Mud Pies

Stewart:  

I think you have the right idea but some things are taken out of context. 
The reason why I wrote in my postings that you can't get a reliable
calibration from a "coffee can" experiment is because of soil depth. 
Gravity relies on soil depth to help drain the soil.  For this reason you
got a wetter soil at seemingly 67% of FC.  A good analogy is the sponge.  
If you take a rectangular sponge and soak it up in a bucket of water and
then hold it up in the air the "flat way" a certain amount of water of
would drain out.  Now tip the sponge "the tall way" and even more water
drains out.  In essence you are simulating changes in soil depth.   The
depth of the soil affects the drainage.  

Without expensive lab equipment the best way I've found to do a "barnyard"
calibration is to install the meters when I know the soil is near 100% FC. 
A day after a heavy rain after gravity has drained the standing water away.
 Also I'm not familiar with the "rapid test", I've had real good results
with the true tensiometers.  The principle they work on makes sense and the
scale is 0-60 centibars so you have quite a spread.   

Try calibrating your meter after a good rain storm, and if still doesn't
work you may want to invest in a true tensiometer.   


Best of luck,

Rick


PS Never give up on your "backyard intuition"  if it seems too wet it
probably is no matter what any meter says......


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