One more problem that biochar could bring is what gets released when we burn biomass. When plants used for biochar were grown with heavy use of chemical fertilizers and pesticides, we do not know how much of these toxins will stay in the end product and how much will pollute the air. The same is true for manure – when poultry and cattle from which manure is taken are raised with the use of antibiotics – the toxins and chemicals need to be accounted for.
Biochar is definitely a reason for hope. Many companies are now working on developing technologies which could help to produce more biochar, as well as global initiatives discuss this solution. But the vast quantities of this precious material that we need to produce and store back in the earth should be approached with the sustainability goal in mind before all. Can we have enough sustainable biomass for biochar without altering current land use in a way that destroys ecosystems? We probably can, but close attention should be paid.