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Robert, We have been mapping soil moisture (0-30cm depth range) using mobile TDR for the last three years - we can do about 50 measurements an hour which is quite quick but it does require some minimal disturbance due to insertion of the TDR probes. We do this using an all-terrain vehicle with the TDR inserted using hydraulics and positions measured using real time DGPS. This has proved to be an efficient means of collecting shallow moisture data. Have a look at http://www.civag.unimelb.edu.au/~western/tarrawarra/tarrawarra.html page for various references to our publications, photos, data etc. Currently we are considering building a system that does moisture and or salinity measurement without probe insertion. The moisture/salinity measure will be based on an EM38 (i.e. inductive electrical conductivity measurement). This will require at least site specific, and possibly daily, calibration for both salinity and moisture. Probably we'll use a combination of TDR and EM38 for this. The key problem to overcome will be calibration and data interpretation due to the multiple influences on the signal. By the way, we have also done some ground truthing of C-band SAR (ERS1/2) in pasture systems with very poor results. It is certainly not a soil moisture sensing system that can be used either operationally or for hydrologic/agric research at present. We will be doing some work on multifrequency SAR soon. Anyway, lets talk some more about our mutual interest. cheers Andrew. ------------------------------------------------------------------------------ Dr Andrew Western Centre for Environmental Applied Hydrology Department of Civil and Environmental Engineering The University of Melbourne 3052 Australia Ph +61 3 9344 7305 Fax +61 3 9344 6215 email: a.western@engineering.unimelb.edu.au www: http://www.civag.unimelb.edu.au/~western -------------------------------------------------------------------------------