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Is there any good home soil pH kit?  RSS feed

 
Matt Zee
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Is there any good soil pH kit?

I am asking this because I did contact my local extension office and they charge $31 per soil sample. Ouch!

It seems like if there is a good home soil pH kit it might be more economical than having 2 or 3 samples done by my extension office...

Thanks!
 
John Polk
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Welcome to permies Matt.

From my experience, most home pH testers are not extremely accurate.

A good compromise might be to buy one of the meters sold at most garden stores.
Take one sample, and measure it with your meter, then send the sample to the extension office to have it tested.
That way, you will have a base for seeing if your meter reads high/low, or is even in the ballpark.

Even if you do not get reasonably close results, you can still use your meter to determine if your improvements are moving your soil closer to your target. Exact numbers are not that critical - soils change over time, and each plant has a range that they do best within. The meters are still useful for watching shifts in either direction, and seeing if your soil is within the suitable range.

Remember that each amendment you use does not change the pH immediately, nor is it permanent. Over time, the soil will revert to closely what it was prior to treatment.
 
Matt Zee
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Thanks for the reply John!

I had been thinking about what you were thinking about getting a meter and 'calibrating' it against my extension 's measurement. That is a good idea.

I thought of another way to measure the pH on the way home from work. What if I make a small hole in the ground (about 1/2" diameter, 3 inch deep) and fill it with distilled water and let it sit for a minute ot two? Then I could test the water with various pH strips I have for home brewing. Any flaws in that?

I take it the soil pH changes back over time because there is so much 'stuff' in the ground that influences pH naturally and it just dominates over time?
 
Bob Dobbs
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Get a glass-probe pH meter from ebay or something, HAS TO BE a glass probe otherwise it doesn't truly test pH, get the calibration solutions as well. Looking at at least $50-$60 not including solutions. Perform an extraction with distilled water, let settle, and test the pH of the soil. Bam, you have a home pH test kit.


Those things with the metal probe measure electroconductivity rather than pH, so they don't really mean anything. If they were regulated in any way, those would be illegal because the readings they give don't mean much.

AFAIK the extension service uses a calibrated glass-probe pH pen to do their testing.
 
John Polk
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I believe that most extension offices send the sample to their land grant university, where the samples are handled in real labs. A far cry more accurate than a garden center 'home test'.
 
Bob Dobbs
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Yes, my point is that in my experience performing said tests for said land grant universities, we used something similar to the pic at the top of this page:
http://en.wikipedia.org/wiki/PH_meter

and that, if one was so inclined, one could purchase something like this:
http://www.amazon.com/Oakton-EcoTestr-Waterproof-Tester-Range/dp/B004G8PWAU/ref=sr_1_2?ie=UTF8&qid=1369173403&sr=8-2&keywords=pH+meter

and be within about 5% of lab accuracy depending on temperature. The real ones have a glass probe , http://en.wikipedia.org/wiki/Glass_electrode
and have a scientific basis as far as accuracy, and can be more accurate depending on calibration than any sort of chemical indicator test, which can still be quite good depending on resolution needed.

Chemical tests do exist involving a barium compound as reagent, but the resolution is dependent on the human eye for interpretation and thus is quite poor.

TLR: Glass probe pH pens can be quite accurate if used correctly. No other type of true pH meter exists. Why they are allowed to sell meters with a metal probe that has no basis in reality I don't know. For the price they charge, if you are only looking for soil pH, I would get the glass meter, though the extension service test would likely give you additional important information such as soil N,P,K,Ca,Mg, etc.
 
Marj Baker
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Location: Ontario, Canada
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I gave up after several different readings from several kits, I sent my soil out for a test to an accredited lab , cost $20.00 but very accurate, I now have grass and flowers growing
were nothing grew before.
 
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