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How do I raise pH of soil while growing one?

Emeraldo

Well-Known Member
OK slurry test in the field is NOT accurate.
Bob, did you use the slurry test method yourself and produce inaccurate results? Those hand-held devices aren't for everybody, I know, you have to keep them cleaned, calibrated, and cared for. Maybe that's not your thing.

I read the article abstract cited by Tortured Soul. It's not the full article, but it states the conclusion well enough.

In Assessment of hand held ion selective electrode technology for direct measurement of soil chemical properties
J. R. Davenport & J. D. Jabro, https://www.tandfonline.com/doi/abs/10.1081/CSS-120001108, the abstract says in pertinent part (emphasis added by Emeraldo):
"The objective of our study was to determine if these devices could be used to directly measure ion content in soils. Two different soils, a Quincy sand and a Warden silt loam, made into slurries by adding water to achieve 50, 40, 30, 27.5, 25, 22.5, 20, 17.5, or 15% soil water content by volume. The slurries were directly applied to the hand held ISE (Cardy meter) five times for each soil texture and moisture content. In addition, soil solution was also sorbed onto absorbent paper and the paper placed directly on the Cardy meter surface. The results were compared to soil NO3-N, K, Na, and pH determined by conventional methods. The hand held soil pH meter worked exceptionally well on soil slurries and did not fail in making measurements even after over 500 readings."

So a good pH meter can work "exceptionally well on soil slurries" tested in the field, says this study.

I still don't know where you got your information, but I tend to believe a published study by professionals over someone's off-the-cuff comments that are unsubstantiated and seem to fly in the face of well-established information and practices. Like the comment about a +/- 4.0 spread for a slurry pH test in the field -- where did you get that? Like the thing about peat moss (or dead cannabis root, for that matter) being "full of nutrients", what is the basis for that? Like the statement about flushing nutrients from soil not being physically possible when the person so stating admitted not even knowing what flushing was, etc. Credibility becomes an issue after a behavioral pattern seems to suggest either insincerity or a disregard for fact, or both (trolling?). I'm here to exchange GOOD, VALID information and maybe learn something from people who actually know what they are talking about.
 
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Emilya

Member of the Month: Mar 2019
so once you do all your scientific tests and are pretty well assured that your soil's base pH is 6.8... what then?
 

bobrown14

Grow Journal of the Month: Dec 2017
We can read what people write all day long and longer.

Extension service provides a soil test basically FREE. It's going to be accurate.

Everyone that wants to grow in soil should take advantage of this free service - after all we all paid for it already with tax dollars.

The tests in the field - may or may not be accurate. Thats my point. I'm saying not accurate.

With pH being a logarithmic scale it doens't take much error to be way off.

You dont have a lab or lab equipment, your results "may" vary.


Should we be checking soil pH regularly? It's not even on my radar, I get a soil test look at the pH hope its a little on the acidic side (helps with the CEC) and move on. If its in the ball park below 7 I'm good.

Time to grow.
 

Emeraldo

Well-Known Member
The tests in the field - may or may not be accurate.
...I get a soil test look at the pH hope its a little on the acidic side (helps with the CEC) and move on. If its in the ball park below 7 I'm good.
Yes. I agree. I test a slurry of equal parts (a) soil and (b) water with pH of 7.0. Shake and allow to settle. Test the liquid on top. (I use a Hanna Instruments meter.) Result may not be within +/- 0.1, but if the result is less than 7, then I have an indication of acidity. For example, a result of pH of 6.0 would be the combined result of the water (pH 7) and the soil (which we know must be less than 6, possibly around 5.5). Not precise, but imho the slurry test is close enough.
A hand-held meter for a slurry test in the field is about as accurate as the alternative. Going to the Agricultural Extension Service with a soil sample will result in the about the same info (a general idea of what the soil pH is).
 

TorturedSoul

Member of the Month: May 2009, Oct 2010, Sept 2017
I read the article abstract cited by Tortured Soul. It's not the full article, but it states the conclusion well enough.
I couldn't find the full article (without paying for it), either. Next time I'm at the local public library, I'll check their big set of... whatchamacallits, lol, the periodical index. Would be nice if the one it was originally published in ends up being available on microfiche.

I still don't know where you got your information, but I tend to believe a published study by professionals over someone's off-the-cuff comments that are unsubstantiated
To be fair, he did post a link to an article - that was written by a professional in the relevant field - which appeared to support his opinion, at least on the face of it. And I certainly don't disagree that it's possible to obtain inaccurate readings from testing one's own soil. There's an old phrase, something about some people managing to tear up anvils with rubber mallets ;) .

But we can... Cannabis growers can be downright... The range of care, attention, et cetera can range anywhere from "<SHRUGS> it's probably good enough, and if not, I've got more seeds in the cupboard" to downright anal / obsessive.

BtW, I'd like to think this discussion wouldn't have... strayed a bit, had the OP not disappeared two days after posting the thread, lol.
 

bobrown14

Grow Journal of the Month: Dec 2017
A hand-held meter for a slurry test in the field is about as accurate as the alternative. Going to the Agricultural Extension Service with a soil sample will result in the about the same info (a general idea of what the soil pH is).
Soil test from the extension service is VERY accurate. Peoples lives depend on it and why the extension service is there for us.

Much more so than a hand held meter in the field. You're guessing really with that. Get a soil test to verify. Remember pH is logarithmic measurement.

With a soil test you get the pH and CEC - these are great to know when it comes to growing in dirt.
 

bobrown14

Grow Journal of the Month: Dec 2017
so once you do all your scientific tests and are pretty well assured that your soil's base pH is 6.8... what then?
Ready set grow! lol

I dont remember where my pH pen is if I even have one.

Our outdoor flowers are killing it - planted Lilly bulbs this spring - they are now 8' tall = stinking up the place too. Smell is outrageous, it's soo loud i need ear protection. lol

Didn't even expect them to grow this year tbh - bulbs from Home Despot too.
 

Emeraldo

Well-Known Member
... I get a soil test look at the pH hope its a little on the acidic side (helps with the CEC) and move on. If its in the ball park below 7 I'm good.
That's what I do, too. No need to obsess about this, just ballpark and out. If too low, add some lime.
 
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