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A fertilizer (
American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American English is the most influential form of ...
) or fertiliser (
British English British English (BrE) is the standard dialect A standard language (also standard variety, standard dialect, and standard) is a language variety that has undergone substantial codification of grammar and usage and is employed by a populatio ...
; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply
plant nutrients Plants are mainly multicellular organisms, predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, plants were treated as one of two kingdoms including all living things that were not animals, and all ...
. Fertilizers may be distinct from liming materials or other non-nutrient
soil amendments A soil conditioner is a product which is added to soil to improve the soil quality, soil’s physical qualities, usually its soil fertility, fertility (ability to provide nutrition for plants) and sometimes its soil mechanics, mechanics. In general ...
. Many sources of fertilizer exist, both natural and industrially produced. For most modern agricultural practices, fertilization focuses on three main macro nutrients:
Nitrogen Nitrogen is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...

Nitrogen
(N),
Phosphorus Phosphorus is a chemical element with the Symbol (chemistry), symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly Reactivity (chemistry), reactive, phosphor ...

Phosphorus
(P), and
Potassium Potassium is a chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...

Potassium
(K) with occasional addition of supplements like
rock dust Rock dust, also known as rock powders, rock minerals, rock flour, and mineral fines, consists of finely crushed rock (geology), rock, processed by natural or mechanical means, containing minerals and trace elements widely used in organic farming p ...
for micronutrients. Farmers apply these fertilizers in a variety of ways: through dry or pelletized or liquid application processes, using large agricultural equipment or hand-tool methods. Historically fertilization came from natural or organic sources:
compost Compost is a mixture of ingredients used to fertilize and improve the soil. It is commonly prepared by decomposing plant and food waste and recycling Organic material, organic materials. The resulting mixture is rich in plant nutrients and Ben ...

compost
,
animal manure Animal manure is often a mixture of animal feces and bedding straw, as in this example from a stable. Manure is organic matter that is used as organic fertilizer in agriculture. Most manure consists of animal feces; other sources include compo ...

animal manure
, human manure, harvested minerals,
crop rotation Crop rotation is the practice of growing a series of different types of crop A crop is a plant that can be grown and harvested extensively for profit or subsistence. Crops may refer either to the harvested parts or to the harvest in a more r ...
s and byproducts of human-nature industries (i.e. fish processing waste, or
bloodmeal Blood meal is a dry, inert powder made from blood Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrient A nutrient is a substance used by an organism to survive, grow, and reproduce. The requi ...
from animal slaughter). However, starting in the 19th century, after innovations in
plant nutrition Plant nutrition is the study of the chemical elements and Chemical compound, compounds necessary for plant growth, plant metabolism and their external supply. In its absence the plant is unable to complete a normal life cycle, or that the element i ...
, an agricultural industry developed around synthetically created fertilizers. This transition was important in transforming the global food system, allowing for larger-scale
industrial agriculture Industrial agriculture is a form of modern farming Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domest ...
with large crop yields. In particular nitrogen-fixing chemical processes such as the
Haber process The Haber process, also called the Haber–Bosch process, is an artificial nitrogen fixation Nitrogen fixation is a chemical process by which molecular nitrogen Nitrogen is the chemical element with the Symbol (chemistry), symbol N and atom ...

Haber process
at the beginning of the 20th century, amplified by production capacity created during World War II led to a boom in using nitrogen fertilizers. In the later half of the 20th century, increased use of nitrogen fertilizers (800% increase between 1961 and 2019) have been a crucial component of the increased productivity of
conventional food systemsThe term food system is used frequently in discussions about nutrition Nutrition is the biochemical and physiological process by which an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') ...
(more than 30% per capita) as part of the so-called "
Green Revolution The Green Revolution, or the Third Agricultural Revolution, is the set of research technology transfer initiatives occurring between 1950 and the late 1960s, that increased agricultural production worldwide, beginning most markedly in the late ...

Green Revolution
". Synthetic fertilizer used in agriculture has wide-reaching environmental consequences. According to the Intergovernmental Panel on Climate Change (IPCC)
Special Report on Climate Change and Land The United Nations The United Nations (UN) is an intergovernmental organization that aims to maintain international peace and international security, security, develop friendly relations among nations, achieve international cooperation, and ...
, production of these fertilizers and associated
land use Land use involves the management and modification of natural environment or wilderness Wilderness or wildlands (usually in the plural), are natural environments on Earth that have not been significantly modified by human activity or any nonur ...
practices are key drivers of
global warming Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. There have been , but the current changes are more rapid than any known events in Earth's history. The main cau ...

global warming
. The use of fertilizer has also led to a number of direct environmental consequences:
agricultural runoff Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated Domestication is a sustained multi-generat ...
which leads to downstream effects like ocean dead zones and waterway contamination, soil microbiome degradation, and accumulation of toxins in ecosystems. Indirect environmental impacts include: the environmental impacts of fracking for
natural gas Natural gas (also called fossil gas; sometimes just gas) is a naturally occurring hydrocarbon gas mixture consisting of methane and commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxid ...

natural gas
used in the
Haber process The Haber process, also called the Haber–Bosch process, is an artificial nitrogen fixation Nitrogen fixation is a chemical process by which molecular nitrogen Nitrogen is the chemical element with the Symbol (chemistry), symbol N and atom ...

Haber process
, the agricultural boom is partially responsible for the rapid growth in human population and large-scale industrial agricultural practices are associated with
habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat Ibex in an alpine habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are pr ...
, pressure on biodiversity and agricultural
soil loss In earth science, erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust, and then sedime ...
. In order to mitigate environmental and
food security Food security is the measure of the availability of food and individuals' Economic inequality, ability to access it. According to the United Nations' Committee on World Food Security, food security is defined as meaning that all people, at all ti ...
concerns, the international community has included food systems in
Sustainable Development Goal 2 Sustainable Development Goal 2 (SDG 2 or Global Goal 2) aims to achieve "zero hunger". It is one of the 17 Sustainable Development Goals established by the United Nations in 2015. The official wording is: "End hunger, achieve food security and im ...

Sustainable Development Goal 2
which focuses on creating a climate-friendly and sustainable food production system.United Nations (2017) Resolution adopted by the General Assembly on 6 July 2017, Work of the Statistical Commission pertaining to the 2030 Agenda for Sustainable Development
A/RES/71/313
Most policy and regulatory approaches to address these issues focus on pivoting agricultural practices towards
sustainable Sustainability is the capacity to endure in a relatively ongoing way across various domains of life. In the 21st century The 21st (twenty-first) century is the current century in the '' Anno Domini'' era or Common Era, in accordance with the ...

sustainable
or regenerative agricultural practices: these use less synthetic fertilizers, better
soil managementSoil management is the application of operations, practices, and treatments to protect soil and enhance its performance (such as soil fertility or soil mechanics). It includes soil conservation, soil conditioner, soil amendment, and optimal soil heal ...
(for example no-till agriculture) and more organic fertilizers.


History

Management of
soil fertility Soil fertility refers to the ability of soil File:Stagnogley.JPG, Surface-water-Gley soil, gley developed in glacial till, Northern Ireland. Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support li ...
has preoccupied farmers for thousands of years. Egyptians, Romans, Babylonians, and early Germans are all recorded as using minerals or manure to enhance the productivity of their farms. The science of plant nutrition started well before the work of German chemist
Justus von Liebig Justus Freiherr (; male, abbreviated as ), (; his wife, abbreviated as , literally "free lord" or "free lady") and (, his unmarried daughters and maiden aunts) are designations used as titles of nobility Traditional rank amongst Euro ...

Justus von Liebig
although his name is most mentioned. Nicolas Théodore de Saussure and scientific colleagues at the time were quick to disprove the simplications of
Justus von Liebig Justus Freiherr (; male, abbreviated as ), (; his wife, abbreviated as , literally "free lord" or "free lady") and (, his unmarried daughters and maiden aunts) are designations used as titles of nobility Traditional rank amongst Euro ...

Justus von Liebig
. There was a complex scientific understanding of plant nutrition, where the role of humus and organo-mineral interactions were central, and which was in line with more recent discoveries from 1990 onwards. Prominent scientists on whom
Justus von Liebig Justus Freiherr (; male, abbreviated as ), (; his wife, abbreviated as , literally "free lord" or "free lady") and (, his unmarried daughters and maiden aunts) are designations used as titles of nobility Traditional rank amongst Euro ...

Justus von Liebig
drew were
Carl Ludwig Sprenger __NOTOC__ Carl Ludwig Sprenger was a German botanist Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, b ...
and
Hermann Hellriegel Hermann Hellriegel (October 21, 1831 – September 24, 1895) was a German agricultural chemist who discovered that leguminous plants assimilate the free nitrogen Nitrogen is the chemical element with the Symbol (chemistry), symbol N and a ...

Hermann Hellriegel
. In this field, a 'knowledge erosion' took place, partly driven by an intermingling of economics and research.
John Bennet Lawes Sir John Bennet Lawes, 1st Baronet, Royal Society, FRS (28 December 1814 – 31 August 1900) was an English entrepreneur and agricultural scientist. He founded an experimental farm at his home at Rothamsted Manor that eventually became Rothamst ...

John Bennet Lawes
, an English
entrepreneur Entrepreneurship is the creation or extraction of value. With this definition, entrepreneurship is viewed as change, generally entailing risk beyond what is normally encountered in starting a business, which may include other values than simply ...

entrepreneur
, began to experiment on the effects of various manures on plants growing in pots in 1837, and a year or two later the experiments were extended to crops in the field. One immediate consequence was that in 1842 he patented a manure formed by treating phosphates with sulfuric acid, and thus was the first to create the artificial manure industry. In the succeeding year he enlisted the services of
Joseph Henry GilbertSir Joseph Henry Gilbert, Fellow of the Royal Society (1 August 1817 – 23 December 1901) was an England, English chemist, noteworthy for his long career spent improving the methods of practical agriculture. He was a fellow of the Royal Society. Li ...
; together they performed crop experiments at the . The
Birkeland–Eyde process The Birkeland–Eyde process was one of the competing industrial processes in the beginning of Nitrogen fertilizer, nitrogen based fertilizer production. It is a multi-step nitrogen fixation reaction that uses electrical arcs to react atmospheric n ...
was one of the competing industrial processes in the beginning of nitrogen-based fertilizer production. This process was used to fix atmospheric
nitrogen Nitrogen is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...

nitrogen
(N2) into
nitric acid Nitric acid (), also known as ''aqua fortis'' (Latin for "strong water") and spirit of niter, is a highly corrosive mineral acid. The pure compound is colorless, but older samples tend to acquire a yellow cast due to decomposition into nitroge ...

nitric acid
(HNO3), one of several chemical processes generally referred to as
nitrogen fixation Nitrogen fixation is a chemical process by which molecular (), with a strong triple , in the is converted into () or related nitrogenous compounds, typically in soil or aquatic systems but also . Atmospheric nitrogen is molecular , a relativel ...
. The resultant nitric acid was then used as a source of
nitrate Nitrate is a polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalently bonded A covalent bond is a chemical bond A chemical bond is a lasting attraction between atoms, ions or molecules that enables the format ...

nitrate
(NO3). A factory based on the process was built in
Rjukan Rjukan () is a town A town is a human settlement. Towns are generally larger than villages and smaller than city, cities, though the criteria to distinguish between them vary considerably in different parts of the world. Origin and ...
and
Notodden Notodden () is a List of towns and cities in Norway, city and List of municipalities of Norway, municipality in Vestfold og Telemark Counties of Norway, county, Norway. It is part of the Districts of Norway, traditional region of Øst-Telemark. ...
in Norway, combined with the building of large
hydroelectric power Hydroelectricity, or hydroelectric power, is electricity produced from hydropower Hydropower (from el, ὕδωρ, "water"), also known as water power, is the use of falling or fast-running water to produce electricity or to power machin ...
facilities. The 1910s and 1920s witnessed the rise of the
Haber process The Haber process, also called the Haber–Bosch process, is an artificial nitrogen fixation Nitrogen fixation is a chemical process by which molecular nitrogen Nitrogen is the chemical element with the Symbol (chemistry), symbol N and atom ...

Haber process
and the
Ostwald processThe Ostwald process is a chemical process used for making nitric acid Nitric acid (), also known as ''aqua fortis'' (Latin for "strong water") and spirit of niter, is a highly corrosive mineral acid. The pure compound is colorless, but older sam ...
. The Haber process produces ammonia (NH3) from
methane Methane (, ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth ...
(CH4) gas and molecular nitrogen (N2). The ammonia from the Haber process is then converted into
nitric acid Nitric acid (), also known as ''aqua fortis'' (Latin for "strong water") and spirit of niter, is a highly corrosive mineral acid. The pure compound is colorless, but older samples tend to acquire a yellow cast due to decomposition into nitroge ...

nitric acid
(HNO3) in the
Ostwald processThe Ostwald process is a chemical process used for making nitric acid Nitric acid (), also known as ''aqua fortis'' (Latin for "strong water") and spirit of niter, is a highly corrosive mineral acid. The pure compound is colorless, but older sam ...
. After World War II, Nitrogen production plants that had ramped up for war-time bomb manufacturing were pivoted towards agriculture uses. The use of synthetic nitrogen fertilizers has increased steadily in the last 50 years, rising almost 20-fold to the current rate of 100 million
tonnes The tonne ( or ; symbol: t) is a metric unit of mass equal to 1,000 kilogram The kilogram (also kilogramme) is the base unit of mass in the International System of Units (SI), the current metric system, having the unit symbol kg. I ...
of nitrogen per year. The development of synthetic nitrogen fertilizer has significantly supported global
population growth Population growth is the increase in the number of people in a population Population typically refers the number of people in a single area whether it be a city or town, region, country, or the world. Governments typically quantify the size ...
 — it has been estimated that almost half the people on the Earth are currently fed as a result of synthetic nitrogen fertilizer use. The use of phosphate fertilizers has also increased from 9 million tonnes per year in 1960 to 40 million tonnes per year in 2000. A maize crop yielding 6–9 tonnes of grain per
hectare The hectare (; SI symbol: ha) is a non-SI metric unit of area Area is the quantity Quantity is a property that can exist as a multitude or magnitude, which illustrate discontinuity and continuity. Quantities can be compared in terms o ...

hectare
() requires of
phosphate In chemistry, a phosphate is an anion, salt (chemistry), salt, functional group or ester derived from a phosphoric acids and phosphates, phosphoric acid. It most commonly means orthophosphate, a derivative of phosphoric acid, orthophosphoric a ...

phosphate
fertilizer to be applied; soybean crops require about half, as 20–25 kg per hectare.
Yara International Yara International ASA is a Norwegian Chemical industry, chemical company. Its largest business area is the production of nitrogen fertilizer, however it also encompasses the production of nitrates, ammonia, urea and other nitrogen-based chemical ...
is the world's largest producer of nitrogen-based fertilizers.


Mechanism

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, emphasises the nutritional aspect. Fertilizers typically provide, in varying proportions: * three main macronutrients: **
Nitrogen Nitrogen is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...

Nitrogen
(N): leaf growth **
Phosphorus Phosphorus is a chemical element with the Symbol (chemistry), symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly Reactivity (chemistry), reactive, phosphor ...

Phosphorus
(P): Development of roots, flowers, seeds, fruit; **
Potassium Potassium is a chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...

Potassium
(K): Strong stem growth, movement of water in plants, promotion of flowering and fruiting; * three secondary macronutrients:
calcium Calcium is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

calcium
(Ca),
magnesium Magnesium is a chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...

magnesium
(Mg), and
sulfur Sulfur (in nontechnical British English: sulphur) is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: th ...

sulfur
(S); * micronutrients:
copper Copper is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

copper
(Cu),
iron Iron () is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behav ...
(Fe),
manganese Manganese is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical e ...

manganese
(Mn),
molybdenum Molybdenum is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behav ...

molybdenum
(Mo),
zinc Zinc is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

zinc
(Zn),
boron Boron is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behav ...

boron
(B). Of occasional significance are
silicon Silicon is a chemical element with the Symbol (chemistry), symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a Tetravalence, tetravalent metalloid and semiconductor. It is a member ...

silicon
(Si),
cobalt Cobalt is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

cobalt
(Co), and
vanadium Vanadium is a chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science tha ...

vanadium
(V). The nutrients required for healthy plant life are classified according to the elements, but the elements are not used as fertilizers. Instead
compounds Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fortified with defensive structu ...
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 The dry matter or dry weight is a measurement of the mass Mass is the quantity Quantity is a property that can exist as a multitude or magnitude, which illustrate discontinuity and continuity. Quantities can be compared in terms of " ...
(DM) (0% moisture) basis. Plants are made up of four main elements: hydrogen, oxygen, carbon, and nitrogen. Carbon, hydrogen and oxygen are widely available as water and carbon dioxide. 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 Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a No ...

protein
s,
DNA Deoxyribonucleic acid (; DNA) is a molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically neutral gro ...

DNA
and other components (e.g.,
chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally ...

chlorophyll
). To be nutritious to plants, nitrogen must be made available in a "fixed" form. Only some bacteria and their host plants (notably
legume A legume () is a plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration, can ...

legume
s) can fix atmospheric nitrogen (N2) by converting it to
ammonia Ammonia is a chemical compound, compound of nitrogen and hydrogen with the chemical formula, formula NH3. A Binary compounds of hydrogen, stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct ch ...

ammonia
. Phosphate is required for the production of DNA and
ATP ATP may refer to: Companies and organizations * Association of Tennis Professionals * American Technical Publishers * ', a Danish pension * Armenia Tree Project * Association for Transpersonal Psychology * ATP architects engineers office * ATP ...

ATP
, the main energy carrier in cells, as well as certain lipids.


Microbiological considerations

Two sets of enzymatic reactions are highly relevant to the efficiency of nitrogen-based fertilizers. ;Urease The first is the hydrolysis (reaction with water) of urea. Many
soil Soil is a mixture In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, comp ...

soil
bacteria possess the enzyme
urease Ureases (), functionally, belong to the superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially ...

urease
, which
catalyzes that utilizes a low-temperature oxidation catalyst to convert carbon monoxide to less toxic carbon dioxide Carbon dioxide (chemical formula ) is a colorless gas with a density about 53% higher than that of dry air. Carbon dioxide molecules ...

catalyzes
conversion of urea to
ammonium The ammonium cation An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects t ...

ammonium
ion (NH4+) and bicarbonate ion (HCO3). ;Ammonia oxidation Ammonia-oxidizing bacteria (AOB), such as species of ''
Nitrosomonas ''Nitrosomonas'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer ...
'', oxidize ammonia to
nitrite The nitrite ion An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects tha ...

nitrite
, a process termed
nitrification '' Nitrification'' is the biological oxidation (mild reducing agent) are added to powdered potassium permanganate Potassium permanganate is an inorganic compound with the chemical formula KMnO4 and composed of potassium ion, K+ and permangan ...
. Nitrite-oxidizing bacteria, especially ''
Nitrobacter ''Nitrobacter'' is a genus comprising Bacillus (shape), rod-shaped, gram-negative, and chemoautotrophic bacteria. The name ''Nitrobacter'' derives from the Latin Grammatical gender, neuter gender noun ''nitrum, nitri'', alkalis; the Ancient Greek ...
'', oxidize nitrite to nitrate, which is extremely mobile and is a major cause of
eutrophication Eutrophication (from Greek ''eutrophos'', "well-nourished") is the process by which an entire body of water (Lysefjord) in Norway Norway, officially the Kingdom of Norway,Names in the official and recognised languages: Bokmål Bokm ...

eutrophication
.


Classification

Fertilizers are classified in several ways. They are classified according to whether they provide a single nutrient (e.g., K, P, or N), in which case they are classified as "straight fertilizers." "Multinutrient fertilizers" (or "complex fertilizers") provide two or more nutrients, for example N and P. Fertilizers are also sometimes classified as inorganic (the topic of most of this article) versus organic. Inorganic fertilizers exclude carbon-containing materials except
ureas 220 px, Biotin, a water-soluble B vitamins, B vitamin, is a urea. In chemistry, ureas are a class of organic compounds with the formula (R2N)2CO where R = H, alkyl, aryl, etc. Thus, in addition to describing a specific chemical compound (H2N)2CO), ...
. Organic fertilizers are usually (recycled) plant- or animal-derived matter. Inorganic are sometimes called synthetic fertilizers since various chemical treatments are required for their manufacture.


Single nutrient ("straight") fertilizers

The main nitrogen-based straight fertilizer is ammonia or its solutions.
Ammonium nitrate Ammonium nitrate is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together ...

Ammonium nitrate
(NH4NO3) is also widely used.
Urea Urea, also known as carbamide, is an organic compound In , organic compounds are generally any s that contain - . Due to carbon's ability to (form chains with other carbon s), millions of organic compounds are known. The study of the prop ...

Urea
is another popular source of nitrogen, having the advantage that it is solid and non-explosive, unlike ammonia and ammonium nitrate, respectively. A few percent of the nitrogen fertilizer market (4% in 2007) has been met by calcium ammonium nitrate (). The main straight phosphate fertilizers are the
superphosphate Monocalcium phosphate is an inorganic compound with the chemical formula Ca(H2PO4)2 ("AMCP" or "CMP-A" for anhydrous monocalcium phosphate). It is commonly found as the monohydrate ("MCP" or "MCP-M"), Ca(H2PO4)2·H2O. Both salts are colourless s ...
s. "Single superphosphate" (SSP) consists of 14–18% P2O5, again in the form of Ca(H2PO4)2, but also
phosphogypsum Phosphogypsum is the calcium sulfate hydrate formed as a by-product of the production of fertilizer A fertilizer (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. Englis ...
(). Triple superphosphate (TSP) typically consists of 44–48% of P2O5 and no gypsum. A mixture of single superphosphate and triple superphosphate is called double superphosphate. More than 90% of a typical superphosphate fertilizer is water-soluble. The main potassium-based straight fertilizer is muriate of potash (MOP). Muriate of potash consists of 95–99% KCl, and is typically available as 0-0-60 or 0-0-62 fertilizer.


Multinutrient fertilizers

These fertilizers are common. They consist of two or more nutrient components. ;Binary (NP, NK, PK) fertilizers Major two-component fertilizers provide both nitrogen and phosphorus to the plants. These are called NP fertilizers. The main NP fertilizers are
monoammonium phosphate Ammonium dihydrogen phosphate (ADP), also known as monoammonium phosphate (MAP) is a chemical compound with the chemical formula (NH4)(H2PO4). ADP is a major ingredient of agricultural fertilizers and some fire extinguishers. It also has signi ...
(MAP) and
diammonium phosphate Diammonium phosphate (DAP; IUPAC name diammonium hydrogen phosphate; chemical formula (NH4)2(HPO4) is one of a series of water-soluble ammonium phosphate salt (chemistry), salts that can be produced when ammonia reacts with phosphoric acid. Solid ...

diammonium phosphate
(DAP). The active ingredient in MAP is NH4H2PO4. The active ingredient in DAP is (NH4)2HPO4. About 85% of MAP and DAP fertilizers are soluble in water. ;NPK fertilizers NPK fertilizers are three-component fertilizers providing nitrogen, phosphorus, and potassium. There exist two types of NPK fertilizers: compound and blends. Compound NPK fertilizers contain chemically bound ingredients, while blended NPK fertilizers are physical mixtures of single nutrient components. NPK rating is a rating system describing the amount of nitrogen, phosphorus, and potassium in a fertilizer. NPK ratings consist of three numbers separated by dashes (e.g., 10-10-10 or 16-4-8) describing the chemical content of fertilizers. The first number represents the percentage of nitrogen in the product; the second number, P2O5; the third, K2O. Fertilizers do not actually contain P2O5 or K2O, but the system is a conventional shorthand for the amount of the phosphorus (P) or potassium (K) in a fertilizer. A bag of fertilizer labeled 16-4-8 contains of nitrogen (16% of the 50 pounds), an amount of phosphorus equivalent to that in 2 pounds of P2O5 (4% of 50 pounds), and 4 pounds of K2O (8% of 50 pounds). Most fertilizers are labeled according to this N-P-K convention, although Australian convention, following an N-P-K-S system, adds a fourth number for sulfur, and uses elemental values for all values including P and K.


Micronutrients

Micronutrients are consumed in smaller quantities and are present in plant tissue on the order of parts-per-million (ppm), ranging from 0.15 to 400 ppm or less than 0.04% dry matter. These elements are often required for enzymes essential to the plant's metabolism. Because these elements enable catalysts (enzymes), their impact far exceeds their weight percentage. Typical micronutrients are boron, zinc, molybdenum, iron, and manganese. These elements are provided as water-soluble salts. Iron presents special problems because it converts to insoluble (bio-unavailable) compounds at moderate soil pH and phosphate concentrations. For this reason, iron is often administered as a
chelate complex Chelation is a type of bonding of ions and molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a Denticity, polydentate (multiple bonded) ligand and a single central atom. These ligands ...
, e.g., the
EDTA Ethylenediaminetetraacetic acid (EDTA) is an aminopolycarboxylic acid left, 120px, a metal complex with the EDTA anion file:Asparaginsäure - Aspartic acid.svg, 120px, Aspartic acid is an aminodicarboxylic acid and precursor to other ligands. An ...
or derivatives. The micronutrient needs depend on the plant and the environment. For example,
sugar beet A sugar beet is a plant whose root contains a high concentration of sucrose Sucrose is a type of sugar Sugar is the generic name for Sweetness, sweet-tasting, soluble carbohydrates, many of which are used in food. Table sugar, granulated ...
s appear to require
boron Boron is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behav ...

boron
, and
legume A legume () is a plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration, can ...

legume
s require
cobalt Cobalt is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

cobalt
, while environmental conditions such as heat or drought make boron less available for plants.


Production


Nitrogen fertilizers

Nitrogen fertilizers are made from
ammonia Ammonia is a chemical compound, compound of nitrogen and hydrogen with the chemical formula, formula NH3. A Binary compounds of hydrogen, stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct ch ...

ammonia
(NH3) produced by the . In this energy-intensive process,
natural gas Natural gas (also called fossil gas; sometimes just gas) is a naturally occurring hydrocarbon gas mixture consisting of methane and commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxid ...

natural gas
(CH4) usually supplies the hydrogen, and the nitrogen (N2) is . This ammonia is used as a
feedstock A raw material, also known as a feedstock, unprocessed material, or primary commodity, is a basic material that is used to produce goods In economics Economics () is the social science that studies how people interact with value; in pa ...
for all other nitrogen fertilizers, such as (NH4NO3) and
urea Urea, also known as carbamide, is an organic compound In , organic compounds are generally any s that contain - . Due to carbon's ability to (form chains with other carbon s), millions of organic compounds are known. The study of the prop ...

urea
(CO(NH2)2). Deposits of
sodium nitrate Sodium nitrate is the chemical compound with the chemical formula, formula . This alkali metal nitrate salt (chemistry), salt is also known as Chile saltpeter (large deposits of which were historically mined in Chile) to distinguish it from ord ...
(NaNO3) (
Chilean saltpeter Nitratine or nitratite, also known as cubic niter (UK: nitre), soda niter or Chile saltpeter (UK: Chile saltpetre), is a mineral, the naturally occurring form of sodium nitrate, NaNO3. Chemically it is the sodium analogue of saltpeter. Nitratine cr ...
) are also found in the in
Chile Chile, officially the Republic of Chile, is a country in the western part of South America South America is a entirely in the and mostly in the , with a relatively small portion in the . It can also be described as the southern ...

Chile
and was one of the original (1830) nitrogen-rich fertilizers used. It is still mined for fertilizer. Nitrates are also produced from ammonia by the
Ostwald processThe Ostwald process is a chemical process used for making nitric acid Nitric acid (), also known as ''aqua fortis'' (Latin for "strong water") and spirit of niter, is a highly corrosive mineral acid. The pure compound is colorless, but older sam ...
.


Phosphate fertilizers

Phosphate fertilizers are obtained by extraction from
phosphate rock Phosphorite, phosphate rock or rock phosphate is a non-detrital sedimentary rock that contains high amounts of phosphate minerals. The phosphate content of phosphorite (or grade of phosphate rock) varies greatly, from 4% to 20% phosphorus pentoxide ...
, which contains two principal phosphorus-containing minerals,
fluorapatite Fluorapatite, often with the alternate spelling of fluoroapatite, is a phosphate mineral with the formula Ca5(PO4)3F (calcium fluorophosphate). Fluorapatite is a hard crystalline solid. Although samples can have various color (green, brown, blue ...

fluorapatite
Ca5(PO4)3F (CFA) and
hydroxyapatite Hydroxyapatite, also called hydroxylapatite (HA), is a naturally occurring mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and ...
Ca5(PO4)3OH. These minerals are converted into water-soluble phosphate salts by treatment with (H2SO4) or
phosphoric acid Phosphoric acid, also known as orthophosphoric acid or phosphoric(V) acid, is a weak acid with the chemical formula . The pure compound is a colorless solid. All three hydrogens are acidic to varying degrees and can be lost from the molecule ...

phosphoric acid
s (H3PO4). The large production of
sulfuric acid Sulfuric acid (American spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography English orthogra ...

sulfuric acid
is primarily motivated by this application. In the
nitrophosphate process The nitrophosphate process (also known as the Odda process) was a method for the industrial production of nitrogen Nitrogen is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry ...
or Odda process (invented in 1927), phosphate rock with up to a 20% phosphorus (P) content is dissolved with
nitric acid Nitric acid (), also known as ''aqua fortis'' (Latin for "strong water") and spirit of niter, is a highly corrosive mineral acid. The pure compound is colorless, but older samples tend to acquire a yellow cast due to decomposition into nitroge ...

nitric acid
(HNO3) to produce a mixture of phosphoric acid (H3PO4) and
calcium nitrate Calcium nitrate, also called ''Norgessalpeter'' (Norwegian saltpeter), is an inorganic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, ...

calcium nitrate
(Ca(NO3)2). This mixture can be combined with a potassium fertilizer to produce a ''compound fertilizer'' with the three macronutrients N, P and K in easily dissolved form.


Potassium fertilizers

Potash Potash () includes various mined and manufactured salts In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structu ...
is a mixture of potassium minerals used to make potassium (chemical symbol: K) fertilizers. Potash is soluble in water, so the main effort in producing this nutrient from the ore involves some purification steps; e.g., to remove
sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salt (chemistry), salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With Molar mass, molar ...
(NaCl) (common
salt Salt is a mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure fo ...

salt
). Sometimes potash is referred to as K2O, as a matter of convenience to those describing the potassium content. In fact, potash fertilizers are usually
potassium chloride Potassium chloride (KCl, or potassium salt) is a metal halide Metal halides are compounds between metals and halogens. Some, such as sodium chloride are ionic, while others are covalently bonded. Covalently bonded metal halides may be discrete m ...

potassium chloride
,
potassium sulfate Potassium sulfate (US) or potassium sulphate (UK), also called sulphate of potash (SOP), arcanite, or archaically potash of sulfur, is the inorganic compound In chemistry Chemistry is the study of the properties and behavior of . It is ...

potassium sulfate
,
potassium carbonate Potassium carbonate is the inorganic compound with the formula K2 CO3. It is a white salt, which is soluble in water Water is an Inorganic compound, inorganic, Transparency and translucency, transparent, tasteless, odorless, and Color o ...

potassium carbonate
, or
potassium nitrate Potassium nitrate is a chemical compound with the chemical formula . It is an ionic salt of potassium ions K+ and nitrate ions NO3−, and is therefore an alkali metal nitrate. It occurs in nature as a mineral, niter (or nitre in the UK). It is a ...

potassium nitrate
.


NPK fertilizers

There are four major routes for manufacturing NPK fertilizers: 1) steam granulation, 2) chemical granulation, 3) compaction, 4) bulk blending. The first three processes are used to produce compound NPKs. During steam granulation raw materials are mixed and further granulated using steam as binding agent. Chemical granulation process is based on chemical reactions between liquid raw materials (such as phosphoric acid, sulphuric acid, ammonia) and solid raw materials (such as potassium chloride, recycle material). Compaction implements high pressure to agglomerate dry powder materials. Lastly, bulk blends are produced by mixing straight fertilizers.


Organic fertilizers

Organic fertilizer File:Bone meal and meat meal.jpg, Bone meal and meat meal can be added to soil to stimulate root growth and to release phosphorus. Organic fertilizers are fertilizers that are naturally produced and contain carbon (C). Fertilizers are materials t ...
s" can describe those fertilizers with an organic – biologic – origin—that is, fertilizers derived from living or formerly living materials. Organic fertilizers can also describe commercially available and frequently packaged products that strive to follow the expectations and restrictions adopted by “
organic agriculture Organic farming is an agricultural system that uses fertilizers of organic origin such as compost manure, green manure, and bone meal and places emphasis on techniques such as crop rotation and companion planting. It originated early in the 20th ...
” and ”
environmentally friendly Environment friendly processes, or environmental-friendly processes (also referred to as eco-friendly, nature-friendly, and green), are sustainability Sustainability is the capacity to endure in a relatively ongoing way across various domains ...
" gardening – related systems of food and plant production that significantly limit or strictly avoid the use of synthetic fertilizers and pesticides. The "organic fertilizer" ''products'' typically contain both some organic materials as well as acceptable additives such as nutritive rock powders, ground sea shells (crab, oyster, etc.), other prepared products such as seed meal or kelp, and cultivated microorganisms and derivatives. Fertilizers of an organic origin (the first definition) include , plant wastes from agriculture,
seaweed Seaweed, or macroalgae, refers to thousands of species of , , . The term includes some types of ' (red), ' (brown) and ' (green) macroalgae. Seaweed species such as s provide essential nursery habitat for fisheries and other marine species an ...
,
compost Compost is a mixture of ingredients used to fertilize and improve the soil. It is commonly prepared by decomposing plant and food waste and recycling Organic material, organic materials. The resulting mixture is rich in plant nutrients and Ben ...

compost
, and treated sewage sludge (biosolids). Beyond manures, animal sources can include products from the slaughter of animals – bloodmeal, bone meal, feather meal, hides, hoofs, and horns all are typical components. Organically derived materials available to industry such as sewage sludge may not be acceptable components of organic farming and gardening, because of factors ranging from residual contaminants to public perception. On the other hand, marketed "organic fertilizers" may include, and promote, processed organics ''because'' the materials have consumer appeal. No matter the definition nor composition, most of these products contain less-concentrated nutrients, and the nutrients are not as easily quantified. They can offer soil-building advantages as well as be appealing to those who are trying to farm / garden more "naturally". In terms of volume, peat is the most widely used packaged organic soil amendment. It is an immature form of coal and improves the soil by aeration and absorbing water but confers no nutritional value to the plants. It is therefore not a fertilizer as defined in the beginning of the article, but rather an amendment. Coir, (derived from coconut husks), bark, and sawdust when added to soil all act similarly (but not identically) to peat and are also considered organic soil amendments – or texturizers – because of their limited nutritive inputs. Some organic additives can have a reverse effect on nutrients – fresh sawdust can consume soil nutrients as it breaks down, and may lower soil pH – but these same organic texturizers (as well as compost, etc.) may increase the availability of nutrients through improved cation exchange, or through increased growth of microorganisms that in turn increase availability of certain plant nutrients. Organic fertilizers such as composts and manures may be distributed locally without going into industry production, making actual consumption more difficult to quantify.


Application

Fertilizers are commonly used for growing all crops, with application rates depending on the soil fertility, usually as measured by a soil test and according to the particular crop. Legumes, for example, fix nitrogen from the atmosphere and generally do not require nitrogen fertilizer.


Liquid vs solid

Fertilizers are applied to crops both as solids and as liquid. About 90% of fertilizers are applied as solids. The most widely used solid inorganic fertilizers are
urea Urea, also known as carbamide, is an organic compound In , organic compounds are generally any s that contain - . Due to carbon's ability to (form chains with other carbon s), millions of organic compounds are known. The study of the prop ...

urea
, diammonium phosphate and potassium chloride. Solid fertilizer is typically granulated or powdered. Often solids are available as prills, a solid globule. Liquid fertilizers comprise anhydrous ammonia, aqueous solutions of ammonia, aqueous solutions of ammonium nitrate or urea. These concentrated products may be diluted with water to form a concentrated liquid fertilizer (e.g., UAN). Advantages of liquid fertilizer are its more rapid effect and easier coverage. The addition of fertilizer to irrigation water is called "fertigation".


Urea

Urea is highly soluble in water and is therefore also very suitable for use in fertilizer solutions (in combination with ammonium nitrate: UAN), e.g., in 'foliar feed' fertilizers. For fertilizer use, granules are preferred over prills because of their narrower particle size distribution, which is an advantage for mechanical application. Urea is usually spread at rates of between 40 and 300 kg/ha (35 to 270 lbs/acre) but rates vary. Smaller applications incur lower losses due to leaching. During summer, urea is often spread just before or during rain to minimize losses from ammonia volatilization from urea, volatilization (a process wherein nitrogen is lost to the atmosphere as ammonia gas). Because of the high nitrogen concentration in urea, it is very important to achieve an even spread. Drilling must not occur on contact with or close to seed, due to the risk of germination damage. Urea dissolves in water for application as a spray or through irrigation systems. In grain and cotton crops, urea is often applied at the time of the last cultivation before planting. In high rainfall areas and on sandy soils (where nitrogen can be lost through leaching) and where good in-season rainfall is expected, urea can be side- or top-dressed during the growing season. Top-dressing is also popular on pasture and forage crops. In cultivating sugarcane, urea is side-dressed after planting, and applied to each ratooning, ratoon crop. Because it absorbs moisture from the atmosphere, urea is often stored in closed containers. Overdose or placing urea near seed is harmful.


Slow- and controlled-release fertilizers


Foliar application

Foliar feeding, Foliar fertilizers are applied directly to leaves. This method is almost invariably used to apply water-soluble straight nitrogen fertilizers and used especially for high-value crops such as fruits. Urea is the most common foliar fertilizer.


Chemicals that affect nitrogen uptake

Various chemicals are used to enhance the efficiency of nitrogen-based fertilizers. In this way farmers can limit the polluting effects of nitrogen run-off. Nitrification inhibitors (also known as nitrogen stabilizers) suppress the conversion of ammonia into nitrate, an anion that is more prone to leaching. 1-Carbamoyl-3-methylpyrazole (CMP), dicyandiamide, nitrapyrin (2-chloro-6-trichloromethylpyridine) and 3,4-Dimethylpyrazole phosphate (DMPP) are popular. Urease inhibitors are used to slow the hydrolytic conversion of urea into ammonia, which is prone to evaporation as well as nitrification. The conversion of urea to ammonia catalyzed by enzymes called
urease Ureases (), functionally, belong to the superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially ...

urease
s. A popular inhibitor of ureases is N-(n-butyl)thiophosphoric triamide (NBPT).


Overfertilization

Careful use of fertilization technologies is important because excess nutrients can be detrimental. Fertilizer burn can occur when too much fertilizer is applied, resulting in damage or even death of the plant. Fertilizers vary in their tendency to burn roughly in accordance with their salt index.


Statistics

Recently nitrogen fertilizers have plateaued in most developed countries. China although has become the largest producer and consumer of nitrogen fertilizers. Africa has little reliance on nitrogen fertilizers. Agricultural and chemical minerals are very important in industrial use of fertilizers, which is valued at approximately $200 billion. Nitrogen has a significant impact in the global mineral use, followed by potash and phosphate. The production of nitrogen has drastically increased since the 1960s. Phosphate and potash have increased in price since the 1960s, which is larger than the consumer price index. Potash is produced in Canada, Russia and Belarus, together making up over half of the world production. Potash production in Canada rose in 2017 and 2018 by 18.6%. Conservative estimates report 30 to 50% of crop yields are attributed to natural or synthetic commercial fertilizers.Vasant Gowariker, V. N. Krishnamurthy, Sudha Gowariker, Manik Dhanorkar, Kalyani Paranjape "The Fertilizer Encyclopedia" 2009, John Wiley & Sons. . Online . Fertilizer consumption has surpassed the amount of farmland in the United States. Market (economics), Global market value is likely to rise to more than US$185 billion until 2019. The European fertilizer market will grow to earn revenues of approx. €15.3 billion in 2018. Data on the fertilizer consumption per hectare arable land in 2012 are published by The World Bank. The diagram below shows fertilizer consumption by the European Union (EU) countries as kilograms per hectare (pounds per acre). The total consumption of fertilizer in the EU is 15.9 million tons for 105 million hectare arable land area (or 107 million hectare arable land according to another estimate). This figure equates to 151 kg of fertilizers consumed per ha arable land on average by the EU countries.


Environmental effects

Use of fertilizers are beneficial in providing nutrients to plants although they have some negative environmental effects. The large growing consumption of fertilizers can affect soil, surface water, and groundwater due to dispersion of mineral use. For each ton of phosphoric acid produced by the processing of phosphate rock, five tons of waste are generated. This waste takes the form of impure, useless, radioactive solid called
phosphogypsum Phosphogypsum is the calcium sulfate hydrate formed as a by-product of the production of fertilizer A fertilizer (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. Englis ...
. Estimates range from 100,000,000 and 280,000,000 tons of phosphogypsum waste are produced annually worldwide.


Water

Phosphorus and nitrogen fertilizers when commonly used have major environmental effects. This is due to high rainfalls causing the fertilizers to be washed into waterways. Agricultural run-off is a major contributor to the eutrophication of fresh water bodies. For example, in the US, about half of all the lakes are eutrophic. The main contributor to eutrophication is phosphate, which is normally a limiting nutrient; high concentrations promote the growth of cyanobacteria and algae, the demise of which consumes oxygen. Cyanobacteria blooms ('algal blooms') can also produce harmful Eutrophication#Toxicity, toxins that can accumulate in the food chain, and can be harmful to humans. The nitrogen-rich compounds found in fertilizer runoff are the primary cause of serious oxygen depletion in many parts of oceans, especially in coastal zones, lakes and rivers. The resulting lack of dissolved oxygen greatly reduces the ability of these areas to sustain oceanic fauna. The number of oceanic Dead zone (ecology), dead zones near inhabited coastlines are increasing. As of 2006, the application of nitrogen fertilizer is being increasingly controlled in northwestern Europe and the United States. If eutrophication ''can'' be reversed, it may take decades before the accumulated nitrates in groundwater can be broken down by natural processes.


Nitrate pollution

Only a fraction of the nitrogen-based fertilizers is converted to plant matter. The remainder accumulates in the soil or is lost as run-off. High application rates of nitrogen-containing fertilizers combined with the high water solubility of nitrate leads to increased Surface runoff#Agricultural issues, runoff into surface water as well as Leaching (agriculture), leaching into groundwater, thereby causing groundwater pollution. The excessive use of nitrogen-containing fertilizers (be they synthetic or natural) is particularly damaging, as much of the nitrogen that is not taken up by plants is transformed into nitrate which is easily leached. Nitrate levels above 10 mg/L (10 ppm) in groundwater can cause 'blue baby syndrome' (acquired methemoglobinemia). The nutrients, especially nitrates, in fertilizers can cause problems for natural habitats and for human health if they are washed off soil into watercourses or leached through soil into groundwater.


Soil


Acidification

Nitrogen-containing fertilizers can cause soil acidification when added. This may lead to decrease in nutrient availability which may be offset by liming (soil), liming.


Accumulation of toxic elements


=Cadmium

= The concentration of cadmium in phosphorus-containing fertilizers varies considerably and can be problematic. For example, mono-ammonium phosphate fertilizer may have a cadmium content of as low as 0.14 mg/kg or as high as 50.9 mg/kg. The phosphate rock used in their manufacture can contain as much as 188 mg/kg cadmium (examples are deposits on Nauru and the Christmas islands). Continuous use of high-cadmium fertilizer can contaminate soil (as shown in New Zealand) and Phytotoxicity, plants. Limits to the cadmium content of phosphate fertilizers has been considered by the European Commission. Producers of phosphorus-containing fertilizers now select phosphate rock based on the cadmium content.Wilfried Werner "Fertilizers, 6. Environmental Aspects" Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim.


=Fluoride

= Phosphate rocks contain high levels of fluoride. Consequently, the widespread use of phosphate fertilizers has increased soil fluoride concentrations. 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. Also of possible concern are the effects of fluoride on soil microorganisms.


= 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. Uranium-238 concentrations can range from 7 to 100 pCi/g in phosphate rock and from 1 to 67 pCi/g in phosphate fertilizers. 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. 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 mSievert, Sv/y).


= Other metals

= Steel industry wastes, recycled into fertilizers for their high levels of
zinc Zinc is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

zinc
(essential to plant growth), wastes can include the following toxic metals: lead arsenic, cadmium, chromium, and nickel. The most common toxic elements in this type of fertilizer are mercury, lead, and arsenic. 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. 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. Although improved crop yields resulting from NPK fertilizers are known to dilute the concentrations of other nutrients in plants, 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. 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. Fertilizers are, in fact, more likely to solve trace mineral deficiency problems than cause them: In Western Australia deficiencies of
zinc Zinc is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical element ...

zinc
, copper,
manganese Manganese is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical e ...

manganese
, iron and
molybdenum Molybdenum is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behav ...

molybdenum
were identified as limiting the growth of broad-acre crops and pastures in the 1940s and 1950s. Soils in Western Australia are very old, highly weathered and deficient in many of the major nutrients and trace elements. Since this time these trace elements are routinely added to fertilizers used in agriculture in this state. 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.


Changes in soil biology

High levels of fertilizer may cause the breakdown of the Symbiosis, symbiotic relationships between plant roots and mycorrhizal fungi.


Energy consumption and sustainability

In the US in 2004, 317 billion cubic feet of natural gas were consumed in the industrial Ammonia production, production of ammonia, less than 1.5% of total U.S. List of countries by natural gas consumption, annual consumption of natural gas. A 2002 report suggested that the production of ammonia consumes about 5% of global natural gas consumption, which is somewhat under 2% of world energy production.IFA – Statistics – Fertilizer Indicators – Details – Raw material reserves, (2002–10)
Ammonia is produced from
natural gas Natural gas (also called fossil gas; sometimes just gas) is a naturally occurring hydrocarbon gas mixture consisting of methane and commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxid ...

natural gas
and air. The cost of natural gas makes up about 90% of the cost of producing ammonia. The increase in price of natural gases over the past decade, along with other factors such as increasing demand, have contributed to an increase in fertilizer price.


Contribution to climate change

The greenhouse gases carbon dioxide,
methane Methane (, ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth ...
and nitrous oxide are produced during the Haber process, manufacture of nitrogen fertilizer. The effects can be combined into an equivalent amount of carbon dioxide. The amount varies according to the efficiency of the process. The figure for the United Kingdom is over 2 kilograms of carbon dioxide equivalent for each kilogram of ammonium nitrate. Nitrogen fertilizer can be converted by Nitrous oxide#Soil, soil bacteria to nitrous oxide, a greenhouse gas. Nitrous oxide emissions by humans, most of which are from fertilizer, between 2007 and 2016 have been estimated at 7 million tonnes per year, which is incompatible with limiting global warming to below 2°C.


Atmosphere

Through the increasing use of nitrogen fertilizer, which was used at a rate of about 110 million tons (of N) per year in 2012, adding to the already existing amount of reactive nitrogen, nitrous oxide (N2O) has become the third most important greenhouse gas after carbon dioxide and methane. It has a global warming potential 296 times larger than an equal mass of carbon dioxide and it also contributes to stratospheric ozone depletion. By changing processes and procedures, it is possible to mitigate some, but not all, of these effects on anthropogenic climate change. Methane emissions from crop fields (notably rice paddy fields) are increased by the application of ammonium-based fertilizers. These emissions contribute to global climate change as methane is a potent greenhouse gas.


Policy


Regulation

In Europe, problems with high nitrate concentrations in runoff are being addressed by the European Union's Nitrates Directive. Within Britain, farmers are encouraged to manage their land more sustainably in 'catchment-sensitive farming'. In the US, high concentrations of nitrate and phosphorus in runoff and drainage water are classified as nonpoint source pollutants due to their diffuse origin; this pollution is regulated at the state level. Oregon and Washington, both in the United States, have fertilizer registration programs with on-line databases listing chemical analyses of fertilizers. In China, regulations have been implemented to control the use of N fertilizers in farming. In 2008, Chinese governments began to partially withdraw fertilizer subsidies, including subsidies to fertilizer transportation and to electricity and natural gas use in the industry. In consequence, the price of fertilizer has gone up and large-scale farms have begun to use less fertilizer. If large-scale farms keep reducing their use of fertilizer subsidies, they have no choice but to optimize the fertilizer they have which would therefore gain an increase in both grain yield and profit. Two types of agricultural management practices include organic agriculture and conventional agriculture. The former encourages soil fertility using local resources to maximize efficiency. Organic agriculture avoids synthetic agrochemicals. Conventional agriculture uses all the components that organic agriculture does not use.


See also

* Agroecology * Circulus (theory) * Fertigation * Food and Agriculture Organization * History of organic farming * Milorganite * Leaf Color Chart * Nutrient Recovery and Reuse * Phosphogypsum * Soil defertilisation *Seaweed fertilizer


References


External links


Nitrogen for Feeding Our Food, Its Earthly Origin, Haber Process

International Fertilizer Industry Association (IFA)

Agriculture Guide, Complete Guide to Fertilizers and Fertilization

Nitrogen-Phosphorus-Potassium Values of Organic Fertilizers
{{Authority control Fertilizers, Horticulture Climate change and agriculture