Article 18453 of rec.gardens:
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Newsgroups: rec.gardens
Subject: Re: soil Electrical Conductivity -- measure of salinity?
Message-ID: <1993Jun11.091419.1@rhea.arc.ab.ca>
From: thacker@rhea.arc.ab.ca
Date: 11 Jun 93 09:14:19 MDT
Followup-To: rec.gardens
References: <1v5kc1INN5c4@network.ucsd.edu>
Organization: Alberta Research Council
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In article <1v5kc1INN5c4@network.ucsd.edu>, cs180sbg@sdcc5.ucsd.edu (smaschue@ucsd.edu) writes:
> 
> 
> 
> 
> Hello.  Can anyone explan what exactly the measure of "SOIL CONDUCTIVITY"
> is?  I keep hearing about the unit E.C.,  This term seems to be used
> frequently in hydroponics texts...and when I was talking to a man
> about getting a huge amount of kelp delivered to our garden, he wanted
> to make sure our salinity was not out of control, first.  What exactly
> are the units?  Is it a logarithmic scale?

Hi, I am a soil scientist and deal a fair bit with E.C.  It is a measure
of soil salinity expressed in milliSiemens per centimetre.  The Alberta
Soils Advisory Committee has determined guidelines for plant growth 
based on the EC of the  soil.  The EC is measured in a saturated paste
extract of soil (wet the soil with just enough water to saturate the 
soil, extract the solution, and measure the EC of the liquid).  (You
need a conductivity meter to do this).  An EC of less than 2 is rated
good for plant growth, 2 to 4 mS/cm is ratedis rated unsuitable for plants.
is rated poor for plants, and above 8 mS/c
Some plants, of course, are better able to tolerate saline soil, the 
scale is designed for agricultural crops in general.

Don


Article 18483 of rec.gardens:
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Newsgroups: rec.gardens
Subject: Re: soil Electrical Conductivity -- measure of salinity?
Message-ID: <1993Jun11.144605.1@rhea.arc.ab.ca>
From: thacker@rhea.arc.ab.ca
Date: 11 Jun 93 14:46:05 MDT
Followup-To: rec.gardens
References: <1v5kc1INN5c4@network.ucsd.edu> <1993Jun11.091419.1@rhea.arc.ab.ca>
Organization: Alberta Research Council
Nntp-Posting-Host: rhea.arc.ab.ca
Lines: 26

Okay, so I see my original message got garbled.  (My fault no doubt).
So in this post I'll fix up the message below.
>> 
>> Hello.  Can anyone explan what exactly the measure of "SOIL CONDUCTIVITY"
>> is?  I keep hearing about the unit E.C.,  This term seems to be used
>> frequently in hydroponics texts...and when I was talking to a man
>> about getting a huge amount of kelp delivered to our garden, he wanted
>> to make sure our salinity was not out of control, first.  What exactly
>> are the units?  Is it a logarithmic scale?
> 
> Hi, I am a soil scientist and deal a fair bit with E.C.  It is a measure
> of soil salinity expressed in deciSiemens per metre.  The Alberta
> Soils Advisory Committee has determined guidelines for plant growth 
> based on the EC of the  soil.  The EC is measured in a saturated paste
> extract of soil (wet the soil with just enough water to saturate the 
> soil, extract the solution, and measure the EC of the liquid).  (You
> need a conductivity meter to do this).  The conductivity of the solution
  is related to the amount of soluble salt in the soil.

  An EC of less than 2 is rated good for plant growth,
  2 to 4 dS/m is rated "fair", 4 to 8 dS/m is rated 
  "poor", and above 8 dS/m is rated unsuitable for plants.
> Some plants, of course, are better able to tolerate saline soil, the 
> scale is designed for agricultural crops in general.
> 
> Don


Article 18454 of rec.gardens:
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Newsgroups: rec.gardens
Subject: Re: soil Electrical Conductivity -- measure of salinity?
Message-ID: <1993Jun11.092556.1@rhea.arc.ab.ca>
From: thacker@rhea.arc.ab.ca
Date: 11 Jun 93 09:25:56 MDT
Followup-To: rec.gardens
References: <1v5kc1INN5c4@network.ucsd.edu>
Organization: Alberta Research Council
Nntp-Posting-Host: rhea.arc.ab.ca
Lines: 5

Oops, sorry, just realized I screwed up the units on my posting a few
minutes ago.  The old "Imperial" units were millimhos per centimetre,
the new "S.I." units are deciSiemens per metre.  Just a cosmetic
difference really, the numbers and ratings for soils are the same.



