I have had pretty mixed results, even with high quality sensors. Continuous good contact with the soil is necessary, and that is sometimes altered after drying or freezing events. You also have to convert the bulk electrical conductivity (measured by the sensor) to salinity by accounting for water content, which varies and is itself determined indirectly from sensor data. Under the right circumstances sensors can provide qualitative information about changes in salinity over time, particularly short time scales, but they are no substitute for good laboratory analysis.

Remote sensing is increasingly used for spatiotemporal monitoring of salinity. Models are developped by correlation between salinity measurements laboratory and image data for estimating soil salinity from images. Laboratory analysis are more precise but require a lot of resources and costs.

Please, have a look at Attachment "A wireless network of sensors that is set to revolutionise soil-based salinity measuring is being developed by a University of Southampton researcher and a team of Australian academics". All the best.

I agree with your opinion about the weak as instruments for accurate evaluation of  soil salinity. But what out? Use homemade instruments we cannot. So, I tried to pay attention to a new device with interesting properties.

 I would recommend to use the laboratory salinometers for precision measurements of salinity. Most accurate on a market are the oceanographic salinometers  with accuracy around 0.002-0.005 for practical salinity, or equivalent to g/kg for absolute salinity. For information please check website: www.salinometry.com

My personal development is the Micro-salinometer MS-315, which can measure salinity of any naturally existed salt concentrations with accuracy equivalent to 0.004psu (PSS-78), or g/kg (for absolute salinity deriving). It uses a ratiometric principle with dual inductive (electrodeless) conductivity cells (sample and reference), which are much more stable in comparison to to traditional conductive electrodes. MS-315 can be installed on the field (12V DC power requires), connected through the Ethernet  and remotely controlled through IP with ability to perform the peristaltic pump operated direct salinity sampling in specified intervals and the real-time streaming of the salinity samples data. 

Good luck!

www.salinometry.com

If you interested in continuous in-situ data I would recommend either the GS3 or 5TE probes manufactured by Decagon Devices. Application considerations include soil disturbance, range, effective sample volume, accuracy and co-located variables available for salinity measurement corrections. Both the GS3 and 5TE measure VWC, temp. and electrical conductivity (EC) within a 0.3L soil volume with ± 10% accuracy from 0 to 10 dS/m, user calibration required above 10 dS/m. Resolution: EC: 0.001 dS/m from 0 to 23 dS/m. Relatively cost effective, can be deployed with cellular or Campbell Sci. CRXXX data logger and can be purchased with SDI-12 or stereo jack configurations. Application Guide.

Follow up with questions if needed.

Additional contact:

Dr. Ray G. Anderson

Research Soil Scientist

USDA-ARS, U.S. Salinity Laboratory

Contaminant Fate and Transport Unit

George E. Brown Jr. Salinity Laboratory

450 W. Big Springs Rd.

Riverside, CA 92507-4617 USA

Office: 1-951-369-4851

http://www.decagon.com/education/electrical-conductivity-application-guide/

http://www.decagon.com/products/soils/volumetric-water-content-sensors/gs3-vwc-ec-temp/

Hi, did you considered to use Rhyzons to extract water from your water samples ? Them you can analyse it for salinity and anything else you want. Of course this is viable only if you have a small number of sampling sites and not so deep. Then you have to extract a soil core and afterwards the water with Ryzhons. Take a look at: http://www.rhizosphere.com/rhizons

Hi Chitrini, 

the topic is very broad. It depends much on the type of application and  the spatial scale you're looking at. Feel free to contact me with a private message if you want to discuss this with me.

Best,

Elia

I have had pretty mixed results, even with high quality sensors. Continuous good contact with the soil is necessary, and that is sometimes altered after drying or freezing events. You also have to convert the bulk electrical conductivity (measured by the sensor) to salinity by accounting for water content, which varies and is itself determined indirectly from sensor data. Under the right circumstances sensors can provide qualitative information about changes in salinity over time, particularly short time scales, but they are no substitute for good laboratory analysis.