The one thing about this thread is today we are dealing with two types of container growing.
1. Closed containers (Earthbox, EarthTainer,) which is basically a one shot deal, where once it's planted thats it's for the rest of the season. You provide water and watch it grow. You can provide foliar amendments.
2. Open containers, top watering with drainage at the bottom. Various amendments can be added during the course of the season wet or dry. Better aeration as air is drawn through the aggregate as the water percolates down.
So in the closed system the aggregate makeup is more critical and I would think the volume as well because once the nutrients are used, thats it. What would be interesting is to do a soil nutrient test if you will of the potting mix prior to plant out and after harvest to see what's left.
Ferts can be applied to close containers either by injectors in Ray's autotop system or by hand in manually watered systems. But that defeats the design concept of this type of growing system.
Another interesting test would be is a side by side comparison of two tainers, using the same tomato variety with one plant grown in the traditional close container configuration and one in an open configuration. Then make comparisons on taste and production. The actual reason I'm suggesting this is Ray's wife said ever since he automated the watering system he's been putting on some weight.
Ami