Editing Fertilizer (section)

===Soil===

==== Acidification ====
Soil acidification refers to the process by which the pH level of soil becomes more acidic over time. Soil pH is a measure of the soil's acidity or alkalinity and is determined on a scale from 0 to 14, with [[Seven (1995 film)|7]] being neutral. A pH value below 7 indicates acidic soil, while a pH value above 7 indicates alkaline or basic soil.

Soil acidification is a significant concern in agriculture and horticulture. It refers to the process of the soil becoming more acidic over time. {{See also|Soil pH|Soil acidification}}
Nitrogen-containing fertilizers can cause [[soil acidification]] when added.<ref>{{cite journal|doi= 10.1126/science.324_721b |pmid = 19423798 |bibcode = 2009Sci...324..721S | volume=324 |issue = 5928 | title=Eutrophication: More Nitrogen Data Needed |journal=Science |pages=721–722|year = 2009 |last1 = Schindler |first1 = D. W. |last2 = Hecky |first2 = R. E. }}</ref><ref>{{cite journal|doi=10.2136/sssaj2007.0071N | volume=72 | issue=1 | title=Phosphorus Solubility in Response to Acidification of Dairy Manure Amended Soils | journal=Soil Science Society of America Journal | pages=238| bibcode=2008SSASJ..72..238P | year=2008 | last1=Penn | first1=C. J. | last2=Bryant | first2=R. B. }}</ref> This may lead to decrease in nutrient availability which may be offset by [[liming (soil)|liming]]. These fertilizers release ammonium or nitrate ions, which can acidify the soil as they undergo chemical reactions.

When these nitrogen-containing fertilizers are added to the soil, they increase the concentration of hydrogen ions (H+) in the soil solution, which lowers the pH of the soil.

====Accumulation of toxic elements====

=====Cadmium=====
The concentration of [[cadmium]] in phosphorus-containing fertilizers varies considerably and can be problematic.<ref>{{cite journal|last1=McLaughlin|first1=M. J.|last2=Tiller|first2=K. G. |last3= Naidu |first3= R.|last4=Stevens|first4=D. P.|title=Review: the behaviour and environmental impact of contaminants in fertilizers|journal=Soil Research|date=1996|volume=34|issue=1 |pages=1–54 |doi= 10.1071/sr9960001|bibcode=1996SoilR..34....1M }}</ref> For example, mono-ammonium phosphate fertilizer may have a cadmium content of as low as 0.14&nbsp;mg/kg or as high as 50.9&nbsp;mg/kg.<ref name=Lugon2014>{{cite journal |last1= Lugon-Moulin |first1= N. |last2= Ryan|first2=L.|last3=Donini|first3=P.|last4=Rossi|first4=L.|title=Cadmium content of phosphate fertilizers used for tobacco production|journal=Agron. Sustain. Dev. |date= 2006 |volume= 26 |issue= 3 |pages= 151–155|url=http://hal.archives-ouvertes.fr/docs/00/88/63/51/PDF/hal-00886351.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://hal.archives-ouvertes.fr/docs/00/88/63/51/PDF/hal-00886351.pdf |archive-date=2022-10-09 |url-status=live|access-date=27 June 2014|doi=10.1051/agro:2006010|s2cid=13996565 }}</ref> The phosphate rock used in their manufacture can contain as much as 188&nbsp;mg/kg cadmium<ref name=Zapata2004>{{cite web|last1=Zapata|first1=F.|last2=Roy|first2=R.N.|title=Use of Phosphate Rocks for Sustainable Agriculture: Secondary nutrients, micronutrients, liming effect and hazardous elements associated with phosphate rock use|url=http://www.fao.org/docrep/007/y5053e/y5053e0d.htm|website=fao.org|publisher=FAO|access-date=27 June 2014 |date=2004}}</ref> (examples are deposits on [[Nauru]]<ref>{{cite journal |vauthors=Syers JK, Mackay AD, Brown MW, Currie CD |title=Chemical and physical characteristics of phosphate rock materials of varying reactivity |journal= J Sci Food Agric |year=1986 |volume=37 |pages=1057–1064 | doi = 10.1002/jsfa.2740371102 |issue=11|bibcode=1986JSFA...37.1057S }}</ref> and the [[Christmas Island]]s<ref>{{cite journal |author= Trueman NA |title= The phosphate, volcanic and carbonate rocks of Christmas Island (Indian Ocean) |journal=J Geol Soc Aust |year=1965 |volume=12 |issue=2 |pages=261–286 |doi= 10.1080/00167616508728596 |bibcode = 1965AuJES..12..261T }}</ref>). Continuous use of high-cadmium fertilizer can contaminate soil (as shown in New Zealand)<ref name=taylor>{{cite journal | author=Taylor MD | title=Accumulation of Cadmium derived from fertilizers in New Zealand soils |journal=Science of the Total Environment |year=1997 |volume=208 | issue=1–2 |pages=123–126 | doi= 10.1016/S0048-9697(97)00273-8 |bibcode= 1997ScTEn.208..123T | pmid=9496656 }}</ref> and [[Phytotoxicity|plants]].<ref name=Chaney2012>{{cite book|last1=Chaney|first1=R.L.|chapter=Food safety issues for mineral and organic fertilizers |title=Advances in Agronomy|date=2012|volume=117|pages=51–99|publisher=Elsevier |doi=10.1016/b978-0-12-394278-4.00002-7|isbn=9780123942784}}</ref> Limits to the cadmium content of phosphate fertilizers has been considered by the [[European Commission]].<ref name=Oosterhuis2000>{{cite web|last1=Oosterhuis|first1=F.H.|last2=Brouwer|first2=F.M.|last3=Wijnants|first3=H.J.|title=A possible EU wide charge on cadmium in phosphate fertilisers: Economic and environmental implications.|url=http://ec.europa.eu/environment/enveco/taxation/pdf/cadium.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://ec.europa.eu/environment/enveco/taxation/pdf/cadium.pdf |archive-date=2022-10-09 |url-status=live|website=dare.ubvu.vu.nl|access-date=27 June 2014|date=2000}}</ref><ref name=FertilizersEurope2014>{{cite web |last1=|title=Putting all the cards on the table|url=http://www.fertilizerseurope.com/fileadmin/user_upload/news_assets/FI-458-decadmiation__3_.pdf|publisher=fertilizerseurope.com|access-date=|date=2014|work = Fertilizers International |archive-url=https://web.archive.org/web/20140808082824/http://www.fertilizerseurope.com/fileadmin/user_upload/news_assets/FI-458-decadmiation__3_.pdf|archive-date=8 August 2014|url-status=dead}}</ref><ref name=Wates2014>{{cite web|last1=Wates|first1=J.|title=Revision of the EU fertilizer regulation and cadmium content of fertilisers|url=http://www.iatp.org/documents/revision-of-the-eu-fertilizer-regulation-and-cadmium-content-of-fertilisers |website=iatp.org|access-date=27 June 2014|date=2014}}</ref> Producers of phosphorus-containing fertilizers now select phosphate rock based on the cadmium content.<ref name=UllmannEnv>Wilfried Werner "Fertilizers, 6. Environmental Aspects" ''Ullmann's Encyclopedia of Industrial Chemistry'', 2002, Wiley-VCH, Weinheim.{{doi |10.1002/14356007.n10_n05}}</ref>

=====Fluoride=====
Phosphate rocks contain high levels of fluoride. Consequently, the widespread use of phosphate fertilizers has increased soil fluoride concentrations.<ref name=Chaney2012 /> It has been found that food contamination from fertilizer is of little concern as plants accumulate little fluoride from the soil; of greater concern is the possibility of fluoride toxicity to livestock that ingest contaminated soils.<ref name=Loganathan2008>{{cite book|last1=Loganathan|first1=P.|last2=Hedley|first2=M.J.|last3=Grace|first3=N.D.|title=Reviews of Environmental Contamination and Toxicology |chapter=Pasture Soils Contaminated with Fertilizer-Derived Cadmium and Fluorine: Livestock Effects |date=2008|volume=192|pages=29–66|doi=10.1007/978-0-387-71724-1_2|pmid=18020303|isbn=978-0-387-71723-4}}<!--|access-date=1 July 2014--></ref><ref name=Cronin2000>{{cite journal|last1=Cronin|first1=S. J.|last2=Manoharan|first2=V.|last3=Hedley|first3=M. J.|last4=Loganathan|first4=P.|title=Fluoride: A review of its fate, bioavailability, and risks of fluorosis in grazed-pasture systems in New Zealand|journal=New Zealand Journal of Agricultural Research|date=2000|volume=43|issue=3|pages=295–3214|doi=10.1080/00288233.2000.9513430|doi-access=free|bibcode=2000NZJAR..43..295C }}<!--|access-date=1 July 2014--></ref> Also of possible concern are the effects of fluoride on soil microorganisms.<ref name=Loganathan2008 /><ref name=Cronin2000 /><ref name=Wilke1987>{{cite journal|last1=Wilke|first1=B.M.|title=Fluoride-induced changes in chemical properties and microbial activity of mull, moder and mor soils|journal=Biology and Fertility of Soils|date=1987|volume=5|issue=1 |pages=49–55|doi=10.1007/BF00264346|bibcode=1987BioFS...5...49W |s2cid=1225884}}<!--|access-date=1 July 2014--></ref>

=====Radioactive elements=====
The radioactive content of the fertilizers varies considerably and depends both on their concentrations in the parent mineral and on the fertilizer production process.<ref name=Chaney2012 /><ref name=Mortvedt2014>{{cite web|last1=Mortvedt|first1=JJ|last2=Beaton|first2=JD|title=Heavy Metal and Radionuclide Contaminants in Phosphate Fertilizers|url=http://www.scopenvironment.org/downloadpubs/scope54/6mortvedt.htm|access-date=16 July 2014|url-status=dead|archive-url=https://web.archive.org/web/20140726193234/http://www.scopenvironment.org/downloadpubs/scope54/6mortvedt.htm|archive-date=26 July 2014}}</ref> Uranium-238 concentrations can range from 7 to 100 pCi/g (picocuries per gram) in phosphate rock<ref name=EPA2016>{{cite web|url=https://www.epa.gov/radiation/tenorm-fertilizer-and-fertilizer-production-wastes|title=TENORM: Fertilizer and Fertilizer Production Wastes|date=2016|publisher=US EPA|access-date=30 August 2017}}</ref> and from 1 to 67 pCi/g in phosphate fertilizers.<ref name=Khater2008>{{cite web|last1=Khater|first1=A. E. M.|title=Uranium and heavy metals in phosphate fertilizers|url=http://www.radioecology.info/Bergen2008/proceedings/26.%20Khater%20Uranium%20P.pdf|website=radioecology.info|access-date=17 July 2014|date=2008|archive-url=https://web.archive.org/web/20140724225807/http://www.radioecology.info/Bergen2008/proceedings/26.%20Khater%20Uranium%20P.pdf|archive-date=24 July 2014|url-status=dead}}</ref><ref name=NCRP1987>{{cite book|last1=NCRP|title=Radiation Exposure of the U.S. Population from Consumer Products and Miscellaneous Sources|date=1987|publisher=National Council on Radiation Protection and Measurements|pages=29–32|url=http://f3.tiera.ru/1/genesis/575-579/575000/1160670d5da187ab055c34ebc07487cf|access-date=17 July 2014}}{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>{{cite journal |author=Hussein EM |title=Radioactivity of phosphate ore, superphosphate, and phosphogypsum in Abu-zaabal phosphate |journal=Health Physics |year=1994 |volume=67 |pages=280–282 | doi = 10.1097/00004032-199409000-00010 |pmid=8056596 |issue=3}}</ref> Where high annual rates of phosphorus fertilizer are used, this can result in uranium-238 concentrations in soils and drainage waters that are several times greater than are normally present.<ref name=NCRP1987 /><ref>{{cite journal |vauthors=Barisic D, Lulic S, Miletic P |title=Radium and uranium in phosphate fertilizers and their impact on the radioactivity of waters |journal=Water Research |year=1992 |volume=26 |pages=607–611 | doi = 10.1016/0043-1354(92)90234-U |issue=5|bibcode=1992WatRe..26..607B }}</ref> However, the impact of these increases on the [[Sievert#Dose examples|risk to human health]] from radinuclide contamination of foods is very small (less than 0.05 m[[Sievert|Sv]]/y).<ref name=NCRP1987 /><ref name=Hanlon2012>{{cite web|last1=Hanlon|first1=E. A.|title=Naturally Occurring Radionuclides in Agricultural Products|url=http://edis.ifas.ufl.edu/ss441|website=edis.ifas.ufl.edu|publisher=University of Florida|access-date=17 July 2014|date=2012|archive-date=25 July 2014|archive-url=https://web.archive.org/web/20140725171240/http://edis.ifas.ufl.edu/ss441|url-status=dead}}</ref><ref name=Sharpley1987>{{cite journal|last1=Sharpley|first1=A. N.|last2=Menzel|first2=R. G.|title=The impact of soil and fertilizer phosphorus on the environment|journal=Advances in Agronomy|date=1987|volume=41|pages=297–324|doi=10.1016/s0065-2113(08)60807-x|isbn=9780120007417|s2cid=83005521 }}</ref>

=====Other metals=====
Steel industry wastes, recycled into fertilizers for their high levels of [[zinc]] (essential to plant growth), wastes can include the following [[Toxic heavy metal|toxic metals]]: [[lead]]<ref name="community.seattletimes.nwsource.com">{{cite web |last=Wilson |first=Duff |url=https://archive.seattletimes.com/archive/19970703/2547772/fear-in-the-fields----how-hazardous-wastes-become-fertilizer----spreading-heavy-metals-on-farmland-is-perfectly-legal-but-little-research-has-been-done-to-find-out-whether-its-safe |title=Business &#124; Fear in the Fields&nbsp;– How Hazardous Wastes Become Fertilizer&nbsp;– Spreading Heavy Metals on Farmland Is Perfectly Legal, But Little Research Has Been Done To Find Out Whether It's Safe |publisher=Community.seattletimes.nwsource.com |date=3 July 1997 |access-date=25 August 2010 |archive-date=18 November 2010 |archive-url=https://web.archive.org/web/20101118013539/http://community.seattletimes.nwsource.com/archive/?date=19970703&slug=2547772 |url-status=live }}</ref> [[arsenic]], [[cadmium]],<ref name="community.seattletimes.nwsource.com"/> chromium, and nickel. The most common toxic elements in this type of fertilizer are [[Mercury (element)|mercury]], lead, and arsenic.<ref name="pirg.org">{{cite web |url=http://www.pirg.org/toxics/reports/wastelands/ |title=Waste Lands: The Threat of Toxic Fertilizer |publisher=Pirg.org |date=3 July 1997 |access-date=25 August 2010 |archive-date=26 November 2010 |archive-url=https://web.archive.org/web/20101126211622/http://www.pirg.org/toxics/reports/wastelands/ |url-status=dead }}</ref><ref>{{cite web |author=mindfully.org |url=http://www.mindfully.org/Farm/Toxic-Waste-Fertilizers.htm |title=Waste Lands: The Threat of Toxic Fertilizer Released by PIRG Toxic Wastes Found in Fertilizers Cat Lazaroff / ENS 7may01 |publisher=Mindfully.org |access-date=25 August 2010 |url-status=dead |archive-url=https://web.archive.org/web/20020111124358/http://www.mindfully.org/Farm/Toxic-Waste-Fertilizers.htm |archive-date=11 January 2002 }}</ref><ref name=FAO2004>{{cite book|last1=Zapata|first1=F|last2=Roy|first2=RN|title=Use of phosphate rocks for sustainable agriculture|date=2004|publisher=FAO|location=Rome|page=82|url=ftp://ftp.fao.org/docrep/fao/007/y5053e/y5053e00.pdf|access-date=16 July 2014}}{{Dead link|date=August 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> These potentially harmful impurities can be removed; however, this significantly increases cost. Highly pure fertilizers are widely available and perhaps best known as the highly water-soluble fertilizers containing blue dyes used around households, such as [[Miracle-Gro]]. These highly water-soluble fertilizers are used in the plant nursery business and are available in larger packages at significantly less cost than retail quantities. Some inexpensive retail granular garden fertilizers are made with high purity ingredients.

====Trace mineral depletion====
Attention has been addressed to the decreasing concentrations of elements such as iron, zinc, copper and magnesium in many foods over the last 50–60 years.<ref name=Davis2004>{{cite journal|last1=Davis|first1=D.R.|last2=Epp|first2=M.D.|last3=Riordan|first3=H.D.|title=Changes in USDA Food Composition Data for 43 Garden Crops, 1950 to 1999|journal=Journal of the American College of Nutrition|date=2004|volume=23|issue=6|pages=669–682|doi=10.1080/07315724.2004.10719409|pmid=15637215|s2cid=13595345}}</ref><ref name=Thomas2007>{{cite journal|last1=Thomas|first1=D.|title=The mineral depletion of foods available to us as a nation (1940–2002) – A Review of the 6th Edition of McCance and Widdowson|journal=Nutrition and Health|date=2007|volume=19|issue=1–2|pages=21–55|doi=10.1177/026010600701900205|pmid=18309763|s2cid=372456}}</ref> [[Intensive farming]] practices, including the use of synthetic fertilizers are frequently suggested as reasons for these declines and organic farming is often suggested as a solution.<ref name=Thomas2007 /> Although improved crop yields resulting from NPK fertilizers are known to dilute the concentrations of other nutrients in plants,<ref name=Davis2004 /><ref name=Jarrell1981>{{cite journal|last1=Jarrell|first1=W.M.|last2=Beverly|first2=R.B.|title=The Dilution Effect in Plant Nutrition Studies|journal=Advances in Agronomy|date=1981|volume=34|pages=197–224|doi=10.1016/s0065-2113(08)60887-1|isbn=9780120007349}}</ref> much of the measured decline can be attributed to the use of progressively higher-yielding crop varieties that produce foods with lower mineral concentrations than their less-productive ancestors.<ref name=Davis2004 /><ref name=Fan2008>{{cite journal|last1=Fan|first1=M. S.|last2=Zhao|first2=F. J.|last3=Fairweather-Tait|first3=S. J.|last4=Poulton|first4=P. R.|last5=Dunham|first5=S. J.|last6=McGrath|first6=S. P.|title=Evidence of decreasing mineral density in wheat grain over the last 160 years.|journal=[[Journal of Trace Elements in Medicine and Biology]]|date=2008|volume=22|issue=4|pages=315–324|doi=10.1016/j.jtemb.2008.07.002|pmid=19013359|bibcode=2008JTEMB..22..315F |url=https://repository.rothamsted.ac.uk/download/763262a2ea615fca85841d665060d217a464dfdf38f0213ae494ada7217517b9/2790912/Fan%20et%20al%20BBK%20wheat%20mineral%20density%20manuscript%20inc%20figures_.doc}}</ref><ref name=Zhao2009>{{cite journal|last1=Zhao|first1=F. J.|last2=Su|first2=Y. H.|last3=Dunham|first3=S. J.|last4=Rakszegi|first4=M.|last5=Bedo|first5=Z.|last6=McGrath|first6=S. P.|last7=Shewry|first7=P. R.|title=Variation in mineral micronutrient concentrations in grain of wheat lines of diverse origin.|journal=Journal of Cereal Science|date=2009|volume=49|issue=2|pages=290–295|doi=10.1016/j.jcs.2008.11.007}}</ref> It is, therefore, unlikely that organic farming or reduced use of fertilizers will solve the problem; foods with high nutrient density are posited to be achieved using older, lower-yielding varieties or the development of new high-yield, nutrient-dense varieties.<ref name=Davis2004 /><ref name=Saltzman2013>{{cite journal|last1=Saltzman|first1=A.|last2=Birol|first2=E.|last3=Bouis|first3=H. E.|last4=Boy|first4=E.|last5=De Moura|first5=F.F.|last6=Islam|first6=Y.|last7=Pfeiffer|first7=W. H.|title=Biofortification: progress toward a more nourishing future|journal=Global Food Security|date=2013|volume=2|issue=1 |pages=9–17|doi=10.1016/j.gfs.2012.12.003|bibcode=2013GlFS....2....9S }}</ref>

Fertilizers are, in fact, more likely to solve trace mineral deficiency problems than cause them: In Western Australia deficiencies of [[zinc]], copper, [[manganese]], iron and [[molybdenum]] were identified as limiting the growth of broad-acre crops and pastures in the 1940s and 1950s.<ref name=Moore>{{cite book|last=Moore|first=Geoff|title=Soilguide – A handbook for understanding and managing agricultural soils|year=2001|publisher=Agriculture Western Australia|location=Perth, Western Australia|isbn=978-0-7307-0057-9|pages=161–207|url=https://researchlibrary.agric.wa.gov.au/bulletins/2/}}</ref> Soils in Western Australia are very old, highly weathered and deficient in many of the major nutrients and trace elements.<ref name="Moore"/> Since this time these trace elements are routinely added to fertilizers used in agriculture in this state.<ref name="Moore"/> Many other soils around the world are deficient in zinc, leading to deficiency in both plants and humans, and zinc fertilizers are widely used to solve this problem.<ref>{{cite web|url=https://www.scribd.com/doc/36383515/Zn-in-Soils-and-Crop-Nutrition-2008 |title=Zinc in Soils and Crop Nutrition |publisher=Scribd.com |date=25 August 2010 |access-date=17 June 2012}}</ref>

====Changes in soil biology====
{{Further|soil biology}}
High levels of fertilizer may cause the breakdown of the [[Symbiosis|symbiotic]] relationships between plant roots and [[mycorrhiza]]l fungi.<ref>{{cite book|last=Carroll and Salt|first=Steven B. and Steven D.|title=Ecology for Gardeners|year=2004|publisher=Timber Press|location=Cambridge|isbn=978-0-88192-611-8}}</ref>