Quote Originally Posted by RackitMan
I am curious as to the whole nutrient ratio conundrum.

When talking about red and blue light, you point out that the solar spectrum changes very little from spring to fall, so that changing indoor light spectrum is probably unnecessary.

Well, 'natural' outdoor soil changes not at all during the entire plant's life and outdoor plants consistently outperform indoor plants as to size and yield. (Of course, I understand there are many other factors at play.) So are there any real controlled studies that point to the need to change nutes?
Natural soil changes constantly in composition and nutrient availability. Factors like microbial cultures in the soil, to the rain that falls from the sky, to the ground temperature, to the amount of wastes the plant produces over its life cycle, everything causes all sorts of chemical reactions, makes different nutrients more or less available, etc. In uncontrolled outdoor conditions, almost everything except the light is constantly varying to different degrees.