I started using charcoal on a large scale when I was living in Central Arnhemland in sand that seemed bottomless. The soil was acidic, never retained moisture, was leached of nutrients, and with the climate and watering, any organic matter broke down rapidly and leached away. Of course if you stopped the watering to preserve the organic content, then your plants would suffer and die. It had the makings of a no win situation.
But there was a large amount of ash available from the seasonal fires. So I shovelled it up by the trailer load and brought it into the gardens. Made a world of difference. From the worst of all worlds it became the best of all worlds. Sand drains well, is easy to dig, plant roots penetrate deeply without effort, etc. The charcoal absorbed nutrients and moisture making them available to the plants over a long period. Microorganisms found shelter and sustenance in the charcoal. And when the warm climate made the organic matter and humus run short, the charcoal being inert and insoluble was always still there holding its abundance.
Well, if I seem a bit biased towards charcoal, it because I so very much am. It's a bit scary when I look back on those early days, they were in the early 1990's, last century!!!!
Terra preta is still a bit of a contentious issue, there are some who still claim it's a naturally occuring soil rather than anthropomorphic. They say it's usually found near rivers where floods could accumulate charcoal and that people only took advantage of it. But no one disputes that it's the best soil you can have. One of the things with Terra preta is that the charcoal is finely ground. From memory, I think the grains were no more than 0.3 millimetres. It becomes a tedious job to achieve that for a large scale garden. What I did was to use a concrete mixer with a few largish rounded lumps of quartz and an old towel covering the opening to prevent the dust from escaping. I made quite a lot of fine charcoal like that. Used it both in garden beds and potting mixes. You just have to watch out for the residual white ash in it raising the pH too high. Done through composting is much better if you have the time.
Charcoal/Carbon, where would we be without it?
