http://www.biochar-international.org/biochar
http://en.wikipedia.org/wiki/Biochar
Hi! I was asked to start a thread on BioChar, so here we are.
My back story: My wife and I spent 4 gardening years wondering why our plants didn't grow very well. We did have harvests, but not much. A few peppers, a few tomatos, some lettuce, etc.
But when we started working with the soil, we made tremendous improvements. I went from growing 1000 sq.ft. Of corn stalks to making wheelbarrow loads of corn! Plump, juicy tomatoes (and lots of them), delicious peppers, and so on. A much greater yield, and near-zero pest damage, and truly zero disease.
I owe it all to BioChar, and Bokashi.
Bokashi is easy – toss your kitchen scraps in a barrel outside and put a lid on them. They rot. We'll come back to bokashi later.
BioChar is nothing more than charcoal that you put into your soil. It holds nutrients from the soil preventing leaching, it holds rainwater to prevent dehydration, it provides safe harbor for soil bacteria, it helps prevent compaction, and so on. In the Andes mountains are large swaths of biochar-enhanced soil that kept entire empires alive. Soil Scientists call this soil “Terra Preta”. You'll call it a miracle when you make it for yourself.
How do you make it? Well, quite simply, BioChar is charcoal, so it is made by pyrolisys, not combustion. So we do not burn the wood, we smolder it without oxygen. A tiny bit of oxygen is actually needed, but any more than that and you combust the wood producing ash instead of char.
Here is my retort:
Quite simple, actually.
- Drill lots of pinky-sized holes in the bottom. Mine has 117!
- Have a welder cut a hole in the lid to fit the stove pipe.
- Install stovepipe by putting it in the hole.
- Put the whole thing on a 3-brick tripod.
Operating the retort is more art than science. You'll need your payload wood, your starter wood, and an optional cardboard barrier.
- Put payload wood in bottom of retort, fill almost to top.
- Put optional cardboard barrier down.
- Build a “Boyscout” type fire with your starter.
- Tend the fire for a while to make sure it generates a good bed of coals.
- When it is up-and-running, put the lid on and walk away.
In my situation, I use deadfall and tree trimmings, as opposed to Mr. Rogers who uses shreds and chips. I chainsaw my wood into lengths no more than 6”, he doesn't get anywhere near that big. He uses wood that is nice and dry, my wood is “kind of” dry, but it varies a lot.
As a result, he burns through a barrel in about an hour, whereas mine takes the better part of a day. He never needs to open his retort, whereas I need to stir mine every 2-3 hours. I stir mine with a piece of rebar. He gets small pieces, I get larger ones. That doesn't seem to cause a problem, though.
Just remember that this retort will be exceedingly hot. Water will bounce off the sides due to explosive boiling. To end the process, I have to open my retort and quench it with water. The intense heat and the cold water generate a steam that could probably kill a small animal. Do be careful when doing any thing with a retort!
After it is quenched, I tip the barrel and invert. Then hose the barrel out a little, and set it on the tripod upside-down to dry. Then I do it all over again the next day.
Quality? Oh yes. Proper BioChar is proper BioChar no matter how it's made.
Just don't put it in your soil yet! Remember I said it holds nutrients? It will grab every bit of nutrient in your soil and sequester it inside. Then your plants won't grow. Oh, my! What to do?
Remember that bokashi I mentioned earlier? Now's when you need that stuff. See, the BioChar needs to be charged with something before you put it in the soil. You can put it in the soil raw, but you'll need to wait a year before planting.
So I start a new barrel of bokashi every year by putting a bunch of BioChar in the bottom first. Then lots of kitchen scraps. Then a layer of BioChar, then more scraps. Kind of like a nasty lasagna!
In this manner, the BioChar absorbs all the liquid goodness from the bokashi, and then I have only a dry-looking product to put into the garden. The BioChar is charged with nutrients and takes them into the garden.
In closing, let me say that making BioChar does require some labor, but the labor isn't back breaking. If you are unable to chainsaw your own wood and move it around, then perhaps a kind neighbor will help. But the finished BioChar weighs a mere fraction of the wood it came from.
The minimal effort needed to make BioChar at home will result in a garden soil that will stay fertile and hold water properly for the better part of a century before it needs a major fertilizer dose. Seems worth it to me to do it now rather than later.
Any questions?
-Johntodd
