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definitions - fertiliser

fertiliser (n.)

1.any substance such as manure or a mixture of nitrates used to make soil more fertile

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fertiliser (n.)


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Fertilizer

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Fertilizers are soil amendments applied to promote plant growth; the main nutrients contributed by fertilizer are nitrogen, phosphorus, and potassium (the 'Macronutrients') and other nutrients ('Micronutrients') are added in smaller amounts. Fertilizers are usually directly applied to soil, and also sprayed on leaves ('foliar feeding').

Fertilizers are roughly broken up between organic and inorganic fertilizer, with the main difference between the two being sourcing, and not necessarily differences in nutrient content.

Organic fertilizers and some mined inorganic fertilizers have been used for centuries, whereas chemically-synthesized inorganic fertilizers were only widely developed during the industrial revolution. Increased understanding and use of fertilizers were important parts of the pre-industrial British Agricultural Revolution and the industrial green revolution of the 20th century[citation needed].

File:Woolbrook (2).JPG
An old fertilizer spreader, New South Wales.

Contents

Nutrient content

The availability of nutrients ( managed as part of liming and manuring practices rather than through purpose made fertilizers[citation needed].

Macronutrients

Fertilizers typically provide, in varying proportions the three primary macronutrients: nitrogen, phosphorus, and potassium (NPK). The macronutrients are consumed in larger quantities and are present in plant tisue in quantities greater than 1% or even 10%(on a dry matter weight basis)[citation needed].

Micronutrients

File:TVA Results of Fertilizer.gif
Fertilizer plot demonstration (1942)

The three main secondary macronutrients: calcium (Ca), sulfur (S), magnesium (Mg).

Micronutrients are present in quantities measured in parts per million (ppm), ranging from 5-100 ppm by mass, or less than 0.01% by percentage dry weight[citation needed].

Labeling of fertilizers

Macronutrient fertilizers

Macronutrient fertilizers are labeled with an NPK analysis and can be referred to by its NPK content. However, these numbers do not directly represent the source composition or absolute nutrient content of the fertilizer[citation needed]--macronutrient fertilizers are not labeled by content but according to traditional analysis[vague].

For example, the fertilizer potash is a naturally occuring mineral composed of nearly pure potassium chloride (KCl). As such, its composition is 1:1 potassium to chloride or 52% potassium and 48% chlorine by weight (owing to differences in molecular weight between the elements). Traditional analysis of 100g. of KCl would yield 60g. K2O. 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 0-0-60, not 0-0-52.

Fertilizer is described in this way dating back to Liebig in the 19th century due to the methods he used then to compare and evaluate fertilizers[1]

Converting nutrient analysis to composition

P2O5 consists of 57.4% oxygen and 43.6% elemental phosphorus. The percentage([mass fraction]) of elemental phosphorus is 43.6% so P= 0.43 x P2O5. K2O consists of 17% oxygen and 83% elemental potassium. The percentage (mass fraction) of elemental potassium is 83% so K = 0.83 x K2O.

Nitrogen values represent actual nitrogen content so these numbers do not need to be converted.

Using these conversion factors we determine that 18−51−20 fertilizer contains (by weight):

  • 18% elemental (N)
  • 22% elemental (P)
  • 16% elemental (K)

In the U.K., fertilizer labeling regulations allow for reporting elemental mass fractions of phosphorus and potassium. The regulations stipulate this should be done in parentheses after standard NPK values. [2].

Other fertilizer designations

Fertilizer containing only the three primary macronutrients can be referred to as artificial or straight[citation needed]. Compound fertilizers are N-P-K fertilizers with other elements purposely intermixed[citation needed]. For example, a mainly nitrogenous fertilizer mix would be described as a nitrogen fertilizer.

History

While manure, cinder and ironmaking slag have been used to improve crops for centuries, use of inorganic artificial fertilizer is one innovations of the 19th century Agricultural Revolution.

Inorganic fertilizer (synthetic fertilizer)

Fertilizers are broadly divided into organic fertilizers (composed of enriched organic matter—plant or animal), or inorganic fertilizers (composed of synthetic chemicals and/or minerals).

Inorganic fertilizer is often synthesized using the Haber-Bosch process, which produces ammonia as the end product. This ammonia is used as a feedstock for other nitrogen fertilizers, such as anhydrous ammonium nitrate and urea. These concentrated products may be diluted with water to form a concentrated liquid fertilizer (e.g. UAN). Ammonia can be combined with rock phosphate and potassium fertilizer in the Odda Process to produce compound fertilizer.

Major users of nitrogen-based fertilizer[3]
CountryTotal N use

(Mt pa)

Amt. used

(feed & pasture)

China18.73.0
U.S.9.14.7
France2.51.3
Germany2.01.2
Brazil1.70.7
Canada1.60.9
Turkey1.50.3
U.K.1.30.9
Mexico1.30.3
Spain1.20.5
Argentina0.40.1

Application

Synthetic fertilizers are commonly used to treat fields used for growing maize, followed by barley, sorghum, rapeseed, soy and sunflower[citation needed]. One study has shown that application of nitrogen fertilizer on off-season cover crops can increase the biomass (and subsequent green manure value) of these crops, while having a beneficial effect on soil nitrogen levels for the main crop planted during the summer season.[4]

Problems of inorganic fertilizer

Trace mineral depletion

Many inorganic fertilizers do 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.[5]

However, a recent review of 55 scientific studies concluded "there is no evidence of a difference in nutrient quality between organically and conventionally produced foodstuffs" [6] Conversely, a major long-term study funded by the European Union[7][8] [9]found that organically-produced milk and produce were significantly higher in antioxidants (such as carotenoids and alpha-linoleic acids) than their conventionally grown counterparts.

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[citation needed]. Soils in Western Australia are very old, highly weathered and deficient in many of the major nutrients and trace elements[citation needed]. Since this time these trace elements are routinely added to inorganic fertilizers used in agriculture in this state[citation needed].

Overfertilization
Fertilizer burn

Over-fertilization of a vital nutrient can be as detrimental as underfertilization.[10] "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.[11]

High energy consumption

The production of synthetic ammonia currently consumes about 5% of global natural gas consumption, which is somewhat under 2% of world energy production.[12]

Natural gas is overwhelmingly used for the production of ammonia, 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.[13] 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[citation needed].

Long-Term Sustainability

Inorganic fertilizers are now produced in ways which cannot be continued indefinitely[citation needed]. Potassium and phosphorus come from mines (or saline lakes such as the Dead Sea) and such resources are limited. Atmospheric (unfixed) 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 (conversion of atmospheric nitrogen to a plant-accessible form).

Artificial nitrogen fertilizers are typically synthesized using fossil fuels such as natural gas and coal, which are limited resources. In lieu of converting natural gas to syngas for use in the Haber process, it is also possible to convert renewable biomass to syngas (or wood gas) to supply the necessary energy for the process, though the amount of land and resources (ironically often including fertilzer) necessary for such a project may be prohibitive (see Energy conservation in the United States).

Organic fertilizers

File:HomeComposting Roubaix Fr59.JPG

Compost bin for small-scale production of organic fertilizer and a larger commercial compost operation.

Organic fertilizers include naturally-occurring organic materials, (e.g. manure, worm castings, compost, seaweed), or naturally occurring mineral deposits (e.g. saltpeter, guano).

Benefits of organic fertilizer

In addition to increasing yield and fertilizing plants directly, organic fertilizers can improve the biodiversity (soil life) and long-term productivity of soil[14][15], and may prove a large depository for excess carbon dioxide[16][17][18].

Organic nutrients increase the abundance of soil organisms by providing organic matter and micronutrients for organisms such as fungal mycorrhiza[19], (which aid plants in absorbing nutrients), and can drastically reduce external inputs of pesticides, energy and fertilizer, at the cost of decreased yield[20].

Comparison with inorganic fertilizer

Organic fertilizer nutrient content, solubility, and nutrient release rates are typically all lower than inorganic fertilizers[21][22].One study[which?] found that over a 140-day period, after 7 leachings:

  • 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 UC IPM, all organic fertilizers are classified as 'slow-release' fertilizers, and therefore cannot cause nitrogen burn[23].

Organic fertilizers from composts and other sources can be quite variable from one batch to the next[citation needed], 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[citation needed].

Organic fertilizer sources

Animal

Decomposing animal manure, an organic fertilizer source

Animal-sourced Urea , are suitable for application organic agriculture, while pure synthetic forms of urea are not[24][25]. 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), as well as being naturally-occurring or via natural biological processes such as composting.

Sewage sludge use in organic agricultural operations in the U.S. has been extremely limited and rare due to USDA prohibition of the practice (due to toxic metal accumulation, among other factors)[26][27][28].The USDA now requires 3rd-party certification of high-nitrogen liquid organic fertilizers sold in the U.S.[29]

Plant

Cover crops are also grown to enrich soil as a green manure through nitrogen fixation from the atmosphere[30]; as well as phosphorus (through nutrient mobilization)[31] content of soils. Minerals such as mined rock phosphate, sulfate of potash and limestone are considered organic fertilizers because they are naturally occurring and non-artificial, (although in chemistry terminology, they are considered "inorganic" because they contain no (carbon) molecules).

Mineral

Naturally mined powdered limestone[32], mined rock phosphate and sodium nitrate, are inorganic (in a chemical sense), and are energetically-intensive to harvest, yet are still approved for usage in organic agriculture in minimal amounts[32][33][34].

Environmental effects of fertilizer use

Water

Eutrophication

A rapid and large-scale influx of available nutrients (especially phosphorus) causes algal bloom, eventually starving other organisms of light and oxygen

The nitrogen-rich compounds found in fertilizer run-off 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.[35] 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 near inhabited coastlines are increasing.[36] As of 2006, the application of nitrogen fertilizer is being increasingly controlled in Britain and the United States[citation needed]. If eutrophication can be reversed, it may take decades[citation needed] before the accumulated nitrates in groundwater can be broken down by natural processes.

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 into groundwater.[37][38][39] 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.[40]

Blue Baby Syndrome

Nitrate levels above 10 mg/L (10 ppm) in groundwater can cause 'blue baby syndrome' (acquired methemoglobinemia), leading to hypoxia (which can lead to coma and death if not treated)[41].

Effects of fertilizer on soil

Acidification

Nitrogen-containing inorganic and organic fertilizers can cause soil acidification[42]. [4]

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[43]

Heavy metal accumulation

The concentration of up to 100 mg/kg of cadmium in phosphate minerals (for example, minerals from Nauru[44]and the Christmas islands[45]) increases the contamination of soil with cadmium, for example in New Zealand.[46] Uranium is another example of a contaminant often found in phosphate fertilizers[citation needed]. Eventually these heavy metals can build up to unacceptable levels and build up in vegetable produce.[46] (See cadmium poisoning)

Steel industry wastes, recycled into fertilizers for their high levels of zinc (essential to plant growth), wastes can include the following toxic metals: lead[47]arsenic, cadmium[47], chromium, and nickel. The most common toxic elements in this type of fertilizer are mercury, lead, and arsenic.[48][49] Concerns have been raised concerning fish meal mercury content by at least one source in Spain[50]

Also, highly-radioactive Polonium-210 contained in phosphate fertilizers is absorbed by the roots of plants and stored in its tissues; tobacco 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.[51][52][53][54][55][56]

For these reasons, it is recommended that nutrient budgeting, through careful observation and monitoring of crops, take place to mitigate the effects of excess fertilizer application.

Other problems

Atmospheric effects

Through the increasing use of nitrogen fertilizer, which is added at a rate of 120 million tons per year presently[57] to the already existing amount of reactive nitrogen, nitrous oxide (N2O) has become the third most important greenhouse gas after carbon dioxide and methane, with a global warming potential 296 times larger than an equal mass of carbon dioxide, while it also contributes to stratospheric ozone depletion.[58]

Storage and application of some nitrogen fertilizers in some[which?] weather or soil conditions can cause emissions of the potent greenhouse gas—nitrous oxide. Ammonia gas (NH3) may be emitted following application of 'inorganic' fertilizers and/or manures and slurries.[citation needed]

The use of fertilizers on a global scale emits significant quantities of greenhouse gas into the atmosphere. Emissions come about through the use of:[59]

By changing processes and procedures, it is possible to mitigate some, but not all, of these effects on anthropogenic climate change{{Citation needed|date=November 2009}.

Increased pest health

Excessive nitrogen fertilizer applications can also lead to pest problems by increasing the birth rate, longevity and overall fitness of certain agricultural pests.[60][61][62][63][64][65]

See also

References

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  2. ^ UK Fertilizers Regulations 1990, Schedule 2 Part 1, Para. 7.
  3. ^ United Nations Food and Agriculture Organization, Livestock's Long Shadow: Environmental Issues and Options, Table 3.3 retrieved 29 Jun 2009
  4. ^ Nitrogen Applied Newswise, Retrieved on October 1, 2008.
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WordGame

The English word games are:
○   Anagrams
○   Wildcard, crossword
○   Lettris
○   Boggle.

Lettris

Lettris is a curious tetris-clone game where all the bricks have the same square shape but different content. Each square carries a letter. To make squares disappear and save space for other squares you have to assemble English words (left, right, up, down) from the falling squares.

boggle

Boggle gives you 3 minutes to find as many words (3 letters or more) as you can in a grid of 16 letters. You can also try the grid of 16 letters. Letters must be adjacent and longer words score better. See if you can get into the grid Hall of Fame !

English dictionary
Main references

Most English definitions are provided by WordNet .
English thesaurus is mainly derived from The Integral Dictionary (TID).
English Encyclopedia is licensed by Wikipedia (GNU).

Copyrights

The wordgames anagrams, crossword, Lettris and Boggle are provided by Memodata.
The web service Alexandria is granted from Memodata for the Ebay search.
The SensagentBox are offered by sensAgent.

Translation

Change the target language to find translations.
Tips: browse the semantic fields (see From ideas to words) in two languages to learn more.

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