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Salt in the Land

 
 
gollum
 
Reply Sat 14 Aug, 2010 07:47 pm
If an area of land is farmed for many years does it become salty and thus no longer fit for farming?
 
roger
 
  2  
Reply Sat 14 Aug, 2010 08:50 pm
@gollum,
If it's irrigated the answer is probably yes.
gollum
 
  1  
Reply Sun 15 Aug, 2010 04:35 am
@roger,
Roger-
Thank you.

How does irrigation cause the land to become salty? I assume irrigation is done with plain water. The land that inspired the question is in San Joaquin Valley, California.

I understand that because of the salt, the land is no longer suitable for farming. Can the salt be removed to make the land arable?
roger
 
  4  
Reply Sun 15 Aug, 2010 09:12 am
@gollum,
Rainwater, with the exception of accumulated dust, is pretty much pure (more or less) water. Irrigation water has passed over hundreds of miles of land containing salt, fertilizers, animal wastes, and insecticides. It evaporates on the land and becomes more concentrated. Lakes with no outlet become very salty, like the Dead Sea and the Great Salt Lake in Utah. The Colorado River is a terrible source of water, by the way.

Some plants, like salt bush and tamarron adsorb salt from the soil. Still, you have got to dispose of the plants, so you are only moving the problem. Also, it takes lots of time.
0 Replies
 
gollum
 
  1  
Reply Sun 15 Aug, 2010 10:56 am
Roger-
Thank you. That is very interesting -- and frightening.

Since the total area land on earth is either staying the same or declining and the land under irrigation will cease to be arable, there will be an ever declining area of land with which to feed the human population.

On the other hand irrigation has been used for thousands of years. Maybe I'm missing something.
tsarstepan
 
  1  
Reply Sun 15 Aug, 2010 11:19 am
@gollum,
That's why farmers have been implementing crop rotation over the centuries.

Plant crops in one corner of the field and leave another area to go fallow.
Quote:
fal·low    [fal-oh]
–adjective
1.
(of land) plowed and left unseeded for a season or more; uncultivated.
3.
land that has undergone plowing and harrowing and has been left unseeded for one or more growing seasons.


Gives the soil a chance to recover some of it's nutrients and also I can imagine lose some of it's salt content to inevitable dilution from the rain.

Is this somewhat correct Roger?
Rockhead
 
  1  
Reply Sun 15 Aug, 2010 11:28 am
@tsarstepan,
modern irrigation water comes from deep wells.

a lot more minerals in it than in the old days...
0 Replies
 
roger
 
  1  
Reply Sun 15 Aug, 2010 08:01 pm
@tsarstepan,
Very true, except when was the last time in rained in the Imperial Valley?

I'm afraid this is a really vital issue that hasn't received much attention. Ah well, we got enough on our plates to worry about.
0 Replies
 
 

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