I believe that you're talking about Terra Preta?

I'd advise against using briquettes, which are manufactured using all kinds of binders, accelerants, coal, etc.

You can use activated charcoal or pure charcoal.

Yeah, I would tend to agree with Rhizo. However, it would be interesting to test both kinds of charcoal to see how much of a difference it made.
-Jmcat

I'm not so sure charcoal is even necessary if you are using a good quality mix to grow in. Store bought peat based "potting soils" are not ideal for growing plants. It's just cheap peat crap the market dumps on us. Peat is a very small percentage of my mix. I haven't used a potting soil as a stand alone mix to grow plants in 15 years.

randy

I agree about the charcoal. I have read in other places that ashes from briquets should not be put into your garden, but couldn't remember specifically what the problem was. You can get the activated charcoal in the pet department at Wal-Mart if they carry aquarium supplies or any pet store that carries aquarium supplies. I would think that basically you are putting Potash back into the soil, since that is why wood ashes are used in flowerbeds, just can't remember if this is good for producing flowers or good for building root systems.

rjj, I don't like peat in my potting soil either, but the one source I had for a potting soil that had little to no peat in it went out of business. Being a small town in Oklahoma, there just isn't anywhere to go. Howard Garrett, the Dirt Doctor, sent a newsletter out a couple of months ago talking about how inhibitive it is to good soil bacterial growth and therefore prevents good soil health.

Butterflyman, keep us posted on your experiments. It should prove to be interesting.

Ms. Faith

You can also use wood ash from the fireplace. However do you have a ph meter so that you can test the ph of the soil. In our area we do not add ash to our soils as the soil already contains those micro-nutrients. For seedling I prefer to add worm compost which is a complete fertilizer.

Penny

There is loads of research demonstrating that charcoal improves the tilth of many soils. If you google bio-char or even search charcoal on this site there is plenty of good info. Bio-char is not activated charcoal, nor is it a fertilizer.

Here is a link that might be useful: bio char info

Penny,

I am also a worm castings user. :) Worm castings has helped to keep White Flies away...as well!

"ancient Amazonian cultures used charcoal as a way to keep their poor jungle soils fertile"

--that's a very PC description of "slash and burn"

Burnt you are mistaken.

Slash and burn is very different than slash and smolder