Base exchange equilibria in soil profiles

Abstract

1. The conditions governing base exchange equilibria in soil profiles are discussed.2. Exchangeable cation contents of six profiles are reported, the results including figures for Ca, Sr, Mg, Na, K, H and exchange capacity, as well as clay content and pH value.3. It is shown that cation displacement occurs as a result of the downward movement of hydrogen ions from the surface layers, and a layer of minimal basic cation content exists at about 30 cm. depth.4. Below this depth the basic cation content increases once again, but the base exchange capacity follows the clay content fairly closely.5. Calcium and strontium are displaced (and readsorbed) at similar rates, in accordance with their exchange constants, although there is about 400 times as much calcium as strontium present. The behaviour of the other cations also appears to be in accordance with theoretical demands.