ABSTRACT
The presence of soil carbonates occurring as solidified masses or dispersed particles can alter soil water dynamics from what would be expected based on noncarbonate soil properties. Carbonate minerals in the soil can be derived from high-carbonate parent material, additions in the form of carbonate mineral containing rain or dust, and high-carbonate groundwater, and formed in situ as secondary minerals. Soil carbonates in the fine-earth fraction are predominately derived from precipitates and are usually of the clay and silt size classes. Carbonate coarse fragments can be derived from carbonate parent material detritus or from pedogenic sources such as nodules and petrocalcic rubble. Parts of the profile can be continuously indurated with carbonates due to either high-carbonate bedrock or the formation of a petrocalcic horizon. The accumulation of dispersed soil carbonates appears to increase available water-holding capacity (AWHC) in coarse-textured soils and some fine-textured soils. Due to the relatively high AWHC of carbonate rock-like material (0.03–0.22 m3 m−3), soil profile AWHC will likely be underestimated if fragments of indurated carbonate material or clasts of carbonate parent material are ignored. The high water-holding capacity of petrocalcic horizons and high-carbonate bedrock and the presence of water within these cemented soil horizons indicate their potential importance as a plant's water source, especially during dry periods.
