Editing Fertilizer (section)

==Mechanism==
[[File:Reuse of urine demonstration - fertilised and not fertilised tomato plant experiment (3617543234).jpg|thumb|upright=1.4|Six tomato plants grown with and without nitrate fertilizer on nutrient-poor sand/clay soil. One of the plants in the nutrient-poor soil has died.]]
[[File:Inorganic Fertilizer Use By Region.svg|thumb|upright=1.5|Inorganic fertilizer use by region<ref>{{Cite book|title=World Food and Agriculture – Statistical Yearbook 2021|url=https://www.fao.org/documents/card/en/c/cb4477en/|access-date=2021-12-10|via=www.fao.org|year=2021|language=en|doi=10.4060/cb4477en|isbn=978-92-5-134332-6|s2cid=240163091}}</ref>]]
Fertilizers enhance the growth of plants. This goal is met in two ways, the traditional one being additives that provide nutrients. The second mode by which some fertilizers act is to enhance the effectiveness of the soil by modifying its water retention and aeration. This article, like many on fertilizers, emphasizes the nutritional aspect.
Fertilizers typically provide, in varying [[Proportionality (mathematics)|proportions]]:<ref name=Ull/>
*[[Labeling of fertilizer|Three main macronutrients (NPK)]]:
** [[Nitrogen]] (N): leaf growth and stems <ref>{{cite web |title=Negative and positive effects of N fertilizer on crops |work=آگروزیست |date=12 June 2023 |publisher=Agrozist |url=https://www.agrozist.com/agriculture/%DA%A9%D9%88%D8%AF-%D9%86%DB%8C%D8%AA%D8%B1%D9%88%DA%98%D9%86-%D8%8C-%D9%85%D8%B2%D8%A7%DB%8C%D8%A7-%D8%8C-%D9%85%D8%B9%D8%A7%DB%8C%D8%A8-%D9%88-%DA%A9%D8%A7%D8%A8%D8%B1%D8%AF%D9%87%D8%A7/ }}</ref>
** [[Phosphorus]] (P): development of roots, flowers, seeds and fruit;
** [[Potassium]] (K): strong stem growth, movement of water in plants, promotion of flowering and fruiting;
* three secondary macronutrients: [[calcium]] (Ca), [[magnesium]] (Mg), and [[sulfur]] (S);
* Micronutrients: [[copper]] (Cu), [[Iron fertilisation|iron]] (Fe), [[manganese]] (Mn), [[molybdenum]] (Mo), [[zinc]] (Zn), and [[boron]] (B). Of occasional significance are [[silicon]] (Si), [[cobalt]] (Co), and [[vanadium]] (V).

The nutrients required for healthy plant life are classified according to the elements, but the elements are not used as fertilizers. Instead, [[chemical compound|compounds]] containing these elements are the basis of fertilizers. The macro-nutrients are consumed in larger quantities and are present in plant tissue in quantities from 0.15% to 6.0% on a [[dry matter]] (DM) (0% moisture) basis. Plants are made up of four main elements: hydrogen, oxygen, carbon, and nitrogen. Carbon, hydrogen, and oxygen are widely available respectively in [[carbon dioxide]] and in water. Although nitrogen makes up most of the [[atmosphere]], it is in a form that is unavailable to plants. Nitrogen is the most important fertilizer since nitrogen is present in [[protein]]s ([[amide bond]]s between [[amino-acid|amino acid]]s), [[DNA]] ([[purine|puric]] and [[pyrimidine|pyrimidic]] bases), and other components (e.g., [[porphyrin|tetrapyrrolic]] [[heme]] in [[chlorophyll]]). To be nutritious to plants, nitrogen must be made available in a "fixed" form. Only some bacteria and their host plants (notably [[legume]]s) can fix atmospheric nitrogen ({{chem2|N2}}) by converting it to [[ammonia]] ({{chem2|NH3}}). [[Phosphate]] ({{chem2|PO4(3-)}}) is required for the production of [[Deoxyribonucleic acid|DNA]] ([[genetic code]]) and [[Adenosine triphosphate|ATP]], the main energy carrier in [[Cell (biology)|cells]], as well as certain [[lipid]]s ([[phospholipid]]s, the main components of the [[liposome|lipidic double layer]] of the [[cell membrane]]s).

===Microbiological considerations===
Two sets of [[enzymatic reaction]]s are highly relevant to the efficiency of nitrogen-based fertilizers. 
;Urease
The first is the [[hydrolysis]] (reaction with water) of [[urea]] ({{chem2|CO(NH2)2}}). Many [[soil]] [[bacteria]] possess the enzyme [[urease]], which [[catalysis|catalyzes]] the conversion of urea to [[ammonium]] ion ({{chem2|NH4+}}) and [[bicarbonate]] [[ion]] ({{chem2|HCO3-}}).
;Ammonia oxidation
[[Ammonia-oxidizing bacteria]] (AOB), such as species of ''[[Nitrosomonas]]'', [[Redox|oxidize]] ammonia ({{chem2|NH3}}) to [[nitrite]] ({{chem2|NO2-}}), a process termed [[nitrification]].<ref>{{cite journal|doi=10.1007/s00374-005-0004-2|title= Availability of urea to autotrophic ammonia-oxidizing bacteria as related to the fate of <sup>14</sup>C- and <sup>15</sup>N-labeled urea added to soil|journal= Biology and Fertility of Soils|volume= 42|issue= 2|pages= 137–145|year= 2005| vauthors = Marsh KL, Sims GK, Mulvaney RL |bibcode= 2005BioFS..42..137M|s2cid= 6245255}}</ref> [[Nitrite-oxidizing bacteria]], especially ''[[Nitrobacter]]'', oxidize [[nitrite]] ({{chem2|NO2-}}) to [[nitrate]] ({{chem2|NO3-}}), which is extremely [[solubility|soluble]] and mobile and is a major cause of [[eutrophication]] and [[algal bloom]].