The UK Soil Testing Labs at Lexington and Princeton, KY test 50,000 to 60,000 soil samples each year. Samples are submitted through the county Extension offices for agronomic (Ag) crops, commercial horticulture, home garden/lawn, greenhouse media, and surface mining reclamation. The Mehlich III extractant (M-3) is used for routine determination of phosphorus (P), potassium (K),calcium (Ca), magnesium (Mg) and zinc (Zn). Amounts of these nutrients extracted are determined by either ICP methodology or by color for P and atomic absorption for K, Ca, Mg and Zn. Soil pH is determined on a 1:1 soil:water mix using appropriate electrodes and pH meter.
Case, Vern, "Kentucky County Soil Sample Summaries" (1995). Agronomy Notes. 32.