Do we need to add iron to our Aquaponics System? The answer in 99%
of the cases is YES.
Iron deficiency in Aquaponics systems is almost guaranteed to occur over time
due to the fact that soluble iron does not naturally occur in our water that is
added to the system either when we first fill our systems or when we top off
the system as needed.
So how do we know
if our plants are deficient in iron? As described by most, it starts with a
yellowing of the leave between the veins of at the leaves on the new growth of
the plant. The veins will remain dark green. As this progresses the leaves will
start to turn whitish and begin to die back. The plants growth is stunted, even
if you don't realize it, as all your plants in a given system have the same
deficiency.
What does this
deficiency look like? Here are some pictures that will help.
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| Cucumber |
Remember, iron deficiency shows up in the new growth, so if you see this in the older growth, you may be seeing a potassium deficiency instead.
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| Peppers at True Aquaponics |
If you also have a potassium deficiency, and you add iron, the
iron deficiency will not be corrected as quickly while your plants are still
lacking potassium. Properly dosing both will insure your plants not only uptake
what they need, but they will also be able to more easily move iron where it
needs to be.
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| Strawberry |
We have seen this with most strawberry growers, and have noticed
that the berry yield is much lower with smaller fruit. Everyone we have helped
to correct this issue has reported much better plant growth and fruit
production.
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| Tomato At True Aquaponics |
Iron deficiency is very easy to diagnose in tomato plants and it happens very quickly due to the very fast growth rate of the plants.
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| Cannabis Plant |
Yes, lack of iron will hurt your cannabis crop as well. We have a
great deal of clients that grow cannabis where it is legal side by side with
their fruiting plants as well as leafy greens and report seeing the deficiency
across all the plants at the same time. After the proper iron chelate is added
to the system, the plants will recover if the damage is not too severe.
So
with all the information on the internet about chelated iron, it is hard to
tell which one you should actually use in your system to get the maximum effect
while causing the least toxic damage. For Aquaponics there are three types that
are available. The first, cheapest and most toxic is FeEDTA. It is used as an
herbicide, but worse, it causes some phytotoxic conditions that most are not
aware of. I am not going into that science as it is very in depth and hard to
follow, however there are iron chelates that are not toxic. FeDTPA and FeEDDHA are both widely used in Aquaponics to bring up
the soluble iron content of the system water without the toxins. FeDTPA 11% is the most commonly used, however many folks use
this product at the wrong pH level. The correct level to use this product
is from pH 7.5 and below, above this level you need to use FeEDDHA 6%. This product is soluble from the pH in the
low 5's up to a pH in the 9's. Overall it is the best product and the least
toxic to your system. One thing to note about this product is that it
will turn your water red. FeDTPA Will only turn your water slightly brownish
or yellowish. FeDTPA can also be used as a foliar spray, cutting down
on the amount of the product that needs to be used.
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| TrueNute Iron Chelate EDDHA 6% |
FeEDDHA needs to be used if your PH level is above 7.5 in order for your plants to be able to uptake the iron.
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| TrueNute Iron Chelate DTPA 11% |
FeDTPA can be used if your system PH is at 7.5 or below. Above 7.5, the availability of the iron drops drastically.
One common misconception is that iron in the form of rust is
water-soluble, this is not true. Although rust appears to move around the
system more freely it is actually ferric iron and is non-soluble, meaning the
plants cannot uptake the iron. In order for plants to able to uptake iron, it
has to be ferrous iron. The difference between ferric Fe+3 and Ferrous
Fe+2 iron is ferric iron has three positive ions this causes the iron to be
non-soluble. Ferrous iron has only two positive ions and therefore can easily be
taking up by your plants. What this means is that if you put rusty nails or any
other Iron based metal into your Aquaponics system, the iron released into the
system will be ferric iron. So with that said, putting re bar, nails or any
other steel or iron pieces will only raise the ferric iron content in the
system which is no help. Also, there is no way of knowing what other heavy
metals will be released into the system water that could be harmful or even
deadly to your fish. So it is just not worth the risk.
Here at True Aquaponics, we take a proactive approach to nutrients in our Aquaponics
Systems today instead of waiting on the plants to show signs of deficiencies.
By waiting you hurt production and open your plants up to attack by pest as
well as bacterial and fungal attack. With proper dosing rates, these issues can
be avoided and your production will stay at its maximum and the produce will
give you a much higher mineral content making it very healthy to eat. We know
that there is little or no naturally occurring soluble iron or potassium in
water from the tap or water well unless it has been added for some reason. This
is not likely to be the case. So for these nutrient supplements and others, we
have to add them to our aquaponics system water or spray them on our plants in
order for the plants to be healthy and for us to be able to harvest food that
is in turn healthy for us to consume.
After all, if you
want unhealthy food to eat, head to the supermarket, they have lots of that.
