A balanced spectrum of the essential nutrients (as specified in
Table 7.20) can be incorporated
into either a 1-part, 2-part or 3-part package.
2 & 3-part plant nutrients
Most 2 & 3-part brands provide adequate levels of macro-nutrients 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 present in the same bottle (Fig 7.1). As
such, the nutrients are strategically distributed among each part. Most
importantly, the calcium is kept separate from the sulfate. In a 2-part
nutrient, calcium is normally in part ‘A’, and the sulfate is in part ‘B’.
When created in the form of a liquid “slurry”, a 1-part is able to provide
superior levels of macro-nutrients than
2 & 3-part nutrients (Graph
The “slurry” is a fully soluble suspension of mainly calcium sulfate
(CaSO4) within a solution containing the balance of necessary
macro-nutrients and trace elements (Fig 7.2). The use of a slurry enables
the manufacturer to exploit the low solubility of calcium sulfate to
squeeze more nutrient elements into a given volume than is possible with 2
Growers must be aware that clear, fully soluble 1-parts not based on
slurry technology are typically deficient in sulfate (S). Manufacturers
reduce the amount of sulfate to avoid the formation of the crystalline
calcium sulfate precipitate which would otherwise form (Fig 7.1).
An alternative strategy used to supply ‘some’ sulfate, is to reduce the
overall concentration of calcium.
Which is best: 1, 2 or 3-part nutrients?
If ease-of-use is desirable then a slurry type 1-part should be used. In
addition to this, 'slurry' type 1-parts usually provide a superior
nutrient balance than 2 or 3-part nutrients.
Growers must be careful when using 2 and 3-part nutrients. Their
performance will be reduced when specific
dosing guidelines are not
followed. For example, the separate parts should never be combined in too
little water. It is also crucial to add the correct amount of each part