[Terrapreta] Charcoal is not OM but Stable Soil Carbon.

[Richard Haard]

Here is an quote from Lehmann et al, 2006 Bio-Char soil management p  
517.

I think the answer to the question is there is a relationship between  
high soil organic matter found in soils of the moist tropics and black  
carbon, or biochar. In other places I have seen the author state that  
biochar emulates organic matter. In my own work soil tests of soils  
emended with charcoal have higher OM.

Rich H

Following is the first few paragraphs from this paper

Maintaining an appropriate level of soil organic matter and biological  
cycling of nutrients
is crucial to the success of any soil management in the humid tropics.  
Cover crops,
mulches, compost, or manure additions have been used successfully,  
supplying nutrients
to crops, supporting rapid nutrient cycling through microbial biomass,  
and helping
to retain applied mineral fertilizers better (Goyal et al., 1999;  
Trujillo, 2002). The benefits
of such amendments are, however, often short-lived, especially in the  
tropics, since
decomposition rates are high (Jenkinson and Ayanaba, 1977) and the  
added organic matter
is usually mineralized to CO2 within only a few cropping seasons (Bol  
et al., 2000). Organic
amendments therefore have to be applied each year to sustain soil  
productivity.
Management of black carbon (C) — increasingly referred to as bio-char  
— may
overcome some of those limitations and provide an additional soil  
management option.
This is a highly aromatic form of organic matter that is present in  
most soils to varying
extents (Schmidt and Noack, 2000; Skjemstad et al., 2002). Interest in  
and application of
biomass-derived black carbon — using incompletely combusted organic  
matter such as
charcoal (Glaser et al., 2002) — was prompted by studies of soils  
found in the Amazon
Basin, referred to as Terra Preta de Indio (Lehmann et al., 2003c).  
These Amazonian Dark
Earths are anthropic soils that were created by Amerindian populations  
between 500 and
2500 years ago. They have maintained high amounts of organic carbon,  
and their high
fertility, even several thousand years after they were abandoned by  
the indigenous
517
population, contrasts distinctly with the low fertility of the  
adjacent acid upland soils
(Lehmann et al., 2003b).
The reasons for these soils’ high fertility are multiple, but the  
source of the large
amounts of organic matter and their high nutrient retention has been  
attributed to the
extraordinarily high proportions of black carbon (Glaser et al.,  
2001). Such large amounts
of black carbon can only originate from incompletely combusted biomass  
carbon, such as
wood from kitchen fires or possibly from in-field burning (Smith,  
1980; Hecht, 2003).Biological Approaches to Sustainable Soil Systems
518
On Mar 31, 2008, at 3:09 PM, Gerald Van K oeverden wrote:

> Brian,
>
> Of course you are correct.  The trouble with char in the soil, is  
> that it doesn't fit into the category of mineral nor organic  
> matter.  It only fits into concepts like 'tilth' or soil structure -  
> in referring to those agglomerations of soil particles in temperate  
> climes that are indicative of a healthy soil.  It is these soil  
> 'agglomerations' that provide a structured environment to optimize  
> the cycling of microbial life.
>
> Typically it is very difficult to promote 'tilth' in the heavily  
> weathered lateritic soils of the tropics.  I suspect that the char  
> in terra pretas is what plays the role of sort-of-duplicating its  
> effect, as well as adding to the CEC.
>
> if this is so, where we will see char being of most benefit in the  
> temperate climes is in soils where tilth - whether because for  
> example of over-tillage, compaction or narrow range of texture (very  
> sandy, clayey or silty) - is hard to get and maintain.
>
> Gerrit
>
> On 30-Mar-08, at 4:14 PM, Brian Hans wrote:
>
>> Tom et al.,
>>
>> I dont see how charcoal can be considered OM. I have been calling  
>> it Stable Soil Carbon. I was taught to not call the endpoint of  
>> composting OM but rather humus and other stable carbons. And  
>> because there is no real humic components in charcoal, we are left  
>> with calling charcoal 'stable carbon in the soil'.
>>
>> I am looking for others opinion here (and Im sure TP readers wont  
>> let me down).
>>
>> Brian
>>
>> Tom Miles <tmiles at trmiles.com> wrote:
>> Jim,
>>
>> “sequestering massive amounts of carbon” is the key. You  
>> seem to be saying that compositing doesn’t scale in a modern  
>> agricultural environment. Composting would seem to fit better at a  
>> small scale, as an urban high value soil amendment, or for a rural  
>> smallholder where the ingredients may be more available.
>>
>> I agree that Eduard in that at least in our environment the TP  
>> product must be prepared so that there are clear and predictable  
>> agronomic and economic benefits. That’s why I think the urban  
>> homeowner would be a good target for TP products that may in  
>> another form be applied to agriculture. Ag buyers will not pay as  
>> much as the homeowner, landscaper or enthusiastic gardener. Â Â Â
>>
>> I look at charcoal as a means of facilitating the growth of  
>> biomass. It becomes a stable part of the mix of OM rather than an  
>> attempt to replace or create OM.
>>
>> Tom
>>
>> >For those thinking about saving the world by reducing CO2,  
>> composting maybe a nice academic subject but it has no place in the  
>> practices for sequestering massive amounts of carbon.
>>
>> >Jim
>>
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