Soil samples are analyzed for P, K, Ca, Mg, S, Na, Mn, Cu and Zn by means of Mehlich-3 extractant using ICAP on a volume basis, which is the standard method of the NCDA&CS Agronomic Division (Mehlich 1984).

Cation exchange capacity (CEC) is determined by summation of basic cations (excluding sodium) and buffer acidity (Mehlich and others 1976).

Soil pH is determined on a 1:1 soil/water volume ratio. Humic matter determinations are made using a NaOH digestion with colorimetric determination (Mehlich 1984).

References

Mehlich A. 1984. Mehlich-3 soil test extractant: a modification of Mehlich-2 extractant. Commun Soil Sci Plant Anal 15(12): 1409-16.

Mehlich A. 1984. Photometric determination of humic matter in soils, a proposed method. Commun Soil Sci Plant Anal 15(12): 1417-22.

Mehlich A, Bowling SS, Hatfield AL. 1976. Buffer pH acidity in relation to nature of soil acidity and expression of lime requirement. Commun Soil Sci Plant Anal 7(3): 253-63.