[Arid_gardener] Question from Home-Hort WWW page

[Dick Gross]

Without knowing precisely how these plants have suffered, i.e.., yellowing 
and/or dying foliage, leaf fringe dieback typical of high salt, this novice 
would select a couple of plants to experiment with. Flush the root zone 
thoroughly and see what happens.  I am not sure about this, but I believe 
"soft water" has a high sodium content that is used through some chemistry 
miracle to replace other "hard" minerals from water. Reverse Osmosis is 
another "better" method, I've been told, but I would use neither in my 
jungle.

Our natural water supply has a high salt content with which virtually any 
species of vegetation can contend with prudent irrigation practices. 
Otherwise this bountiful, green desert would resemble the Sahara.

Shallow, frequent, irrigation with our low humidity, high temperatures and 
extremely high evaporation rate, concentrates salts in the root zone to 
levels toxic to the plant. Deep, flush irrigation will wash those salts 
through and out of reach of the feeder roots. The water evaporating from the 
basin or from the foliage by transpiration is distilled water. All the salt 
in the water is left behind to concentrate, or buildup, in the root zone. 
Every gram of water traveling through the vascular system and evaporated 
from leaf stomata leaves behind a small residue of salt that cannot 
evaporate except in a more extreme environment--like on Mars, perhaps.  Salt 
must be physically flushed out of the root zone with deep irrigation for 
most plants to be healthy. If anyone doubts that, go see what grows in the 
Sonora desert or visit the Imperial Valley where, with a half inch annual 
rainfall, exists one of the most lush and productive agricultural areas in 
the world using water with the same level of salt that we use. Farmers there 
commonly flood entire fields for days on end to flush salts out of the root 
zone and detoxify the soil, in a way of speaking.

If salt from your r/o system is the culprit, you might minimize the problem 
with flush irrigation but, to the best of my knowledge, there is no 
fertilizer or chemical treatment to neutralize salts in soil or dissolved in 
the water.  I have read that soil sulfur might help but follow directions 
carefully. Salts are soluble and an accumulation can be flushed beyond the 
root zone in soil with good drainage properties but one can never get the 
soil below salt content of our water that is about 8% if my failing memory 
is stable at this moment. I have in past years experimented cautiously with 
pool acid but could not document any benefits with my unscientific technique 
and I would not encourage anyone to try it. A high organic content helps to 
counteract alkaline (salty) soils. Desert soils, incidentally, are typified 
by a very low organic content. Organic materials, all hydrocarbon compounds 
(asphalt is only one of millions of them) are the most notable deficiency in 
desert soils. Virtually all other ingredients are already there in adequate 
amounts but in chemical forms that  plants can't absorb in an alkaline 
environment.

Sorry, I did not intend to be so wordy,  fitnessgirlaz, but got in too deep 
and tried to work my way out. Hopefully, someone with more knowledge will 
correct any mis-statements or mis-apprehensions in my analysis that I also 
might learn from this exchange.

Dick Gross, Master Gardener Volunteer
University of Arizona
Maricopa County Cooperative Extension



----- Original Message ----- 
From: <fitnessgirlaz at hotmail.com>
To: <arid_gardener at Ag.arizona.edu>
Sent: Tuesday, June 19, 2007 7:18 PM
Subject: [Arid_gardener] Question from Home-Hort WWW page


>
> 85205
> fitnessgirlaz at hotmail.com
>
> I was using soft water to water all of my plants/trees for the last 
> several years before I realized that it was not good for the plants.  I 
> have now been able to use hard water for the last 6 months on the outside 
> plants.  My question is that several of my plants (oleander, flowers, 
> cottonwood tree, etc) are looking very unhealthy.  Would I need to use a 
> certian fertalizer to replace or "fix" whatever damage the softwater would 
> have done to the soil or plants?  Also my various plants that flower will 
> rarely produce flowers anymore.  Could this have been caused by the 
> softwater use also????  Some are planted in the ground and some are in 
> pots.
>
>
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