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Re:benefit of Peat
>>On the subject of using peat in the substrate, I mainly use soil under
gravel as my substrate for most of my planted aquariums. This approach
has proven itself over and over for many years. About 1 yeat ago, I
tried using 1/3 peat 2/3 soil and this too worked. It didn't work
better though. So, does anyone know what the role of peat is in the
substrate. Is it simply an additional source of organic material that
will produce CO2? Or does it add something else? My experience with it
is that I cannot observe any difference with it in the soil.
From my point of view, the main benefit of peat in the substrate is its CEC,
(Cation Exchange Capacity).
In technical terms, CEC quantifies the ability of media to provide a
nutrient reserve for plant uptake. It is the sum of exchangeable cations, or
positively charged ions, media can adsorb per unit weight or volume. It is
usually measured in milligram equivalents per 100 g or 100 cm3 (meq/100 g or
meq/100 cm3, respectively). A high CEC value characterizes media with a high
nutrient-holding capacity that can retain nutrients for plant uptake between
applications of fertilizer.
In simple terms, think of it like a sponge aborsbing nutrients and hold them
for the plants as a reserve.
The CEC capacity for Sphagnum peat is 100 - 180 meq/100g ,
and Peat moss: vermiculite 1:1 is 141 meq/100g according to Bunt, AC 1988
and Landis, TD 1990 see http://www.aquabotanic.com/sfintro.htm
Here is another quote from the article: "Sphagnum peat moss, derived from
the genus Sphagnum, contains at least 90% organic matter on a dry weight
basis. In addition, this peat moss contains a minimum of 75% Sphagnum fiber,
consisting of recognizable cells of leaves and stems. Approximately 25
species of Sphagnum exist in Alberta, Canada and 335 species are present
throughout the world. Sphagnum fuscum is an important species bearing many
desirable traits. Sphagnum grows in northern cool regions and is also
located in peat bogs found in Washington, Maine, Minnesota, and Michigan.
Many pores are present in the leaves of sphagnum; when used as growing
media, as much as 93% of the water occupying this internal pore space is
available for plant uptake (Peck, 1984). After draining, sphagnum peat can
hold 59% water and 25% air by volume. Sphagnum is usually characterized by
an acidic pH, low soluble salts content, structural integrity, and the
ability to serve as a nutrient reserve (Landis, 1990). Although peat mosses
are classified into four different groups, variation may exist within any
one type of peat moss. Peats of the same classification often differ notably
in quality, and even peats from the same bog taken from separate layers can
possess different chemical and physical properties.
Sphagnum peat moss is classified as light or dark peat, based on its color.
Light peats are characterized by a large amount of internal pore space,
15-40% of the pore space comprises aeration porosity Dark sphagnum peat does
not display the elasticity of light peat and is usually not as long
lasting.. Dark sphagnum peat moss maintains twice the cation exchange
capacity of light peats, yet does not possess as much total or aeration
Robert Paul H
Plants, combo packs, equipment, SAEs