Iron Sulfate Safe for Palms?

[Dartolution]

Looking at Iron Sulfate to correct a higher soil pH issue and iron deficiencies in a few plants and possibly in a Butia. 

Has anyone used this to correct soil pH and iron issues? Specifically the high-yield brand Iron Sulfate? 

 

 

[amh]

I haven't used iron sulfate, but I do use elemental sulfur to lower pH and to alleviate chlorosis. Usually once you lower the pH, the plant will be able to use existing iron. Don't use high phosphorus in alkaline soils!

[Tyrone]

On 6/5/2021 at 10:41 AM, Dartolution said:

Looking at Iron Sulfate to correct a higher soil pH issue and iron deficiencies in a few plants and possibly in a Butia. 

Has anyone used this to correct soil pH and iron issues? Specifically the high-yield brand Iron Sulfate? 

 

 

Yes. I’ve used it to lower pH. It does work and gives an iron boost but as already mentioned the sulfate in it releases locked iron anyway. What is your base pH. If it’s 8 or above you will likely have something close to pure limestone and it will take a heap of it to bring it down to 6.5. 

[manuel2021]

throwing straw help lower the ph, i used both sulfur and iron sulfate and lot of stuff like straw, mixing organic stuff helps lowering it when it decompose...

[Dartolution]

I think its around 7.8 based on liquid tests, but I need to test again since its been 3 years and I've been working on it with the addition of loads of organic matter and mulches. 

Its not a huge problem at this point, but there are some things that are clearly not as happy as I'd like. 

 

[Looking Glass]

I put iron sulfate on the lawn, and I’ve put it on palms.  Didn’t seem to do anything, good or bad for me.   It is great at staining stone and concrete wherever a stray granule lands though.   I’ve had better luck with chelated iron for quick fixes, and mixing peat and manure into my native sand to lower pH.   

[sonoranfans]

You should read about what happens to plants with excess iron: stunted growth, leaf bronzing and spotting.  Then you can observe what happens when you add iron sulfate.  Iron sulfate will change the pH suddenly if too much is added.  IF you use palm gain, you have plenty of iron in your soil as its about 2.7% of typical 8-2-12 fertilizer.  The iron that is there is just not bioavailable at that pH(it exists as an insoluble hydroxide).  So the best solution would be to just change the pH independent of the iron level to release the iron you have been adding with palmgain.  Iron doesnt wash away as readily as K, Mg so if you are using a decent palm fertilizer you likely have plenty of iron in the soil.   I would add the sulfur pellets, did that years ago when I had alkaline pH in arizona, works great but you need to add every 4 months or so in the heat.

[Tyrone]

The finer the Sulfur powder added the better it reacts. Always apply with copious water to wash it into the profile. Probably a little and often for a few years could bring the pH down steadily. 

At a pH of 7.8 a few applications of iron sulfate will harm nothing in my opinion. If anything is iron deficient due to the pH levels being high for a while they will love it. 

I don’t know how much iron causes a toxicity issue but in this part of the world the ground and ground water are iron rich and I’ve never experienced any iron toxicity. Excess iron can start to lock Phosphorus up but palms don’t have a huge need for Phosphorus anyway in my experience. 

[Dartolution]

9 hours ago, sonoranfans said:

You should read about what happens to plants with excess iron: stunted growth, leaf bronzing and spotting.  Then you can observe what happens when you add iron sulfate.  Iron sulfate will change the pH suddenly if too much is added.  IF you use palm gain, you have plenty of iron in your soil as its about 2.7% of typical 8-2-12 fertilizer.  The iron that is there is just not bioavailable at that pH(it exists as an insoluble hydroxide).  So the best solution would be to just change the pH independent of the iron level to release the iron you have been adding with palmgain.  Iron doesnt wash away as readily as K, Mg so if you are using a decent palm fertilizer you likely have plenty of iron in the soil.   I would add the sulfur pellets, did that years ago when I had alkaline pH in arizona, works great but you need to add every 4 months or so in the heat.

@sonoranfans Thanks, I came to this conclusion as well, and have added soil acidifier as recommended where it is needed. I looked everywhere for the bags of elemental or combined sulfur but could not find them anywhere. Espoma soil acidifier is what is available locally, so thats what I went with. 

Our native clay is rich in iron anyway. I didn't think that was necessary. 

 

Thanks everyone for your input!