[Terrapreta] Black soil

[Greg and April]

Comments below.


----- Original Message ----- 
From: "Kevin Chisholm" <kchisholm at ca.inter.net>
To: "Richard Haard" <richrd at nas.com>
Cc: "Philip Small" <psmall2008 at landprofile.com>; "Terrapreta" 
<terrapreta at bioenergylists.org>
Sent: Tuesday, June 03, 2008 19:58
Subject: Re: [Terrapreta] Black soil


SNIP

>>
>> 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
>
> If the soil pigmentation was primarily from Iron Sulphides and
> Manganese, the soil itself would probably be toxic to growth.

Maybe, maybe not.    I am beginning to suspect that the composition of the 
rest of the soil may be a deciding factor.    The local soils are saline 
and/or salic and require the addition of sulfur or acid the break the bonds.

The local soils also have an iron deficit, so I can't help but wonder if I 
can add crushed iron pyrite to take care of both problems.

Greg H.