The "Potager du Laesseux" in the Dordogne

[sicetaitsimple]

but on the contrary the fact that the result may surprise compared to what we expected and which is however perhaps correct.

"maybe however correct" is the whole problem! A pH that goes from 7 on the surface to 5 to 20cm on a natural meadow, it seems to me "perhaps however inaccurate"! In any case I would do nothing (in this case liming with ashes, since Lachanette has a profusion of it)) before getting to the bottom of it.

[Did67]

I don't think so, but it's not very important. I just wanted to say that it is better to have a measurement which is certainly approximate (+/- 0,5 point) but in which we have a certain confidence (the colored tests) than in something which displays a value which is certainly very precise (at 0,1 , XNUMX point) without having the slightest conviction that he is not saying anything. I have tried to find an independent "test" of this type of device, without success.

As said, this is not a real pH meter (which have special, sensitive, fairly expensive electrodes and which are calibrated with buffer solutions of known pH).

And I think they are sensitive to soil moisture.

Afterwards, ahmed "corrected" me a bit, in the sense that I implied that on a limestone base, an acidic pH was unlikely (exactly, I was asking if, given the apparently acidic pH, the vegetable garden was safe. crystalline base). And he's right. If in general, soils on a limestone base are rich in active calcium, therefore have a neutral to alkaline pH, the particular circumstances inherent in pedology mean that this is only an approximation ... As always, it is a lot more complex than a simple linear correlation ...

[Lachanette]

I bought strips of pH paper and I will keep you posted on the results after the Ascension ...

[jpg43]

About limestone and acidic ph. In the massive limestone Vercors we find beautiful expanses of heather and blueberry acidophilous plants on a soil made up of flush limestone rocks.

[Did67]

For this measurement story with "'the device", I think the humidity is playing. This must be a measurement of the electrical conductivity type between two electrodes of different materials, then "converted" into pH ...

I therefore suggest taking enough soil to fill half a bottle on the surface; same thing at 15 cm; same thing at 30 cm. Soak the 3 pierced bottles well. Leave to dry and repeat the measurement.

[Lachanette]

About limestone and acidic ph. In the massive limestone Vercors we find beautiful expanses of heather and blueberry acidophilous plants on a soil made up of flush limestone rocks.

The answer of a geo = morphologist: in karst soil, clays are formed from the decalcification of rock. So on limestone, we have clays without limestone, so acidic.

On the other hand, I was 3 days on the spot with a MASS of things to do, so I neither did analyzes with pH paper, nor took soil to put in the lab. Just no time, plus a heat to burst from 11h to 18h ... I only made a measurement on paper of the water from the well: between 7 and 7.5.
I'll do a little review later ..

[Did67]

Yes, clays were present as impurities in limestone rocks. These "dissolve" under the action of acids (CO² in water). The clays remain, deposited on the surface. But it is calcium, not limestone, which regulates the pH (there is of course calcium in limestone, which is calcium carbonate - very very very poorly soluble; therefore the calcium in the limestone plays no role in soil chemistry; it is "immobilized" in calcium carbonate).

But in fact, we can therefore have an acid horizon. The level you indicate surprises me all the same.

However, there can also be an increase in calcium (for example by water or by the activity of worms) which can neutralize surface acidity.

[Moindreffor]

Hello
I am a chemist by training and I was an aquarist,
for your ph story i will say that you have to trust nature

I no longer tested the water in my aquariums, because I knew it and if a fish went wrong, I knew it was not coming from the water, I always had hard water and fish that "liked "or" did not like "that according to the books, I went to a foreign specialist who had been breeding rare species in 60L for years, while for these same species we were shouting in France for the murderer if we didn't did not give at least 250L, so everything is relative

if your garden produced before, it will still produce, did you care about the pH before? There is the question

why did you come to measure pH?

[Lachanette]

Hello
if your garden produced before, it will still produce, did you care about the pH before? There is the question
why did you come to measure pH?

Well to progress in the knowledge of soil processes and to think about the best possible practices. Of course, we can garden "as we have always done" and repeat the same gestures from year to year, but I find that less interesting.

Making a vegetable garden is an activity that involves a lot: affect, intellect, desire, the desire to better decipher natural processes ...
For example, there are very few earthworms in my vegetable garden, why? Yet it has not been worked, and it is an old meadow. Why this absence of earthworms? Could it be due to the acidity of the soil? Will my soil get worse anyway? Should I make calcium amendments? etc ..
The pH is only one of the data, of course, but I intend to know more, to inform my decisions.
Hence a scheduled soil test. I also want to do a deep core to find out what thickness of soil I have on top of this clay bank ...
For me, all this questioning is part of the pleasure of gardening, and all the more so since I am away from my vegetable garden for 9 months out of 12. I "think" about it, because I cannot "be" there.

[Moindreffor]

ah seen like that, no complaints
I hope you find the answers to your questions