# Waypoint: PH & Iron relationship



## Ohio Lawn (Mar 20, 2019)

Does anyone have any thoughts on the relationship between my slightly alkaline soil and my iron levels? Is the iron not available for the grass when the soil is at my ph?


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## jha4aamu (Oct 16, 2017)

i believe your soil ph needs to be slightly acidic for the iron to be available to the plant. for alkaline soils, foliar apps of iron are more efficient


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## bernstem (Jan 16, 2018)

As pH rises, soil available iron declines. What that means is that you need more iron in the soil at higher pH for the same effect. 7.4 isn't that crazy high and your Fe levels are decent. If you want to get an even darker green, you should look for chelated iron sources for soil application or consider foliar sprays. Ironite isn't going to do much. Milorganite and similar products will work better.


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## Ohio Lawn (Mar 20, 2019)

bernstem said:


> As pH rises, soil available iron declines. What that means is that you need more iron in the soil at higher pH for the same effect. 7.4 isn't that crazy high and your Fe levels are decent. If you want to get an even darker green, you should look for chelated iron sources for soil application or consider foliar sprays. Ironite isn't going to do much. Milorganite and similar products will work better.


Are there any other iron sources for soil application on the market?


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## bernstem (Jan 16, 2018)

Ohio Lawn said:


> Are there any other iron sources for soil application on the market?


There are a lot, but... I don't use them (my soil iron levels are high) so don't have any real experience. A search, or a new post in the cool season forum will likely get you a lot of opinions.


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## Ohio Lawn (Mar 20, 2019)

bernstem said:


> Ohio Lawn said:
> 
> 
> > Are there any other iron sources for soil application on the market?
> ...


Thanks. I'm thinking with my 7.4 ph and current iron level, I'd be better off with foliar apps of Iron. Isn't my soil iron locked up at a 7.4 ph?


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## bernstem (Jan 16, 2018)

@Ohio Lawn It is locked up some, but still available and your iron levels are good. If your pH was 8.2, it would be different, 7.4 isn't that high. Foliar applications will have an effect on almost all turf, regardless of pH, so try them and see if it is worth the work.

You can also try methods that will temporarily drop the pH, like spraying Citric acid at 1-2 lbs/1000. If you do use Citric acid, water it in immediately as it will burn. Limit your applications to 2 lbs/month.


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## Ohio Lawn (Mar 20, 2019)

bernstem said:


> @Ohio Lawn It is locked up some, but still available and your iron levels are good. If your pH was 8.2, it would be different, 7.4 isn't that high. Foliar applications will have an effect on almost all turf, regardless of pH, so try them and see if it is worth the work.
> 
> You can also try methods that will temporarily drop the pH, like spraying Citric acid at 1-2 lbs/1000. If you do use Citric acid, water it in immediately as it will burn. Limit your applications to 2 lbs/month.


Will the citric acid unlock some of the iron by lowering the PH? Would it have the same net appearance affect as spraying FAS?


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## bernstem (Jan 16, 2018)

@Ohio Lawn The Citric acid will unlock some of the soil iron by lowering pH. I use it (and elemental Sulfuf) on my front lawn and it is darker than my back lawn. The lawns get treated basically the same otherwise. Spraying FAS will have more of an effect on color than just about anything else, but it only lasts ~2 weeks or less. Citric acid on lawns is a bit more lawn crazy than some of the other things we do, so...maybe try the other stuff first and see how they work.


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## mowww (Jan 16, 2018)

For reference:


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## Ohio Lawn (Mar 20, 2019)

bernstem said:


> @Ohio Lawn The Citric acid will unlock some of the soil iron by lowering pH. I use it (and elemental Sulfuf) on my front lawn and it is darker than my back lawn. The lawns get treated basically the same otherwise. Spraying FAS will have more of an effect on color than just about anything else, but it only lasts ~2 weeks or less. Citric acid on lawns is a bit more lawn crazy than some of the other things we do, so...maybe try the other stuff first and see how they work.


Ok thank you. Last question; do you think I'm better off in the long run by applying elemental sulfur? Would that be a permanent fix, or would that require annual apps?


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## bernstem (Jan 16, 2018)

Ohio Lawn said:


> Ok thank you. Last question; do you think I'm better off in the long run by applying elemental sulfur? Would that be a permanent fix, or would that require annual apps?


If you want the last 5% of appearance and health out of your lawn, it may be worth it, but I don't think bringing the pH down will have a huge impact on appearance or performance. You would be better off focusing on P and K. They will have a much bigger and more noticeable impact on the grass then the pH.

Try sulfur if you want and retest next year to see if it has an effect. It won't hurt. Depending on why it is high would determine if you need repeat applications. If you have a calcareous base soil, then it may take a lot of Sulfur to drop it and it may always work back to high. Similarly, if your irrigation water has a pH of 8.5, it will constantly push the pH up. If the pH is high from overzealous liming, then it will be temporary.


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## Ohio Lawn (Mar 20, 2019)

bernstem said:


> Ohio Lawn said:
> 
> 
> > Ok thank you. Last question; do you think I'm better off in the long run by applying elemental sulfur? Would that be a permanent fix, or would that require annual apps?
> ...


Looking at my soil test results, is there a good time to apply SOP and MAP? Can I apply those anytime of year to increase my P & K?


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## bernstem (Jan 16, 2018)

Potassium and Phosphorus can be applied at any time. Limit each to 1 lb/month. I would limit Nitrogen to 0.5 lbs/month or less in the summer.


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