Editing Soil pH (section)

==pH effects on soil biota==
[[Soil biota]] (soil [[Microbiota|microflora]], soil animals) are sensitive to soil pH, either directly upon contact or after soil ingestion or indirectly through the various soil properties to which pH contributes (e.g. [[nutrient]] status, [[metal toxicity]], [[humus form]]). According to the various physiological and behavioural [[Adaptation|adaptations]] of soil biota, the species composition of soil microbial and animal communities varies with soil pH.<ref>{{cite journal |last1=Lauber |first1=Christian L. |last2=Hamady |first2=Micah |last3=Knight |first3=Rob |last4=Fierer |first4=Noah |title=Pyrosequencing-based assessment of soil pH as a predictor of soil bacterial community structure at the continental scale |journal=[[Applied and Environmental Microbiology]] |date=August 2009 |volume=75 |issue=15 |pages=5111–20 |doi=10.1128/AEM.00335-09 |pmid=19502440 |pmc=2725504 |bibcode=2009ApEnM..75.5111L }}</ref><ref name="Loranger2001"> {{cite journal |last1=Loranger |first1=Gladys |last2=Bandyopadhyaya |first2=Ipsa |last3=Razaka |first3=Barbara |last4=Ponge |first4=Jean-François |title=Does soil acidity explain altitudinal sequences in collembolan communities? |journal=[[Soil Biology and Biochemistry]] |date=March 2001 |volume=33 |issue=3 |pages=381–93 |doi=10.1016/S0038-0717(00)00153-X |s2cid=84523833 |url=https://www.academia.edu/48908569 |access-date=4 June 2023}}</ref> Along altitudinal gradients, changes in the species distribution of soil animal and microbial communities can be at least partly ascribed to variation in soil pH.<ref name="Loranger2001"/><ref>{{cite journal |last1=Tian |first1=Qiuxiang |last2=Jiang |first2=Ying |last3=Tang |first3=Yanan |last4=Wu |first4=Yu |last5=Tang |first5=Zhiyao |last6=Liu |first6=Feng |title=Soil pH and organic carbon properties drive soil bacterial communities in surface and deep layers along an elevational gradient |journal=[[Frontiers in Microbiology]] |date=30 July 2021 |volume=12 |issue=646124 |page=646124 |doi=10.3389/fmicb.2021.646124 |pmid=34394018 |pmc=8363232 |doi-access=free}}</ref> The shift from toxic to non-toxic forms of [[aluminium]] around pH5 marks the passage from acid-tolerance to acid-intolerance, with few changes in the species composition of soil communities above this threshold, even in [[calcareous soils]].<ref>{{cite journal |last=Ponge |first=Jean-François |title=Biocenoses of Collembola in atlantic temperate grass-woodland ecosystems |journal=Pedobiologia |date=July 1993 |volume=37 |issue=4 |pages=223–44 |doi=10.1016/S0031-4056(24)00100-8 |url=https://www.academia.edu/50930736 |access-date=11 June 2023}}</ref><ref>{{cite journal |last1=Desie |first1=Ellen |last2=Van Meerbeek |first2=Koenraad |last3=De Wandeler |first3=Hans |last4=Bruelheide |first4=Helge |last5=Domisch |first5=Timo |last6=Jaroszewicz |first6=Bogdan |last7=Joly |first7=François-Xavier |last8=Vancampenhout |first8=Karen |last9=Vesterdal |first9=Lars |last10=Muys |first10=Bart |title=Positive feedback loop between earthworms, humus form and soil pH reinforces earthworm abundance in European forests |journal=[[Functional Ecology (journal)|Functional Ecology]] |date=August 2020 |volume=34 |issue=12 |pages=2598–2610 |doi=10.1111/1365-2435.13668 |bibcode=2020FuEco..34.2598D |s2cid=225182565 |url=https://besjournals.onlinelibrary.wiley.com/doi/pdfdirect/10.1111/1365-2435.13668 |access-date=11 June 2023|hdl=1893/31777 |hdl-access=free }}</ref> Soil animals exhibit distinct pH preferences when allowed to exert a choice along a range of pH values,<ref>{{cite journal |last1=Van Straalen |first1=Nico M. |last2=Verhoef |first2=Herman A. |title=The development of a bioindicator system for soil acidity based on arthropod pH preferences |journal=[[Journal of Applied Ecology]] |date=February 1997 |volume=34 |issue=1 |pages=217–32 |doi=10.2307/2404860 |jstor=2404860 |bibcode=1997JApEc..34..217V |url=https://www.jstor.org/stable/2404860 |access-date=18 June 2023}}</ref> explaining that various field distributions of soil organisms, motile microbes included, could at least partly result from active movement along pH gradients.<ref>{{cite journal |last1=He |first1=Bin |last2=Wang |first2=Zhipeng |last3=Xu |first3=Changhui |last4=Shen |first4=Runjie |last5=Hu |first5=Sanqing |title=The study on pH gradient control in solution for driving bacteria |journal=Biocybernetics and Biomedical Engineering |date=2013 |volume=33 |issue=2 |pages=88–95 |doi=10.1016/j.bbe.2013.03.003 |url=https://daneshyari.com/article/preview/5279.pdf |access-date=18 June 2023}}</ref><ref>{{cite journal |last1=Wang |first1=Congli |last2=Bruening |first2=George |last3=Williamson |first3=Valerie M. |title=Determination of preferred pH for root-knot nematode aggregation using pluronic F-127 gel |journal=[[Journal of Chemical Ecology]] |date=20 October 2009 |volume=35 |issue=10 |pages=1242–51 |doi=10.1007/s10886-009-9703-8 |pmid=19838866 |pmc=2780626 |bibcode=2009JCEco..35.1242W |s2cid=8403899 |url=https://link.springer.com/content/pdf/10.1007/s10886-009-9703-8.pdf |access-date=18 June 2023}}</ref> Like for plants, [[Competition (biology)|competition]] between acido-tolerant and acido-intolerant soil-dwelling organisms was suspected to play a role in the shifts in species composition observed along pH ranges.<ref>{{cite journal |last=Hågvar |first=Sigmund |title=Reactions to soil acidification in microarthropods: is competition a key factor? |journal=Biology and Fertility of Soils |date=April 1990 |volume=9 |issue=2 |pages=178–81 |doi=10.1007/BF00335804 |bibcode=1990BioFS...9..178H |s2cid=5099516 |url=https://link.springer.com/content/pdf/10.1007/BF00335804.pdf |access-date=25 June 2023}}</ref>

The opposition between acido-tolerance and acido-intolerance is commonly observed at [[species]] level within a [[genus]] or at genus level within a [[Family (biology)|family]], but it also occurs at much higher [[taxonomic rank]], like between soil fungi and bacteria, here too with a strong involvement of competition.<ref>{{cite journal |last1=Rousk |first1=Johannes |last2=Brookes |first2=Philip C. |last3=Bååth |first3=Erland |title=Investigating the mechanisms for the opposing pH relationships of fungal and bacterial growth in soil |journal=[[Soil Biology and Biochemistry]] |date=June 2010 |volume=42 |issue=6 |pages=926–34 |doi=10.1016/j.soilbio.2010.02.009 |url=https://repository.rothamsted.ac.uk/download/8a1be26f776ec3bb7631f8512543ad4ea02e370f15d38ee5f89db2178ff4cdba/569077/1-s2.0-S0038071710000623-main.pdf |access-date=25 June 2023}}</ref>
It has been suggested that soil organisms more tolerant of soil acidity, and thus living mainly in soils at pH less than 5, were more [[Primitive (phylogenetics)|primitive]] than those intolerant of soil acidity.<ref>{{cite journal |last=Ponge |first=Jean-François |title=Acidophilic Collembola: living fossils? |journal=Contributions from the Biological Laboratory, Kyoto University |date=March 2000 |volume=29 |pages=65–74 |url=https://www.researchgate.net/publication/45794239 |access-date=2 July 2023}}</ref> A [[Cladistics|cladistic]] analysis on the [[Springtail|collembolan]] genus [[Willemia]] showed that tolerance to soil acidity was correlated with tolerance of other [[Stress (biology)|stress]] factors and that stress tolerance was an [[Ancestral reconstruction|ancestral]] character in this genus.<ref>{{cite journal |last1=Prinzing |first1=Andreas |last2=D'Haese |first2=Cyrille A. |last3=Pavoine |first3=Sandrine |last4=Ponge |first4=Jean-François |title=Species living in harsh environments have low clade rank and are localized on former Laurasian continents: a case study of Willemia (Collembola) |journal=[[Journal of Biogeography]] |date=February 2014 |volume=41 |issue=2 |pages=353–65 |doi=10.1111/jbi.12188 |bibcode=2014JBiog..41..353P |s2cid=86619537 |url=https://www.researchgate.net/publication/259967386 |access-date=2 July 2023}}</ref> However the generality of these findings remains to be established.

At low pH,  the [[oxidative stress]] induced by aluminium (Al<sup>3+</sup>) affects soil animals the body of which is not protected by a thick [[chitinous]] [[exoskeleton]] like in [[Arthropod|arthropods]], and thus are in more direct contact with the soil solution, e.g. [[Protist|protists]], [[Nematode|nematodes]], [[Rotifer|rotifers]] ([[microfauna]]), [[Enchytraeidae|enchytraeids]] ([[mesofauna]]) and [[Earthworm|earthworms]] ([[macrofauna]]).<ref>{{cite journal |last1=Li |first1=Yin-Sheng |last2=Sun |first2=Jing |last3=Robin |first3=Paul |last4=Cluzeau |first4=Daniel |last5=Qiu |first5=Jiangping |title=Responses of the earthworm ''Eisenia andrei'' exposed to sublethal aluminium levels in an artificial soil substrate |journal=Chemistry and Ecology |date=April 2014 |volume=30 |issue=7 |pages=611–21 |doi=10.1080/02757540.2014.881804 |bibcode=2014ChEco..30..611L |s2cid=97315212 |url=https://www.researchgate.net/publication/267103805 |access-date=2 July 2023}}</ref>

Effects of pH on soil biota can be mediated by the various functional interactions of soil [[Food web|foodwebs]]. It has been shown experimentally that the collembolan ''[[Heteromurus nitidus]]'', commonly living in soils at pH higher than 5, could be cultured in more acid soils provided that predators were absent.<ref>{{cite journal |last1=Salmon |first1=Sandrine |last2=Ponge |first2=Jean-François |title=Distribution of ''Heteromurus nitidus'' (Hexapoda, Collembola) according to soil acidity: interactions with earthworms and predator pressure |journal=[[Soil Biology and Biochemistry]] |date=July 1999 |volume=31 |issue=8 |pages=1161–70 |doi=10.1016/S0038-0717(99)00034-6 |url=https://www.researchgate.net/publication/222442654 |access-date=16 July 2023}}</ref> Its attraction to earthworm [[Excretion|excreta]] ([[mucus]], [[urine]], [[Feces|faeces]]), mediated by [[ammonia]] emission,<ref>{{cite journal |last=Salmon |first=Sandrine |title=Earthworm excreta (mucus and urine) affect the distribution of springtails in forest soils |journal=Biology and Fertility of Soils |date=November 2001 |volume=34 |issue=5 |pages=304–10 |doi=10.1007/s003740100407 |bibcode=2001BioFS..34..304S |s2cid=33455553 |url=https://www.researchgate.net/publication/225534906 |access-date=23 July 2023}}</ref> provides food and shelter within earthworm burrows in mull [[humus form]]s associated with less acid soils.<ref>{{cite journal |last=Salmon |first=Sandrine |title=The impact of earthworms on the abundance of Collembola: improvement of food resources or of habitat? |journal=Biology and Fertility of Soils |date=17 September 2004 |volume=40 |issue=5 |pages=523–33 |doi=10.1007/s00374-004-0782-y |bibcode=2004BioFS..40..323S |s2cid=9671870 |url=https://www.researchgate.net/publication/225542635 |access-date=23 July 2023}}</ref>