SummaryUnder transient conditions, the precipitation of carbonates in a calcareous and a non‐calcareous soil was influenced by calcium, magnesium and bicarbonate ions from soil sources. These sources were: the soil solution, the soil exchange complex and the dissolution of aluminosilicates. There was no significant difference between the amount of carbonates which precipitated in the two soils when in contact with the same water. It was found that for small portions of water in contact with the two soils, precipitation of carbonates took place both from under‐saturated and the over‐saturated waters. As the cumulative amounts of water in contact with the soils increased, the amount of ions contributed by the residual soil solutions and the exchange complexes decreased, and the amount of precipitating carbonates decreased also. At very large cumulative amounts of water, the precipitation of carbonates in the soils was controlled by both the water and the ions released from the