Hidden in the Amazon basin lie swathes of dark, rich earth.
Known as terra preta, this soil is believed to have been made thousands of years ago by ancient pre-Columbian civilisations. Even today it is highly prized by farmers.
The secret ingredient? Biochar.
"Biochar itself is inert, but it facilitates a whole lot of life and fungi and bacteria," said Christina Giudici, co-founder of New Black, a growing biochar business in southern Tasmania.
"By having that stable carbon structure in there, it's a bit like a coral reef."
Biochar is a type of charcoal, although it is a bit different to what you throw on the barbecue.
Organic material is 'cooked' in a process called pyrolysis, which uses high temperatures and low oxygen levels to create charcoal with a very stable carbon structure.
Co-founder of New Black, Bodie Cavanagh, has spent the past 18 months designing and building a biochar machine.
It runs solely on sawdust produced at Mr Cavanagh's sawmill.
"It takes sawdust, burns that nice and cleanly, and then at the same time takes a little more sawdust and pyrolyses that to produce biochar," he said.
Nothing goes to waste. The excess heat will be used to dry wood for the timber mill and the business will soon sell not just biochar but carbon credits too.
"So the trees capture the carbon, the pyrolysis stabilises it, and then the use of the biochar stores it, and if you can get those three things – capture, stabilise and store – then you've got one of the solutions to climate change," Ms Giudici said.
Is black the new green?
There is no doubt biochar production captures and stores carbon. There is also plenty of evidence it's good for your soil.
But it's not a silver bullet technology.
Professor Mark Howden is the Director of the ANU Institute for Climate, Energy and Disaster Solutions.
He believes the potential of biochar is huge but warns it is not a panacea for our climate woes.
"It's only part of a set of solutions for climate change, and it's only part of a set of solutions for sustainable agriculture," Professor Howden said.
"I think there is a lot of very positive commentary, some of which isn't supported by the science.
There are also trade-offs involved.
Crop stubble, for example, can be burnt and made into biochar. But it can also be used in no-till farming to reduce erosion while increasing organic matter in the soil.
That said, other forms of biomass do exist such as invasive weeds and logging waste.
Ultimately, biochar is a good news story.
It can help fight global warming and, just maybe, bring a bit of the Amazon's terra preta to Australian farms.
"I actually think there are lots of good things about biochar used wisely and in an informed way," Professor Howden said.
"So let's be positive, but let's not over hype it."
