Fertilizer/ja: Difference between revisions

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 | image1 = Compound fertiliser.jpg

 | alt1 = Compound fertiliser

 | caption1 = 化成肥料

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 | alt2 = Bulk-blend fertiliser

 | caption2 = バルクブレンド肥料

{{excerpt|Controlled-release fertilizer/ja}}

===Water===

{{Main|Eutrophication}}

[[File:Aquatic Dead Zones.jpg|thumb|Red circles show the location and size of many [[Dead zone (ecology)|dead zones]].]]

Phosphorus and nitrogen fertilizers can affect soil, surface water, and groundwater due to the dispersion of minerals into waterways due to high rainfall, snowmelt and can leaching into groundwater over time. Agricultural run-off is a major contributor to the eutrophication of freshwater 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. Fertilizer run-off can be reduced by using weather-optimized fertilization strategies.

The nitrogen-rich compounds found in fertilizer runoff are the primary cause of serious oxygen depletion in many parts of [[ocean]]s, especially in coastal zones, [[lake]]s and [[river]]s. 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 is increasing.

As of 2006, the application of nitrogen fertilizer is being increasingly controlled in northwestern Europe and the United States. In cases where eutrophication can be reversed, it may nevertheless take decades and significant soil management 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]]). Run-off can lead to fertilizing blooms of algae that use up all the oxygen and leave huge "dead zones" behind where other fish and aquatic life can not live.

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===Soil===

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==== Acidification ====

Soil acidification refers to the process by which the pH level of soil becomes more acidic over time. Soil pH is a measure of the soil's acidity or alkalinity and is determined on a scale from 0 to 14, with [[Seven (1995 film)|7]] being neutral. A pH value below 7 indicates acidic soil, while a pH value above 7 indicates alkaline or basic soil.

Soil acidification is a significant concern in agriculture and horticulture. It refers to the process of the soil becoming more acidic over time. {{See also|Soil pH|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]]. These fertilizers release ammonium or nitrate ions, which can acidify the soil as they undergo chemical reactions.

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When these nitrogen-containing fertilizers are added to the soil, they increase the concentration of hydrogen ions (H+) in the soil solution, which lowers the pH of the soil.

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====Accumulation of toxic elements====

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=====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&nbsp;mg/kg or as high as 50.9&nbsp;mg/kg. The phosphate rock used in their manufacture can contain as much as 188&nbsp;mg/kg cadmium (examples are deposits on [[Nauru]] and the [[Christmas Island]]s). 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.

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=====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.

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=====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 (picocuries per gram) 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 m[[Sievert|Sv]]/y).

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=====Other metals=====

Steel industry wastes, recycled into fertilizers for their high levels of [[zinc]] (essential to plant growth), wastes can include the following [[Toxic heavy metal|toxic metals]]: [[lead]] [[arsenic]], [[cadmium]], chromium, and nickel. The most common toxic elements in this type of fertilizer are [[Mercury (element)|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.

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====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]], copper, [[manganese]], iron and [[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.

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====Changes in soil biology====

{{Further|soil biology}}

High levels of fertilizer may cause the breakdown of the [[Symbiosis|symbiotic]] relationships between plant roots and [[mycorrhiza]]l fungi.

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===Organic agriculture===

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===Hydrogen consumption and sustainability===

Most fertilizer is made from dirty hydrogen. Ammonia is produced from [[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<!-- over which period? -->.

====Contribution to climate change====

{{See also|Greenhouse gas emissions from agriculture}}

The amount of [[greenhouse gas]]es [[carbon dioxide]], [[methane]] and [[nitrous oxide]] produced during the [[Haber process|manufacture]] and use of nitrogen fertilizer is estimated as around 5% of [[anthropogenic greenhouse gas emissions]]. One third is produced during the production and two thirds during the use of fertilizers. 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&nbsp;°C.

===Atmosphere===

[[File:AtmosphericMethane.png|thumb|Global [[methane]] concentrations (surface and atmospheric) for 2005; note distinct plumes]]

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

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==Policy==

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===Regulation===

In Europe, problems with high nitrate concentrations in runoff are being addressed by the European Union's Nitrates Directive. Within [[Great Britain|Britain]], farmers are encouraged to manage their land more sustainably in 'catchment-sensitive farming'. In the [[United States|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 (state)|Washington]], both in the United States, have fertilizer registration programs with on-line databases listing chemical analyses of fertilizers. [[Carbon emission trading]] and [[eco-tariff]]s affect the production and price of fertilizer.

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===Subsidies===

In [[China]], regulations have been implemented to control the use of N fertilizers in farming. In 2008, Chinese governments began to partially withdraw fertilizer [[subsidy|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.

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In March 2022, the United States Department of Agriculture announced a new $250M grant to promote American fertilizer production. Part of the Commodity Credit Corporation, the grant program will support fertilizer production that is independent of dominant fertilizer suppliers, made in America, and utilizing innovative production techniques to jumpstart future competition.