Australia agency calls for more biochar research

By Ryan C. Christiansen
Web exclusive posted March 12, 2009, at 4:00 p.m. CST

The Commonwealth Scientific and Industrial Research Organization, Australia's national science agency, has published a new report that states more research should be completed before biochar, a byproduct of biomass gasification or pyrolysis, should be applied to soils to sequester carbon.

In the report titled "Biochar, climate change and soil: A review to guide future research," Evelyn Krull, a senior research scientist at CSIRO, said that most of the research that has been completed about biochar and carbon sequestration has consisted of small-scale studies, the results of which should not be generalized and which leave important unanswered questions.

For example, Krull said, because the chemical and physical properties of biochar is affected by the biomass feedstock and also by the specific gasification or pyrolysis process conditions used to create it, how that biochar byproduct might affect the soil, air and water is not known.

Krull said biochar samples have not been analyzed for the broad range of potentially harmful chemical contaminants that are associated with combustion. Biochar produced from various feedstocks should be examined for toxic substances, she suggested, adding that a rapid screening technique must be developed so that varieties of biochar can be identified.

Krull said given the apparent stability of biochar, safe application rates for individual soil types need to be determined.

The affects that biochar might have on microbial communities in the soil and their interaction with crops grown there are not yet understood, Krull said. Also, the ways biochar affects the water-holding capacity of soils have not been determined and only recently have there been studies initiated to examine how biochar moves through soils into waterways.

"Current studies are, in many cases, conceptually or geographically limited," Krull said, "and are often constrained by limited experimental data." She said her report aimed to identify gaps where new research should be focused in a way that will enable biochar to be used for climate change mitigation and to maintain soil productivity.