Most of the time in the USA you end up with iron deficiency in soil by having it too alkaline. There's iron but the plants can't use it above pH 7 or so. Very much like dehydrating in an ocean, plenty of H2O just can't adsorb it from the seawater. So most iron problems in the USA are actually pH problems causing a lack of iron not a lack of iron itself. So most commercial "iron fertilizer" etc is something to acidify the soil and only a little actual iron sulfate.
It takes VERY little iron sulfate to provide the required iron for soil. It takes a lot of stuff to drop the pH a point or two.
If you research this you'll find that fixing iron deficiency in the USA caused by excessive use of certain fertilizers and it is REALLY EXPENSIVE and labor intensive because most of the money is blown on fixing the pH to make the plentiful existing iron available.
In the unlikely even you're low on actual iron in the soil, iron sulfate is ridiculously cheap and it doesn't take much, like a spoonful per 100 sq ft, so a $10 bag should be something like a lifetime supply for an entire village...
Also some fertilizers are good iron sources so supplementation is not necessary or even a good idea.
Given where I live banana cultivation isn't a serious issue so I don't know how bananas and their fertilizers interact WRT soil pH.
The TLDR is don't confuse soil pH repair with Fe supplementation (especially since one costs 100x more than the other) and iron may not even theoretically be a possible problem depending on local fertilization practices.