Editing Soil pH (section)

===Nutrient availability in relation to soil pH===
[[File:Soil-pH.svg|thumb|right|Nutrient availability in relation to soil pH<ref>{{cite book |first=Arnold |last=Finck |location=Kiel, Germany |year=1976 |title=Pflanzenernährung in Stichworten |publisher=Hirt |isbn=978-3-554-80197-2 |page=80}}</ref>]]

Soil pH affects the availability of some [[Plant nutrition|plant nutrients]]:

As discussed above, aluminium toxicity has direct effects on plant growth; however, by limiting root growth, it also reduces the availability of plant nutrients. Because roots are damaged, nutrient uptake is reduced, and deficiencies of the [[macronutrients]] (nitrogen, phosphorus, potassium, calcium and magnesium) are frequently encountered in very strongly acidic to ultra-acidic soils (pH<5.0).<ref name="Sumner2002">{{cite journal |last1=Sumner |first1=Malcolm E. |last2=Yamada |first2=Tsuioshi |title=Farming with acidity |journal=Communications in Soil Science and Plant Analysis |date=November 2002 |volume=33 |issue=15–18 |pages=2467–96 |doi=10.1081/CSS-120014461 |bibcode=2002CSSPA..33.2467S |s2cid=93165895}}</ref> When aluminum levels increase in the soil, it decreases the pH levels. This does not allow for trees to take up water, meaning they cannot photosynthesize, leading them to die. The trees can also develop yellowish colour on their leaves and veins.<ref>{{cite journal |last1=Cape |first1=J. N. |title=Direct damage to vegetation caused by acid rain and polluted cloud: definition of critical levels for forest trees |journal=[[Environmental Pollution (journal)|Environmental Pollution]] |date=1 January 1993 |volume=82 |issue=2 |pages=167–180 |doi=10.1016/0269-7491(93)90114-4 |pmid=15091786 |url=https://articles-pdjrj4ripo5k3r4j2r4mhmo5.late.re/book/19978680/d768f2 |access-date=2 April 2023}}</ref>

[[Plant nutrition#Molybdenum|Molybdenum]] availability is increased at higher pH; this is because the molybdate ion is more strongly sorbed by clay particles at lower pH.<ref name="Huang2011">{{cite book |last1=Bolan |first1=Nanthi |last2=Brennan |first2=Ross |last3=Budianta |first3=Dedik |last4=Camberato |first4=James J. |last5=Naidu |first5=Ravi |last6=Pan |first6=William L. |last7=Sharpley |first7=Andrew |last8=Sparks |first8=Donald L. |last9=Sumner |first9=Malcolm E. |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: resource management and environmental impacts |date=2012 |publisher=[[CRC Press]] |location=Boca Raton, Florida |isbn=978-1-4398-0308-0 |pages=11–1 to 11–80 |edition=2nd |chapter=Bioavailability of N, P, K, Ca, Mg, S, Si, and micronutrients |url=https://lib-nhwjx7zkiyjoeipfyn7m37ed.late.re/book/2214335/a4c9a4 |access-date=2 April 2023}}</ref>

[[Plant nutrition#Zinc|Zinc]], [[Plant nutrition#Iron|iron]], [[Plant nutrition#Copper|copper]] and [[Plant nutrition#Manganese|manganese]] show decreased availability at higher pH (increased [[sorption]] at higher pH).<ref name="Huang2011"/>

The effect of pH on [[Plant nutrition#Phosphorus|phosphorus]] availability varies considerably, depending on soil conditions and the crop in question. The prevailing view in the 1940s and 1950s was that P availability was maximized near neutrality (soil pH 6.5–7.5), and decreased at higher and lower pH.<ref name="Truog1946">{{cite book |last1=Truog |first1=Emil |title=Science in farming, USDA Yearbook, 1941–1947 |date=1946 |pages=566–76 |chapter=The liming of soils |chapter-url=https://naldc.nal.usda.gov/download/IND43893966/PDF |access-date=9 April 2023}}</ref><ref name="Sumner1986">{{cite book |last1=Sumner |first1=Malcolm E. |last2=Farina |first2=Mart P.W. |editor1-last=Stewart |editor1-first=Bob A. |title=Advances in soil science |date=1986 |publisher=[[Springer Publishing|Springer]] |location=New York, New York |isbn=978-1-4613-8660-5 |pages=201–36 |chapter=Phosphorus interactions with other nutrients and lime in field cropping systems |doi=10.1007/978-1-4613-8660-5_5 |chapter-url=https://www.researchgate.net/publication/286120267 |access-date=9 April 2023}}</ref> Interactions of phosphorus with pH in the moderately to slightly acidic range (pH 5.5–6.5) are, however, far more complex than is suggested by this view. Laboratory tests, glasshouse trials and field trials have indicated that increases in pH within this range may increase, decrease, or have no effect on P availability to plants.<ref name="Sumner1986"/><ref name="Haynes1982">{{cite journal |last1=Haynes |first1=R. J. |title=Effects of liming on phosphate availability in acid soils: a critical review |journal=[[Plant and Soil]] |date=October 1982 |volume=68 |issue=3 |pages=289–308 |doi=10.1007/BF02197935 |s2cid=22695096 |url=https://articles-pdjrj4ripo5k3r4j2r4mhmo5.late.re/book/6871474/3b010d |access-date=9 April 2023}}</ref>