cycl
chelation
utrient molecules are often present in soil or grow
media yet not available for root systems to absorb
N
and take them up. Enter chelation. The process is a tad
technical, but it isn’t rocket science. Also, understand-
ing nutrient mobility is key to advancing your crops from
good to great when it comes to plant health and yield.
After all, if the nutrients that the plant needs are in the
soil and not available for uptake, symptoms of malnutri-
tion will eventually show up.
Most molecules in grow media or soil have negative
charges. So too does the plant root wall. Plant nutrients,
however, normally have a positive charge surrounding
them. These opposite charges tend to bind the nutrients
with the soil and not release them into the plant roots.
Ever put the opposite poles of a magnet together and see
how stuck they become? It’s kind of like that. (A quick note,
nutrients in organic fertilizers are not yet in the ionic form.
Thus, they do not have a negative nor positive charge,
but neither are they plant available. Soil microbes are
required to work on these nutrients and convert them.)
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NUTRIENT MOBILITY
IN PLANT MOBILITY
IN SOIL
Nitrogen Mobile Mobile as NO 3-
Immobile as NH 4+
Phosphorus Somewhat
mobile Immobile
Potassium Very mobile Somewhat mobile
Calcium Immobile Somewhat mobile
Magnesium Somewhat
mobile Immobile
Sulfur Mobile Mobile
Boron Immobile Very mobile
Copper Immobile Immobile
Iron Immobile Immobile
Manganese Immobile Mobile
Zinc Immobile Immobile
Molybdenum Immobile Somewhat mobile
Chlorine Mobile Mobile
Cobalt Immobile Somewhat mobile
Nickel Mobile Somewhat mobile
grow cycle
“ IT IS LIKE A BLANKET
AROUND THE CHARGED
NUTRIENT ELEMENT;
IN EFFECT,, IT CREATES
A NEUTRAL CHARGE. ”
To a degree, the plant and the biology of the soil can
once again make the nutrient available, but this is a
limited feature. More often, precipitation occurs. For
example, iron, a basic trace element, could react to
ethyl alcohol, another element, and form insoluble ferric
hydroxide. This change of form is called precipitation.
We want as much as possible to prevent precipitation
from happening in the first place.
What would help the plant to absorb the nutrients
would be to make the charge neutral. Enter the chelate,
or coating, for the nutrient. It is like a blanket around the
charged nutrient element; in effect, it creates a neutral
charge, allowing for the binding or fixing of the nutrient
at the plant root or pore. (Making the trace nutrient a
complex by chelating it also prevents precipitation.) The
nutrient is no longer attracted to the negative grow media
molecules and is instead allowed, and encouraged, to
exercise mobility. The natural process of diffusion causes
nutrient to disperse throughout the soil. This repulsion is
similar to what happens when you place two magnetic
north poles together. Once bound with a nutrient, a
chelate keeps it free and mobile until needed. Then, the
chelate releases the nutrient for plant use. (The chelating
agent itself does not actually provide plant nutrition, but
rather makes the nutrition present more available.)
Chelates work both outside and inside the plant.
Outside and in the grow media, a chelate keeps a
nutrient in reserve and prevents it bonding with other
elements and precipitating. Then, once inside the plant,
where some mineral nutrients might be prevented from
mobility, the chelate helps the element move freely. As
such, the chelated nutrient easily moves to areas of the
plant that need it the most. If we look at the mobility
chart, it is apparent just how important chelating
nutrients can be for initial root uptake as well as
transport throughout the plant.