Adjusting the pH of soil.

I have a plant that likes a pH of 5.5.
Can I just use a potassium phosphate buffer adjusted to this value to water the plant with?
Peter
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Peter Jason wrote:

My TOTH answer is probably not as buffer solutions are designed to hold pH steady not to alter it but it might do some good depending on the situation. I am guessing that you want to lower the pH in which case the traditional method is to add elemental sulphur and wait.
What exactly is the content of this buffer solution? What is the pH of the soil now? How much soil do you want to amend? What is the soil like, as in how much clay and organic material is there compared to sand and grit?
David
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On Tue, 11 Dec 2012 13:54:39 +1100, "David

I have one of these
http://en.wikipedia.org/wiki/File:Wollemia_nobilis_fg03.JPG
that is doing rather well in a large pot, but it will need transplanting out next season. I mix my soil 50:50 from two types; an industrial heavy clay from a dirt road that has been sloughed up by large turning trucks (easy to dig), and the usual sandy stuff collected from the roof guttering and yard sweepings.
I fertilize with cow & chicken manure.
I could make & adjust the buffer from KOH & Phos Acid with a pH meter, and I have some flowers of sulfur. How does one test the pH of soil?
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On 12/10/12 8:28 PM, Peter Jason wrote:

There are a number of test kits available at nurseries. If you are in the U.S., you might be able to get a complete soil analysis -- pH and nutrients -- from your local agricultural extension service.
--
David E. Ross
Climate: California Mediterranean, see
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Peter Jason wrote:

My assumption that you want to lower pH is clearly wrong as at this point you don't know that, so hold on to the sulphur.
The most reliable cheap way to test soil pH is with a dye indicator. You can get a kit with the dye, colour reference card etc for about $20 and that will do hundreds of tests. I am puzzled that you know what a buffer is and how to make it but you are charging off to alter your soil chemistry without first finding out if it is required.
I am so happy that my roof gutters don't collect enough sand to be useful to make soil. :-)
D
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On Tue, 11 Dec 2012 17:55:17 +1100, "David

I live in town and I don't trust that synthetic soil in plastic bags. It dries out too quickly.
I tested the soil in the Wollemi Pine pot by slurrying some in water, and it gave a pH of 6. Maybe this is why it's doing so well.
I have a few other plants in pots and so perhaps I need to take greater note of pH requirements.
Is there some database of plants and the soil-pH requirements? The botanical name is usually given on a tag when a plant is purchased.
Peter
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Peter Jason wrote:

Don't mess with it then

I have not seen such a general database.
D
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On 12/11/12 5:26 PM, Peter Jason wrote:

If you are west of the Rocky Mountains in the U.S. or Canada, the major portion of Sunset's "Western Garden Book" is a plant encyclopedia that indicates climate, water, and soil requirements for each listed garden plant. No, the soil requirements do not indicate pH; but they do indicate whether a plant tolerates alkaline, acidic, or saline soil.
There is also a Sunset garden book that covers the whole U.S., but I don't know if it is as comprehensive. I would suspect there are excellent garden books specific to other nations and climates. Also, a good plant nursery -- not a hardware store or lumber yard -- should be able to advise you on whether a particular plant requires an alkaline or acidic soil. Finally, there are various national and international societies devoted to specific plant families: roses, bromeliads, daylilies, orchids, etc.
--
David E. Ross
Climate: California Mediterranean, see
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On Tue, 11 Dec 2012 19:09:04 -0800, "David E.

Thanks, I'll check this out. Maybe there's some government publication around.
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On Tue, 11 Dec 2012 19:09:04 -0800, "David E.

PS. Wiki have something too.. http://en.wikipedia.org/wiki/Soil_pH
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The notes at the top are right - this article is pretty weak.
The section on pH determination is quite misleading. The barium sulphate is NOT the basis of the test as the test can be conducted without it. The basis of the test is a mixture of dyes which change colour over a wide range to give a gradation of indication of pH. Such test kits often include an inert white powder to use as a backdrop to make the colour of the dye easier to read against dark soil, Barium sulphate may be one such. Also litmus changes colour quite quickly within a narrow range of pH so it only tells you if the pH is above or below that point which is of very little practical use.
The part on increasing pH is pretty bad too. You would have to be desperate to use quicklime CaO as it may burn your plants (or you) and it will change the pH very quickly which will shock the soil orgainisms. Calcium magnesium carbonate is usually called dolomite not agricultural lime which is calcium carbonate. Sodium, calcium and potassium ions do not raise soil pH, it is the anions (typically carbonate) that often accompany them that do the job.
I could go on. I probably have gone on too much already.
D
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