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NOTE: To get off this list, send email to majordomo@aqua.ccwr.ac.za with the body of the message containing the line: unsubscribe sowacs Soil temperature monitoring is no problem when using thermocouples and data loggers. Soil water content with depth is more difficult. Manual neutron probe monitoring (using an access tube) is reliable in most soils, but will need to be calibrated for specific soils. I have heard that Vertisols with much cracking cause difficulties with maintaining the access tube. Dielectric monitoring is less reliable on any soil with high CEC and high surface area. In the past I attempted to use a cable tester with TDR waveguides. I now am recalibrating the water content as a function of "apparent dielectric" and temperature, with separate calibrations for each soil and for each depth in the soil. Some of the newer TDR do not use the cable tester, but still require site-specific calibration (in spite of what the literature says). Even worse are the capacitance probes that function at a lower frequency (around 100 MHz), where bound water dielectric relaxation and electrical conductivity can r! esult in larger dielectric numbers. Do you want data you can trust, or do you merely want a lot of numbers (that could cause grief for years to come when trying to interpret)? You would be further ahead monitoring fewer stations using gravimetric sampling, which is most accurate. Your second best choice would be manual neutron probe monitoring. Your third choice would be to eliminate all soils with high amounts of 2:1 clays and high amounts of organic matter, and use some of the newer soil water sensors on the rest of the sites. "Sally Logsdon" <logsdon@nstl.gov>