Jeff Schahczenski is an Agricultural and Natural Resource Economist with the National Center for Appropriate Technology (NCAT).

After lurking in the world of biochar for many years, I feel confident in my conclusion that biochar is an emerging movement — a set of diverse scientific, social, economic, technological and political topics and activities surrounding a common theme or issue. But what is this movement-inspiring miraculous substance called biochar? Why might it be important to sustainable agriculture?

Biochar is…

Biochar can technically be made from any biomass product (wood, manure, grasses or crop residues), and is created through an energy-conversion process called pyrolysis. Pyrolysis is the combustion of biomass in the complete or near absence of oxygen. The outputs of pyrolysis— in addition to biochar — are heat, oils, and gases, all possible sources of renewable energy. The amount and quality of these outputs depend on the type (or combination) of biomass used and the processing conditions under which is produced. The quality of biochar used as a soil amendment for agriculture depends on the type of biomass used to create it, and generally is of greater benefit if the pyrolysis process was done slowly and at a lower temperature (known as “slow pyrolysis”).

Proper rates and methods of biochar application in crop production are still not well understood, and use in agriculture production is currently low. However, the biochar industry appears to be growing with an estimated 326 biochar companies worldwide, with China becoming one of the biggest producers and users of biochar.

Biochar, agriculture & carbon capture

But what makes biochar relevant to sustainable agriculture? Biochar has been claimed to be carbon negative and a climate-friendly source of renewable energy, in additional to increasing carbon sequestration as a soil amendment.

However, most of these claims remain exactly that — claims.

In understanding these claims, it is important to separate biochar as a product and the process of its production. For instance, if in making biochar the biomass source is sustainably produced and all the heat, oil and gas co-products are fully utilized, the resulting biochar product may be deemed sustainable.

But if in producing biochar we destroy tropical forests for biomass production, use corn stover instead of returning it to the soil or displace land used for current food production to produce biomass, how sustainable can biochar really be?

The future of biochar

Life cycle analysis studies that explore this question of the sustainability of biochar are very limited, and while generally supportive of energy efficiency and lowered greenhouse gas emissions, there are still controversies surrounding these results and a need for further research. Biochar must be evaluated for its ecological, economic and social costs, and somehow those costs need to be applied to the actual biochar applied.

To date the market price for biochar appears to be highly variable, with some experts suggesting huge price ranges between $240 and $3,000 per ton depending on the type of biochar market. Finally, biochar has not yet been able to take advantage of carbon sequestration markets because of sustainability issues and lack of sufficient evidence that biochar will remain stable when applied to soils.

Like all good movements, the “biochar movement” is full of potential but has many unknowns. It is important to understand that biochar in agriculture is a tool — one input component within a holistic sustainable system that integrates crop rotations, cover crops, careful tillage and judicious use of organic inputs including compost as well as biochar itself — to promote soil health and net carbon sequestration.

Biochar highlights the critical and ever-present need to have civil dialogue and democratic engagement about just why and how new tools and technologies affect individuals, communities and the planet.

Photo: Simon Dooley | Flickr