I should have put my experiment here instead it went under TIPS AND TECHNIQUES...
Here's a link to the post in 'tips and techniques'.
(I'm doing this hoping that by adding a response, this posting will not remain at the top of this forum forever.)
Here is a link that might be useful: pH experiment
I read some years ago somewhere, it might have been in OG or Acres USA, but they conducted tests by many different labs. They sent the same soil samples to several different labs, and they all were different. None that you could call reliable. They tested for pH and nutrients.
I have had the same results. I do not test for soil pH anymore. I use plenty of compost and grow plants that prefer a ph 6.5 to 7.0 and acid loving plants in the same soil and cannot tell the difference.