Approximately 15 years ago, before any serious research was carried out on the topic, fantastic claims were made about biochar being a solution to all kinds of problems. After addition to soils, biochar would increase agricultural production, solve the climate change crisis (by sequestering carbon in soils), decrease the release of greenhouse gases by soils, and so on... Biochar was not only a win-win, or win-win-win solution, it was a "win-finity" solution, as Professor Janice Thies of Cornell once said, tongue in cheek. After the research was finally carried out that should have been carried out before making those claims, the reality unfortunately did not quite live up to the hype. At present, most of the claims are still hotly debated, the alleged advantages of biochar often still far from proven, the disadvantages of incorporating biochar to soils more and more evident (e.g., in terms of not maintaining soil functions), and economists have shown that there is little to no financial incentive for farmers to spread biochar on their fields. Diehards, against all evidence, are still trying to promote biochar use in agriculture, but some have begun a few years ago to say that the real potential of biochar is in waste water treatment. In a few years, when the research in the area is done, perhaps these new claims will be verified, or not... Perhaps, as Mohammad suggests, the real potential of biochar is as a nutritional supplement, or as an additive to toothpaste, as a whitening agent, in replacement of charcoal? To me, biochar research in the last decade has been tantamount to walking around with a hammer, looking for a nail. I believe that good research works the other way around.

For those who are interested in reading a little more on this topic, I wrote an article on hyperbole and bypass in soil research, in which there is a whole section on biochar, with a number of references. Its DOI is: 10.1111/ejss.12941

Undoubtedly, biochar can be of great value and high applicability. But considering it a single solution for every universal problem will in turn build up more problems. It needs dedicated research and trials for each and every aspect for which it can be used for, to announce it as a 'heal-all' or a wonder-drug

Biochar has limited uses when applied to marginal soils, such as sandy soils. Alas, these are the soils that are best left alone and not be brought into agriculture.

Indeed, any organic amendment such as biochar has improved agriculture and environmental properties. But it is not true to accept that there is no defect. And the effect of long-term time in biochar application should be investigated.