Biochar

Biochar may – and the key word is ‘may’ – become an important, and therefore valuable, material for agriculture and for dealing with some environmental issues.

On 16 February, at Queens University, Dr Hugh McLaughlin, visiting from the United States, ran a workshop titled: Understanding Adsorption in Carbonaceous Materials with Implications for Biochar. More than two dozen researchers, academics, farmers, students, gardeners; both private and professional, and interested individuals spent several hours together learning about and discussing carbon.

Biochar is the result of heating wood, grasses or nutshells in the absence of oxygen to temperatures higher than that needed to make simple charcoal, and then – very important – removing the heat before the biochar starts to burn.

The material is a mixture of moisture, ash, and mobile and resident matter which has a capacity for both cation exchange and significant adsorption. On the latter, carbon’s adsorptive powers have been exploited since servants of the Pharaohs used it to remove bitterness from wine, which in turn greatly improved the servants’ chances for long service. Today’s imbibers may not appreciate how much their love of scotch and whisky depend on it.

Without going into very detailed and complex chemistry, biochar’s characteristics give it the following admirable permanent qualities when mixed with soil:

  • encourages moisture retention and aeration
  • influences the pH value; and fertilizer retention
  • stimulates soil microbiology.

Together these mean, in theory, that biochar can permanently reduce the need for agricultural water, fertilizer and pesticides, which, of course, have to be regularly added. As well, if biochar can improve soils, there is the chance that less forest will be cut and burned to open new fields to replace those whose soils have worn out. And, if small-scale biochar production kits – similar to those we learned to construct at the 16 February workshop – were more widely available and used, poor families in lesser developed regions could be doubly served: They could cook their food while the biochar is being produced, and then sell the biochar; either as a soil strengthener or a fuel.

‘In theory’. There are many challenges to commercialization, to exploiting biochar beyond small scale. There is not yet a single high-volume producer. This is likely to remain the case until two issues are resolved; uniformity and regulation. Every biochar batch is different from every other batch; even two made, one after the other with the same materials and process, are different. Who or what will call for, set and regulate standards of biochar? In Canada, the Canadian Food Inspection Agency is responsible for the Fertilizers Act. Is biochar a fertilizer? In fact, there is still no widely accepted single definition of biochar.

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David Harries is a member of the Global Issues Project committee.