buffering up
If the cations of Ca, Mg, Na and K are all present in the
solution at the same concentration, they will be adsorbed
at different levels, with calcium and magnesium being
adsorbed at double the rate as they both have a doublepositive charge, while potassium and sodium have a singlepositive charge (Ca++, Mg++, K+, Na+).
For example, many coco product manufacturers buffer
their coco with 8 kg of calcium nitrate per cubic meter of
coco. Calcium nitrate has a value of 19% calcium, which
equals 1,520 g of Ca with almost no Mg, K or Na if the
water is clean. As the process commences, a high concentration of Ca molecules attaches to the
media—as each Ca++ molecule is adsorbed,
two molecules of K+ or Na+ are released
because the Ca has a double-plus charge
“If you are using an un-buffered
coco product, a well-balanced
nutrient solution goes into the coco and
starts to buffer the coco as well as feed
the plants, instead of all of the nutrients
going directly to plants.”
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Maximum Yield USA | April 2015
and K and Na are single-plus charges. In the beginning,
the exchange goes very quickly, but as the exchange
continues, the concentration of the K and Na molecules
released into the solution slows the exchange down and
it will eventually come into equilibrium. The buffering
process can be done in 10-15 minutes—the point at
which the exchange slows down enough that the greater
exchange is not worth the wait.
Some coco products have been buffered with a higher
treatment of Ca and Mg concentration. This creates a
lower K and Na percentage on the
exchange and adds the benefit of Mg
to the CEC. These more advanced
buffering processes involve a much
greater amount of time, but result
in much lower K and Na levels
on the exchange. This essentially
creates a better coco product from
day one, ensuring all of a nutrient
mix goes straight to the plant versus
amending the coco’s CEC.
What Does This All Mean for the Grower?
As a grower, your goal is to create and use a well-balanced
nutrient solution. If you are using an un-buffered coco
product, a well-balanced nutrient solution goes into the
coco and starts to buffer the coco as well as feed the plants,