[Terrapreta] Black soil

[Richard Haard]

Kevin - i know you have been puzzling on this.

Here is a very nice, basic piece from NRCS on soil color. It  
specifically deals with soil colors of the prairie states, Iowa and  
Kansas

http://soils.usda.gov/education/resources/k_12/lessons/color/

It seems there are a number of factors that effect soil color. First  
the mineral composition can cause black soil colors. These are Iron  
sulphides FeS, pyrite (FeS2), and manganese oxide. In addition, humus  
gives soil the same munsell color as above (black). It is interesting  
there is no mention of black carbon as a reason for soil color

So far as the role of organic matter, not only is the organic matter  
responsible for the color of some soils it is also the interaction of  
the soluble organic pigments that move down in the soil with minerals.  
Also interesting is Kansas (prairie) vs Wisconsin (forested) in the  
latter example water soluble carbon leaves the surface and white  
quartz remaining. We find all examples in Washington from the dark  
soils of the Olympic rain shadow to the silica sand on the surface at  
Snoqualamie Pass in the subalpine zone barely 70 miles away.

Ain't nature great?

------------------------------------------

Your point # 2

> 2: Fully degraded organic matter that is basically only Carbon.

Fully degraded organic matter is CO2 not C . Lets do some reading on  
this but my thought is that the endpoint of organic matter  
decomposition in soil are these humic acids that are very complex,  
resistant molecules that serve use in soil just like clay colloids.  
Eventually they do decay through metabolic action of microbes and  
oxidation.

If carbon were the end product on this then in the desert where  
virtually all detritus is consumed by oxidation then where are the  
dark soils in these places? Hmm
There is some searching that can be done on this and what analytical  
methods they use to isolate charcoal from organic matter.  I think Ron  
Deluca's papers may have something.

I think I mentioned to the list at some point, the farm where i work  
was cleared from second growth forest about 1947 and the original  
farmer, George Giardi, who was born here in 1901 used a boxcar of  
dynamite to clear the stumps. Last winter walking around a section we  
leveled with a bull dozer and looking at the ground with slight sheet  
erosion and there were tiny pieces of charcoal everywhere that I was  
picking up. I suspect most soils are like this.

Rich
On Jun 3, 2008, at 1:35 PM, Kevin Chisholm wrote:

> Dear Richard
>
> Richard Haard wrote:
>> Kevin We have boggy soil out here in western Washington that is  
>> black and is now drained and farmed for blueberries. I cannot see  
>> how this could be charcoal causing this color but rather high om.
>
> That is exactly the point. I believe we can get "black carbon" from  
> two sources:
> 1: Charcoal/burned grass
> 2: Fully degraded organic matter that is basically only Carbon.
>
> "Organic Matter" is C with significant H and O. That is biologically  
> available. On the other hand, as far as I know, charcoal, char,  
> soot, etc are incapable of entering into a biological reaction.
>
> The question is: Is there any effective difference between charcoal,  
> char, soot, and "free carbon" that came from other organic matter  
> sources?
>>
>> In Iowa I am always amazed by those soils. Having lived in Kansas  
>> and watched annual burning of natural prairie in the Flint Hills I  
>> cannot see how much charcoal can accumulate from this practice. Its  
>> benefit is release of nutrients to grasses in early spring .
>
> These soils are high in "organic matter". They may also be high in  
> "free carbon" from degradation of organic matter, either through  
> pyrolytic action, or through biological action.
>>
>> I think we are looking at a climatic zone. The old soil terminology  
>> for these soils are chernozem or chestnut soils. Chestnut is the  
>> color, not black. It has reddish tone when you look at it. I do not  
>> know what the 'modern terminology' is for this soil type,  however  
>> on the west coast of Washington in rain shadow areas such as  
>> Olympia and Whidbey Island there are more limited areas of these  
>> soils. These black soils in the corn belt is a band literally from  
>> Iowa to Illinois and their persistence under cultivation is  
>> interesting. 150 years of cultivation and still black??
>
> Is it possible that they have a lot of "free black carbon", and that  
> claims of "soil degradation are because the associated organic  
> matter is being depleted?
>>
>> If I come across anything I will forward to you guys. It should  
>> show up in a literature search.
>
> Please do!! This is one fascinating puzzle.
>
> Best wishes,
>
> Kevin
>>
>> My sister in law, Sac City Iowa has these totally amazing summer  
>> vegetable gardens with production that outshines anything I can do.  
>> On Jun 3, 2008, at 11:37 AM, Philip Small wrote:
>>
>>> I do not have the reference at hand, but I have read that some  
>>> soil scientists are persuaded that, to a significant degree, the  
>>> black appearance of prairie soils is due to charcoal, and that 10  
>>> - 30% of the organic-C in these soils is in the form of charcoal.  
>>> My thought is that it was probably a lower percent before tillage  
>>> increased the rate at which org-C evolves to CO2, (pre-Columbian  
>>> was 5-15% of the org-C maybe?) since char would be more persistent.
>>>
>>> On Tue, Jun 3, 2008 at 10:56 AM, Kevin Chisholm <kchisholm at ca.inter.net 
>>>  <mailto:kchisholm at ca.inter.net>> wrote:
>>>
>>>    Dear Rich
>>>
>>>    Richard Haard wrote:
>>>    > Not all black soil soil is Terra Preta
>>>    > <http://www.flickr.com/photos/rchaard/2548787688/>
>>>
>>>    Very interesting point! What are your thoughts on the difference
>>>    between
>>>    "Black Soil" and "Terra Preta"?
>>>
>>
>> I had hoped to run tp thru my fingers earlier this year but did not  
>> have a proper visa. Maybe next fall I can give first hand report.
>>>
>>>
>>>
>>>    When is a "dark earth" simply "Black Soil", and when is it Terra
>>>    Preta?
>>>
>>>    Kevin
>>>
>>>
>>>
>>>    _______________________________________________
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>>> >
>>>    http://tech.groups.yahoo.com/group/biochar/
>>>    http://terrapreta.bioenergylists.org
>>>    http://info.bioenergylists.org
>>>
>>>
>>>
>>>
>>> -- 
>>> Philip Small, RPSS
>>> Land Profile, Inc. * PO Box 2175 * Spokane, WA 99210
>>> 509-844-2944 cell * 509-838-4996 fax * 509-838-9860 office
>>> Profile: http://www.linkedin.com/in/philipsmall
>>
>
>
>