Editing Hubbert peak theory (section)

===Phosphorus===
{{Main|Peak phosphorus}}
[[Phosphorus]] supplies are essential to farming and depletion of reserves is estimated at somewhere from 60 to 130 years.<ref>{{cite web |url=http://www.apda.pt/apda_resources/APDA.Biblioteca/eureau%5Cposition%20papers%5Cthe%20reuse%20of%20phosphorus.pdf |title= APDA - Home|website=www.apda.pt |archive-url=https://web.archive.org/web/20061006120520/http://www.apda.pt/apda_resources/APDA.Biblioteca/eureau%5Cposition%20papers%5Cthe%20reuse%20of%20phosphorus.pdf |archive-date=October 6, 2006}}</ref> According to a 2008 study, the total reserves of phosphorus are estimated to be approximately 3,200 MT, with peak production at 28 MT/year in 2034.<ref>
{{cite web |author=White |first1=Stuart |last2=Cordell |first2=Dana |author-link2=Dana Cordell |year=2008 |title=Peak Phosphorus: the sequel to Peak Oil |url=http://phosphorusfutures.net/peak-phosphorus |access-date=2009-12-11 |publisher=Global Phosphorus Research Initiative (GPRI)}}</ref> Individual countries' supplies vary widely; without a recycling initiative America's supply<ref>{{cite web|url=http://minerals.usgs.gov/minerals/pubs/commodity/phosphate_rock/phospmcs06.pdf |title=Phosphate Rock|author=Stephen M. Jasinski |publisher=[[U.S. Geological Survey]], Mineral Commodity Summaries |date=January 2006 |access-date=2013-12-27}}</ref> is estimated around 30 years.<ref>{{cite web |url=http://www.ecosanres.org/PDF%20files/Fact_sheets/ESR4lowres.pdf |title=Closing the Loop on Phosphorus |author=Ecological Sanitation Research Programme |publisher=[[Stockholm Environment Institute]] |date=May 2008 |access-date=2013-12-27 |url-status=dead |archive-url=https://web.archive.org/web/20060805112847/http://ecosanres.org/PDF%20files/Fact_sheets/ESR4lowres.pdf |archive-date=2006-08-05 |author-link=Ecological Sanitation Research Programme }}</ref> Phosphorus supplies affect agricultural output which in turn limits alternative fuels such as biodiesel and ethanol. Its increasing price and scarcity (the global price of rock phosphate rose 8-fold in the 2 years to mid-2008) could change global agricultural patterns. Lands, perceived as marginal because of remoteness, but with very high phosphorus content, such as the [[Gran Chaco]]<ref>{{cite news
 |title=A postcard from the central Chaco 
 |author=Don Nicol 
 |access-date=2009-01-23 
 |url=http://www.breedleader.com.au/images/chaco%20postcard%20.pdf 
 |quote=alluvial sandy soils have phosphorus levels of up to 200–300 ppm 
 |url-status=dead 
 |archive-url=https://web.archive.org/web/20090226104329/http://www.breedleader.com.au/images/chaco%20postcard%20.pdf 
 |archive-date=2009-02-26 
}}</ref> may get more agricultural development, while other farming areas, where nutrients are a constraint, may drop below the line of profitability.