Do you find this surprising? Seems to me none of us treats each area of our gardens identically so the SFW will develop differently changing the pH.

Should qualify this - if one was growing a mono-culture and treated the entire area the same perhaps it could be expected to remain the same pH throughout.

This post was edited by luckygal on Sat, Jan 12, 13 at 16:58

What does that pH meter say about the pH of vinegar?
I have not yet found a pH meter that cost from $29.95 to $79.95 that was useful.
How much lime was put down where those blueberries are?

The least expensive method for checking soil pH that I have been able to find (for blueberries) is bromocresol green indicator. The solution is yellow at pH of 3.8, blue at pH of 5.4, and green if the pH is halfway between, around 4.6. A two dollar bottle will do about 100 soil tests, and you will also need distilled water and a paper filter, like a coffee filter to prepare the sample. The process is straightforward. Take a one tablespoon sample of soil, & mix with enough distilled water to make a slurry. Filter the slurry to get a small sample, about 5ml is enough. Add just enough bromocresol green to get a color change, and note the color. This method was developed around the time that the pH scale was invented. The only disadvantage is that you don't get the same precision as you would with a calibrated pH meter.

Kimmse, the meter reads 2.5 in the old distilled white vinegar I have.

Kimmsr, I added lime because it was reading 3 something with both meter and solution testing. There are still some very acid pockets because I don't want to disturb the roots. I don't know how much lime was added, but I needed to make a fairly rapid raise in ph and now I will have to add enough soil sulfur to bounce it down and then may need to bounce it up and.....

Now & then I get a low pH reading around our blueberry shrubs, typically 3.8 or 4.0. However, so far, at least, the shrubs have not shown any indication of distress. The cure is easy enough to accomplish, all I have to do is water the shrubs a few times with our Madison City tap water, which has pH around 7.6. In a month or two the pH will be back up around 4.5. But the soil pH is not very stable, I must say. Given that our native soil has pH around 7.6, my effort to get the pH down to 4.5 around the blueberry shrubs has been only approximately successful.

How much lime was added to that soil and which lime? Calcitic or Dolomitic? Which lime was needed? Is your soil deficient in Magnesium?
That pH reading in the vinegar sounds quite low, Acetic acid is supposed to be a weak acid not something on a par with sulfuric acid.

That pH reading in the vinegar sounds quite low, Acetic acid is supposed to be a weak acid not something on a par with sulfuric acid.

University of Washington dept. of Chemistry:

"Discussion: Acetic acid solutions with the following concentrations have the pH indicated.
0.1 M acetic acid = pH 2.87
0.01 M acetic acid = pH 3.37
0.001 M acetic acid = pH 3.8
0.0001 M acetic acid = pH 4.3
0.00001 M acetic acid = pH
Vinegar is ~5% acetic acid solution which is ~0.9 M which is ~pH 2.4"

Link.

Gargwarb,

Good info!

This post was edited by TheMasterGardener1 on Mon, Jan 14, 13 at 13:17

"How much lime was added to that soil and which lime? Calcitic or Dolomitic? Which lime was needed? Is your soil deficient in Magnesium?
That pH reading in the vinegar sounds quite low, Acetic acid is supposed to be a weak acid not something on a par with sulfuric acid.

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The vinegar reading is fine....google distilled white vinegar.

I have added some dolomite years ago in some areas, but now I add only calcium. Too much magnesium in relation to calcium can make soils with a fair amount of clay to become tight, sticky, and cloddy.

How wet is the soil when you're making these tests? I would be tempted to mix the sample 50/50 with distilled water before testing just to make sure the result is accurate.

The soil was moist [re op]. Perhaps a test or two dry with distilled water to give a control group would be good. Then, if the results were similar, then it is much easier to test 25 places without lab samples. If the results were off about so much, then this could be taken into account.

As I understand it, 5.0 ph is 10 times more acidic than 6.0
As I understand it, 6.1 ph is double in acidic values [hydrogen ions] than 6.0. 6.2 is three times more acidic than 6.0 etc.

Yes, that is basically how a log scale works.

And that sounds like a good way to test the need for using a slurry with your meter. Although you might want to try it with various moisture levels in the soil. It may work fine when fairly wet but not when fairly dry.

This post was edited by toxcrusadr on Tue, Jan 15, 13 at 17:54

" It may work fine when fairly wet but not when fairly dry."

You are probably right about that. Also, if tests were made in the soil immediately after a heavy rain, likely they would test more acidic ....because of acidic rain [carbonic acid].