Most cost effective way to build soil carbon

[Kiwi Pete]

I have been putting my tree prunings in a windrow for a couple of years, chipped some in 2015, and begun to autumn sow lupins in them. I want to raise the gorund level a few inches where I am doing this - there is a piped former ditch immediately the other side of a fence where I am doing this and the ground on the other side is higher, so run-off leaves the area wet. The idea is to recreate a ditch over the drain.

I am interested in the design of your "pyrolyzer" and any info you care to add. I came on this thread a few minutes ago to ask whether anyone was making their own charcoal (biochar as some like to call it) and remembered your post.

As a general question is anybody else making it? I am thinking small scale - an aquaponics system of raising my own crayfish to replace bought prawns, and to supply a few summer vegetables without the need to apply copious quantities of water.

The pyrolyzer design that seems to work best for me is the TLUD (top lit, up-draft) made out of a metal oil drum:
About 20 1/2 inch holes in the bottom, raise off the ground on a block or two so you can regulate the air coming in the bottom..
Cut the top off about 4cm below the top rim, and open a cross in the top, fold out the 'petals' and make a short flue to sit on top.
The idea is to stack the wood inside then put a "bird's nest" on top and light that up, then sit the lid on a couple of inch box spacers.. the burning doesn't happen due to lack of oxygen and the air goes in the inch gap to mix with the wood gas and burns it off cleanly, once it has charred well down then you remove the blocks and it smothers itself out- or all the char burns to ash.

In a windrow, it's entirely possible to simply put a coating of soil on top to limit the air and light the wood- an 'underground fire' which is similar to how it used to be done.
Google is your friend 'terra preta' and 'TLUD' will give you some ideas for your own situatuon. Best of luck, can soon take some pictures if you like

 

[Old McDonald]

@Kiwi Pete I have read a lot of articles about "terra preta" (and there are a lot of people writing who appear to know nothing) and am familiar with TLUD. Your type of charcoal maker seems to be the most popular. My favourite video of how to make one similar is www.youtube.com/watch?v=YIbGkmt1VdE

They are not very safety conscious but make a good job of showing how to do it.

I had rather hoped you had invented something different that worked. My short term use is for the media in an aquaponics system so I want lumpy rather than crushed, but the type you use seems OK for tht.

 

[Old McDonald]

For the past couple of days I have been receiving soil carbon in possibly the worst way. Wildfires have been burning on three sides of us (not really close, so no danger) for several days. It was white ash to begin with, but since yesterday afternoon it has been raining black cornflakes as my son named them. Enormous quantities of charcoal. Not quite totally covering the ground, but not far off. The interesting thing is that most of yesterday afternoon's was made up of Acacia seed pods. this morning it was pine needles, bark and the occasional Eucalyptus leaf. Interesting, as I said, but not pleasant for those affected and burnt out.

The week-end before last I saw a report that there had been 231 fires in Portugal on the Saturday and 220 on the Sunday. Many are easily extinguished, but not all. There were six fixed wing aeroplanes and several helicopters water bombing the one closest to us today. Numerous men and women on the ground too, of course. Fortunately I have not heard of any firefighter being killed, but several have been injured. Numerous people have been arrested for deliberately starting fires.

 

[Kiwi Pete]

@Kiwi Pete I have read a lot of articles about "terra preta" (and there are a lot of people writing who appear to know nothing) and am familiar with TLUD. Your type of charcoal maker seems to be the most popular. My favourite video of how to make one similar is www.youtube.com/watch?v=YIbGkmt1VdE

They are not very safety conscious but make a good job of showing how to do it.

I had rather hoped you had invented something different that worked. My short term use is for the media in an aquaponics system so I want lumpy rather than crushed, but the type you use seems OK for tht.

Sorry to miss your tag..

I imagine the feedstock you put in and temperatures/air intake will have a fair part to what comes out, going on what I've found at least, lower temperatures don't tend to crystallise it quite as much.
That's what I want too, as it's all going in the compost pile to be spread in the future, so size doesn't matter really.
A bit like the size of lime granules in a way, I'm not looking for immediate response as the SOM% is increasing here every year by itself. It's just long term storage.