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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 Reply to Jason Murray, I would NOT recommend TDR in that environment. The TDR only works when there is a continuous water film. Isolated water does not register. Try a simple experiment. Get a course grained material (eg diat. earth or a sand) and mix it with a pure silt. The idea is to get two distinct pore sizes. Add water to field capacity approx. then dry and test with TDR. You will find that when the sand dries, the TDR no longer registers the water in the silt. this phenomena is documented in the literature. I suspect this situation will happen frequently in the sort of materials you describe. I see no reason why tensiometers would not work . Cliff.hignett@soilwater.com.au owner-sowacs@aqua.ccwr.ac.za wrote: > 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 > > I am conducting a study examining variability issues associated with using > Time Domain Reflectometry to monitor moisture and thus control irrigation > in horticultural substrates. I am using pine bark mix, hardwood bark > mix, pro-mix, perlite, sand, and rockwool. I am looking for (and have > yet had a hard time finding) data on the variability associated with using > tensiometers to monitor moisture in these same/similar substrates. I am > looking to find whether TDR is a less variable source of moisture data for > irrigation scheduling than tensiometers. So, actual tensiometer > variability data is what I really need. > > Thank you for the help, > either email me direct at jmurray@wam.umd.edu, > or reply to the list. > Much appreciated, > Jason Murray -- Cliff Hignett Soil Water Solutions 45a Ormond Ave Daw Park South Australia 5041 pH 61 (08) 8276 7706 WWW.SOILWATER.COM.AU