proudly sponsored by
|
archiving of SOWACS proudly sponsored by |
|
In response to Luke Esprey 's query, In general, long cables in a field trial are asking for trouble. I don't know if they affect the sensors (probably not) but unless you have elaborate earthing techniques and protection against surges, they will pick up every bit of electromagnetic rubbish for miles around (including lightning). Both the Campbell (so called) TDR's (I am told they are not actually TDR's but a frequency domain device) and the neutron meter measure volumetric water. If you want to use gravimetric water measures to calibrate then you had better be very confident that the field density you are using is good and does not vary across the field. Volumetric sampling is difficult - but at least you can be confident that you know the right answer - gravimetric methods are fast but leave the possibility that the density is wrong - and you have to do it again. (cliff.hignett@soilwater.com.au) -- Cliff Hignett Soil Water Solutions 45a Ormond Ave Daw Park South Australia 5041