Fig. 5. Effect of soil moisture content on the soil solution cation composition per unit mass (total cations = Ca + Mg + Na + K, divalent cations = Ca + Mg, monovalent cations = Na + K) of soil for several Vertisols (V, left) and an Oxisol (O, right); S = saline, G = gypsiferous, C = calcareous, S(1) = NaCl added at 1 g kg^–1, S(2) = NaCl added at 2 g kg^–1.