Calcium-Magnesium exchange equilibria in a range of New Zealand soils

Abstract

Calcium-magnesium exchange equilibria were studied in several New Zealand topsoils. All soils showed a preference for calcium which increased with increasing proportion of magnesium in the equilibrium solution (XMg) Soils containing allophane had greater (P <0.05) selectivity preference for calcium than the 'non-allophanic' soils and had significantly (P <0.05) higher contents of organic carbon and Tamm's aluminium.