Talk:Soil pH

Wiki Education Foundation-supported course assignment
This article was the subject of a Wiki Education Foundation-supported course assignment, between 11 January 2021 and 7 April 2021. Further details are available on the course page. Student editor(s): Olympianskater.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 09:44, 17 January 2022 (UTC)

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

-- 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)

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

This article is needs citations, it is very poor to write such large amounts and leave the citations to someone else. Can we delete it all and start again?Matthewcgirling (talk) 11:42, 11 November 2010 (UTC)

Yes, massive correction needed
Although I oppose the wording from the anonymous contributer of the line above, I do agree that massive correction is needed. There are problems even with the fundamentals. As an example, pH is not restricted to a well defined range as discussed e.g. by this teacher and by a PhD here. Furthermore, the explanations about Al3+ is really backwards and implies that Al3+ appears in the soil in some magical fashion. Compare the wiki entry on Acid Neutralizing Capacity. The source of aluminium in soils are primarily minerals. Aluminium is released from minerals by weathering. What controls inorganic aluminium concentration is rather complicated. If the Al concentration is too high at the current pH amorphous Al(OH)3 is formed instantly and this amorphous Al(OH)3 may in turn gradually turn into micro-crystalline gibbsite with the same chemical formula. Amorphous Al(OH)3, micro-crystalline gibbsite and crystalline gibbsite all have different solubility constants. In modelling of soil chemistry a "gibbsite-like" relation is often used, but usually not because the creator of the model believes that gibbsite controls Al concentration but rather that it may be a reasonable curve fit for the intended purpose of the model. What is definitely true is that the Al-system buffers the soil which is the reason for the flat left end part of the ANC-pH curve in the wiki entry on Acid Neutralizing Capacity.

Factors affecting soil pH
 * + minerals rich in base cations (cations to strong bases: Ca2+, Mg2+, K+, Na+)
 * + easily weathered minerals
 * + surface area of minerals
 * - deposition of sulphate, nitrate and ammonia
 * + deposition of base cations
 * - organic matter (decomposition of organic matter produces organic acids, which lowers the pH. However, these organic acids are rather weak acids, so there is a limit to how much they can reduce pH)

Note: If deposition of ammonia (NH4) is not extreme, NH4 is nitrified to NO3 in the soil and NH4 deposition will have the same effect on pH as if NO3 was deposited. (Saittam GMT 18:22, 11 April 2012)

Chart needs a legend
The chart needs a legend to describe that Blue=available nutrient White=unavailable nutrient

Affecting Acidity
What happens if i want to increase the acidity of soil. It goes very in depth about redution but has little information on increasing the pH. --Iamcon 11:39, 31 May 2007 (UTC)


 * As of now there are a few sentences on acidifying soil. Feel free to expand with some references. Kingdon 13:07, 6 September 2007 (UTC)

Commentary
I'm moving the following commentary by to here:


 * Unattributable commenter "... thi[s] is totally wrong don't believe in this." removed from citation. I'm sorry, mystery commenter, but this is how science works. You are free to believe or disbelieve anything you wish.  However, demonstrated facts are just that.  If you disagree so strongly with the above conclusions, please conduct your own experiments that show the above article to be untrue. Please do not interfere with others who seek knowledge gained by the scientific method.

The talk page is the place to discuss the article, not the article itself. Kingdon 13:19, 6 September 2007 (UTC)

Basic Soil
The page lacks information on the basic side of the experiment, which is extrememly important to complete the page. Half the world's soil is basic, information on acidic soil only is making the page incomplete. — Preceding unsigned comment added by 75.189.155.251 (talk) 02:43, 21 February 2012 (UTC)

Assessment comment
Substituted at 06:28, 30 April 2016 (UTC)

"Mediacid" listed at Redirects for discussion
An editor has asked for a discussion to address the redirect Mediacid. Please participate in the redirect discussion if you wish to do so. signed,Rosguill talk 18:31, 6 August 2019 (UTC)

Natural science
How can i test the PH of the soil on my farm 41.115.118.255 (talk) 15:36, 21 February 2022 (UTC)