I think you're still a bit confused (maybe because we didn't explain it well enough). The point of a soil test is to estimate
how much of a particular nutrient is available for plant uptake from the soil and correlate that to plant responses in order to gauge fertilizer needs. Mycorrhizae have very little to do with this.
Also, optimal soil test ranges and fertilizer recomendations are done for specific crops -- there's not a "one size fits all" system like you're talking about. Check out this "Understanding the numbers on your soil test report" paper from the University of Arkansas (http://www.uaex.edu/Other_Areas/publ...F/FSA-2118.pdf
). Pay special attention to the "Nutrient Availability Index" section and the 'Phosphorus (P) and Potassium (K)' paragraph. You'll see there that optimum soil test levels are different for different plants. For example, little yield response is seen in row crops and forages when fertilizer is added and Mehlich III soil test-P exceeds 36 ppm, but vegetable crops will benefit form fertilizer applications until Mehlich III soil test-P reached 75 ppm.
Because turfgrass is not grown for grain or biomass harvest, yield is not a factor used in corelation/calibration studies. Instead, color and growth are often used to determine when a fertilizer response occurs in turf crops. Optimum levels and recommendations are not designed to drive corn production, but are designed to produce green healthy turf.
You need to understand what the soil test report means before you can use it.