<p>the soil already contains salts, dry soils are especially prone to this as there is not enough water movement to move salts away. there are several ways the salt can get there, from slowly accumulating due to precipitation or from direct weathering of the minerals in or around the soil.  leeching just drives it deep. Irrigation then remobilizes this salt bringing it to the surface, instead of staying in the deeper parts of soil. remember irrigation adds orders of magnitude more water to dry soils then they had before, completely changing how the soil behaves.</p>
<p><a href="https://i.sstatic.net/MVzAn.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/MVzAn.png" alt="enter image description here" /></a></p>
<p><a href="https://www.researchgate.net/figure/Hydrological-processes-and-salinity-development-commonly-found-in-cropping-systems-in_fig3_228776735" rel="nofollow noreferrer">https://www.researchgate.net/figure/Hydrological-processes-and-salinity-development-commonly-found-in-cropping-systems-in_fig3_228776735</a></p>

CC BY-SA 4.0
2021-07-19T20:29:38.790Z
Re "from slowly accumulating due to precipitation". Could you expand/clarify this? Most precipitation should be free of dissolved minerals, as the water originates from evaporation. There is probably some aerosolized salt spray in the direct vicinity of large bodies of saltwater.
njuffa
CC BY-SA 4.0
2021-07-19T20:50:31.937Z
rain varies quite a lot in its composition, most rain water contains microscopic amounts of salt which over millions of years can accumulate, this can come from sea water and   aerosolized dust pulled out of the atmosphere by rain. remember rain can be transported thousands of miles before it falls.
John
CC BY-SA 4.0
2022-10-17T22:20:17.370Z
Thanks, but I'm still not sure how exactly irrigation brings the salt up
Sergey Zolotarev
CC BY-SA 4.0
2022-10-17T22:54:13.283Z
It adds more water, which dissolves some of the salt then through capillary action brings it towards the surface.
John
CC BY-SA 4.0
2021-07-19T14:12:00.147Z
2021-07-19T14:12:00.147Z
John
<p>The Aral Sea region has a problem with salinization of soils and drinking water, e.g. water coming from wells. As I understand it, it's caused by unsustainable cotton farming, but what is the exact mechanism? <a href="https://ejfoundation.org/resources/downloads/EJF_Aral_report_cotton_net_ok.pdf" rel="nofollow noreferrer">This</a> publication says something about over-irrigation of soils and liberation of salts locked beneath soil surface, but because of the way the sentence is phrased (&quot;The result is...&quot;), I'm not sure it's what triggered it initially.</p>
<blockquote>
<p>The result is that over-irrigated soils have accumulated excessive amounts of water capable of liberating salt locked deep beneath the soil surface.</p>
</blockquote>

CC BY-SA 4.0
2021-07-19T02:02:28.357Z
https://en.wikipedia.org/wiki/Soil_salinity specifically the part titled "Salinity due to irrigation"
John
CC BY-SA 4.0
2021-07-19T05:27:53.117Z
One thing to consider is how was ground water replenished in the region prior to the use of prolonged massive irrigation schemes & how is it replenished now. It is well known all water contains some salt. With decades of extensive use of irrigation water salt has accumulated in soils. Depending on the level of the water tables in the region (proximity to the land surface), the salt accumulated in the soil can contaminate underground water & thus contaminate once potable water.
Fred
CC BY-SA 4.0
2021-07-19T06:43:43.640Z
@John It's not detailed and clear enough. If all water contains salt, even rainfall, then what difference does it make if it's irrigation and not precipitation?
Sergey Zolotarev
CC BY-SA 4.0
2021-07-19T09:03:00.690Z
The amount of salt in rain water is much less than water from rivers which flow over minerals (all forms of rocks) accumulating dissolved salts as they flow. Salt in rain water is due to salt based aerosols acting a nucleus for water droplets for form on.
Fred
CC BY-SA 4.0
2021-07-19T13:57:56.657Z
@SergeyZolotarev look at the image, read the whole article, you can also follow links, dry land salinity and environmental impact of irrigation each has it's own page for instance. precipitation adds little water at a time, irrigation adds huge amounts which can bring deeper minerals to the surface.
John
<agriculture>
How exactly is cotton production linked to salinization of potable water?
Sergey Zolotarev
# How exactly is cotton production linked to salinization of potable water?

(Asked by: username_0 on 2021-07-18)

The Aral Sea region has a problem with salinization of soils and drinking water, e.g. water coming from wells. As I understand it, it's caused by unsustainable cotton farming, but what is the exact mechanism? [This](https://ejfoundation.org/resources/downloads/EJF_Aral_report_cotton_net_ok.pdf) publication says something about over-irrigation of soils and liberation of salts locked beneath soil surface, but because of the way the sentence is phrased ("The result is..."), I'm not sure it's what triggered it initially.

> The result is that over-irrigated soils have accumulated excessive amounts of water capable of liberating salt locked deep beneath the soil surface.

**Tags:** agriculture

> **Comments:**
> **username_1**: https://en.wikipedia.org/wiki/Soil_salinity specifically the part titled "Salinity due to irrigation"  
> **username_2**: One thing to consider is how was ground water replenished in the region prior to the use of prolonged massive irrigation schemes & how is it replenished now. It is well known all water contains some salt. With decades of extensive use of irrigation water salt has accumulated in soils. Depending on the level of the water tables in the region (proximity to the land surface), the salt accumulated in the soil can contaminate underground water & thus contaminate once potable water.  
> **username_0**: @username_1 It's not detailed and clear enough. If all water contains salt, even rainfall, then what difference does it make if it's irrigation and not precipitation?  
> **username_2**: The amount of salt in rain water is much less than water from rivers which flow over minerals (all forms of rocks) accumulating dissolved salts as they flow. Salt in rain water is due to salt based aerosols acting a nucleus for water droplets for form on.  
> **username_1**: @username_0 look at the image, read the whole article, you can also follow links, dry land salinity and environmental impact of irrigation each has it's own page for instance. precipitation adds little water at a time, irrigation adds huge amounts which can bring deeper minerals to the surface.  

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## 1 answers

### Answer by username_1 on 2021-07-19. Score: 1 | Accepted answer

the soil already contains salts, dry soils are especially prone to this as there is not enough water movement to move salts away. there are several ways the salt can get there, from slowly accumulating due to precipitation or from direct weathering of the minerals in or around the soil. leeching just drives it deep. Irrigation then remobilizes this salt bringing it to the surface, instead of staying in the deeper parts of soil. remember irrigation adds orders of magnitude more water to dry soils then they had before, completely changing how the soil behaves.

[![enter image description here](https://i.sstatic.net/MVzAn.png)](https://i.sstatic.net/MVzAn.png)

<https://www.researchgate.net/figure/Hydrological-processes-and-salinity-development-commonly-found-in-cropping-systems-in_fig3_228776735>

> **Comments:**
> **username_3**: Re "from slowly accumulating due to precipitation". Could you expand/clarify this? Most precipitation should be free of dissolved minerals, as the water originates from evaporation. There is probably some aerosolized salt spray in the direct vicinity of large bodies of saltwater.  
> **username_1**: rain varies quite a lot in its composition, most rain water contains microscopic amounts of salt which over millions of years can accumulate, this can come from sea water and   aerosolized dust pulled out of the atmosphere by rain. remember rain can be transported thousands of miles before it falls.  
> **username_0**: Thanks, but I'm still not sure how exactly irrigation brings the salt up  
> **username_1**: It adds more water, which dissolves some of the salt then through capillary action brings it towards the surface.  

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