Are they suggesting people with a home garden go out and get a bag of charcoal, like used for the barbecue, grind it up and mix it in the soil???
The natural lump charcoal is more along the lines of what they are talking about.
Charcoal briquettes have too many additives.
Natural charcoal works best. And because it needs time for microbes to colonize it, I suggest adding it to the compost bin rather than directly into the soil.
I have seen charcoal sold specifically as a soil amendment. I think Jung’s carries it.
If you decide to make your own, you can use any organic materials, not just wood. You can even use materials that shouldn’t otherwise be composted. Diseased or infested plant materials, dog or cat feces, etc, up to and including “waste”. There’s a sawdust toilet on my farm that’s made using a steel bucket, just so I can burn the contents into charcoal without having to transfer containers. I haven’t had to do that yet, but I wanted a backup plan in place in case plumbing isn’t an option. The process of burning stuff into charcoal will kill off anything that might be lurking inside.
It can’t be barbeque charcoal.
What you can do is put all your biomaterial, like uneaten vegetables or whatever you cut when you’re cooking. Put it into a compost or put it where it can dry out completely.
Burn it to an ash and then work it into the soil.
On a video I saw, a guy took left over meats and rotten eggs, along with plant material. He would burn to an ash and cover it with clay that was mixed with water and turned into a slurry. He would throw it on top before he throught the surface dirt to cover it all up.
So, every spring you can do that. Take your bio material and and clay and throw it on the garden and roto till it thoroughly, Then plant your garden.
From what I’ve been able to find out, leaving a share fallowed every year has imporance as well. So, you can section off your garden and leave a portion unused for a growing season so it can recover.