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Laterite and Clay

booth (re improving upon):
Nope, the Dupla method has worked just great for us with
only minor adjustments to nutrient dosing


I recently posted on laterite and clay and the possibility
of a new substrate methodology.

First, regards definitions, I believe clay has two important
properties which distinguish it from laterite:

1)  Size. Two (2) micrometers or less.  This causes it
     to remain in suspension in water.
2) Mineral composition.  Rich in silicate clay minerals.

The laterite for planted aquaria fails the definition of clay
with regard to point 1 ( it is generally larger than 2 micrometers
and does not remain in suspension after being allowed to settle )
and point 2 (most of the silicates and 'tropical' nutrients are by
definition leached  out )

The real point of my post was to suggest that plain laterite
substrates can sequestor phosphate but lack the ability to sequestor
nutrient cations and that a combination of both soils would allow
for the best of both worlds.  It would offer some of the benefit
of a 'rich' soil substrate without concern for types and amounts
of leached nutrients. As I have pondered the value in this,
it was with some trepidation as the traditional APD montra is not
to mess. But how than I ask is the world to move forward?  Justin
Collins seemed  to understand:

>  [Justin Collins wrote]
>  I guess I'm not totally sure why a hybrid substrate
>  is bad.  While I understand that most people get poor
>  results with them, I'm not sure what happens that
>  creates such problems.  I could understand it if we
>  were talking about a rich soil substrate mixed with laterite
>  or something like that, but I fail to see why mixing
>  laterite with flourite, clay balls, or other non-rich substrate
>  could create such problems.  Any help would be greatly
>  appreciated.

The point was raised that clay because of its suspension property,
could create a cloudy mess whenever plants are uprooted.  I would
raise two questions:

1) What is the effect of calcinization (baking) of clay on CEC
2) Does anyone know the CEC of popular calcined clays such
    as Flourite ( Greg Morin? )

Christopher Coleman
christopher.coleman at worldnet_att.net