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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 I find it fascinating to watch the convergence of thought around developing technology - product ideas are born independently in different places, based on the state-of-the-art technology in a particular area (in this case data loggers and gypsum blocks), and perceived demand in the market place by user groups, which drives technology on to the next stage. MEA (Measurement Engineering Australia) has been manufacturing and supplying gypsum blocks to the Australian viticultural market for many years (some 23 000 in the last three years). In recent years, we have also been supplying (2000) Watermark sensors, which are a gypsum block better suited to lighter textured soils. Our own gypsum block has been manufactured here in South Australia since the early 1950's, based on the original design by Aitchison, Butler and Gurr entitled "Techniques associated with the use of gypsum block soil moisture meters", 1950, CSIRO Division of Soils and Waite Agricultural Research Institute ADELAIDE SA. This is an excellent paper for those interested in gypsum block manufacture. MEA manufacturers a hand-held reader/data logger for collecting and storing up to 100 gypsum block readings, and down-loading them to the free-ware software with the product, which does all the graphing, tabling etc under Windows. The reader works with both types of gypsum block we supply . The GBHeavy for clay-based soil works best over the range 60kPa to 600kPa, while the GBLight (the Watermark sensor) works in lighter textures sandy soils over the range 10kPa to 200kPa. The unit has a display that gives readings directly in kPa, for those users happier with pencil and graph paper rather than computers. And yes, MEA builds cable and radio-linked gypsum block systems. But between these two extremes, there is indeed a gap in the product market, for those who don't want large inter-linked systems, but aren't able to get around more than a few times a week to read the gypsum blocks manually. To this end we are designing a stand-alone logger (based on our hand-held reader technology, calibrations and existing software) that will read 4 gypsum blocks at programmable intervals. The data reader can be carried on the motor bike, and will zip up the latest data from the gypsum block field station over a quick radio-link from a few meters away. (Radio technology saves the user having to stop and plug in cables). The user carries the reader back to the office, where the computer unloads and sorts it into site-based graphs and plots. These "GBugs" (as they are code named during the development stage) will be released from the start of the next Australian growing season, which is September here "down-under". Nice to hear the humble gypsum block getting some air-time! At Aud$17 each, they are certainly the least-expensive soil moisture sensor around. Andrew Skinner FIICA FIEAust CPEng Engineering Director Measurement Engineering Australia 41 Vine Street MAGILL SA 5072 Ph 08 8332 9044 Fax 08 8332 9577 Andrew.Skinner@mea.com.au www.mea.com.au