Several peopIe in this forum have been doing ongoing soil tests on soil replacements.
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I just compleated a legnthy series of pH tests of the soil components I use.
All were mostly neutral, or just above 7.0 ; 7.0 -7.3 .
That includes 5 years old, stored, premixed 1:1:1 Akadama, pumice, red lava. And, my decideous 1 part humus (organic potting soil). Im also trying Napa Floor dry; its a type of zeolite(?).
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One VERY interesting test-- the 6 month IN USE, biologically active soil mix pH (has some surface moss) was 6.7 … (Dug down 2 inches in bonsai pot for sample…). Repeated on a similar bonsai pot to confirm, pH 6.7 . The active microbiom must be reducing the internal pH— down significantly. I tried this test last summer, and was very confused… This is a HAPPY pH point for bonsai…
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Also, LIVE bonsai pot effluent water was collected in a clean tray and tested… it was also 6.7 .
Test were repeated on two other different LIVE bonsai.
All tests had similar results. 6.6-6.8 pH .
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(Tests were a modified standard lab procedure (SLP)…
Note— the probe HAS to be submerged in water and moving slightly, to get a proper pH. Just sticking it in soil doesn’t work.)
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Procedure: 2 heaping tablespoons of test soil per 200 millileters of tap water. Into a clean pint glass bottle with lid. Seal. Shake for 1 minute. Settle 3 minutes. Skimm if needed (!), with a stainless steel mesh spoon.
pH meter was properly calibrated using pH 4 and 7 buffers. During the testing the probe was properly recalibrated several times,
Probe was vigerously rinsed in distilled water [measured pH at 7.1] after EVERY test, and calibration checked as needed in pH 7.0 buffer. Check that the probe bulb has no cling-ons…
Rinse test bottle, lid, and utensils with tap water.
My tap / drinking water is 8.3 .
All pH tests had the probe about 1 inch below surface of water with slight stirring circular motion.)
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It IS interesting that the microbiom in the pot is adjusting the water pH down by at least 1.6 points…!
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Anyone else out there seeing similar interesting tests results?
Bonsai On!9
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