That’s interesting..
I always thought they were like snake oil so I never tried one.
It is not that they don't work, it is that they are not very practical. They work great in the RM containers I uses to grow trees. The problem is that pH can vary quite a bit. When we take soil samples, we take them in many spots in the field and mix the soil and at root depth. Many folks don't do sufficient sampling. A soil test is measuring the average (for everything they measure).
One would need to do something similar with a pH meter, walking through the field taking samples at multiple spots and multiple depths to get an average. I think the correct way is to do what the lab does and mix the samples and apply water that you know is neutral and then test the solution with the meter. There is also more that goes into a lime recommendation from a reputable lab. In addition to your soil type and your crop, they will ask about when it was previously limed and how much. With my soils, they tell me to apply no more than 3 tons/ac in one application and then wait 6 months and apply the rest.
So, I think a pH meter is fine for giving your confidence that your lime application is moving the pH in the right direction, but it is not a substitute for proper sampling and a recommendation from a good lab.
Thanks,
Jack