bisco_bonsai

Joanie, these kind of tests have been done and uniformity seems to be the scientific answer for providing the best plant-available water, but seeing as how we are measuring what is best for the plant, I think that the plant should be part of the experiment as well. However, there are so many variable to plant growth and health that I don't think you could pin down a superior soil stucture with any certainty. Even if you determine that one soil type is best at holding water (stratified) through this kind of bulk density experiment, I don't think you can determine if the extra water is plant available (non-gravitational). I'm sure that this can be measured, but it is beyond my knowledge. For now, I will settle with my perched water table with drainage holes (bottom of the pot) over a perched water table in the form of an extra layer. If the goal is to get rid of the excess water (gravitational), I don't see how you can argue that stratification is better than uniformity. But that's just my two cents.
All the best,
JDL