[Terrapreta] -----and Net Present Value of TP Benefits

[Richard Haard]

On Mar 14, 2008, at 8:47 PM, Kevin Chisholm wrote:

> Peter Read wrote:


Hello Kevin  - drifting a bit from the thread but an interesting topic  
to me.

by NPV you mean direct value to farmer such as added CEC  or OM  
equivalent? The real value to farmer - not discounted carbon credit is  
what will make this all happen as general practice in agriculture.

What is the real economic benefit to the farmer per ton applied to  
land will depend on  soil type, climate and needs for fertilizer  
supplements to maintain fertility levels and as yet unquantified  
benefits of charcoal additive in soil. This figure of NPV $50  could  
be quite higher.

Most important in soils where organic matter needs to be monitored  
carefully to maintain productive capacity (not all do), what needs to  
be calculated is the cost of raising soil organic matter an equivalent  
amount permanently.  Ie the cost in lost production of fallow periods  
and the cost of reestablishing farming if the land has gone back to  
forest during fallow.

I am hoping the block research currently underway at our farm  
comparing compost to charcoal to fertilizer and permutations will  
answer this question for us at 4CN.

In our farming we are holding organic matter at 4 % minimum with  
biannual applications of 1 cubic yard of compost made from sewage  
solids and sawmill wood waste per 1000 sq. feet. In addition, we are  
adding summer and winter cover cropping when a particular section is  
fallow. So far as a OM supplement sawdust alone will do the job when  
balanced with garden fertilizer to compensate for binding of N and P  
by the decomposing wood. But this OM benefit in tilled soil is gone in  
a few years whereas the charcoal lasts as I am trying to quantify at  
our soil.

Buying charcoal at $ 200/ton will not happen for us in the short term  
anyway because of these economic factors. I do not know what a cubic  
yard of dry sawdust weighs but cost is  most likely 5 % or less and we  
use about 250 yards or more  annually. What might happen though in the  
near term is our on farm waste wood summer dried and converted to  
charcoal by some sort of smothered combustion. In our climate dry  
weather July through September will allow us to do this by windrowing  
with farm machinery.

We will have significant quantities available, probably each year 300  
cubic yards of loose twigs, roots and reject plant trimmings. Right  
now we either burn this stuff or use the soil/weed and reject plants  
as fill. Labor and use of equipment on farm does not equate to  
purchases outside of normal operations hence costs we incur on such a  
project are more easily absorbed as I suppose they are elsewhere. I am  
thinking some sort of buried pyrolysis with movable scrap sheet metal  
and wet spoiled hay in a top lit bottom draft system similar to our  
project 2 years ago.

If the value of farm waste worked into soil, say corn or wheat  is  
higher when converted to charcoal then the most efficient method for  
doing this onsite will rule in the end.


On Mar 14, 2008, at 8:47 PM, Kevin Chisholm wrote:
>  If we assume that Charcoal in TP gives a return with aNet Present  
> Value  equivalent to $50 per tonne of Charcoal applied,