I grew disgusted with biochar advocacy.

[N]ot too long ago biochar was interesting to a very few growers, soil scientists and archaeologists. Then climate nutters and various other rent seekers grew excited about its possibilities for advancing their nefarious objectives and made many laughable claims for biochar while advocating a variety of convoluted subsidies and taxes to realize their dreams and line their pockets. The result was an equal and opposite dung-storm from their opponents and a growing distaste for the whole subject.

Another turd has been hurled at the now slowly turning fan.

In this paper we estimate the maximum sustainable technical potential of biochar to mitigate climate change. Annual net emissions of carbon dioxide (CO2), methane and nitrous oxide could be reduced by a maximum of 1.8 Pg CO2-C equivalent (CO2-Ce) per year (12% of current anthropogenic CO2-Ce emissions; 1 Pg=1 Gt), and total net emissions over the course of a century by 130 Pg CO2-Ce, without endangering food security, habitat or soil conservation. Biochar has a larger climate-change mitigation potential than combustion of the same sustainably procured biomass for bioenergy, except when fertile soils are amended while coal is the fuel being offset.

It's buzzword compliant, but evades the real issues.

To truly increase organic matter in soils it is necessary to produce it on site, not haul it in from somewhere else. The Keeling concept of fairly rapid recycling of atmospheric carbon does indicate an intervention opportunity to shift the balance of carbon from the atmosphere to the soil, but only if done by increasing growth on site and retaining a larger portion of the result. . .

To increase soil organic matter in already exhausted soils, which includes most soils that have been in agronomic production for a while, you need to face reality. It's a slow process that requires a "bootstrap". To get it started you need manufactured fertilizer and a system to retain the increased production it brings. Slowly, over time, soil organic matter will build up. Using some of that production to make biochar retards that process at first since it repurposes some of the organic matter, depriving soil microorganisms of groceries. They can't eat charcoal, that's the whole idea. Over time the charcoal can have beneficial effects that make a better environment for microorganisms so they will make up for earlier losses so long as they have a continuing and increased supply of new organic matter to eat.

The reason to do this isn't that some bureaucrat with only the most cursory knowledge of agronomic systems bribes you to do it, it is to increase the value of your primary asset - your land - and increase your production of food and fiber. The reason to do it is that it is a superior agronomic system with increasing returns over time. The more growers that do this the more productive the whole system. The secondary effect that the atmosphere is being mined of its carbon is largely irrelevant so long as there is plenty. If done assiduously for long enough the atmosphere would be depleted of carbon and some bureaucratic wanker would want to start charging growers for the atmospheric carbon that they take for free, but not soon.

The 12% maximum is for current emissions, which are rising and must continue to rise. The maximum is laughably improbable even if possible, so the real effect of any program of spending would be a fraction of a fraction of the 12% - in other words, negligible. It's merely another bureaucratic rent seeking effort that would have no measurable effect on the problem it purports to address, but would be a tidy sinecure for some number of rent seekers.

This does not mean that the use of charcoal in agronomic systems has no benefit, it just means that climate wankers are a nuisance and should move along. Charcoal is not about climate.