Terra Preta?

[dave45]

Anyone tried charcoal-enriched earth for veggie growing? What does best in it?

http://en.wikipedia.org/wiki/Terra_preta

[dave45]

and what are the recommended methods of producing large quantities of biochar?

[frozenthunderbolt]

http://www.twinoaksforge.com/BLADSMITHI ... ARCOAL.htm
fantastic site

[frozenthunderbolt]

also here
http://www.clt.astate.edu/elind/charcoalvalentine.htm
and here
http://terrapreta.bioenergylists.org/makingcharcoal

Note: you will find that Google is a great asset.

[dave45]

http://www.twinoaksforge.com/BLADSMITHI ... ARCOAL.htm
fantastic site

yes - I've seen that site... it looks great for volume production and has the typical American attitude, just use 2 spare oildrums, build this little house out of scrap concrete blocks, weld this and that, use 100 quids worth of surplus plumbing equipment bla bla

in contrast:

I have an empty 1-litre paint tin
I belted 6 holes in the lid with a 6-inch nail
I fill it with handfuls of shredded and dried hedge clippings and fit the lid
when the woodburner is nice and hot, and just burning down from max wood volume I open the door and chuck the paint-tin on.
Watch the gases ignite thru the 6 holes and leave it for 30-60 minutes
extract when next re-charging with wood and leave to cool
no heat wasted, no humungous welding/building/plumbing
but very small batch size

Paint tins are good for about 25 goes, then they expire with large holes in them, and proceed to recycling bin
Rolled up newspaper works instead of hedge clippings.

If u try this for godsake don't take the lid off the paint tin while its still hot - the incoming air/oxygen will ignite the charcoal fast ! This can be scary!. wait at least until you can hold the tin with your bare hands.

A slight difference in scale I think... is there anything in between?
I've run out of 1l metal paint tins.. all the new ones are crappy plastic

[Enormous Sage]

If it's any help, I found this website on how charcoal is made the traditional way in India.

http://e-charcoalmakingprocess.blogspot.com/

All done using wood, straw and earth (and fire!)

[Peggy Sue]

Everyone down our allotment just burns wood and spreads the ash- it's pretty much charcoal?

[dave45]

I don't think wood ash and charcoal are the same at all.... that is the point !

[frozenthunderbolt]

I don't think wood ash and charcoal are the same at all.... that is the point !

You are right.
While hardwood ashes contain potash that is a valuable nutrient for many plants it doesnt have the same effect as charcoal.

As i understand it, the charcoal that makes TP what it is has the effect of providing a micromatrix (my word) that collects and holds vital minerals and nutrients that would otherwise wash through the soil and out very quickly.
In addition to this it lightens the soil and i have heard mention that the tiny gaps in the char vastly increase the surface area of the soil leading to a much higher level of esential micro flora and fauns in the soil which contributes to its health and productivity.

If someone wants to chime in with a more scientific explanation please feel free.