If you aren't set up space, equipment or timewise to make your own charcoal, and then innoculate it, or don't have the $$ to buy a lot of commercial biochar, you might consider using an unusual form of charcoal. Typically bbq briquettes are verboten... Kingsfords, et al, are chock full of bad stuff. However, Trader Joe's BBQ Briquettes are advertised as 'sustainably harvested, with only cornstarch as a binder, and you can use the ashes in your garden!". They are approx $8 for 18 lbs. I did some research and found that this is the Rancher brand of 100% Natural Charcoal, made by The Original Charcoal Co., repackaged for TJ's. It is made from coppiced hardwoods grown in Latin American, i.e., sustainably.

I mention this because I think the carbon sequestration is significant, and the water/nutrient holding capacity is critically important, and equally valuable on (many, many) small city lots, as it is on acreage. This form of biochar, while non-toxic and natural, may not be optimum, but letting the 'perfect be the enemy of the good' can be self-defeating, perhaps :)

Thanks for the tip. I usually make my own biochar but I'd like to see the difference (if any) trying that brand.

Update... I spent hours last summer crushing Trader Joe's 100% Natural BBQ Briquettes with sledge hammer, concrete paver, etc.... whew! BUT just now, I soaked some in 'golden elixer' for several days.... and they DISINTEGRATED!! ... read to be incorporated into my sandy loam. I guess the cornstarch binder dissolves very quickly. Better learning late than never (BTW I checked the pH and didn't find any extremes... maybe a tad alkaline (7.5) so I gave it a dash of vinegar for good measure

Nice job. I may have to try some just to see how it works out. Thanks for the update.

Does the crushing pressure of compressing briquets not collapse the very porous nature of the charcoal thus working against the very idea of surface area which in its part makes the value of char so high? I am sure the longevity is still there, but 1 gram of char can have the surface area of 2 tennis courts or more, and I would think that a visual microscopic inspection should provide a  observation that at least leads in a direction of an answer.

Tom Rodgers wrote:Does the crushing pressure of compressing briquets not collapse the very porous nature of the charcoal thus working against the very idea of surface area which in its part makes the value of char so high? I am sure the longevity is still there, but 1 gram of char can have the surface area of 2 tennis courts or more, and I would think that a visual microscopic inspection should provide a  observation that at least leads in a direction of an answer.

Hi Tom.  If you were to crush it to single walls then you will loose the micropores, but not the nanopores that reside within those walls.  This will reduce the water holding capacity within the Biochar, but the nutrient retaining and redox properties of the Biochar will remain.  Not ideal, but still quite useful.