Talk:Soil pH

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Soil pH is included in the 2006 Wikipedia CD Selection, or is a candidate for inclusion in the next version. Please maintain high quality standards and, if possible, stick to GFDL-compatible images.

I just set up a little HTML-table to fix the typos in the image. Perhaps you might replace the image by this table:

	Acid					Neutral			Alkali
	4	4.5	5	5.5	6	6.5	7	7.5	8	8.5	9	9.5	10
Nitrogen N
Phosphor P
Potassium K
Calcium Ca
Magnesium Mg
Sulphur S
Iron Fe
Manganese Mn
Boron B
Copper Cu
Zinc Zn
Molybdenum Mo

-- JeLuF

pH is not the ratio of hydrogen ion to hydroxyl. If it were, then neutral pH would be 0, not 7. Dwmyers 22:22 Feb 12, 2003 (UTC)

[edit] Massive correction needed

Ouch! I don't have the time currently to fix this article, but there are several problems with it. I can't see that there is any support whatsoever that Ca, Mg, K etc. become insoluble. Rather the opposite is true. During acidification the relase of cations is increased. So, in the short term, soil acidification increases the availability of Ca, Mg and K availability. Eventually, however, the cation exchange resin gets depleted. Also, an article that talk about soil acidification must mention mineral weathering. Mineral weathering might either increase or decrease due to acidification: Low pH, high pOH (yes, that's right), high DOC, high pCO2 and wetness (mineral surfaces needs to be wetted) are factors that all increase weathering rates (there are thus 5 weathering reactions), but weathering is product inhibited, thus high Al, Ca, Mg, K, Na concentrations decrease weathering rates. An article about soil acidification (or indeed lake acidification) should also talk about Acid Neutralizing Capacity (ANC), positive ANC being alkalinity and negative ANC being acidity (although alkalinity and acidity often have operational definitions that differ from the definition of ANC (which is based on a charge balance).

One advanced place to start reading about soil acidification is the webpage of the Coordination Center for Effects (which is a body under the United Nations Convention on Long Range Transboundary Air Pollution): http://www.rivm.nl/cce/publ/ You'll find plenty of links there and information of state-of-the-art modeling of soil acidification. Saittam 08:40 21 Aug 2005 (CET)

OK, no one pithed in and I have a course coming up where I don't want my students to spend time trying to learn things that are simply wrong (some of them do go to wikipedia to get an overview). I thus made a quick and dirty fix to the article, removing some things which I deem as not consistent with the current scientific understanding, and adding a few things which explain why the world isn't quite as simple as the prior text seemed to indicate. Saittam 12:27 Sep 30 2005 (CET)

Also in review of the Hydrangea, the uptake of Aluminum is most important in causing the blue color of the flower. This requires a ph of 5.0 to 5.5 to release the Aluminum from the soil and make it available to the plant. The mere addition of Aluminum Sulfate is not the answer. The ph must be in range as well. 8:42 am EST FEB.17 2007