bisco_bonsai

It's been curious how many opionions there are on bonsai soil, but one area that I don't think has been explored is the notion of stratifying your soil. In many bonsai books, the correct way to repot is listed as first laying a base of gravel at the bottom, then a coarser of bonsai soil to mound the tree, then topping in off with a lighter blend for ornamentation and moss. But as I continue soil and soil properties, I'm curious if this is the best method. For instance, soil texture plays a huge roll in water movement throught the soil and plant available water. Every soil scientist I know agrees that the best draining soils are where you have a single texture all the way through the soil horizon. So why should bonsai soil be different? Doesn't putting gravel at the bottom of your pot reduce unsaturated flow through the soil because of the reduced attraction to water offered by the macropores in the gravel? Said a simpler way, wouldn't water be more attracted to the micropores of the soil (clay,turface,akadama,etc) above than to the macropores of the underlying material? I believe this might cause the same effect as laying gravel beneath a sidewalk or foundation to block the capillary action of the soil water. In a sense, by placing soil first in a bonsai pot, might we be only producing a micro perched water table for our tree to its detriment? I propose that a consistent column of soil thoughout the pot would be the best way, according to science, to maintain "field" capacity and plant available water for our bonsai. I'd love to hear some other thoughts on this topic.
All th best,
JDL

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