also creating a production version of his process at a biochar facility near Bendigo, Vic, and with Dr Taylor has scheduled a workshop there on April 13-14.

The Biochar Revolution is available via the book's website: biochar-books.com.



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