New Mexico Geological Society Annual Spring Meeting — Abstracts

Calcic horizons are ubiquitous features of semi-arid-to-arid soils. The accumulation of calcium carbonate over time produces systematic morphological and textural changes in the soils described as stages of calcic horizon development. These changes in soil properties influence the partitioning of precipitation into infiltration and runoff in semiarid environments. The calcium carbonate arrives at the soil surface along with dust (primarily silt and clay) so there is also a systematic increase in the silt and clay content of semi-arid soil with time. There has been no systematic study of the impact of increasing amounts of calcium carbonate on the hydrologic properties of semi-arid soils.

This study describes some of the changes in hydrologic properties associated with increasing amounts of calcium carbonate. Three surfaces in Sevilleta National Wildlife Refuge were located to carry out the analysis. Physical and hydrologic properties from three soil profiles of different ages and stages of carbonate development were gathered. Soil textures, total carbonate content, and bulk densities were measured for each horizon. In situ measurements of soil hydraulic conductivity were taken at every soil horizon using a tension disk infiltrometer. The amount and morphology of the calcium carbonate, and thus the hydraulic properties, varied with soil depth for each of the soils. The calcium carbonate cements soil particles changing the apparent texture of the soil horizon and thus other soil properties such as structure, porosity, moisture retention, and unsaturated and saturated hydraulic conductivity also change significantly. The ultimate goal of this study is to provide a basis for developing more accurate pedotransfer functions, which is the main method for obtaining soil hydrologic properties of rangeland soils.