Soil Acidifier - Which plants benefit the Most from it?

[エドガー]

I'm using this:

Espoma 6 lb. Organic Soil Acidifier-100508616 - The Home Depot

Espoma - 6 lb. Soil Acidifier - Use as a soil amendment to lower the pH of alkaline soil. Use to provide plants with sulfur to encourage growth and dark greening. Organic ingredients for natural soil conditioning. - THD SKU# 910174

www.homedepot.com

https://images.homedepot-static.com/catalog/pdfImages/5b/5ba407d3-c410-4575-9955-633704a38293.pdf

I have ph paper strips similar to your link (I used to use it to test drinks and food). I can dab the paper to the visible moist-soil on the pots' drainage-holes, and match to corresponding ph colors.
But, even then, ok, I know the ph of soil, now what?... there is no specific calculations nor detailed instructions to get from an "exact point A" to an "exact point B" (eg: how many tbs per 4"-of-container or soil volume to drop 1 point of ph). It only states how much to add/amend in general.
It seems like more of an amendment to help with simple things like what we have in SoCal - alkaline water.

 

[MichaelS]

I'm using this:

Espoma 6 lb. Organic Soil Acidifier-100508616 - The Home Depot

Espoma - 6 lb. Soil Acidifier - Use as a soil amendment to lower the pH of alkaline soil. Use to provide plants with sulfur to encourage growth and dark greening. Organic ingredients for natural soil conditioning. - THD SKU# 910174

www.homedepot.com

https://images.homedepot-static.com/catalog/pdfImages/5b/5ba407d3-c410-4575-9955-633704a38293.pdf

I have ph paper strips similar to your link (I used to use it to test drinks and food). I can dab the paper to the visible moist-soil on the pots' drainage-holes, and match to corresponding ph colors.
But, even then, ok, I know the ph of soil, now what?... there is no specific calculations nor detailed instructions to get from an "exact point A" to an "exact point B" (eg: how many tbs per 4"-of-container or soil volume to drop 1 point of ph). It only states how much to add/amend in general.
It seems like more of an amendment to help with simple things like what we have in SoCal - alkaline water.

Looks like it's only 18% S so to lower the pH of a potting mix we usually use 0.3 grams of pure S to 10 Litres of mix and repeat after 2 months if necessary. ( you must check ) So you should be able to add 1.5 grams of your stuff to the top of a 10 litre pot. Therefore I would (as a rough guess) think you could sprinkle about 0.5 grams to the top of an average size bonsai container of say 10 inches x 6 inches x 2 inches which is probably around 2 litres capacity. This should lower the pH of your mix by aprox 1 unit. A useful lowering of pH may take several months but don't use more and think it will be better. it is quite difficult to lower the pH of your soil if it's over 8.
But remember too that you can use ammonium or urea type fertilizers to counteract most alkaline waters of about pH 7.5 to 8 or so. In that way you may only need to add the S to azaleas and other really acid loving plants.
Another option is to lower the pH of your water by using citric acid which you can get at hydroponic stores. Connect a proportioner to your tap, work out how much to use, and away you go..

 

[エドガー]

Thanks for the detailed reply.
I just followed their instructions for container'ed plants - 1tbs per 4" of container (regular nursery containers).

 

[hemmy]

hard-to-find pumice and is inexpensive (I know pumice is also available at bonsai stores tho).

Congrats! You live in the West! Pumice is very available when you know where to look. If you can’t do bulk shipments, you should be able to get 1.5cuft bags ($8.99) of Unigro Horticultural Pumice from Green Thumb Nurseries. If you can’t find it, call Unigro and they can help locate a distributor. I also get a fine bark for Orchids 2cuft (~$10) at Green Thumb. It makes for a pretty cheap mix even in big containers.

 

[エドガー]

The plants that enjoy more acidic soils: azalea, gardenia, camellia. Conifers. Maples. Oaks.

Consider this product:

View attachment 247632

How many tbs do you use... for let's say, per 4" of nursery container?
Their instructions only state for in-ground plants... their instructions also sounds like a lot of fertilizer (lbs per plant!)

Can I kill 2 birds and also use it for my front lawn?
I noticed my lawn (as well as pretty much everyone around my neighborhood) is starting to get some browning on their lawns with summer around the corner.

 

[エドガー]

Congrats! You live in the West! Pumice is very available when you know where to look. If you can’t do bulk shipments, you should be able to get 1.5cuft bags ($8.99) of Unigro Horticultural Pumice from Green Thumb Nurseries. If you can’t find it, call Unigro and they can help locate a distributor. I also get a fine bark for Orchids 2cuft (~$10) at Green Thumb. It makes for a pretty cheap mix even in big containers.

Wow, thanks for the tip!! I never thought Green Thumb would have pure pumice! O.O
Actually, I've never even been there, but I've seen Green Thumb all my life, haha... I usually just frequent Armstrong, sometimes Plant Depot, or Home Depot.
I never hunted for pure pumice nor made my own soil mixes (because I always just use cactus soil with pumice + potting soils)... but now I am interested.
The only place I've seen bags of pure pumice before was House of Bonsai.. but that's a bit out of the way and far.

 

[hemmy]

A useful lowering of pH may take several months but don't use more and think it will be better. it is quite difficult to lower the pH of your soil if it's over 8.
But remember too that you can use ammonium or urea type fertilizers to counteract most alkaline waters of about pH 7.5 to 8 or so. In that way you may only need to add the S to azaleas and other really acid loving plants.
Another option is to lower the pH of your water

As stated and if possible, rain water and acid modified tap water are the way go. It is the water, after all that moves the pH of most of our mildly acid to neutral substrates.

My water is of marginal quality with respect to alkalinity and bicarbonates. But with little kids getting into everything, I’ve avoided acidification and relied on acid fertilizers.

 

[hemmy]

After you have added sulphur (S) to the mix, bacteria slowly convert it to sulphuric acid. With watering, the acid will begin to dissolve calcium carbonate (usually) but the pH will not change until it is all dissolved and has no neutralizing ability left. After that the pH will fall rapidly.

Michael, so assuming my irrigation water is elevated in bicarbonates, carbonates, and alkalinity, the constant input of water supplies CaCO3 which reacts with the bacteria created sulfuric acid. The pH will move depending on which is present in greater portion. Do you have any sulphur rate guidelines based on irrigation water quality?

 

[Bonsai Nut]

Michael, so assuming my irrigation water is elevated in bicarbonates, carbonates, and alkalinity, the constant input of water supplies CaCO3 which reacts with the bacteria created sulfuric acid. The pH will move depending on which is present in greater portion. Do you have any sulphur rate guidelines based on irrigation water quality?

Calcium and carbon have nothing to do with it You just need the correct bacteria and O2, H20 and S... plus a little time... which eventually yields H2SO4 and lowers the soil pH.

Note that the process takes a while depending on your soil bacteria cultures. And it also can take a LOT of sulfur. If your soil pH starts at 7.5 and is clay (like a lot of Southern California), the application rate to drop the pH to 5.0 in the top 6" of soil is 87.5 lbs / 1000 ft2. If you have a product that is 10% sulfur... that is 875 lbs of base product I apply a CUP of Super Iron to every citrus tree that I own, twice per year.

For what it's worth CaCO3 is a buffering agent that resists lowering pH... so the presence of CaCO3 in your soil or water will increase the application rate necessary to overcome the buffering potential.

 

[Leo in N E Illinois]

WHOOAH there partner!

Is that pure elemental sulphur + gypsum? While it takes a while, the smallest amount of S will quickly damage plants under certain circumstances.
It works like this... After you have added sulphur (S) to the mix, bacteria slowly convert it to sulphuric acid. With watering, the acid will begin to dissolve calcium carbonate (usually) but the pH will not change until it is all dissolved and has no neutralizing ability left. After that the pH will fall rapidly. This is why it is ESSENTIAL that you first know the pH of the mix you are trying to acidify, AND then know EXACTLY how much to add to do the job and no more. (Gypsum does not alter the pH usually but it's often contaminated with Calcium carbonate in which case it will raise pH)
In container growing, it is BY FAR better to start with the correct pH than to alter it later with S. Everyone should buy themselves a pH kit (like this below) and learn the pH of the materials they use. Knowledge is power.

https://stratagreen.com.au/shop/images/products/mto8000_405.jpg

I disagree, elemental sulfur dissolution rate is slow under normal back yard and farm applications. Sulfur does not automatically break down into sulfuric acid, more often organisms break it down into sulfur dioxide, SO2, and various bisulfites, -SO3 which in a water solution are in equilibrium with sulfurous acid, H2SO3, one less oxygen and significantly less chemically reactive. Sulfur sold as a soil acidifier is a moderately coarse grind, meaning less surface area per particle for chemical reactions to occur. This coarse grind, which to the touch feels like beach sand, normally takes one full year to dissolve. Farmers have to pay mortgages, if elemental sulfur were really that dangerous to their tree and shrub crops like blueberries and cherries they would not use it. Guess what, sulfur is a regular component used to increase acidity of soils and counteract the alkalinity of high calcium irrigation water. .

I'm not going to argue at length on this, we will have to just agree to disagree.

There are some crops sensitive to sulfur used as a fungicide. The elemental sulfur used as a fungicide is a much finer grind than the sulfur used for soil acidification. To the touch it feels like a very fine flour. When this sulfur is sprayed on leaves of sensitive crops there can be leaf spotting or other damage. On the soil this finer grind of sulfur simply degrades more quickly.

Even the

 

[Leo in N E Illinois]

For my relatively moderate irrigation water, running at 178 or so mg/liter as calcium carbonate, and my pine bark, pumice potting media, I use roughly 1 tablespoon by volume per gallon (nursery pot gallon) of potting media of elemental Sulfur ground to be used as soil acidifier. It is 89% pure elemental sulfur. Fine beach sand consistency. This is roughly 15 ml / 4 liters for the rest of the world.

It is an approximate guess. Other parts of the country or world would need different amounts.

 

[エドガー]

I apply a CUP of Super Iron to every citrus tree that I own, twice per year.

Great info!

For Super Iron... how many Tbs for 3gal, 5gal, 7gal, 15gal, 30gal nursery pots?

 

[エドガー]

I apply a CUP of Super Iron to every citrus tree that I own, twice per year.

Finally got some! I’m super excited to use it..
Will use it on all my JBPs, J maples, junipers, azaleas... but also my lawn that seems to be browning in spots.

I hope for deep green lawns and gigantic conifers, maples and azaleas. Haha.

Telperion Farms also told me the #1 reason why some people give up on bonsai, and also slower growth, is alkaline water.

 

[Bonsai Nut]

Since you live in OC, use it on EVERYTHING.

Don't let it sit on foliage, because it will burn. Just make sure to sprinkle it on the soil. Other than that, I can't say I have ever burnt a plant of any type. The fertilizer component is actually very low.

Expect to see your JM leaves turning dark green / purple

 

[エドガー]

use it on EVERYTHING.

Don't let it sit on foliage, because it will burn. Just make sure to sprinkle it on the soil. Other than that, I can't say I have ever burnt a plant of any type. The fertilizer component is actually very low.

Expect to see your JM leaves turning dark green / purple

Hahaha.. ok, will do!

Btw, since ALL of my landscape soil areas are covered in beach pebbles (besides the lawn) with landscape fabric underneath (water permeable of course)... will the fertilizer still work if I spread it on top of the pebbles/landscape-fabric for my old in-ground trees and plants??

I assume it should be okay and work still, since the fabric is permeable. ?

 

[Bonsai Nut]

Hahaha.. ok, will do!

Btw, since ALL of my landscape soil areas are covered in beach pebbles (besides the lawn) with landscape fabric underneath (water permeable of course)... will the fertilizer still work if I spread it on top of the pebbles/landscape-fabric for my old in-ground trees and plants??

I assume it should be okay and work still, since the fabric is permeable. ?

Yes.