So as long as there are sufficient elements, then photosynthesis (C supply) becomes the limitation. So the actual ratio doesn't matter as long as there is enough of each (Ray's view).
Some nutrients are taken up at the expense of or more easily than others. This is the reason why ratios are so vital.
BTW, I'm also talking about the FORM of the nutrient as well as how much of it.
You cannot disolve 10 or 50mg of every nutrient in water and expect the plants to sort it out.
Another example, Some hydroponic people discovered that they could reduce their concentration by 50% without affecting the yield at all! That is reducing the concentrations of ALL nutrients by 50%! The ratios do not change.
It is vital that the correct ratios are determined (as near as possible) for a species. Eg, I think I have the ratios of elements pretty good for my Phaleanopsis. (I went roughly by this:
http://www.researchgate.net/profile...omposition/links/53e9bba10cf28f342f413ba4.pdf
(you may have trouble with this link but if you type it into google scholar you will find the full text)
I got massive growth so ratios are good so far. The concentration varies between 0.5 and 1.0 dS/m. I'm sure I could feed the kind of concentrations seen in the habitat (almost nothing) and still get healthy growth. (but much reduced)
If I used the Peters or Ross formulas rather than Ichihashi in this paper growth would reduced. However, all formulas give more than enough concentration of each nutrient. (remember the habitat concentrations)
It's the ratios (or composition) which makes all the difference.