So, Marion Calmer has done soil sampling every 2" down to 8", and he thinks the soils are deficient?  How does he KNOW that? Has he done the work to prove they are deficient?  Early in my career, I did a very similar thing - took 2" samples down to a depth of, I don't recall.... maybe 16" or so.  You could see the nutrient level decreased as you went down in depth.  I sent the results to a University soil fertility specialist, and asked for his opinion.  His response was " we don't know what those numbers mean. We haven't done the research to know what those numbers should be."  

So, if we expect, say, phosphorus to be be, say, 30, or 40, it is only because someone has done the research to know that a level of 30, or 40, is adequate for optimal yield, and a level of 20 will likely reduce yield.  And that is at a soil depth of 0-6".  No one that I know has done the research to know if you pull soil samples at 4-6" soil depth, what those numbers should look like for optimal yield, as opposed to soil sampling 0-6" soil depth.  So, unless Marion has done the work to correlate a reduced yield level with those reduced soil nutrient levels, then he is looking at a bunch of numbers - you can't deduce nothing more from them.