[Terrapreta] observations on charcoal weathering

[Richard Haard]

Few weeks ago hiking on a clearcut above my home I came across a burn  
pile with charcoal that had been exposed to weather for 2 winters.  
Here is a flickr image of this weathered charcoal. Looking at this you  
can see how the char lumps are flaking as perhaps the water works into  
an freeze/thaw cycles. Perhaps though it is strictly water working  
into the pores. This weekend Larry and I worked on the charcoal piles  
we had stored under a tree at my property. We had 2 types left over  
from last years research project and were curious how each kind would  
change with simple aging.

First the batch of our homemade was about 2 inch minus when stored.  
Here and here   and here is how it looked when we first made it and  
stored. Our current plan is to take this charcoal batch and the other,  
a charcoal powder supplied by John Flottvik then combine them into a  
compost with alfalfa and organic rich soil we had available. Since our  
charcoal  was great in barbecue we were planning to rake out big  
pieces and save for cooking. We noticed though that the charcoal had  
become rather soft and broke up as we raked it around. Here and here  
are some images of it at present. Since we were sheltered in my dense  
forest homesite the ground did not freeze hard so this crumbling must  
just be a function of water saturation. I wonder if this kind of  
breakdown happens in the tropics?

Here and here are images of the charcoal/compost pile under  
construction. As Larry and I are convinced that charcoal is best pre- 
seasoned with nutrients and microbes before using in soil, this is our  
current effort to match Larry's success of 2 years ago.  The pile is  
laid out about 18 inches deep to keep it from heating too much between  
turnings and will most likely be ready to use by July. My share of the  
pile will be worked into my planned winter vegetable patch shown here  
ready for spring planting. Growing vegetables in the forest like this  
is a challenge as sunlight is both seasonal when the sun is high and  
passing through the summer tree canopy.

Lastly we did find some earthworms in the charcoal powder just under  
the soil cap we put over the top. Also a spectacular mushroom we have  
in this corner of my place, Lepiota procera - the Parasol Mushroom  
that grows in fairy rings, did have mycelium moving into the char  
shown as above.

Rich
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