[Terrapreta] Abstract on Charcoal in soil

[Kevin Chisholm]

Dear Michael

Michael Bailes wrote:
>>
>> The carbon in most biomass is in the carbohydrate or hydrocarbon form,
>> and is in a form that various life forms can "sink their teeth" into it.
>> It has a nutritive value, and it is worthwhile for them to attack it.
>>
> It seems the resins and bio-oils on the char are most important for
> encouraging microbial growth.
> In the Amazon hardwoods were used containing a lot of resins.
> I would agree there are many types of carbon as well as many types of
> charcoal.
> One problem with research is that few researchers characterise what sort of
> charcoal they are using; making comparisons difficult.
> 
> On 16/05/07, Christoph Steiner <Christoph.Steiner at uni-bayreuth.de> wrote:
>>
>> Dear Kevin,
>>
>> Terra Preta fertility is the result of increased nutrient availability
>> (mainly phosphorus and calcium), lower pH and acidity,
> 
> 
> Chris I have always been puzzled by charcoal and pH.
> How can putting something with a pH of 8-9 on the soil,  lower soil pH.?
> It is most odd, unless the char contains a lot of ash.
> 
> So does the presence of charcoal slows the decomposition of organic matter
> yes/no?/don't know?

To polarize the issue, I would hypothesize as follows:

1: Charcoal per se has no effect on soil pH
2: Residual alkaline earths (Cao, MgO) and alkali metals (Na2O, K2O) in 
associated ash can raise pH.
3: The charcoal and nutrients promote growth of bacteria, and roots 
interact with the increased bacterial concentrations to produce humic 
acids which lower pH.

Would you have any thoiughts that would tend to support or refute these 
hypotheses?

Thanks!!

Kevin


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