Comparison of mehlich 1 and mehlich 3 extractants for P, K, Ca, Mg, Mn, Cu and Zn in atlantic coastal plain soils

Abstract

Abstract The Mehlich 3 (M3) extractant was introduced in 1981 to improve the efficiency of soil testing laboratories by eliminating the need for multiple extractants for P, K, Ca, Mg, Mn, Cu and Zn. The M3 was also intended to be suitable for a wide range of soils, perhaps to serve as a “universal”; soil test extractant. At present, regional soil testing committees throughout the U.S. are investigating the M3 in this regard. Development of a field calibration data base for a new soil testing extractant is an essential, but expensive and time‐consuming process. An interim measure is the use of conversion equations between new and current extractant(s). These equations allow for use of the new extractant with existing field calibration data. The objectives of this study were (i) to develop conversion equations for the Mehlich 1 (M1) and M3 extractants for Atlantic Coastal Plain soils, and (ii) to determine the influence of soil pH and organic matter content on the relative extractability of P, K, Ca, Mg, Mn...