The effects of exchangeable sodium and of exchangeable potassium upon soil physical condition were compared by means of permeability ratio, air to water, and modulus of rupture determinations. The permeability ratio is a measure of the change in pore‐size distribution due to the action of water and the modulus of rupture is a measure of soil crusting. The permeability ratio and modulus of rupture increased markedly with increasing exchangeable‐sodium‐percentage, whereas, increases in the exchangeable‐potassium‐percentage had little effect. The relation of the permeability ratio to exchangeable‐sodium‐percentage can be expressed by an exponential equation of the form, y = ae bx , whereas, the modulus of rupture is linearly related to exchangeable‐sodium‐percentage by the equation y' = mx + c. The parameters a, b, m and c of the respective equations are positively correlated with cation exchange capacity and total specific surface.