Modeling limestone dissolution in soils

The model includes four coupled reactions; dissolution of calcite in a stagnant aqueous system, cation exchange, leaching and accumulation of dissolved components as well as the carbonate equilibrium system. Two different modeling approaches for the over-all rate of the cation exchange were evaluated, one based on rate limitation by the intrinsic exchange rate, and the other on the transport of substances from the bulk of the soil solution to the exchanger surface. The model calculations were compared with published dissolution data and suggest a mass transfer limitation imposed on cation exchange in limed soils. The ability of the soil liming model to reproduce data indicates that the model is successful in describing the key chemical processes involved in soil liming, and demonstrates the enhancing effect by the exchanger reaction on the over-all dissolution rate.