The black, flaky miracle that is biochar | Climate Tasmania

An ancient soil enricher is set to be an important tool in the battle to reduce atmospheric carbon, while also helping us grow more food.

[Peter Boyer: posted 6 July 2010]

Every now and again in the big, unfolding saga that is climate change you find yourself heading back to the future, looking at something simple and basic that’s been around forever. I had just that experience at a meeting in Hobart last week.


Flakes of carbon-rich biochar ready for digging in. PHOTO Adriana Downie, Pacific Pyrolysis)
The Tasmanian Biochar Workshop put a spotlight on charcoal, that dirty, unmanageable residue of burnt plant and animal matter, and provided its participants with ample evidence that this humble substance has big implications both for reducing atmospheric carbon and growing plants.

Simply put, biochar is charcoal created by slow smouldering of organic material which, if dug into the ground, serves as a long-term carbon store while enriching soils, boosting plant growth and improving water quality. It can hold carbon in soil for many centuries, even thousands of years.

Biochar has an ancient history. Early peoples of the Amazon basin in South America are believed to have made it by smouldering food and agricultural waste, digging it into the region’s naturally infertile soil to be further broken down by native earthworms. European settlers called this wonder-soil “terra preta” (Portuguese for “black earth”).

In more modern times, the charcoal-burner was a familiar part of every settlement in Europe and elsewhere, including Australia, producing fuel for cooking and heating. The application of fine-grained char as a soil additive is an old-new idea whose time has come around again.

But the idea of biochar has taken a while to catch on in Tasmania. In 2008 it got caught up in the debate about biomass energy from Tasmanian forestry operations, involving gathering up the woody debris left after logging and burning it in a biomass electricity generator.

Some forests activists accused biochar advocates of aiding and abetting native forest clearfelling by providing the logging industry with a convenient repository for its waste and a reason to extend its harvesting operations.

The debate ignored the fact that the primary focus of biochar production is carbon storage and increased soil fertility. Energy generation from pyrolysis (the process of producing biochar) and production of biofuel are additional outcomes. The process is carbon-negative, which means that it takes more carbon out of the atmosphere than it releases.

The Hobart meeting was organised by international biochar consultant Attilio Pigneri, now living in Tasmania. Held under the auspices of the Australia New Zealand Biochar Researchers Network, it brought together specialists from the University of Tasmania, CSIRO, government and industry.

Farmers, soil scientists and biochar business representatives mixed with interested outsiders to hear research outcomes from trials happening in Australia (including Tasmania) and New Zealand.

The 60-strong audience heard that biochar production was potentially a highly-valuable greenhouse mitigation and growth-enhancing tool for Tasmania whose efficacy depended on environmentally-friendly biomass sourcing and production techniques and good knowledge of the best kind of biochar for particular soils.

The meeting was told that feedstock, or raw material, for biochar can come from a big range of sources, including green waste from gardens and orchards, woody weeds such as gorse or willow, food processing waste, sewage sludge and manure (including poultry litter), seaweed, crop stubble, sawdust and wood “from responsible forest management operations”.

Different sources produced different results, with biochar from animal waste providing better productivity for some crops and woody material benefiting others. Other variables included different soil types and climatic conditions.

The workshop examined key environmental and economic issues in use of biochar in Tasmania, questions about logistics and sustainability, synergies between environmental mitigation and regional development, commercial possibilities, and the challenges of bringing biochar activities into a national carbon pricing scheme.

To Dr Pigneri, the workshop has significantly raised awareness of current biochar activities, including five University of Tasmania projects, and begun to link researchers and their work across Australia and New Zealand, while providing a base for a permanent industry association.

He and his team will use discussion outcomes from the workshop to guide future planning and inform governments about the technology’s potential both in reducing atmospheric carbon and helping Tasmania improve its agricultural productivity.

My father grew up on a farm and was a lifelong vegetable gardening enthusiast, but on that score I’d have been a disappointment to him. Like so many post-war children, I turned away from my rural background towards a city life, becoming part of the “great forgetting” that served to distance much of modern humanity from the production of food.

Now, our roots are calling us back. Besides finding better ways of keeping carbon out of the atmosphere, communities everywhere need to start taking an interest in how they derive sustenance from their lands, and that means getting heads around how to manage soil to grow better plants.

For me, the great appeal of biochar is its basic simplicity. There’s much more work to be done — years of trialling different scenarios to ensure we maximise the gain from the effort — but all the signs are that public support for a biochar industry will be a splendid investment in the future.