I like this quote, it applies here.

 

 

A number of years ago there was a PoorDoo piled higher and deeper (PhD) who insisted I needed Gypsum.
Like hauling Wyoming Coal to West Virginia.

 

Now to Ca & Mg ratios, something I have learned chasing hay analysis for hay is,  calcium is very forgiving.  Build a yield plant element percentage and it will be a bell curve,.
For calcium the bell curve is almost a flat line.  My alfalfa usually has double the desired/optimum/ideal calcium level with little detectable effect on yield. Positive or negative.

For magnesium the yield bell curve is a true bell curve. 

 

Now phosphate is something else again. It has a distinct bell curve with a definite yield penalty for  deficient or excessive levels.

 

I contend it is important what  the plant is finding to use, more than what some Lab can find using modern chemistry.

If that were not true my alfalfa would not have all the characteristics for potassium deficiency with a soil test reporting 320 ppm K.  ( 640 Lbs K 768 #/A K2O)