Editing Sulfur (section)

===Fertilizer===
[[Amino acid]]s synthesized by [[Organism|living organisms]] such as [[methionine]] and [[cysteine]] contain [[Organosulfur compounds|organosulfur]] groups ([[thioester]] and [[thiol]] respectively). The [[antioxidant]] [[glutathione]] protecting many living organisms against [[free radical]]s and [[oxidative stress]] also contains organic sulfur. Some [[crop]]s such as [[onion]] and [[garlic]] also produce different [[organosulfur compounds]] such as [[syn-Propanethial-S-oxide|''syn''-propanethial-''S''-oxide]] responsible of lacrymal irritation (onions), or [[diallyl disulfide]] and [[allicin]] (garlic). [[Sulfate]]s, commonly found in [[soil]]s and [[groundwater]]s are often a sufficient natural source of sulfur for plants and bacteria. [[Deposition (aerosol physics)|Atmospheric deposition]] of [[sulfur dioxide]] (SO<sub>2</sub>) is also a common artificial source ([[Coal combustion products|coal combustion]]) of sulfur for the soils. Under normal circumstances, in most agricultural soils, sulfur is not a [[Limiting factor|limiting nutrient]] for plants and [[microorganism]]s (see [[Liebig's law of the minimum#Liebig's barrel|Liebig's barrel]]). However, in some circumstances, soils can be depleted in [[sulfate]], e.g. if this later is leached by [[meteoric water]] ([[rain]]) or if the requirements in sulfur for some types of crops are high. This explains that sulfur is increasingly recognized and used as a component of [[fertilizer]]s. The most important form of sulfur for fertilizer is [[calcium sulfate]], commonly found in nature as the mineral [[gypsum]] (CaSO<sub>4</sub>·2H<sub>2</sub>O). Elemental sulfur is [[hydrophobic]] (not soluble in water) and cannot be used directly by plants. Elemental sulfur (ES) is sometimes mixed with [[bentonite]] to amend depleted soils for crops with high requirement in organo-sulfur. Over time, [[Redox|oxidation]] [[Abiotic component|abiotic]] processes with [[Earth atmosphere|atmospheric]] [[oxygen]] and [[Soil microbiology|soil bacteria]] can [[Redox|oxidize]] and convert elemental sulfur to soluble derivatives, which can then be used by microorganisms and plants. Sulfur improves the efficiency of other essential plant nutrients, particularly [[Nitrate|nitrogen]] and phosphorus.<ref name="sulphurinstitute-2020">{{Cite web |url=https://www.sulphurinstitute.org/about-sulphur/faq/#plants |title=FAQ – The Sulphur Institute |date=2020 |website=sulphurinstitute.org |publisher=[[The Sulphur Institute]] |access-date=27 February 2020}}</ref> Biologically produced sulfur particles are naturally [[Hydrophile|hydrophilic]] due to a [[biopolymer]] coating and are easier to disperse over the land in a spray of diluted slurry, resulting in a faster uptake by plants.

The plants requirement for sulfur equals or exceeds the requirement for [[phosphorus]]. It is an [[plant nutrition|essential nutrient for plant]] growth, [[root nodule]] formation of legumes, and immunity and defense systems. Sulfur deficiency has become widespread in many countries in Europe.<ref>{{cite journal|doi= 10.1006/jcrs.1998.0241|title= Sulphur Assimilation and Effects on Yield and Quality of Wheat|date= 1999|last1= Zhao|first1= F.|journal= Journal of Cereal Science|volume= 30|issue= 1|pages= 1–17|last2= Hawkesford|first2= M. J.|last3= McGrath|first3= S. P.}}</ref><ref>{{cite journal|title= Diagnosing sulfur deficiency in field-grown oilseed rape (Brassica napus L.) and wheat (Triticum aestivum L.)|doi= 10.1023/A:1026503812267|date= 2000|last1= Blake-Kalff|first1= M. M. A.|journal= Plant and Soil|volume= 225|issue= 1/2|pages= 95–107|bibcode= 2000PlSoi.225...95B|s2cid= 44208638}}</ref><ref>{{cite journal|doi= 10.1007/BF00747690|title= Plant nutrient sulphur-a review of nutrient balance, environmental impact and fertilizers|date= 1996|last1= Ceccotti|first1= S. P.|journal= Fertilizer Research|volume= 43|issue= 1–3|pages= 117–125|s2cid= 42207099}}</ref> Because atmospheric inputs of sulfur continue to decrease, the deficit in the sulfur input/output is likely to increase unless sulfur fertilizers are used. Atmospheric inputs of sulfur decrease because of actions taken to limit [[acid rain]]s.<ref name="NASA-2011">{{Citation|title=Glossary |at=acid rain |publisher=[[NASA Earth Observatory]] |location=United States |url=http://earthobservatory.nasa.gov/Glossary/?mode=all |access-date=February 15, 2013 |archive-url=https://web.archive.org/web/20111213175357/http://earthobservatory.nasa.gov/Glossary/?mode=all |archive-date=December 13, 2011 |url-status=live }}</ref><ref name="sulphurinstitute-2020" />