Market Farming

[dave.kathy AT att.net]

>I suppose it would be possible to use an ohm meter to measure the solution
concentration.  Specifically I want to look at plant health and determine
when the highest nutrient density is reached in a plant.  The ohm meter
might work well for a vat of syrup, honey, or pail of maple sap, but
checking the sap concentration of a clover plant might be difficult with an
ohmmeter.<

Actually, this ohm-meter thing is a subject I have a bit of professional 
experience with, and I know: it doesn't work, even in a vat of liquid.  Ohm 
meters are made to measure circuits, with wires going around, and a vat 
doesn't have clear current paths of that sort.  Actually, most pH meters 
(which will work in vats) actually measure electrical conductivity and 
translate it over to a pH value.  So you could use a pH meter and UNtranslate 
it, I guess. However. I don't think nutrient elements are ionic in nature, 
anyway.  Bottom line: forget electrical conductivity as a surrogate for 
nutrients or flavor.  Refractometers, instead!

Dave Campbell, retired USGS geophysicist
Tiffin Iowa