A mate of mine is the lead author on a recent Publication in Nature Communications on Biochar. Fair Play Dom!
Here's a longer version of a piece I wrote for the Examiner on it, in my weekly Organic Diary (every Thursday)
Is there a way for farms to be fertilized and to reduce farming's Green House Gas emissions at the same time? The principles and practices of organic farming, such as the use of clover for nitrogen fixing, are no doubt helpful in highlighting the options and opportunities for conventional farming.
There may now also be another option. According to new research, just published by a team of international scientists in the journal Nature, a substance which can be made from farm waste could reduce the world's greenhouse emissions by up to 12 per cent.
The scientists writing in the journal Nature say "Biochar" is a fine charcoal that can store carbon while helping to improve soil.
Biochar is made by decomposing biomass like plants, wood and other organic materials at high temperature in a process called slow pyrolysis.
"Biochar offers one of the few ways we can create power while decreasing carbon dioxide levels in the atmosphere. And it improves food production in the world's poorest regions by increasing soil fertility. It's an amazing tool," said Jim Amonette, a soil chemist at the US Department of Energy's Pacific Northwest National Laboratory.
Some of the specific benefits of biochar include the fact that it can take carbon and store it for hundreds of years, as well as: improve the soil's functioning (water retention and nutrient levels), decrease nitrous oxide and methane emissions from the soil into which it is tilled, and produce some bio-based gas and oil during pyrolysis.
It is also one of the few substances that can disrupt the Carbon Dioxide cycle, as it releases oxygen from the Cycle as did coal in its formation millions of years ago.
Interestingly, the researchers looked to the world's sources of biomass that aren't already being used by humans as food. So they looked at waste crop leaves, stalks and rice husks, livestock manure and yard trimmings.
Lead author Dominic Woolf's abstract for the article states that the reductions of 12% of current anthropogenic CO2_C equivalent emissions can be achieved "without endangering food security, habitat or soil conservation".
According to a detailed Science Daily report on the study:
"The researchers then calculated the carbon content of that biomass and how much of each source could realistically be used for biochar production.
With this information, they developed a mathematical model that could account for three possible scenarios. In one, the maximum possible amount of biochar was made by using all sustainably available biomass....
"the maximum scenario could offset up to the equivalent of 1.8 petagrams -- or 1.8 billion metric tons -- of carbon emissions annually and a total of 130 billion metric tons throughout in the first 100 years. Avoided emissions include the greenhouse gases carbon dioxide, methane and nitrous oxide.
The estimated annual maximum offset is 12 percent of the 15.4 billion metric tons of greenhouse gas emissions that human activity adds to the atmosphere each year.....
Adding biochar to the most infertile cropland would offset greenhouse gases by 60 percent more than if bioenergy were made using the same amount of biomass from that location, the researchers found."
The origins of Biochar are in South America. Before settlers arrived, agricultural waste was smouldered by the farming inhabitants to help with soil fertility. This involved covering burning biomass with soil and then letting it smoulder. This process was labelled Terra Preta, or Terra Pretta de Indio by the European settlers who arrived.
This soil is still today more fertile and indeed dark (from the charcoal) than surrounding soils.
As with all supposed magic bullet solutions to climate change, there are pros and cons. Most who query biochar's potential, and indeed many undecided experts, see it as a small part of a multi-strand solution.
Even in this, it is acknowledged that only with careful management of its potential, can it emerge as a positive:
"Using biochar to reduce greenhouse gas emissions at these levels is an ambitious project that requires significant commitments from the general public and government. We will need to change the way we value the carbon in biomass," according to Jim Amonette.
This latter point is the key. While Biochar can work, throwing it to the wolves of global carbon trading could lead to a very messy situation, full of unintended consequences.
Critics worry about plantations to produce biochar displacing forestry: anything from 200 million to over a billion hectares have been suggested. This would replace existing forest, Savannah and woodlands with biochar plantations.
Ironically people who currently use these, in western terms, uneconomical lands, also produce hardly any Green House Gases.
Massive commercial tree plantations have, all over the world, been shown to be environmentally destructive in a myriad of ways, from soil erosion to pesticide run off.
There are also examples where biochar has been shown to suppress rather than improve plant growth, and also stimulate bacterias which cause other types of climate change anyway.
Of course, it doesn't have to be like this. Biochar can simply be a case of baby steps in the right direction, using farm wastes that would otherwise be costly to treat and climate change causing if left untreated.
Here in Ireland, FEASTA (the Foundation for the Economics of Sustainability) have been engaged in a Department of Environment funded multi agency initiative to examine carbon cycles and sinks. Research into biochar for arable farming has been part of this.
The journal article reference: Dominic Woolf, James E. Amonette, F. Alayne Street-Perrott, Johannes Lehmann, Stephen Joseph. Sustainable biochar to mitigate global climate change. Nature Communications, Aug. 10, 2010)
For more see feasta's Carbon Sinks and Cycles site
