ABSTRACT
During the past few years, numerous techniques and methods have been developed to
estimate soil nutrient availability. Among these methods, the Mehlich 3 (M3) is considered
an appropriate and economic chemical method since it is suitable for a wide range of soils
and can serve as a ‘‘universal’’ soil test extractant (Sims 1989; Zbiral 2000a; Bolland et al.
2003). M3 was developed by Mehlich (1984) as multielement soil extraction and is widely
used, especially in agronomic studies, to evaluate soil nutrient status and establish fertilizer
recommendations mainly for P and K in humid regions. The following elements can be
successfully analyzed using M3 extracting solution: P, K, Ca, Mg, Na, Cu, Zn, Mn, B, Al,
and Fe. The extracting solution is composed of 0:2 M CH3COOH, 0:25 M NH4NO3, 0:015 M NH4F, 0:013 M HNO3, and 0.001 M ethylene diamine tetraacetic acid (EDTA). M3-extractable phosphorus (M3-P) is obtained by the action of acetic acid and fluoride
compounds, while K, Ca, Mg, and Na (M3-K, M3-Ca, M3-Mg, and M3-Na, respectively) are
removed by the action of ammonium nitrate and nitric acid. The Cu, Zn, Mn, and Fe (M3-Cu,
M-Zn, M3-Mn, and M3-Fe) are extracted by NH4 and the chelating agent EDTA.
