[Terrapreta] Chardb and characterisation

[Rex Manderson]

Christelle,

            I think that you will need to be encouraging further
characterisation of the char to improve the value of comparison of results
and methods.  The need for a quick test(s) was a key point to the Eprida
presentation at the IAI conference in Australia last year.  There is not
going to be much comparison between [ West Australian wheat trials ~35% C
(IBI  "Improving wheat production with deep banded Oil Mallee charcoal in WA
30 Apr 07),  Wollongbar/Best Energies greenwaste biochar ~36% ( Australian
Journal of Soil Research, 2007, 45, 629-634 ) ] and on the other hand [ CIAT
pots ~82% carbon  ( Biol Fertil Soils (2007) 43:699-708 )  or our own trials
at ~80% carbon ( unpublished ) ].

 

I understand that analytical chemical tests are not available to many who
may wish to contribute.  My suggestion is that we start at least discussion
to identify a priority in terms of characterisation of properties, and then
publish some protocols for " kitchen laboratory" approximations.

 

For our efforts we can have total carbon content analysis done by a nearby
laboratory for less than $15 per sample, so this is a basic parameter.
Please consider adding it as a specific field, together with a method text
qualifier.  Eg 79% Dumas method or 85% home test.

 

After %C it gets a lot more complicated, and there has been discussion of
CEC and other nutrient analysis.  While we have no experience yet, it seems
the ASTM D 4607 "Standard Test Method for the Determination of Iodine Number
of Activated Carbon" may be useful.  This standard warns "4.2 The presence
of adsorbed volatiles, sulphur, and water extractables may affect the
measured iodine number of an activated carbon".  It could be that for a high
carbon char ( > 70% say ) that a larger iodine number = quicker positive
soil cropping impact.  

 

In a previous posting I asked about this test without result, so for this I
will be more specific.  Have you been involved in testing char?  Was this
ASTM method used?  Do you really need a balance accurate to +/- 0.0001g to
do the test?   Any advice would be appreciated.

 

I look forward to more test proposals.

 

Regards

Rex Manderson

Chaotech Pty Ltd

 

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