This article is from our 2009/10 Annual Report, Redefining Conservation.
Over the past two years, a ‘buzz’ has been building amongst experts in the fields of climate change and agriculture. Media reports have highlighted a new product: one that promises to sequester CO2 in a cost-effective way, increase agricultural yields, reduce polluting run-off from agricultural land, and increase the efficiency of fertilizer and water use. This “new” product is called biochar. It is a complex substance with many possible variations in composition, structure and quality. When produced from wood fuel, we know it as charcoal.
Biochar’s first use as an agricultural amendment was by the indigenous cultures of the Amazon rainforest, thousands of years ago. By burying charcoal mixed with organic wastes, such as food scraps, the ancient people were able to turn poor, low fertility rainforest soils into fertile cropland. Scientists currently studying these soils (called terra preta) are amazed that they have retained their fertility to this day, without any further human inputs.
The modern, high-tech method of biochar production is called pyrolysis. Fuel – usually wood or agricultural waste, but any organic material can be used – is heated to a high temperature in a low-oxygen environment. The products generated include oil, gas and biochar. The latter can contain as much as half the carbon in the original fuel. The oil can be processed into a biofuel and/or a variety of different oil-based products, while the gas can be used to fuel the pyrolysis process itself. Biochar can be produced at a very high-tech scale – as at least one Canadian company is already doing so in Ontario – or at a low-tech, individual scale, using simple cooking stoves.
Adding biochar to soil provides two basic benefits. The first arises from the fact that most of the carbon in biochar resists decomposition by microbes in the soil. In essence, the concept is one of delaying the carbon cycle. Biological material that has been created by fixing atmospheric carbon through photosynthesis ordinarily delivers its carbon back into the atmosphere when the organic material decomposes. By delaying this decomposition, biochar effectively sequesters the carbon in soil. The second benefit has to do with soil health. Studies show that biochar can enhance nutrient-holding capacity, increase moisture retention and build biological biodiversity – substantially improving the soil’s health, fertility and resilience.
However, biochar has its detractors. Some question its value for Ontario’s young and relatively fertile soils. Although more research is needed, an early trial in Quebec suggests some increase in yields and increased fertilizer-use efficiency. OMAFRA’s soil specialists consider the positive claims for biochar as “intriguing but unproven,” and the ministry has already provided scientific support for new research.
Skeptics have also questioned the length of time the carbon in biochar will remain sequestered. While recent research suggests that the sequestration is very long term (i.e., hundreds or even thousands of years), caution and more research are definitely required.
Finally, some observers feel that if biochar were eligible for carbon credits it would put the world’s remaining natural areas at risk – as well as the human and ecological communities that depend on them. The concern is that large multinationals may convert these areas into crop or forest monocultures designed to fuel biochar production.
In current times, as in ancient times, biochar brims with promise. Several internationally acclaimed scientists have gone on record as supporting increased research and the development of policy and programs to promote biochar production and use. Despite its tantalizing promise, however, there are undeniable risks if the technology is misused.
The ECO encourages OMAFRA to give biochar research, both by its staff and in partnership with universities and the private sector, a very high priority. The ECO also encourages OMAFRA to begin to address the risks associated with biochar production, with an eye to the development of guidelines. In our 2008/2009 Annual Report, the ECO recommended that Ontario develop a provincial biofuels strategy to address the full ecological implications of the increased use of biomass energy. Guidelines for biochar production and use should be a major component of that strategy.
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