Testing substrate pH - how?

[MartyB]

I am new here and I have been crusing this forum trying to find some info on soil pH. Hopefully there are no threads in obvious places since the search function is not doing much for 2-character searches...

In any case, I have been growing for a short while now using pre-mixed substrate and am looking to start putting together my own. I have been trusting up until now the pH of the soil however I don't think in the long run its a very good idea. I believe Ficus benefit from a slightly acidic soil, and my newly growing Olive trees would prefer soil tending towards alcalinity.

So my first question is, how do you folks test your pH? And assuming it is doable, what methods do you use to raise or lower it??

thanks in advance for your help!

 

[jk_lewis]

Well, some folks obsess about it, but in my years growing these little trees I've discovered that -- with the exception of azalea which MUST have acid soil -- bonsai don't care that much. Most plants prefer soil somewhat on the acidic side, and the fertilizers we use keeps it there, generally speaking. Virtually all plants (except azalea and their ilk) are perfectly happy in more-or-less neutral soil, which, if you don't put too much organic material in the mixture our soils generally lean toward.

I'm sure you will hear from fussbudgets all sorts of ways to measure pH; I don't bother and in 40 years my trees haven't seemed to mind.

 

[Eric Group]

Yeah, on stuff like azaleas that really PREFER more acidic growing environments, I just add some slightly more acidic materials to the soil... Organics like peat moss.. Kanuma is supposed to be the best, but I have never used it and my Azaleas grow fine... I bought a meter to measure soil PH, but it always reads about the same for me. Don't know if it is broken or if my PH ranges don't vary much... In the end- Trees are happy so I am happy.

 

[Geo]

There are test kits available at home depot,or wherever.Sorry I don't live in Canada now.They have a little capsule(you get ten)which you mix with a soil sample and water.But the readout is calibrated in an amateur hour sort of way,according to a color code. Any more accurate method is going to cost you.I would say be very careful changing PH.Gradual is best,I think.Maybe give the thread a run down of what your substrate is composed of, or what you propose to use a substrate for the Ficus or the Olive.Many trees have a PH tolerance as well.Just new here too.Happy Canada day in advance!!

 

[Cypress187]

I used vinegar to make it more acidic, but it didn't work so well.

 

[jk_lewis]

No one should have much problem with acidifying the soil; most tend toward acidity, anyway. It is the alkalinity that is hard to keep steady. That's why farmers have to lime their pastures every other year or so.

 

[0soyoung]

No one should have much problem with acidifying the soil; most tend toward acidity, anyway. It is the alkalinity that is hard to keep steady. That's why farmers have to lime their pastures every other year or so.

Alkalinity (pH>7) and acidity (pH<7) are just opposite sides of the pH scale, not independent things. Lime is added to add calcium to calcium depleted soil.

 

[coh]

Make sure you have your terminology correct.

"Alkalinity is a measure of the capacity of water or any solution to neutralize or “buffer” acids. This measure of acid-neutralizing capacity is important in figuring out how “buffered” the water is against sudden changes in pH.

Alkalinity should not be confused with pH. pH is a measure of the hydrogen ion (H+) concentration, and the pH scale shows the intensity of the acidic or basic character of a solution at a given temperature. The reason alkalinity is sometime confused with pH is because the term alkaline is used to describe pH conditions greater than 7 (basic).

The most important compounds in water that determine alkalinity include the carbonate (CO32-) and bicarbonate (HCO3-) ions. Carbonate ions are able to react with and neutralize 2 hydrogen ions (H+) and the bicarbonate ions are able to neutralize H+ or hydroxide ions (OH-) present in water. The ability to resist changes in pH by neutralizing acids or bases is called buffering.

Alkalinity is important to aquatic organisms because it protects them against rapid changes in pH. Alkalinity is especially important in areas where acid rain is a problem." etc

Taken from http://water.me.vccs.edu/exam_prep/alkalinity.html

 

[coh]

Testing soil pH is tricky for several reasons. First, soil really doesn't have a pH since it's not a liquid. So most methods rely on taking a sample of a soil and either soaking it in distilled water, then measuring the pH of the water...or pouring water through the soil, and measuring the pH of that water. Several methods are described in http://repotme.info/orchid-fertilizer/Part4_Substrates.pdf

Also, those cheap pH meters you find in Lowes and Home Depot are essentially useless. I've found the liquid test kits to be a little more reliable but even those can be tough to get a good reading from.

 

[MartyB]

thanks all for your helpful info.

currently the substrate I am getting appears to be a gritty-mix type composed of granite grit, haydite, pine bark and another type of porous-type rock I haven't really identified, possibly pumice or some sort of volcanic rock. But I have been basically trusting this mix, whereas if I start to roll my own I will likely be naturally critical of whether or not it is near neutral pH....

I think I will soak whatever I come up with in distilled water for a few hours and test with a liquid pH test . I am starting to be under the impression that it is not very high on the list of worries for the more experienced folks on this forum

 

[coh]

Are you using municipal water or well water?

 

[M. Frary]

What's PH? Lol. I'm one of the people who don't worry about it at all. Got bigger fish to fry. Although I give the evergreens a huge shot of Mir Acid once a month. Not sure it helps but it ain't hurting.

 

[MartyB]

Are you using municipal water or well water?

its municipal water. I keep it in a bucket for 24hrs for the temperature to warm and for any chlorine to evaporate.

thanks for that pdf link, I am going to try the pour-thru method.

 

[coh]

Marty, I've talked to a lot of people about water quality. Unless you're using some exotic soil components (kanuma, for example which tend to be low pH) or fertilizer, the biggest driver of soil pH is the type of water you use. If the water has high alkalinity (NOT necessarily high pH, though), it can raise the pH of your soil over time, leading to problems - since most of the plant nutrients are best absorbed at slightly acidic pH. That said - most of the bonsai people I know who are on municipal systems do not have any issues with soil pH. That includes people like Bill Valavanis (who is on the same municipal system I am).

If your plants are healthy and growing well, you probably don't have to worry about the pH. If you start having problems that seem to be due to nutrient deficiencies, then I would start to investigate, and I would start by having the water tested by a professional lab. If your plants look OK and you come up with high or low values on your soil tests, I still wouldn't change anything unless the plants start to show problems.

Sometimes people wind up chasing issues which don't really matter, which in turn causes real problems.

 

[cmeg1]

I was always under the assumption that organics ferts make the soil acidic.
I learned a recipe for neutralizing the soil twice a season.
I mix 1 part wood ash to 9 parts water,then stir and let settle.And then water the trees with it.
I probably don't have to cause' my soil is already ph adjusted,but I do fertilize with every watering a liquid organic,so I just do it to be on the safe side.
I actually need to burn some wood this evening,I do it at the end of June and then again in Autumn.

 

[qwade]

wood ash is derived from plant material, it contains most of the 13 essential nutrients the soil must supply for plant growth. Of course the main use of wood ash is K. potash, or potassium carbonate. It also, as stated above will neutralize the soil PH. These days lime is probably the favored mineral.. I believe you would need to add about 1 lb. of ash per tree to effectively neutralize Ph. I would defer to Coh for further information as he definitely has a better understanding of soil composition than I.

 

[MartyB]

Marty, I've talked to a lot of people about water quality. Unless you're using some exotic soil components (kanuma, for example which tend to be low pH) or fertilizer, the biggest driver of soil pH is the type of water you use. If the water has high alkalinity (NOT necessarily high pH, though), it can raise the pH of your soil over time, leading to problems - since most of the plant nutrients are best absorbed at slightly acidic pH. That said - most of the bonsai people I know who are on municipal systems do not have any issues with soil pH. That includes people like Bill Valavanis (who is on the same municipal system I am).

If your plants are healthy and growing well, you probably don't have to worry about the pH. If you start having problems that seem to be due to nutrient deficiencies, then I would start to investigate, and I would start by having the water tested by a professional lab. If your plants look OK and you come up with high or low values on your soil tests, I still wouldn't change anything unless the plants start to show problems.

Sometimes people wind up chasing issues which don't really matter, which in turn causes real problems.

I was just getting some information pre-emptively since I will start rolling my own soil - thanks for your comments, I will just keep an eye out for anomalies or changes.

 

[coh]

It's good to have the information available if you need it down the road.

I should expand a little on my comments above. The reason I mentioned Bill is because I've been having some problems with some of my trees, problems that I thought were due to water quality and soil pH. But I'm using basically the same type of soil and the same water source as Bill, and he isn't having the same problems. So that points to something different. I believe it's that I've been systematically under fertilizing for the past few years. After talking with him I increased my rate of fertilizer quite a bit and things seem to be better this year. We'll see if that continues.

The other thing, the type of fertilizer will also impact the soil pH over time. This is mainly determined by the type of nitrogen (urea, ammoniacal, or nitrate) in the fertilizer. I can never remember which does which, but I think nitrate pushes the pH up and ammoniacal/urea push it down. There are many papers on the internet describing this process and how one can match the fertilizer type to the water quality to keep soil pH where you want it. It can get very complicated, but for most people on municipal systems it seems that using the standard miracle gro type fertilizer will work pretty well.

Someone else commented about organic fertilizers making the soil more acidic, I have no idea if that is true or not.

Good luck!

 

[ChristianDGreat]

Question

Since Kanuma is consider acidic.
And in California the water is in high PH.
Would Kanuma helps to offset those water?

 

[63pmp]

It will for a little while, but substrate pH is finite and the potting media pH will start to drift, up or down, depending on fertilizer and water quality.