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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 Dear site owner: Relating to message by Hignett (30/4, 5/5), Ornstein, (30/4), Reynolds (3/5), and Broomhill (8/5) I would like to make a four points: 1.Lets define our messages: I am suggesting that each contributor to the site will categorize his message in the subject line or subtitle: For example, quest, response to, speculation, idea, request for info, equipment performance, cooperation, conference, exhibition,Ö 2.Lets keep authorities separated: When dealing with water content measurements lets discuss the techniques, the interpretation and the application separately from each other. (A bull and a calf were standing on the top of the hill, looking down the valley where all the cows were grazing. The calf had an idea:î Lets get ALL of them!î. But the old bull said:î Sure, but Para paraî meaning, one cow at a time. 3. Qualitative descriptions (e.g., ìman-made-soilî, ìexotic mineralsî, ìI have not actually tried this but I believe the tensiometer would indeed workî ) and illustrative examples may be useful for teaching. For our practical interests we have to stick to facts. We have parenthesis and bars (in Tables and Figures, respectively) announcing the level of confidence we have in the numbers reported . These are evaluated by impartial, widely-accepted, standard, mathematical, and most important, non-emotional methods. It will be nice if we stick to it. 4.Regarding the super-galactic (and beyond?) soil moisture techniques comparison: Hold Your Horses. Hignett comments that ìThat there is no device on the market that allows trouble free, always accurate measurement of soil waterî. Why should there be?! Picking up from Broomhill, does there exist a car that drives through desert dunes, snow, ice, asphalt, boulder, glacier, ploughed field, or mine spoils? In case such a car did exists, do you imagine how it would have looked like? Would you want to own one? Even for the moon they had to construct a special one and wouldnít use a Buick! By the same token, for the above list of media not a single moisture sensing technology will serve us flawlessly, even for the specific use it was designed for. Such a situation is called REALITY. Monitoring boggy swamps, mine tailings, and irrigated sandy soils, calls for different solutions, different accuracy levels, different sampling frequencies, different degree of automation, and different volume of sampling. They will sustain different costs, and will be differently affected by environmental factors. One doesnít not gain anything by measuring WC in mine tailing by a tensiometer. One doesnít not gain anything by measuring WC in cracked soils by a TDR. One doesnít not gain anything by measuring WC in soil surface by a neutron Probe So why lump them all together or compare them? Bottom line: Get acquainted with the advantages and disadvantages of your optional techniques, experience them extensively, and get the best (NOT EVEN NECESSARILY GOOD) horse to pull your unique wagon. The contribution from farmers, extension people and engineers is invaluable. Originating from the field, it feed backs research, and presents the demands that set the direction for more research. Still, we have to keep the messages entitled ëspeculationí to a minimum, otherwise the site will turn into a chat room. I donít believe I wrote all this, arie nadler Specifically to Hignett: 1.When told by colleagues that ìphenomenon was known and ìpublishedî - you should have ask where. 2.How can you say in a revised version:î the TDR doesnít correctly registerî? There may be another possibility: Itís the operatorís fault, not the instrumentís. Arie Nadler, Hort Research, Palmerston North, private bag 11030 New Zealand 64-6-356-8080 ext 7746 fax:64-6 354-6731 Home 64-6-356-4269 [Bruce (the list owner) comments: Categorising posts by subject or subtitle has been tried in the past, and unfortunately does not work... despite being a good idea. In order not to limit the scope or ability of sowacs to be open and frank, there can be no passive or enforced method of restricting matters of opinion... they just need to be expressed as such more clearly.. perhaps we need to go as far as citing all "facts"? We all have to be tolerant of differing levels of knowledge, and of different areas of interest and application. Inevitably there will be those that are more or less knowledgable than one's self. I still don't think the number of posts on sowacs is large enough to justify splitting it up into more specific subsets, and the administration load is enough as it is than you very much! (In order to prevent junkmail and to avoid unnecessary traffic, I moderate each and every message manually). Whilst we are editorialising, I will put in my two cents worth on the "universally applicable sensor" that doesn't (or can't) exist.. There can be no sensor that measures across all ranges of wetness in all media WITH THE REQUIRED ACCURACY*. Sure, some sensors more universally applicable, and these might be fine for less scientific applications, whilst as the requirements for greater accuracy increase, so the flexibility of the sensors must decrease. The reason for measuring must be the primary criterion in choosing a sensor.. relative versus absolute, accuracy required, longevity, repeatability, independence of salinity or density etc. And finally, of course, cost. There are probably to other opposing primary areas of interest: those who simply want to know the moisture content, and those who are more interested in the sensors themselves. These two camps to me are the most likely candidates to be split on sowacs. Having said that, each camp would do well to listen in on the other - thereby negating this suggestion! Let's face it, we need sensor developers and scientists to delve into the subtleties and complexities of making it simple for the rest of us to be able to just plug 'n play, so to speak :) However, it usually isn't that simple, and we end up calibrating, comparing and generally spending more time preparing than measuring.. which is why I started sowacs! Bruce]