FEATURESTORY
by Ray Barkalow
Dealing with Fertilizer Powders
M
any of the fertilizers available in the mar-
ketplace are in powder form, as they can
be formulated to be more concentrated
and can be shipped less-expensively
than liquids. While that does make them more eco-
nomical to purchase, there are some issues with
fertilizer powders that can complicate life for the
hobbyist. One of those problems may be a lack of
homogeneity or uniformity in the powder.
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22
A fertilizer manufacturer typically makes many
different formulations utilizing a variety of miner-
als. They therefore keep stocks of those mineral raw
materials and blend them in specific proportions to
create different formulas. Some of those raw mate-
rials are powders, some are chunks, and some are
“prills” – little spherical particles – and when you
mix them, it’s not a truly uniform blend. To a large-
scale user who might consume entire bags, it’s not a
problem, but for those of us dipping a spoonful out
of the package, it may result in slight differences in
the final chemistry each time we mix up a batch of
nutrient solution. Then there’s the measuring of the
powder itself.
There are mixing recommendations of “teaspoons
per gallon” or “milliliters per liter”, but those are
volumetric measurements while the contents of the
fertilizer package are expressed in weight percent-
ages on the label. Even if we’ve graduated to using
parts-per-million controls – a mass-to-mass measure-
ment – we’re still stuck, because we don’t know the
bulk density (weight per volume) of the formula (un-
less it’s provided by the manufacturer), which would
allow us to do a simple mathematical conversion.
www.GardenandGreenhouse.net
March 2019