View source for Alkali soil

{{Short description|Soil type with pH > 8.5}}
{{Cleanup|reason=General layout and markup, especially with respect to chemical formulas and equations|date=February 2018}}
{{Infobox soil
| name = Alkali soil
| alternative_name = Alkaline soils
| image = Rice Field.jpg
| image_caption = Rice cultivation / [[paddyfield]] in alkali soils
| image_size =
| type = Clay soil
| classification_system =
| code =
| profile = 
| mineral = Sodium carbonate and sodium bicarbonate
| process = Lime softening
| parent_material =
| climate =
| ph => 8.5
| horizons =
| composition =
| composition_secondary = 
}}

'''Alkali''', or ''' alkaline''', '''soils''' are [[clay]] [[soil]]s with high [[Soil pH|pH]] (greater than 8.5), a poor [[soil structure]] and a low infiltration capacity. Often they have a hard [[calcareous]] layer at 0.5 to 1&nbsp;metre depth. Alkali soils owe their unfavorable [[Physical chemistry|physico-chemical]] properties mainly to the dominating presence of [[sodium carbonate]], which causes the soil to swell<ref name="oregonstateedu">[http://extension.oregonstate.edu/umatilla/mf/sites/default/files/pnw597-e.pdf Managing irrigation water quality, Oregon State University, USA], Retrieved on 2012-10-04.</ref> and difficult to clarify/settle. They derive their name from the [[alkali metal]] group of elements, to which [[sodium]] belongs, and which can induce [[basicity]]. Sometimes these soils are also referred to as alkaline [[sodic soils]]. Alkaline soils are [[Base (chemistry)|basic]], but not all basic soils are [[alkali]]ne.

==Causes==

The causes of soil alkalinity can be natural or man-made:
# The natural cause is the presence of soil minerals producing [[sodium carbonate]] (Na<sub>2</sub>CO<sub>3</sub>) and [[sodium bicarbonate]] (NaHCO<sub>3</sub>) upon [[weathering]].
# Coal-fired boilers / power plants, when using coal or lignite rich in [[limestone]], produce [[Fly ash|ash]] containing [[calcium oxide]]. CaO readily dissolves in water to form [[slaked lime]], Ca(OH)<sub>2</sub>, and carried by rain water to rivers / irrigation water. [[Lime softening]] process precipitates Ca<sup>2+</sup> and Mg<sup>2+</sup> ions / removes hardness in the water and also converts sodium bicarbonates in river water into sodium carbonate.<ref>{{cite web|url=http://www.gewater.com/handbook/ext_treatment/ch_7_precipitation.jsp|archive-url=https://archive.today/20130124043954/http://www.gewater.com/handbook/ext_treatment/ch_7_precipitation.jsp|url-status=dead|archive-date=January 24, 2013|title=Precipitation softening, GE Power & Water|access-date=11 October 2012}}</ref> Sodium carbonates (washing soda) further reacts with the remaining Ca<sup>2+</sup> and Mg<sup>2+</sup> in the water to remove / precipitate the total [[Hard water|hardness]]. Also water-soluble sodium salts present in the ash enhance the sodium content in water. The global [[coal]] consumption in the world was 7.7 billion tons in the year 2011.{{Citation needed|date=June 2021}} Thus river water is made devoid of Ca<sup>2+</sup> and Mg<sup>2+</sup> ions and enhanced Na<sup>+</sup> by coal-fired boilers.{{Clarify|date=June 2021}}
# Many sodium salts are used in industrial and domestic applications such as [[sodium carbonate]], [[sodium bicarbonate]] (baking soda), [[sodium sulphate]], [[sodium hydroxide]] (caustic soda), [[sodium hypochlorite]] (bleaching powder),  etc. in huge quantities. These salts are mainly produced from [[sodium chloride]] (common salt). All the sodium in these salts enter into the river / ground water during their production process or consumption enhancing water sodicity. The total global consumption of [[sodium chloride]] is 270 million tons in the year 2010. This is nearly equal to the [[Dissolved load|salt load]] in the mighty [[Amazon River]]. Man made sodium salts contribution is nearly 7% of total salt load of all the rivers. Sodium salt load problem aggravates in the downstream of intensively cultivated river basins located in China, India, Egypt, Pakistan, west Asia,  Australia, western US, etc. due to accumulation of salts in the remaining water after meeting various transpiration and evaporation losses.<ref>{{cite web|url=http://irrisoft.org/cms/fileadmin/content/zfb/1998_02/keller_keller_davids_1998_river_basin_development_phases_implications_closure.pdf|title=River basin development phases and implications of closure|author=J. Keller, A. Keller and G. Davids|access-date=25 August 2012|archive-url=https://web.archive.org/web/20131019161418/http://irrisoft.org/cms/fileadmin/content/zfb/1998_02/keller_keller_davids_1998_river_basin_development_phases_implications_closure.pdf|archive-date=19 October 2013|url-status=dead}}</ref>
# Another source of man-made sodium salts addition to the agriculture fields / land mass is in the vicinity of the [[Cooling tower|wet cooling towers]] using sea water to dissipate [[waste heat]] generated in various industries located near the sea coast. Huge capacity cooling towers are installed in oil refineries, petrochemical complexes, fertilizer plants, chemical plants, nuclear & thermal power stations, centralized [[HVAC]] systems, etc. The drift / fine droplets emitted from the cooling towers contain nearly 6% sodium chloride which would deposit on the vicinity areas. This problem aggravates where the national pollution control norms are not imposed or not implemented to minimize the drift emissions to the best industrial norm for the sea water based wet cooling towers.<ref>{{cite web|url=http://www.ec.gc.ca/inrp-npri/default.asp?lang=En&n=2ED8CFA7-1|title= Wet Cooling Tower Guidance For Particulate Matter, Environment Canada|date= 25 November 2008|access-date=2013-01-29}}</ref> 
# The man-made cause is the application of [[water softening|softened water]] in [[irrigation]] (surface or ground water) containing relatively high proportion of [[sodium bicarbonate]]s and less calcium and magnesium.<ref name="oregonstateedu" />

==Agricultural problems==
[[File:World_Soil_pH.svg|right|thumb|500x500px|Global variation in soil pH: '''<span style="color:blue;">blue</span>''' denotes alkaline soils widespread in, e. g., [[MENA]]]]
Alkaline soils are difficult to take into agricultural production. Due to the low [[infiltration capacity]], rain water stagnates on the soil easily and, in dry periods, cultivation is hardly possible without copious irrigated water and good drainage.  Agriculture is limited to crops tolerant to surface [[waterlogging (agriculture)|waterlogging]] (e.g. [[rice]], grass) and the productivity is lower.

==Chemistry==
Soil alkalinity is associated with the presence of [[sodium carbonate]] (Na<sub>2</sub>CO<sub>3</sub>) or [[sodium bicarbonate]] (NaHCO<sub>3</sub>) in the soil,<ref name="Handbook">[https://web.archive.org/web/20061012023422/http://www.ars.usda.gov/SP2UserFiles/Place/53102000/hb60_pdf/hb60complete.pdf US Salinity Lab Handbook 60]</ref> either as a result of natural [[weathering]] of the soil particles or brought in by irrigation and/or flood water.

This salt is extremely soluble, when it undergoes [[hydration reaction|hydration]], it dissociates in:

:{{chem|Na|2|CO|3}} → 2 {{chem|Na|+}} + {{chem|C|O|3|2-}}

The carbonate anion {{chem|CO|3|2−}}, is a weak [[base (chemistry)|base]] accepting a proton, so it [[hydrolysis|hydrolyses]] in water to give the [[bicarbonate]] ion and a [[hydroxyl ion]]:

:{{chem|CO|3|2-}} + {{chem|H|2|O}} → {{chem|H|C|O|3|-}} + {{chem|OH|-}}

which in turn gives [[carbonic acid]] and hydroxyl:

:{{chem|H|CO|3|-}} + {{chem|H|2|O}} → {{chem|H|2|C|O|3}} + {{chem|OH|-}}

See [[Carbonate#Chemical properties|carbonate]] for the equilibrium of carbonate-bicarbonate-carbon dioxide.

The above reactions are similar to the dissolution of [[calcium carbonate]], the solubility of the two salts being the only difference. Na<sub>2</sub>CO<sub>3</sub> is about {{val|78000}} times more soluble than CaCO<sub>3</sub>, so it can dissolve far larger amounts of {{chem|CO|3|2−}}, thus rising the pH to values higher than 8.5, which is above the maximum attainable pH when the equilibrium between calcium carbonate and dissolved [[carbon dioxide]] are in equilibrium in soil solution.

:''Notes'':
:* Water (H<sub>2</sub>O) is partly dissociated into H<sub>3</sub>O<sup>+</sup> ([[hydronium]]) and OH<sup>–</sup> ([[hydroxyl]]) ions. The [[ion]] H<sub>3</sub>O<sup>+</sup> has a positive [[electric charge]] (+) and its concentration is usually written as [H<sup>+</sup>]. The hydroxyl ion OH<sup>–</sup> has a negative charge (−) and its concentration is written as [OH<sup>−</sup>].
:* In pure water, at 25&nbsp;°C, the [[dissociation constant]] of water (''K''<sub>w</sub>) is 10<sup>−14</sup>.<br />Since K<sub>w</sub> = [H<sup>+</sup>] × [OH<sup>–</sup>], then both the concentration of H<sub>3</sub>O<sup>+</sup> and OH<sup>–</sup> ions equal 10<sup>−7</sup>&nbsp;M (a very small concentration).
:* In neutral water, the [[pH]], being the negative decimal [[logarithm]] of the H<sub>3</sub>O<sup>+</sup> concentration, it is 7. Similarly, the [[PH#pOH|pOH]] is also 7. Each unit decrease in pH indicates a tenfold increase of the H<sub>3</sub>O<sup>+</sup> concentration. Similarly, each unit increase in pH indicates a tenfold increase of the OH<sup>–</sup> concentration.
:* In water with [[Dissolution (chemistry)|dissolved]] [[Salt (chemistry)|salts]], the concentrations of the H<sub>3</sub>O<sup>+</sup> and the OH<sup>–</sup> ions may change, but their sum remains constant, namely {{nowrap|7 + 7 {{=}} 14}}. A pH of 7 therefore corresponds to a pOH of 7, and a pH of 9 with a pOH of 5.
:* Formally it is preferred to express the ion concentrations in terms of [[chemical activity]], but this hardly affects the value of the pH.
:* Water with excess H<sub>3</sub>O<sup>+</sup> ions is called acid ({{nowrap|pH < 7}}), and water with excess OH<sup>–</sup> ions is called alkaline or rather basic ({{nowrap|pH > 7}}). Soil moisture with {{nowrap|pH < 4}} is called very acid and with {{nowrap|pH&nbsp;>&nbsp;10}} very alkaline (basic).

H<sub>2</sub>CO<sub>3</sub> ([[carbonic acid]]) is unstable and produces H<sub>2</sub>O (water) and CO<sub>2</sub> ([[carbon dioxide]] gas, escaping into the atmosphere). This explains the remaining [[alkali]]nity (or rather [[basicity]]) in the form of soluble [[sodium hydroxide]] and the high [[pH]] or low [[PH#pOH|pOH]].

Not all the dissolved sodium carbonate undergoes the above chemical reaction. The remaining sodium carbonate, and hence the presence of {{chem|CO|3|2−}} ions, causes CaCO<sub>3</sub> (which is only slightly soluble) to precipitate as solid [[calcium carbonate]] (limestone), because the product of the  {{chem|CO|3|2−}} concentration and the  Ca<sup>2+</sup> concentration exceeds the allowable limit. Hence, the calcium ions Ca<sup>2+</sup> are immobilized.
<!--This equation seems superfluous
:2Na<sup>+</sup> + {{chem|CO|3|2−}} + Ca<sup>2+</sup> → 2Na<sup>+</sup> + CaCO<sub>3</sub> (solid)
-->
[[File:ExchangeESP.JPG|thumb|300px|Sodium exchange process between ions adsorbed at the surface of clay particles and those in the [[soil moisture]]]]
The presence of abundant Na<sup>+</sup> ions in the soil solution and the precipitation of Ca<sup>2+</sup> ions as a solid mineral causes the [[clay]] particles, which have negative electric charges along their surfaces, to adsorb more Na<sup>+</sup> in the ''diffuse adsorption zone'' (DAZ, also more commonly called ''[[diffuse double layer]]'' (DDL), or [[electrical double layer]] (EDL), see the corresponding figure)<ref name="Bolt">G.H. Bolt (ed.), 1981. Soil chemistry: A. basic elements. Vol 5a, Elsevier, Amsterdam, the Netherlands</ref> and, in exchange, release previously adsorbed Ca<sup>2+</sup>, by which their ''exchangeable sodium percentage'' (ESP) is increased as illustrated in the same figure.

Na<sup>+</sup> is more mobile and has a smaller electric charge than Ca<sup>2+</sup> so that the thickness of the DDL increases as more sodium ions occupy it. The DDL thickness is also influenced by the total concentration of ions in the soil moisture in the sense that higher concentrations cause the DDL zone to shrink.

Clay particles with considerable ESP (> 16), in contact with non-saline soil moisture have an expanded DDL zone and the soil swells ([[dispersion (geology)|dispersion]]).<ref name="Bolt"/>
The phenomenon results in deterioration of the [[soil structure]], and especially crust formation and compaction of the top layer.
Hence the infiltration capacity of the soil and the water availability in the soil is reduced, whereas the surface-water-logging or [[surface runoff]] is increased. Seedling emergence and crop production are badly affected.

:''Note'':
:* Under saline conditions, the many ions in the soil solution counteract the swelling of the soil, so that saline soils usually do not have unfavorable physical properties. ''Alkaline soils, in principle, are not saline since the alkalinity problem is worse as the salinity is less.''

Alkalinity problems are more pronounced in [[clay]] soils than in loamy, silty or sandy soils. The clay soils containing [[montmorillonite]] or [[smectite]] (swelling clays) are more subject to alkalinity problems than [[illite]] or [[kaolinite]] clay soils. The reason is that the former types of clay have larger [[specific surface]] areas (''i.e.'' the surface area of the soil particles divided by their volume) and higher [[cation exchange capacity]] (CEC).

:''Note'':
:* Certain clay minerals with almost 100% ESP (i.e. almost fully sodium saturated) are called [[bentonite]], which is used in civil engineering to place impermeable curtains in the soil, e.g. below dams, to prevent seepage of water.

The quality of the irrigation water in relation to the [[alkalinity]] hazard is expressed by the following two indexes:
<ol>
<li>The [[sodium adsorption ratio]] (SAR,<ref name="Handbook"/> )

The formula for calculating sodium adsorption ratio is:

:{{math|1=SAR = {{sfrac|[Na<sup>+</sup>]|{{sqrt|[Ca<sup>2+</sup>/2 + Mg<sup>2+</sup>/2]}}}} = {{sfrac|{Na<sup>+</sup>/23}|{{sqrt|{{mset|Ca<sup>2+</sup>/40 + Mg<sup>2+</sup>/24}}}}}}}}
where: [ ] stands for concentration in [[milliequivalents]]/liter (briefly meq/L), and { } stands for concentration in mg/L.

It is seen that Mg ([[magnesium]]) is thought to play a similar role as Ca ([[calcium]]).

The SAR should not be much higher than 20 and preferably less than 10;

When the soil has been exposed to water with a certain SAR value for some time, the ESP value tends to become about equal to the SAR value.
</li>
<li>The [[residual sodium carbonate index|residual sodium carbonate]] (RSC, meq/L):<ref name="Handbook"/>

The formula for calculating the residual sodium carbonate is:

{|
| style="text-align:right" | RSC ||= [{{chem|HCO|3|−}} + {{chem|CO|3|2−}}] − [Ca<sup>2+</sup> + Mg<sup>2+</sup>]
|-
|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;||= {{{chem|HCO|3|−}}/61 + {{chem|CO|3|2−}}/30} − {Ca<sup>2+</sup>/20 + Mg<sup>2+</sup>/12}
|}
which must not be much higher than 1 and preferably less than 0.5.

The above expression recognizes the presence of [[bicarbonates]] ({{chem|HCO|3|−}}), the form in which most carbonates are dissolved.
</li>
</ol>
While calculating SAR and RSC, the water quality present at the root zone of the crop should be considered which would take into account the [[Soil salinity control|leaching]] factor in the field.<ref>{{cite report|chapter-url=https://publications.qld.gov.au/en/dataset/salinity-management-handbook/resource/104ce9f9-25cd-4839-ade6-670d9d25a688|title=Salinity management handbook|chapter = Chapter 11: Water quality| page =85|date = 19 December 2013|publisher = Queensland Government}}</ref> The partial pressure of dissolved CO<sub>2</sub> at the plants root zone also decides the calcium present in dissolved form in the field water. [[USDA]] follows the adjusted SAR<ref>{{cite web|url=http://naldc.nal.usda.gov/download/30435/PDF|title=A short note on calculating the adjusted SAR index|author=Lesch S. M. and SuarezD. L.|access-date=5 October 2012|archive-date=8 April 2013|archive-url=https://web.archive.org/web/20130408115530/http://naldc.nal.usda.gov/download/30435/PDF|url-status=dead}}</ref> for calculating water sodicity.

== Soil improvement ==
Alkaline soils with solid CaCO<sub>3</sub> can be reclaimed with [[Green manure|grass cultures]], organic compost, waste hair / feathers, organic garbage, waste paper, rejected lemons/oranges, etc. ensuring the incorporation of much [[Soil acidification|acidifying material]] (inorganic or [[organic material]]) into the soil, and enhancing dissolved Ca in the field water by releasing CO<sub>2</sub> gas.<ref name="Chhabra">Chhabra, R. 1996. Soil Salinity and Water Quality. 284 pp. Oxford & IBH Publishing Co. Pvt. Ltd., New Delhi (South Asian edition) and A.A. Balkema Uitgevers BC, Rotterdam (edition elsewhere). {{ISBN|81-204-1049-1}}.</ref> Deep [[ploughing]] and incorporating the calcareous [[subsoil]] into the top soil also helps.

Many times salts' migration to the top soil takes place from the underground water sources rather than surface sources.<ref>{{cite web|url=http://www.qmdc.org.au/publications/download/690/website-pdfs/land-soils/salinity-risk-assessment-for-the-queensland-murray-darling-region.pdf|title=Salinity Risk Assessment for the Queensland Murray-Darling Region (see appendix-2), Queensland Department of Environment and Resource Management|access-date=29 October 2012|archive-url=https://web.archive.org/web/20130410074047/http://www.qmdc.org.au/publications/download/690/website-pdfs/land-soils/salinity-risk-assessment-for-the-queensland-murray-darling-region.pdf|archive-date=2013-04-10|url-status=dead}}</ref> Where the underground water table is high and the land is subjected to high solar radiation, ground water oozes to the land surface due to capillary action and gets evaporated leaving the dissolved salts in the top layer of the soil. Where the underground water contains high salts, it leads to acute salinity problem. This problem can be reduced by applying [[mulch]] to the land. Using poly-houses or shade netting during summer for cultivating vegetables/crops is also advised to mitigate soil salinity and conserve water / soil moisture. Poly-houses filter the intense summer solar radiation in tropical countries to save the plants from water stress and leaf burns.

Where the ground water quality is not alkaline / saline and ground water table is high, salts build up in the soil can be averted by using the land throughout the year for growing plantation trees / permanent crops with the help of lift irrigation. When the ground water is used at required [[Soil salinity control|leaching factor]], the salts in the soil would not build up.

Plowing the field soon after cutting the crop is also advised to prevent salt migration to the top soil and conserve the soil moisture during the intense summer months. This is done to break the capillary pores in the soil to prevent water reaching the surface of the soil.

Clay soils in high annual rain fall (more than 100&nbsp;cm) areas do not generally suffer from high alkalinity as the rain water runoff is able to reduce/leach the soil salts to comfortable levels if proper [[rainwater harvesting]] methods are followed. In some agricultural areas, the use of subsurface "tile lines" are used to facilitate drainage and leach salts. Continuous [[drip irrigation]] would lead to alkali soils formation in the absence of leaching / drainage water from the field.

It is also possible to reclaim alkaline soils by adding acidifying minerals like [[pyrite]] or cheaper [[Ammonium aluminium sulfate|alum]] or [[aluminium sulfate]].

Alternatively, [[gypsum]] ([[calcium sulfate]], {{chem|Ca|S|O|4}} · 2 {{chem|H|2|O}}) can also be applied as a source of Ca<sup>2+</sup> ions to replace the [[sodium]] at the exchange complex.<ref name="Chhabra"/> Gypsum also reacts with sodium carbonate to convert into [[sodium sulphate]] which is a neutral salt and does not contribute to high pH. There must be enough natural drainage to the underground, or else an artificial subsurface drainage system must be present, to permit leaching of the excess sodium by percolation of [[rain]] and/or [[irrigation]] water through the [[soil profile]].

[[Calcium chloride]] is also used to reclaim alkali soils. CaCl<sub>2</sub> converts Na<sub>2</sub>CO<sub>3</sub> into NaCl precipitating CaCO<sub>3</sub>. NaCl is drained off by leaching water. [[Calcium nitrate]] has a similar effect, with [[sodium nitrate|NaNO<sub>3</sub>]] in the leachate. [[Spent acid]] (HCl, H<sub>2</sub>SO<sub>4</sub>, etc.) can also be used to reduce the excess Na<sub>2</sub>CO<sub>3</sub> in the soil/water.
 
Where [[urea]] is made available cheaply to farmers, it is also used to reduce the soil alkalinity / salinity primarily.<ref>{{cite web |url=http://www.fao.org/docrep/x5871e/x5871e00.htm#Contents|title=  Salt-Affected Soils and their Management, refer para 4.7|author=I.P. Abrol, J.S.P. Yadav and F.I. Massoud|access-date=23 December 2012}}</ref> The [[ammonium]] ({{chem|N|H|4|+}}) cation produced by urea [[hydrolysis]] which is a strongly sorbing [[cation]] exchanges with the weakly sorbing Na<sup>+</sup> cation from the soil structure and Na<sup>+</sup> is released into water. Thus alkali soils adsorb / consume more urea compared to other soils.

To reclaim the soils completely one needs prohibitively high doses of amendments. Most efforts are therefore directed to improving the top layer only (say the first 10&nbsp;cm of the soils), as the top layer is most sensitive to deterioration of the [[soil structure]].<ref name="Chhabra"/> The treatments, however, need to be repeated in a few (say 5) years' time. Trees / plants follow [[gravitropism]]. It is difficult to survive in alkali soils for the trees with deeper [[Plant root|rooting system]] which can be more than 60 meters deep in good non-alkali soils.

It will be important to refrain from irrigation (ground water or surface water) with poor quality water. In viticulture, adding naturally occurring chelating agents such as tartaric acid to irrigation water has been suggested, to solubilize calcium and magnesium carbonates in sodic soils.<ref name="Ashworth">Ashworth, J. 2007. The effect of chelating agents on soil sodicity. Soil and Sediment Contamination 16: 301-312.</ref>

One way of reducing sodium carbonate is to cultivate [[glasswort]] or [[saltwort]] or [[barilla]] plants.<ref>{{cite web |url=http://www.scielo.br/pdf/sn/v22n1/10.pdf|title= Karnal / Kallar grass cultivation in sodic alkaline soils in Pakistan|author=Farooq Ahmad|access-date=22 January 2013}}</ref> These plants sequester the sodium carbonate they absorb from alkali soil into their tissues. The ash of these plants contains good quantity of sodium carbonate which can be commercially extracted and used in place of sodium carbonate derived from  common salt which is highly energy intensive process. Thus alkali lands deterioration can be checked by cultivating barilla plants which can serve as food source, biomass fuel and raw material for soda ash and [[potash]], etc.

==Leaching saline sodic soils==
[[Soil salinity control|Saline soils]] are mostly also sodic (the predominant salt is [[sodium chloride]]), but they do not have a very high [[pH]] nor a poor infiltration rate. Upon leaching they are usually not converted into a (sodic) alkali soil as the Na<sup>+</sup> ions are easily removed. Therefore, saline (sodic) soils mostly do not need gypsum applications for their reclamation.<ref name="Chacupe">[http://www.waterlog.info/pdf/chacupe.pdf Chacupe case study]</ref>

== Remediation and utilization via aquaculture ==
Since the 1990s, research and experimentation have been conducted in China and elsewhere for remediation and utilization of alkali land via combined agriculture and aquaculture practices, with considerable success and gains in experience.<ref name="gmw_20230629"/><ref name="springer">{{Cite web |date=2023-04-05 | url=https://link.springer.com/chapter/10.1007/978-981-19-5486-3_11 |title=Pond Aquaculture in Waterlogged Salt-Alkali Land|website=[[Springer Science+Business Media|Springer]]}}</ref><ref>{{Cite Q|Q124547052|url=https://journal.hep.com.cn/sscae/EN/article/downloadArticleFile.do?attachType=PDF&id=18028}}</ref> Aquaculture technology of utilizing inland saline-alkali water for seafood production is becoming mature, covering wide range of seafood species including shrimps, crabs, shellfish and fish such as sea bass and grouper.<ref>{{Cite web |date=2023-09-26 |title=盐碱地养海鲜让不毛之地勃发多样生机 |url=http://www.zhhjw.org/m/view.php?aid=18596 |author=王春琳 |access-date=2024-02-14 }}</ref><ref>{{Cite web |date=2023-12-04 |title=海鲜返销沿海省市 新疆何以成中国的"大漠渔乡" |url=http://www.china.com.cn/txt/2023-12/04/content_116855647.shtml |website=[[China News Service]] |access-date=2024-02-16 }}</ref>

In recent years, [[aquaculture]] (or ''salt-alkali land aquaculture'') has been recommended by the [[Ministry of Agriculture and Rural Affairs|Ministry of Agriculture and Rural Affairs of China]] as a successful model for the transformation and utilization of saline-alkali land.<ref name="gmw_20230629">{{Cite web |date=2023-06-29 |title=科技"拯救"荒滩，向盐碱地要粮食 |url=https://kepu.gmw.cn/2023-06/29/content_36662502.htm |website=光明网 |access-date=2024-01-20 }}</ref><ref>{{Cite web |date=2023-02-14 |title=关于推介2022年盐碱地水产养殖典型案例的通知|url=http://www.moa.gov.cn/nybgb/2023/202301/202302/t20230214_6420465.htm |website=中华人民共和国农业农村部|access-date=2024-01-16 }}</ref><ref>{{Cite web |date=2021-12-18 |title=China: Utilizing water resources in saline-alkali land for agriculture and fisheries |url=https://www.tridge.com/news/turning-wastes-into-treasures-and-treating-alkali- |website=tridge.com |access-date=2024-01-21 }}</ref><ref name="springer"/> [[Food and Agriculture Organization|FAO]] noted in a recent newsletter that alkaline land is one area that there are innovative ways and opportunities for aquaculture to expand.<ref>{{Cite web |date=2023-06-01 |title=FAO Aquaculture News, June 2023|url=https://www.fao.org/3/cc6639en/cc6639en.pdf |website=[[Food and Agriculture Organization|FAO]] |access-date=2024-01-21 }}</ref>

== See also ==
{{div col|colwidth=22em}}
* [[Ammonia volatilization from urea]]
* [[Salsola soda|Agreti green vegetable]]
* [[Barilla]]
* [[Biosalinity]]
* [[Cation-exchange capacity]]
* [[Drip irrigation]]
* [[Environmental impact of irrigation]]
* [[Fertilizer]]
* [[Halotolerance]]
* [[Index of soil-related articles]]
* [[Phosphate rich organic manure]]
* [[Phosphogypsum]]
* [[Red mud]]
* [[Residual Sodium Carbonate Index]]
* [[Salsola stocksii|Sajji Khar]]
* [[Soda lake]]
* [[Soil fertility]]
* [[Soil pH]]
* [[Soil salinity]]
* [[Soil salinity control]]
{{div col end}}

==References==
{{Reflist|2}}

{{soil science topics}}
{{Land use}}

{{DEFAULTSORT:Alkali Soils}}
[[Category:Alkaline soils]]
[[Category:Land reclamation]]