This low iron condition has several adverse effects on the plant and is much more serious a condition then just looking pale and yellow. Low iron levels compromises the plants ability to make chlorophyll. It also is essential for the plant to synthesize proteins and absorb necessary nutrients such as nitrogen and phosphorous. For the backyard gardener, waiting for this indication is certainly tolerable however for the aquaponic farmer whose livelihood depends on healthy, desirable crops, how can we insure that a Basil crop is at the utmost quality and color every week or every day when it goes out to multiple customers? Waiting for that deficiency to show its color, or lack of, for a crop such as Basil that has to go into a Chef’s vibrant green Pesto is too late. So what can we do?
Non deficient leaf on left, iron deficient leaf on right
(image credit – Texas AgriLife Extension)
One option is to routinely add iron to the system. This can surely insure that there is an adequate amount of iron, but if that iron is not being absorbed as frequently as it is added, how would we then know if it is too much? There are indicators for excess iron as well and it can actually cause greater problems then having an inadequate amount. Whereas plants need iron to create Chlorophyll, too much can cause the chlorophyll to change and then inhibits the plant’s ability to absorb sunlight and the energy it derives from it. Too much iron can also impede the plants ability to take up nutrients and absorb sugars and once these vital processes are impaired the plant begins to fail from within and eventually will die. Really then we can actually be creating a greater problem by oversaturating our systems with iron. The other effect is that Chelated iron at a 13% strength, which is what we use, is not cheap. Depending upon where it is purchased it can be as much as $16 or more per pound so having a way to manage how much iron to add can be crucial.
Since implementing this process at our farm, we no longer see iron deficiencies in our plants and have minimized the risks of adding an unmeasured amount of iron that might create an excess and also avoid incurring an additional expense from adding too much. Some advocate using things such as a rusted piece of metal as a source and this may be suitable for backyard or hobby systems but we recommend using a chelated product and implementing a similar procedure so iron additions are a metered and measured addition to your system much like additives to alter pH, especially if you are growing for profit. As farmers, controlling as many variables as possible can help insure a good quality crop, satisfied customers and help protect your bottom line.
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