Extractant type

Extractants used

Reason for using

1. Dilute Solutions of either weak acids (Acetic acid, 0.1 M HCl) or strong acids (1 M HCl, 1M HNO₃)

1 M HCl

Releases elements from the non-residual metals and silicate mineral matrix.

2. Complexing extractants (0.005 M DTPA, EDTA)

0.005 M DTPA

Releases ions or nutrients that are bound organically

3. Weak replacement of non-buffered salts (MgCl₂, CaCl₂, NH₄Cl, NH₄NO₃)

1M NH₄Cl

Releases ions from exchange sites on the soil solid-phase