Re: Soil Moisture Measurement in Shallow Saline Soil

[Bengt Espeby <espeby@aom.kth.se>]

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I recommend reading an article of Can. Geotech Journal,  1985, No 
22, pp 95-101, DE Pattersson & MW Smith. "Unfrozen water 
content in saline soils: results using time-domain reflectometry"

It is an old journal article but delas with TDR, Saline soils and 
water content!!'

The PROBLEM using TDR in very SALINE SOILS is that the signal 
is attenuated so it is difficult to accurately determine th Ka (the 
apparent dielectric constant) which is used in dtermining the soil 
water content!

I might not be up to date with new probe technology!! There may be 
probes that deal with the saline soils!

All the best from Bengt Espeby, KTH, Stockholm
**************************************************
Bengt Espeby, Ph.D., Director of Studies
Div of Land and Water Resources
Dept of Civil and Environmental Engineering
KTH
S-100 44 Stockholm
Sweden
Tel:+46-(0)8-790 61 41
Fax:+46-(0)8-411 07 75
E-mail: espeby@aom.kth.se
HTTP://www.ce.kth.se/AOM/AMOV/PEOPLE/ESPEBY/espeby.htm
**************************************************


> I have received a request from a client for information about appropriate
> soil moisture sensors for a shallow, saline soil.  The soil is not only
> extremely shallow (10cm in places), but is underlain by Class II carbonate,
> otherwise known as sheet calcrete (solid rock).  As a result, installation
> and operation of neutron probes is extremely problematic.
> 
> I had recommended that TDR sensors would be appropriate, based on
> information on the SOWACS web page that TDR are unaffected by salinity.
> This has been contradicted, however, by a third party, who is also an
> independent source like myself, so I have no reason to doubt his sincerity.
> 
> Consequently, I am confused, and also at a loss to help my client.  I am
> quite possibly opening a can of worms, but I am sure that others out there
> have had the same problem.  Please offer your opinions, preferably with
> supporting evidence, on both the sensitivity of TDR to salinity, and
> alternative devices to overcome my problem.
> 
> I will be away for the next week, but I hope to return to a full e-mail
> basket.  Thanks in advance for your participation in this discussion.
> 
> Mark Skewes
> Senior Water Management Consultant
> Irrigated Crop Management Service
> Primary Industries and Resources SA
> Ph. 08 8595 9149
> Fax 08 8595 9180
> E-mail skewes.mark@saugov.sa.gov.au