Fertilizer
Overview
 
Fertilizer is any organic or inorganic material of natural or synthetic origin (other than liming materials) that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use. They are essential for high-yield harvest: European fertilizer market is expected to grow to €15.3 billion by 2018.

Mined inorganic fertilizers have been used for many centuries, whereas chemically synthesized inorganic fertilizers were only widely developed during the industrial revolution
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

.
Encyclopedia
Fertilizer is any organic or inorganic material of natural or synthetic origin (other than liming materials) that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use. They are essential for high-yield harvest: European fertilizer market is expected to grow to €15.3 billion by 2018.

Mined inorganic fertilizers have been used for many centuries, whereas chemically synthesized inorganic fertilizers were only widely developed during the industrial revolution
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

. Increased understanding and use of fertilizers were important parts of the pre-industrial British Agricultural Revolution
British Agricultural Revolution
British Agricultural Revolution describes a period of development in Britain between the 17th century and the end of the 19th century, which saw an epoch-making increase in agricultural productivity and net output. This in turn supported unprecedented population growth, freeing up a significant...

 and the industrial Green Revolution
Green Revolution
Green Revolution refers to a series of research, development, and technology transfer initiatives, occurring between the 1940s and the late 1970s, that increased agriculture production around the world, beginning most markedly in the late 1960s....

 of the 20th century.

Inorganic fertilizer use has also significantly supported global population growth
Population growth
Population growth is the change in a population over time, and can be quantified as the change in the number of individuals of any species in a population using "per unit time" for measurement....

 — it has been estimated that almost half the people on the Earth are currently fed as a result of synthetic nitrogen fertilizer use.

Fertilizers typically provide, in varying proportions
Proportionality (mathematics)
In mathematics, two variable quantities are proportional if one of them is always the product of the other and a constant quantity, called the coefficient of proportionality or proportionality constant. In other words, are proportional if the ratio \tfrac yx is constant. We also say that one...

:
  • six macronutrients: nitrogen
    Nitrogen
    Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

     (N), phosphorus
    Phosphorus
    Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

     (P), potassium
    Potassium
    Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

     (K), calcium
    Calcium
    Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

     (Ca), magnesium
    Magnesium
    Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

     (Mg), and sulfur
    Sulfur
    Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

     (S);
  • seven micronutrients: boron
    Boron
    Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...

     (B), chlorine
    Chlorine
    Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

     (Cl), copper
    Copper
    Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

     (Cu), iron
    Iron
    Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

     (Fe), manganese
    Manganese
    Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

     (Mn), molybdenum
    Molybdenum
    Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...

     (Mo), and zinc
    Zinc
    Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

     (Zn).


The macronutrients are consumed in larger quantities and are present in plant tissue in quantities from 0.15% to 6.0% on a dry matter (0% moisture) basis (DM). 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 DM, or less than 0.04% DM.

Only three other macronutrients are required by all plants: carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

, hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

, and oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

. These nutrients are supplied by water and carbon dioxide.

The nitrogen-rich fertilizer ammonium nitrate is also used as an oxidizing agent
Oxidizing agent
An oxidizing agent can be defined as a substance that removes electrons from another reactant in a redox chemical reaction...

 in improvised explosive device
Improvised explosive device
An improvised explosive device , also known as a roadside bomb, is a homemade bomb constructed and deployed in ways other than in conventional military action...

s, sometimes called fertilizer bombs, leading to sale regulations.

Labeling

The labeling of fertilizers varies by country in terms of analysis methodology and subsequent nutrient labeling. In most countries the macronutrients are labeled with an NPK
NPK rating
NPK rating is used to label fertilizer based on the relative content of the chemicals nitrogen, phosphorus, and potassium that are commonly used in fertilizers....

analysis (in Australia, "N-P-K-S" adding sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

).

The three numbers on the fertilizer label represent an analysis of the composition by weight. These three numbers correspond to nitrogen, phosphorus, and potassium (N-P-K) and always appear in that specific order. When a 4th number is included, it indicates the sulfur content (N-P-K-S).

While the number for "N" represents the percentage weight of nitrogen, the other two components are not for the analysis of the element, but rather, the analysis of the "available" or "soluble" form of the element. In traditional chemical analysis, the tests used treated the sample so as to measure the equivalent P2O5 and K2O. For instance, some potassium-bearing rocks do not count as having available potassium.

The number for "P" is actually the weight of an equivalent quantity of P2O5 and not elemental phosphorus. In order to calculate the weight of P in the formulation, the weight of P2O5 can be multiplied by 0.44 to compensate for the weight of the oxygen in the molecule. For example, a bag of 10-10-10 has 10 pounds of nitrogen, 10 pounds of P2O5, but only 4.4 pounds of P.

Likewise, the number for "K" is actually the weight of an equivalent quantity of K2O, and not elemental potassium. In order to calculate the weight of K in the formulation, the weight of K2O can be multiplied by 0.83 to compensate for the weight of the oxygen in the molecule. For example, a bag of 10-10-10 has 10 pounds of K2O, but only 8.3 pounds of K.

As an example, the fertilizer potash
Potash
Potash is the common name for various mined and manufactured salts that contain potassium in water-soluble form. In some rare cases, potash can be formed with traces of organic materials such as plant remains, and this was the major historical source for it before the industrial era...

(in modern times, potassium chloride) is composed of 52% potassium and 48% chlorine by weight; chemical analysis of 100g of potassium chloride (KCl
KCL
KCL or KCl may stand for:*KCl, the chemical symbol for potassium chloride*Kirchhoff's current law*King's College London, constituent college of the University of London*Kyoto Common Lisp...

), would show 63g of equivalent potassium oxide (K2O
Potassium oxide
Potassium oxide is an ionic compound of potassium and oxygen. This pale yellow solid, the simplest oxide of potassium, is a rarely encountered, highly reactive compound...

) when done in the manner of fertilizer analysis. The percentage yield of K2O from the original 100g of fertilizer is the number shown on the label. A potash fertilizer would thus be labeled 0-0-63, and not 0-0-52.

History

The modern understanding of plant nutrition dates to the 19th century and the work of Justus von Liebig
Justus von Liebig
Justus von Liebig was a German chemist who made major contributions to agricultural and biological chemistry, and worked on the organization of organic chemistry. As a professor, he devised the modern laboratory-oriented teaching method, and for such innovations, he is regarded as one of the...

, among others. Management of soil fertility, however, has been the pre-occupation of farmers for thousands of years.

Forms

Fertilizers come in various forms. The most typical form is granular fertilizer (powder form). The next most common form is liquid fertilizer; some advantages of liquid fertilizer are its immediate effect and wide coverage. There are also slow-release fertilizers (various forms including fertilizer spikes, tabs, etc.) which reduce the problem of "burning" the plants due to excess nitrogen.

More recently, organic fertilizer is on the rise as people are resorting to environmental friendly (or 'green') products. Although organic fertilizer usually contain less nutrients, some people still prefer organic due to natural ingredients .

Inorganic fertilizer (synthetic fertilizer)

Fertilizers are broadly divided into organic
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 fertilizers
(composed of enriched organic matter—plant or animal), or inorganic
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

 fertilizers
(composed of synthetic chemicals and/or minerals).

Inorganic fertilizer is often synthesized using the Haber-Bosch process
Haber process
The Haber process, also called the Haber–Bosch process, is the nitrogen fixation reaction of nitrogen gas and hydrogen gas, over an enriched iron or ruthenium catalyst, which is used to industrially produce ammonia....

, which produces ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 as the end product. This ammonia is used as a feedstock for other nitrogen fertilizers, such as anhydrous ammonium nitrate and urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....

. These concentrated products may be diluted with water to form a concentrated liquid fertilizer (e.g. UAN
UAN
UAN is a solution of urea and ammonium nitrate in water used as a fertilizer. The combination of urea and ammonium nitrate has an extremely low critical relative humidity and can therefore only be used in liquid fertilizers...

). Ammonia can be combined with rock phosphate and potassium fertilizer in the Odda Process to produce compound fertilizer.

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 of nitrogen per year. 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 requires 31–50 kg of phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...

 fertilizer to be applied, soybean requires 20–25 kg per hectare. Yara International
Yara International
Yara International ASA is a Norwegian-based chemical company. Its largest business area is the production of nitrogen fertilizer, however it also encompasses the production of dry ice, nitrates, ammonia, urea and other nitrogen-based chemicals....

 is the world's largest producer of nitrogen based fertilizers.

Controlled-release types

Urea and formaldehyde, reacted together to produce sparingly soluble polymers of various molecular weights, is one of the oldest controlled-nitrogen-release technologies, having been first produced in 1936 and commercialized in 1955. The early product had 60 percent of the total nitrogen cold-water-insoluble, and the unreacted (quick release) less than 15%. Methylene ureas were commercialized in the 1960s and 1970s, having 25 and 60% of the nitrogen cold-water-insoluble, and unreacted urea nitrogen in the range of 15 to 30%. Isobutylidene diurea, unlike the methylurea polymers, is a single crystalline solid of relatively uniform properties, with about 90% of the nitrogen water-insoluble.

In the 1960s the National Fertilizer Development Center began developing Sulfur-coated urea; sulfur was used as the principle coating material because of its low cost and its value as a secondary nutrient. Usually there is another wax or polymer which seals the sulfur; the slow release properties depend on the degradation of the secondary sealant by soil microbes as well as mechanical imperfections (cracks, etc.) in the sulfur. They typically provide 6 to 16 weeks of delayed release in turf applications. When a hard polymer is used as the secondary coating, the properties are a cross between diffusion-controlled particles and traditional sulfur-coated.

Other coated products use thermoplastics (and sometimes ethylene-vinyl acetate and surfactants, etc.) to produce diffusion-controlled release of urea or soluble inorganic fertilizers. "Reactive Layer Coating" can produce thinner, hence cheaper, membrane coatings by applying reactive monomers simultaneously to the soluble particles. "Multicote" is a process applying layers of low-cost fatty acid salts with a paraffin topcoat.

Besides being more efficient in the utilization of the applied nutrients, slow-release technologies also reduce the impact on the environment and the contamination of the subsurface water.

{| align="left" class="wikitable"
|+ Top users of nitrogen-based fertilizer
|-
! Country
! Total N use
(Mt pa)
! Amt. used
(feed/pasture)
|-
| China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...


| 18.7
| 3.0
|-
| U.S.
| 9.1
| 4.7
|-
| France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...


| 2.5
| 1.3
|-
| Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...


| 2.0
| 1.2
|-
| Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...


| 1.7
| 0.7
|-
| Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...


| 1.6
| 0.9
|-
| Turkey
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...


| 1.5
| 0.3
|-
| U.K.
| 1.3
| 0.9
|-
| Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...


| 1.3
| 0.3
|-
| Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...


| 1.2
| 0.5
|-
| Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...


| 0.4
| 0.1
|}

Application

Synthetic fertilizers are commonly used to treat fields used for growing maize
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...

, followed by barley
Barley
Barley is a major cereal grain, a member of the grass family. It serves as a major animal fodder, as a base malt for beer and certain distilled beverages, and as a component of various health foods...

, sorghum
Sorghum
Sorghum is a genus of numerous species of grasses, one of which is raised for grain and many of which are used as fodder plants either cultivated or as part of pasture. The plants are cultivated in warmer climates worldwide. Species are native to tropical and subtropical regions of all continents...

, rapeseed
Rapeseed
Rapeseed , also known as rape, oilseed rape, rapa, rappi, rapaseed is a bright yellow flowering member of the family Brassicaceae...

, soy and sunflower
Sunflower
Sunflower is an annual plant native to the Americas. It possesses a large inflorescence . The sunflower got its name from its huge, fiery blooms, whose shape and image is often used to depict the sun. The sunflower has a rough, hairy stem, broad, coarsely toothed, rough leaves and circular heads...

. One study has shown that application of nitrogen fertilizer on off-season cover crops can increase the biomass (and subsequent green manure
Green manure
In agriculture, a green manure is a type of cover crop grown primarily to add nutrients and organic matter to the soil. Typically, a green manure crop is grown for a specific period of time , and then plowed under and incorporated into the soil while green or shortly after flowering...

 value) of these crops, while having a beneficial effect on soil nitrogen levels for the main crop planted during the summer season.

Nutrients in soil can be thrown out of balance with high concentrations of fertilizers. The interconnectedness and complexity of this soil ‘food web’
Soil food web
The soil food web is the community of organisms living all or part of their lives in the soil. It describes a complex living system in the soil and how it interacts with the environment, plants, and animals....

 means any appraisal of soil function must necessarily take into account interactions with the living communities that exist within the soil. Stability of the system is reduced by the use of nitrogen-containing fertilizers, which cause soil acidification
Soil acidification
Soil acidification is the buildup of hydrogen cations, also called protons, reducing the soil pH. This happens when a proton donor is added to the soil. The donor can be an acid, such as nitric acid and sulfuric acid . It can also be a compound such as aluminium sulfate, which reacts in the soil to...

.

Applying excessive amounts of fertilizer has negative environmental effects, and wastes the growers' time and money. To avoid over-application, the nutrient status of crops should be assessed. Nutrient deficiency can be detected by visually assessing the physical symptoms of the crop. Nitrogen deficiency
Nitrogen deficiency
All plants require sufficient supplies of macronutrients for healthy growth, and nitrogen is a nutrient that is commonly in limited supply. Nitrogen deficiency in plants can occur when organic matter with high carbon carbon content, such as sawdust, is added to soil. Soil organisms use any...

, for example has a distinctive presentation in some species. However, quantitative tests are more reliable for detecting nutrient deficiency before it has significantly affected the crop. Both soil test
Soil test
In agriculture, a soil test is the analysis of a soil sample to determine nutrient and contaminant content, composition and other characteristics such as acidity or pH level. Tests are usually performed to measure the expected growth potential of a soil...

s and Plant Tissue Test
Plant tissue test
The nutrient content of a plant can be assessed by testing a sample of tissue from that plant. These tests are important in agriculture since fertilizer application can be fine-tuned if the plants nutrient status is known. Nitrogen most commonly limits plant growth and is the most managed...

s are used in agriculture to fine-tune nutrient management to the crops needs.

Trace mineral depletion

Many inorganic fertilizers may not replace trace mineral elements in the soil which become gradually depleted by crops. This depletion has been linked to studies which have shown a marked fall (up to 75%) in the quantities of such minerals present in fruit and vegetables.

In Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

 deficiencies of zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

, copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

, manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

, iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 and molybdenum
Molybdenum
Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...

 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 inorganic fertilizers used in agriculture in this state.

Overfertilization

Over-fertilization of a vital nutrient can be as detrimental as underfertilization. "Fertilizer burn" can occur when too much fertilizer is applied, resulting in a drying out of the roots and damage or even death of the plant.

High energy consumption

In the USA in 2004, 317 billion cubic feet of natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

 was consumed in the industrial production of ammonia, less than 1.5% of total U.S. 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.

Ammonia is overwhelmingly produced from natural gas, but other energy sources, together with a hydrogen source, can be used for the production of nitrogen compounds suitable for fertilizers. 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.

Long-Term Sustainability

Inorganic fertilizers are now produced in ways which theoretically cannot be continued indefinitely by definition as the resources used in their production are non-renewable. Potassium and phosphorus come from mines (or saline lakes
Salt lake
A salt lake or saline lake is a landlocked body of water which has a concentration of salts and other dissolved minerals significantly higher than most lakes . In some cases, salt lakes have a higher concentration of salt than sea water, but such lakes would also be termed hypersaline lakes...

 such as the Dead Sea
Dead Sea
The Dead Sea , also called the Salt Sea, is a salt lake bordering Jordan to the east and Israel and the West Bank to the west. Its surface and shores are below sea level, the lowest elevation on the Earth's surface. The Dead Sea is deep, the deepest hypersaline lake in the world...

) and such resources are limited. However, more effective fertilizer utilization practices may decrease present usage from mines. Improved knowledge of crop production practices can potentially decrease fertilizer usage of P and K without reducing the critical need to improve and increase crop yields. Atmospheric (unfixed
Nitrogen fixation
Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...

) nitrogen is effectively unlimited (forming over 70% of the atmospheric gases), but this is not in a form useful to plants. To make nitrogen accessible to plants requires nitrogen fixation
Nitrogen fixation
Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...

 (conversion of atmospheric nitrogen to a plant-accessible form).

Artificial nitrogen fertilizers are typically synthesized using fossil fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...

s such as natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

 and coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

, which are limited resources. In lieu of converting natural gas to syngas
Syngas
Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...

 for use in the Haber process
Haber process
The Haber process, also called the Haber–Bosch process, is the nitrogen fixation reaction of nitrogen gas and hydrogen gas, over an enriched iron or ruthenium catalyst, which is used to industrially produce ammonia....

, it is also possible to convert renewable biomass
Biomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....

 to syngas (or wood gas
Wood gas
Wood gas is a syngas fuel which can be used as a fuel for furnaces, stoves and vehicles in place of petrol, diesel or other fuels. During the production process biomass or other carbon-containing materials is gasified within the oxygen-limited environment of a wood gas generator to produce hydrogen...

) to supply the necessary energy for the process, though the amount of land and resources (ironically often including fertilizer) necessary for such a project may be prohibitive.

Organic fertilizer

Organic fertilizers include naturally occurring organic materials, (e.g. manure
Manure
Manure is organic matter used as organic fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen, that are trapped by bacteria in the soil...

, worm castings, compost
Compost
Compost is organic matter that has been decomposed and recycled as a fertilizer and soil amendment. Compost is a key ingredient in organic farming. At its most essential, the process of composting requires simply piling up waste outdoors and waiting for the materials to break down from anywhere...

, seaweed
Seaweed
Seaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...

, guano
Guano
Guano is the excrement of seabirds, cave dwelling bats, and seals. Guano manure is an effective fertilizer due to its high levels of phosphorus and nitrogen and also its lack of odor. It was an important source of nitrates for gunpowder...

), or naturally occurring mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

 deposits (e.g. saltpeter
Sodium nitrate
Sodium nitrate is the chemical compound with the formula NaNO3. This salt, also known as Chile saltpeter or Peru saltpeter to distinguish it from ordinary saltpeter, potassium nitrate, is a white solid which is very soluble in water...

).

Benefits of organic fertilizer

Organic fertilizers have been known to improve biodiversity (soil life
Soil life
Soil life or soil biota is a collective term for all the organisms living within the soil.-Overview:In balanced soil, plants grow in an active and steady environment. The mineral content of the soil and its heartiful structure are important for their well-being, but it is the life in the earth that...

) and long-term productivity of soil, and may prove a large depository for excess carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

.

Organic nutrients increase the abundance of soil organisms by providing organic matter and micronutrients for organisms such as fungal mycorrhiza
Mycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....

, (which aid plants in absorbing nutrients), and can drastically reduce external inputs of pesticides, energy and fertilizer, at the cost of decreased yield.

Disadvantages of organic fertilizers

  • Organic fertilizers may contain pathogens and other disease causing organisms if not properly composted
  • Nutrient contents are very variable and their release to available forms that the plant can use may not occur at the right plant growth stage
  • Organic fertilizers are comparatively voluminous and can be too bulky to deploy the right amount of nutrients that will be beneficial to plants
  • More expensive to produce

Comparison with inorganic fertilizer

Organic fertilizer nutrient content, solubility, and nutrient release rates are typically all lower than inorganic fertilizers.
One study found that over a 140-day period, after 7 leachings
Leaching (agriculture)
In agriculture, leaching refers to the loss of water-soluble plant nutrients from the soil, due to rain and irrigation. Soil structure, crop planting, type and application rates of fertilizers, and other factors are taken into account to avoid excessive nutrient loss.Leaching may also refer to ...

:
  • Organic fertilizers had released between 25% and 60% of their nitrogen content
  • Controlled release fertilizers (CRFs) had a relatively constant rate of release
  • Soluble fertilizer released most of its nitrogen content at the first leaching


In general, the nutrients in organic fertilizer are both more dilute and also much less readily available to plants. According to the University of California's integrated pest management program, all organic fertilizers are classified as 'slow-release' fertilizers, and therefore cannot cause nitrogen burn.

Organic fertilizers from composts and other sources can be quite variable from one batch to the next. Without batch testing, amounts of applied nutrient cannot be precisely known. Nevertheless they are at least as effective as chemical fertilizers over longer periods of use.

Example of organic fertilizer

Chicken litter, which consists of chicken manure mixed with sawdust, is an organic fertilizer that has been shown to better condition soil for harvest than synthesized fertilizer. Researchers at the Agricultural Research Service
Agricultural Research Service
The Agricultural Research Service is the principal in-house research agency of the United States Department of Agriculture . ARS is one of four agencies in USDA's Research, Education and Economics mission area...

 (ARS) studied the effects of using chicken litter, an organic fertilizer, versus synthetic fertilizers on cotton fields, and found that fields fertilized with chicken litter had a 12% increase in cotton yields over fields fertilized with synthetic fertilizer. In addition to higher yields, researchers valued commercially sold chicken litter at a $17/ton premium (to a total valuation of $78/ton) over the traditional valuations of $61/ton due to value added as a soil conditioner
Soil conditioner
A soil conditioner, also called a soil amendment, is a material added to soil to improve plant growth and health. A conditioner or a combination of conditioners corrects the soil's deficiencies in structure and-or nutrients.-Purpose:...

.

Other ARS studies have found that algae used to capture nitrogen and phosphorus runoff from agricultural fields can not only prevent water contamination of these nutrients, but also can be used as an organic fertilizer. ARS scientists originally developed the "algal turf scrubber" to reduce nutrient runoff and increase quality of water flowing into streams, rivers, and lakes. They found that this nutrient-rich algae, once dried, can be applied to cucumber and corn seedlings and result in growth comparable to that seen using synthetic fertilizers.

Animal

Animal-sourced and human urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....

 are suitable for application organic agriculture, while pure synthetic forms of urea are not. The common thread that can be seen through these examples is that organic agriculture attempts to define itself through minimal processing (in contrast to the man-made Haber process
Haber process
The Haber process, also called the Haber–Bosch process, is the nitrogen fixation reaction of nitrogen gas and hydrogen gas, over an enriched iron or ruthenium catalyst, which is used to industrially produce ammonia....

), as well as being naturally occurring or via natural biological processes such as composting.

Besides immediate application of urea to the soil, urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...

 can also be improved by converting it to struvite
Struvite
Struvite is a phosphate mineral with formula: NH4MgPO4·6H2O. Struvite crystallizes in the orthorhombic system as white to yellowish or brownish-white pyramidal crystals or in platey mica-like forms. It is a soft mineral with Mohs hardness of 1.5 to 2 and has a low specific gravity of 1.7...

 already done with human urine by a Dutch firm. The conversion is performed by adding magnesium to the urine. An added economical advantage of using urine as fertilizer is that it contains a large amount of phosphorus, a mineral whose production is rapidly decreasing (peak phosphorus
Peak phosphorus
Peak phosphorus is the point in time at which the maximum global phosphorus production rate is reached. Phosphorus is a scarce finite resource on earth and due to its non-gaseous environmental cycle has resulted in alternative means other than mining being unavailable...

) as the mines are running dry.

Sewage sludge (aka biosolids) use is only available to less than 1% of US ag land. USDA prohibits use of sewage sludge in organic agricultural operations in the U.S. has been extremely limited and rare due to of the practice (due to toxic metal accumulation, among other factors).
The USDA now requires 3rd-party certification of high-nitrogen liquid organic fertilizers sold in the U.S.

Plant

Leguminous cover crop
Cover crop
Cover crops are crops planted primarily to manage soil fertility, soil quality, water, weeds, pests, diseases, biodiversity and wildlife in agroecosystems , ecological systems managed and largely shaped by humans across a range of intensities to produce food, feed, or fiber.Cover crops are of...

s are also grown to enrich soil as a green manure
Green manure
In agriculture, a green manure is a type of cover crop grown primarily to add nutrients and organic matter to the soil. Typically, a green manure crop is grown for a specific period of time , and then plowed under and incorporated into the soil while green or shortly after flowering...

 through nitrogen fixation
Nitrogen fixation
Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...

 from the atmosphere; as well as phosphorus (through nutrient mobilization) content of soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

s.

Mineral

Mined powdered limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

, rock phosphate and sodium nitrate
Sodium nitrate
Sodium nitrate is the chemical compound with the formula NaNO3. This salt, also known as Chile saltpeter or Peru saltpeter to distinguish it from ordinary saltpeter, potassium nitrate, is a white solid which is very soluble in water...

, are inorganic (not of biologic origins) compounds which are energetically intensive to harvest and are approved for usage in organic agriculture in minimal amounts.

Negative environmental effects

Eutrophication

The nitrogen-rich compounds found in fertilizer runoff is the primary cause of a serious depletion of oxygen in many parts of the ocean, especially in coastal zones; the resulting lack of dissolved oxygen is greatly reducing the ability of these areas to sustain oceanic fauna
Fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...

. Visually, water may become cloudy and discolored (green, yellow, brown, or red).

About half of all the lakes in the United States are now eutrophic, while the number of oceanic dead zones
Dead zone (ecology)
Dead zones are hypoxic areas in the world's oceans, the observed incidences of which have been increasing since oceanographers began noting them in the 1970s. These occur near inhabited coastlines, where aquatic life is most concentrated...

 near inhabited coastlines are increasing. As of 2006, the application of nitrogen fertilizer is being increasingly controlled in Britain and the United States. If eutrophication
Eutrophication
Eutrophication or more precisely hypertrophication, is the movement of a body of water′s trophic status in the direction of increasing plant biomass, by the addition of artificial or natural substances, such as nitrates and phosphates, through fertilizers or sewage, to an aquatic system...

 can be reversed, it may take decades before the accumulated nitrates in groundwater can be broken down by natural processes.

Blue Baby Syndrome

High application rates of inorganic nitrogen fertilizers in order to maximize crop yields, combined with the high solubilities of these fertilizers leads to increased runoff into surface water as well as leaching
Leaching (agriculture)
In agriculture, leaching refers to the loss of water-soluble plant nutrients from the soil, due to rain and irrigation. Soil structure, crop planting, type and application rates of fertilizers, and other factors are taken into account to avoid excessive nutrient loss.Leaching may also refer to ...

 into groundwater. The use of ammonium nitrate in inorganic fertilizers is particularly damaging, as plants absorb ammonium ions preferentially over nitrate ions, while excess nitrate ions which are not absorbed dissolve (by rain or irrigation) into runoff or groundwater.

Nitrate levels above 10 mg/L (10 ppm) in groundwater can cause 'blue baby syndrome
Blue baby syndrome
Blue baby syndrome is a layman's term used to describe newborns with cyanotic heart lesions, such as* Persistent Truncus Arteriosus* Transposition of the great vessels* Tricuspid atresia* Tetralogy of Fallot...

' (acquired methemoglobinemia
Methemoglobinemia
Methemoglobinemia is a disorder characterized by the presence of a higher than normal level of methemoglobin in the blood. Methemoglobin is an oxidized form of hemoglobin that has an increased affinity for oxygen, resulting in a reduced ability to release oxygen to tissues. The oxygen–hemoglobin...

), leading to hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...

 (which can lead to coma and death if not treated).

Soil acidification

Nitrogen-containing inorganic and organic fertilizers can cause soil acidification
Soil acidification
Soil acidification is the buildup of hydrogen cations, also called protons, reducing the soil pH. This happens when a proton donor is added to the soil. The donor can be an acid, such as nitric acid and sulfuric acid . It can also be a compound such as aluminium sulfate, which reacts in the soil to...

 when added. http://soil.scijournals.org/cgi/content/full/72/1/238. This may lead to decreases in nutrient availability which may be offset by liming.

Persistent organic pollutants

Toxic persistent organic pollutants ("POPs"), such as Dioxins, polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) have been detected in agricultural fertilizers and soil amendments

Heavy metal accumulation

The concentration of up to 100 mg/kg of cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...

 in phosphate minerals
Phosphate minerals
Phosphate minerals are those minerals that contain the tetrahedrally coordinated phosphate anion along with the freely substituting arsenate and vanadate...

 (for example, minerals from Nauru
Nauru
Nauru , officially the Republic of Nauru and formerly known as Pleasant Island, is an island country in Micronesia in the South Pacific. Its nearest neighbour is Banaba Island in Kiribati, to the east. Nauru is the world's smallest republic, covering just...


and the Christmas island
Christmas Island
The Territory of Christmas Island is a territory of Australia in the Indian Ocean. It is located northwest of the Western Australian city of Perth, south of the Indonesian capital, Jakarta, and ENE of the Cocos Islands....

s) increases the contamination of soil with cadmium, for example in New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

.

Steel industry wastes, recycled into fertilizers for their high levels of zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

 (essential to plant growth), wastes can include the following toxic metals: lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...

 arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

, cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...

, chromium
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...

, and nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...

. The most common toxic elements in this type of fertilizer are mercury, lead, and arsenic. Concerns have been raised concerning fish meal
Fish meal
Fish meal, or fishmeal, is a commercial product made from both whole fish and the bones and offal from processed fish. It is a brown powder or cake obtained by rendering pressing the cooked whole fish or fish trimmings to remove most of the fish oil and water, and then ground...

 mercury content by at least one source in Spain

Radioactive element accumulation

Uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...

 is another example of a contaminant often found in phosphate fertilizers (at levels from 7 to 100 pCi/g). Eventually these heavy metals can build up to unacceptable levels and build up in vegetable produce. Average annual intake of uranium by adults is estimated to be about 0.5 mg (500 μg) from ingestion of food and water and 0.6 μg from breathing air.

Also, highly radioactive Polonium-210 contained in phosphate fertilizers is absorbed by the roots of plants and stored in its tissues; tobacco
Tobacco
Tobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines...

 derived from plants fertilized by rock phosphates contains Polonium-210 which emits alpha radiation estimated to cause about 11,700 lung cancer deaths each year worldwide.
For these reasons, it is recommended that nutrient budgeting
Nutrient budgeting
Nutrient budgeting is used in agriculture.The process involves balancing nutrients coming into the farming system with those leaving. The aim is to prevent pollution events and save costs by precisely matching the nutrient requirements of the crop with application of organic and inorganic...

, through careful observation and monitoring of crops, take place to mitigate the effects of excess fertilizer application.

Atmosphere

Methane emissions from crop fields (notably rice paddy field
Paddy field
A paddy field is a flooded parcel of arable land used for growing rice and other semiaquatic crops. Paddy fields are a typical feature of rice farming in east, south and southeast Asia. Paddies can be built into steep hillsides as terraces and adjacent to depressed or steeply sloped features such...

s) are increased by the application of ammonium-based fertilizers; these emissions contribute greatly to global climate change as methane is a potent greenhouse gas.

Through the increasing use of nitrogen fertilizer, which is added at a rate of 1 billion tons per year presently to the already existing amount of reactive nitrogen, nitrous oxide
Nitrous oxide
Nitrous oxide, commonly known as laughing gas or sweet air, is a chemical compound with the formula . It is an oxide of nitrogen. At room temperature, it is a colorless non-flammable gas, with a slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic...

 (N2O) has become the third most important greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

 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.

Storage and application of some nitrogen fertilizers in some weather or soil conditions can cause emissions of the potent greenhouse gas—nitrous oxide. Ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 gas (NH3) may be emitted following application of 'inorganic' fertilizers and/or manures and slurries.

The use of fertilizers on a global scale emits significant quantities of greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

 into the atmosphere. Emissions come about through the use of:
  • animal manures and urea
    Urea
    Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....

    , which release methane
    Methane
    Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

    , nitrous oxide
    Nitrous oxide
    Nitrous oxide, commonly known as laughing gas or sweet air, is a chemical compound with the formula . It is an oxide of nitrogen. At room temperature, it is a colorless non-flammable gas, with a slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic...

    , ammonia
    Ammonia
    Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

    , and carbon dioxide
    Carbon dioxide
    Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

     in varying quantities depending on their form (solid or liquid) and management (collection, storage, spreading)
  • fertilizers that use nitric acid
    Nitric acid
    Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...

     or ammonium bicarbonate
    Ammonium bicarbonate
    Ammonium bicarbonate, a compound with formulaNH4, also called bicarbonate of ammonia, ammonium hydrogen carbonate, hartshorn, AmBic or powdered baking ammonia, is the bicarbonate salt of ammonia....

    , the production and application of which results in emissions of nitrogen oxides, nitrous oxide
    Nitrous oxide
    Nitrous oxide, commonly known as laughing gas or sweet air, is a chemical compound with the formula . It is an oxide of nitrogen. At room temperature, it is a colorless non-flammable gas, with a slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic...

    , ammonia
    Ammonia
    Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

     and carbon dioxide
    Carbon dioxide
    Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

     into the atmosphere.


By changing processes and procedures, it is possible to mitigate some, but not all, of these effects on anthropogenic climate change.

Increased pest fitness

Excessive nitrogen fertilizer applications can also lead to pest problems by increasing the birth rate, longevity and overall fitness of certain agricultural pests, such as aphid
Aphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...

s (plant lice).

See also

  • Soil fertility
  • Manure
    Manure
    Manure is organic matter used as organic fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen, that are trapped by bacteria in the soil...

  • Organic fertilizer
    Organic fertilizer
    Organic fertilizers are naturally occurring fertilizers .Naturally occurring organic fertilizers include manure, slurry, worm castings, peat, seaweed, humic acid, and guano. Sewage sludge use in organic agricultural operations in the U.S...

  • Fertigation
    Fertigation
    Fertigation is the application of fertilizers, soil amendments, or other water-soluble products through an irrigation system.Chemigation, a related and sometimes interchangeable term, is the application of chemicals through an irrigation system...

  • NPK rating
    NPK rating
    NPK rating is used to label fertilizer based on the relative content of the chemicals nitrogen, phosphorus, and potassium that are commonly used in fertilizers....

  • Fertilizer labeling
    Labeling of fertilizer
    The labeling of fertilizers varies by country in terms of analysis methodology and subsequently nutrient labeling, and minimum nutrient requirements.-Macronutrient fertilizers:...

  • Agriculture and the environment
  • Phosphogypsum
    Phosphogypsum
    Phosphogypsum refers to the gypsum formed as a by-product of processing phosphate ore into fertilizer with sulfuric acid.Phosphogypsum is produced from the fabrication of phosphoric acid by reacting phosphate ore with sulfuric acid according to the following reaction:Phosphogypsum is radioactive...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK