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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 Cliff Hignett writes: ===8<============== While both the devices you are considering are accurate if installed correctly, they are nearly impossible to install correctly except in pure sand or stone free silts or loams. The problem is that the measurement volume of these devices is very small - the same volume most likely to be disturbed during installation. This leads to precision problems - that is if you install in several sites they give poor replication. If you want a device which measures soil water by dropping a sensor down a tube then the neutron moisture meter cannot be beaten for both accuracy and precision. (However it is a pain getting the necessary licences) This is an old, very mature technology with no nasty surprises. If you are not familiar with the instrument then there is a lot on SOWACS site and more on my site www.soilwater.com.au. Suction devices (by definition) read the suction over a large soil volume and are therefore almost immune to poor installation. They are cheap and robust. If you are prepared to use a suction measurement rather than a water content measure (remember the plant responds to suction - not water content) then you are best off using gypsum blocks for clays to clay loams and watermark sensors for lighter texture soils. cliff.hignett@soilwater.com.au owner-sowacs@aqua.ccwr.ac.za wrote: > Ken Flower writes: > ===8<============== > > We are about to purchase some equipment for measuring soil moisture. This > is for irrigation scheduling. The options that I am considering are the > Gopher (dielectric constant)and the Diviner 2000 (capacitance). > > If possible, I would like an/some opinions on which is the most accurate, > robust and cost effective of the options. > ===8<=========== > > [Bruce comments > Ken I have left your email address off so that all replies come back > through this forum. > > Anonymous comments will be posted, but preferably be bold enough to put > your name under comments! > Bruce] > > > > -- Cliff Hignett Soil Water Solutions 45a Ormond Avenue Daw Park South Australia 5041 61 (08) 8276 7706 cliff.hignett@soilwater.com.au www.soilwater.com.au ===8<===========