Editing Soil pH (section)

=== Sources of alkalinity ===
Total soil alkalinity increases with:<ref name="Bloom2012">{{cite book |last1=Bloom |first1=Paul R. |last2=Skyllberg |first2=Ulf |editor1-last=Huang |editor1-first=Pan Ming |editor2-last=Li |editor2-first=Yuncong |editor3-last=Sumner |editor3-first=Malcolm E. |title=Handbook of soil sciences: properties and processes |date=2012 |publisher=[[CRC Press]] |location=Boca Raton, Florida |isbn=9780429095986 |doi=10.1201/b11267 |pages=19–1 to 19–14 |edition=2nd |chapter=Soil pH and pH buffering |url=https://lib-nhwjx7zkiyjoeipfyn7m37ed.late.re/book/6097110/94f24a |access-date=12 March 2023}}</ref><ref name="Oosterbaan2003">{{cite web |last1=Oosterbaan |first1=Roland J.|title=Soil alkalinity (alkaline-sodic soils) |url=https://www.waterlog.info/pdf/acidalka.pdf |website=www.waterlog.info |access-date=12 March 2023}}</ref>
* Weathering of [[Silicate mineral|silicate]], [[aluminosilicate]] and [[carbonate mineral|carbonate]] minerals containing {{chem|Na|+}}, {{chem|Ca|2+}}, {{chem|Mg|2+}} and {{chem|K|+}};
* Addition of silicate, aluminosilicate and carbonate minerals to soils; this may happen by deposition of material eroded elsewhere by wind or water, or by mixing of the soil with less weathered material (such as the [[Liming (soil)|addition of limestone]] to acid soils);{{cn|date=August 2024}}
* Addition of water containing dissolved [[bicarbonate]]s (as occurs when [[Irrigation|irrigating]] with high-bicarbonate waters).{{cn|date=August 2024}}

The accumulation of alkalinity in a soil (as carbonates and bicarbonates of Na, K, Ca and Mg) occurs when there is insufficient water flowing through the soils to leach soluble salts. This may be due to arid conditions, or poor internal soil [[drainage]]; in these situations most of the water that enters the soil is transpired (taken up by plants) or evaporates, rather than flowing through the soil.<ref name="Bloom2012"/>

The soil pH usually increases when the total [[alkalinity]] increases, but the balance of the added cations also has a marked effect on the soil pH. For example, increasing the amount of sodium in an alkaline soil tends to induce dissolution of [[calcium carbonate]], which increases the pH. [[Calcareous]] soils may vary in pH from 7.0 to 9.5, depending on the degree to which {{chem|Ca|2+}} or {{chem|Na|+}} dominate the soluble cations.<ref name="Bloom2012"/>