bencelest

Chong : Everything that you said is true- the symptoms and effect to the plants.
But I trust my meter. I have PHH-715 Mini-pH Meter.
I bought that years ago.And it is accurate up to .02 of a point. I have a buffer solution pH4.00 and 7.00 and I calibrate the meter before I use it.
It is true that the symptoms you describe yellowing of leaves is due to iron or nitrogen difficiiency provided that the pH is at the norm but things will turn helter skelter if your pH is too low or too high because there are some nutrients not available to plants in either way. Your plants will be just like a baby with her mouth close so no matter how much you feed her she will still be hungry because nothing gets into her tummy.
Here's some excerpts from 'Understanding pH Management":
5. Soil pH affects the amount of nutrients that are
6. soluble in soil water and, therefore, the amount of
7. nutrient available to plants. Some nutrients are more
8. available under acid conditions while others are
9. more available under alkaline conditions. However,
10. most mineral nutrients are readily available to plants
11. when soil pH is near neutral.
12.
13. The development of strongly acidic soils (pH less
14. than 5.5) can result in poor plant growth as a result
15. of one or more of the following factors: low pH,
16. aluminium toxicity, manganese toxicity, calcium
17. deficiency, magnesium deficiency, and low levels
18. of essential plant nutrients such as phosphorus
19. and molybdenum.

Nitrogen (N)
uptake can be indirectly affected by medium pH
because low pH decreases nitrification (conversion of
ammoniacal nitrogen to nitrate nitrogen) or the
conversion of urea to ammoniacal nitrogen.
Some species will
perform better when grown at a low pH, some will
perform better when grown at a high pH, and for some,
it will not matter. However, for each of these groups,
the acceptable range where they will grow and perform
the best will be relatively narrow and will be similar
that of other plant species. If you had to choose a pH
range to grow, then the recommended range
would 5.8 to 6.2,
So whatever the case maybe, I will have to correct my soil pH to near neutral before I do anything.
And normally, when I have a reading near normal pH my plants return to normal.
You ought to see my citrus how nice and green looking they are and what I normally do is watch my soil pH. I can not overemphasize this.
Many people have the wrong notion that if your plants are yellowing, add ironite or fertilize the plant high on nitrogen. I totally disagree.
It should be : correct your soil pH first before you do anything.

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Banana Nut