The Simulation Model for Acid Sulphate Soils (SMASS) has been developed to predict the effects of water management strategies on acidification and de-acidification in areas with acid sulphate soils. It has submodels for solute transport, chemistry, oxygen transport and pyrite oxidation. The model must be used together with the water transport model SWACROP. It combines physical and chemical processes. The output includes the acidity and chemical quality of soil and groundwater, and the occurrence of toxic compounds. This user's manual presents an outline of input and output files, guidelines for installation on a VAX-VMS computer, and the description of an application
