Fig. 1 Solubility of Al relative to gibbsite (Al(OH)₃) in fresh, frozen, and dried soils; logAl is log₁₀ activity of dissolved Al³⁺. Broken lines indicate theoretical equilibrium with respect to crystalline gibbsite and microcrystalline gibbsite . Arrows indicate no addition of acid or base. Al solubility increased as a result of drying the soils