Nutrient balance
1, 2 or 3-part nutrients
A balanced suite of the essential nutrients (as specified in
Chart 3.1) can
be incorporated into either a 1-part, 2-part or 3-part package.
2
& 3-part nutrient:
Most 2 & 3-part brands provide adequate levels of macronutrients and trace
elements. The 2 or 3 part packaging format is often deemed necessary by
manufacturers to avoid stability/compatibility problems between certain
nutrient species when they are present in the same bottle (Fig 3.1).
As such, the nutrients are strategically distributed among each part.
Most importantly, the calcium is kept separate from the sulphate and
phosphate i.e. in a 2-part, calcium is normally in part ‘A’, whereas
sulphate and phosphate are in part ‘B’.
1-part nutrient:
When created in the form of a “slurry”, a 1-part is able to provide
superior levels of macronutrients than what 2 & 3-part nutrients are
capable of (Graph 3.1).
The slurry is a ‘suspension’ of mainly CaSO4 (solid) within a solution
containing the balance of necessary macronutrients and trace elements.
It is shaken just prior to use and remains homogenized (i.e. blended) for
sufficient time to dispense a blended dose (Fig 3.2). Once the dose
is added to water and briefly stirred, the CaSO4 suspension dissolves
immediately. The use of a slurry enables the formulator to exploit
the solubility limits of calcium and sulphate, to squeeze more nutrient
species into a given volume than what is possible with the standard
solution technology used in 2 & 3-parts.
Note: 1-parts
not based on slurry technology however are typically deficient in
at least one macro-nutrient. This is due to the difficulty of formulating
a product with equivalent concentration to 2 & 3-part nutrients, along
with a complete balance of all necessary macronutrients. The main problem
is accommodating sulfur (as sulphate), because, in order to include
meaningful quantities, a precipitate will always form (Fig 3.1):
i.e. Ca2+ +
SO42-
à
CaSO4 (solid)
This is due to calcium’s affinity for sulphate, which results in a
precipitate of calcium sulphate, CaSO4 (note in 2 & 3-parts, calcium and
sulphate are kept in separate bottles). The precipitate is usually in the
form of either:
1.
Heavy sludge: which cannot be homogenized to enable a blended dose
to be poured.
2.
Crystalline precipitate: this cannot be homogenized or easily
dissolved.
To
avoid the ‘sludge’ or ‘crystalline precipitate’, most 1-part manufacturers
either eliminate all sulphate from the formulation or, in an attempt to
supply ‘some’ sulphate, the overall nutrient concentration is reduced,
particularly the calcium.
Trace elements:
Note that mention of trace elements is often excluded on labels
because their concentration falls below the ‘minimum’
reporting threshold imposed by certain jurisdictions.
'Grow’ and ‘Bloom’ nutrients
1 and 2 part nutrients
are usually available in separate ‘Grow’ and ‘Bloom’ formulations. 3-part
nutrients incorporate the ‘Grow’ and ‘Bloom’ formula across all 3
containers.
Note that plants take up nutrients in a ratio which is essentially
independent of the nutrient ratios present in the nutrient. This is
particularly noticeable when comparing the growth phase (i.e. vegetative)
with the bloom (i.e. flowering / fruiting) phase.
In the growth phase,
plants have a particularly high demand for nitrogen. Consequently, “Grow”
nutrients contain a relatively high concentration of nitrogen. Their use
helps ensure plants do not run out of nitrogen prematurely.
In the bloom phase
however, the demand for phosphorus and potassium increases. Consequently,
“Bloom” nutrients contain a relatively high concentration of both
phosphorus and potassium, but relatively low nitrogen. Hence, switching
to ‘Bloom’ during the flowering phase will help ensure plants do not
become deficient in potassium and phosphorus (especially for heavy
fruiting plants such as tomatoes and strawberries).
The use of ‘Grow’ and ‘Bloom’ nutrients at the appropriate times is also
much more economical because for example, the use of ‘Bloom’ during the
growth phase would result in excessive phosphorus and potassium being
wasted. This wasted nutrient potentially becomes an environmental concern
when the nutrient is dumped – particularly in large commercial operations.
Additives
“Flowering” additives
usually contain primarily phosphate and potassium. Heavy fruiting plants
such as tomatoes and strawberries have a high demand for potassium and
phosphorus during the fruiting phase. The additional use of ‘flowering
additives’ with ‘bloom’ nutrients will help ensure no deficiencies occur.
Note that EC readings will be of essentially zero benefit in determining
if sufficient potassium and phosphorus is in reserve.
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