Lowering the pH - has anyone succeeded?

[Than]

I read a lot of discussion about how to lower the garden soil's pH; using sulphur, ferrous sulfate, pine bark, mulch and what not. I wonder if anyone has tried any method with long term success. If yes, please share your story.

[Phoenikakias]

@sonoranfans is able to help you by giving more details. He used to grow palms in Az and had to cope with natural soil alkalinty too. 

[Xenon]

Yes, constant application of pelleted sulfur every 2-3 months. Fertilize with ammonium sulfate and polymer sulfur coated urea during the growing season.  Helps if you have a lot of rainfall and organic matter/biological activity to break down the elemental sulfur into sulfuric acid (organic matter is also a buffer against alkalinity). 

For the ultra sensitive things, you can also apply humic/fulvic acids and use chelated minerals (EDTA, Iron EDDHA if ph > 7.5). These aren't acidifying the soil as much as making the nutrients that would be less available due to high pH more available through chelation (changing into forms more readily absorbed by plants). 

[Than]

11 hours ago, Xenon said:

Yes, constant application of pelleted sulfur every 2-3 months. Fertilize with ammonium sulfate and polymer sulfur coated urea during the growing season.  Helps if you have a lot of rainfall and organic matter/biological activity to break down the elemental sulfur into sulfuric acid (organic matter is also a buffer against alkalinity). 

For the ultra sensitive things, you can also apply humic/fulvic acids and use chelated minerals (EDTA, Iron EDDHA if ph > 7.5). These aren't acidifying the soil as much as making the nutrients that would be less available due to high pH more available through chelation (changing into forms more readily absorbed by plants). 

Thanks a lot Xenon, very useful and compact advice is always the best!

Did you use these methods yourself and by how much did you manage to lower the pH?

[Xenon]

On 11/8/2024 at 2:10 AM, Than said:

Thanks a lot Xenon, very useful and compact advice is always the best!

Did you use these methods yourself and by how much did you manage to lower the pH?

I haven't done a before/after soil test but natural soil pH here is around 7.5-8 and the tap/irrigation water is also ~8 and that's an even bigger driver of pH increase here. It's fairly hard to grow things that want acidic soil here. Using the above methods has allowed me to keep rainforest palms, jaboticaba, lychee, citrus, etc lime green whereas they'd be quite chlorotic in natural soil.

I also amend with peat moss when first planting, it's a short term fix (6 months-year) while you apply the other methods. You also have to keep acidifying year after year as the soil will return to natural pH if you don't keep working to acidify it. Ideally you would do a soil test to track progress, but I just do it by ear/observation of growth (plus my natural soil is heavy clay and requires a lot of effort to move pH even a few tenths of a point). If you have sandy soil, pH is much easier to change.

[sonoranfans]

22 hours ago, Xenon said:

I haven't done a before/after soil test but natural soil pH here is around 7.5-8 and the tap/irrigation water is also ~8 and that's an even bigger driver of pH increase here. It's fairly hard to grow things that want acidic soil here. Using the above methods has allowed me to keep rainforest palms, jaboticaba, lychee, citrus, etc lime green whereas they'd be quite chlorotic in natural soil.

I also amend with peat moss when first planting, it's a short term fix (6 months-year) while you apply the other methods. You also have to keep acidifying year after year as the soil will return to natural pH if you don't keep working to acidify it. Ideally you would do a soil test to track progress, but I just do it by ear/observation of growth (plus my natural soil is heavy clay and requires a lot of effort to move pH even a few tenths of a point). If you have sandy soil, pH is much easier to change.

I agree with all but the ammonium sulfate as it will drive pH too quickly if you are not careful.  A little bit to start could be a plus.  But pH control of the soil is almost as important as pH.  If you have calcareous soil, trying to change the pH could be impractical. . For example, how much sulfur->sulfate do you want in your soil?  The simplest approximation is it will take as much sulfate as calcium in the soil and calcareous soils can be  15%- to 70% calcium salts.  So you would end up with very high calcium salt content in the soil.  Not sure how good a soil that would be for growing palms.  You cant lose putting down elemental sulfur sulfur pellets if yore soil is not calcareous.  Im sure there is a local geological soil survey report for your area.

[Than]

Thanks a lot guys, this has been excellent advice! I'll take notes.

I was wondering, would it make more sense to try and alter the irrigation water's pH rather than the soil's per se?

[Xenon]

19 hours ago, sonoranfans said:

I agree with all but the ammonium sulfate as it will drive pH too quickly if you are not careful.  

I use it as the primary nitrogen source, would be hard to move pH much before incurring nitrogen burn I would think. But every little bit of acidifying power helps. Plus the ammonium binds well to my clay soil.