The High Water-Holding Capacity of Petrocalcic Horizons
- Michael C. Duniway *a,
- Jeffrey E. Herricka and
- H. Curtis Mongerb
Petrocalcic soil horizons occur in most arid and semiarid ecosystems around the world, often within the plant rooting zone. Little is known, however, about the water-holding characteristic of soils indurated with CaCO3 We conducted a replicated experiment to define the soil-water release curve (SWRC) for a range of petrocalcic horizon materials. Samples from both plugged and laminar zones of two Stage V petrocalcic horizons in southern New Mexico were characterized. Wetter soil-water potentials were measured using a pressure plate; more negative potentials (down to less than < −10 MPa) were measured using a chilled mirror water activity meter. Measured SWRC data were fitted to the van Genuchten equation. The SWRC methods used were found to be both reliable and repeatable. Plant-available water-holding capacity (AWHC) for desert species (with wilting point set at −4.0 MPa) ranged from 0.26 m3 m−3 in plugged zones to 0.06 m3 m−3 in some laminar zones in contrast to about 0.07 m3 m−3 in the loamy sand parent material. Correlation analyses across morphologies of AWHC and soil properties resulted in significant statistical relationships only with bulk density and porosity. The AWHC and CaCO3 content, however, were significantly negatively correlated within the laminar and positively correlated within the plugged petrocalcic horizon morphologies. Cementation by CaCO3 dramatically alters the water-holding characteristics of soils and understanding these horizons is crucial to understand patterns of soil water in desert systems throughout the world.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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