Dataset for Soil Hydraulic Parameter Estimates Along an Elevation Gradient in Dryland Soils

Soil physical and hydrologic properties were determined on soils ranging from 1425 to 2111 m elevation within the Reynolds Creek Critical Zone Observatory (CZO). Climate varied between elevations, with mean annual precipitation (MAP) from 292 to 800 mm, respectively, and mean annual temperature (MAT) from 9.4 to 5.6 °C. Vegetation was dominated by various sub-species of sagebrush at all sites. Lithology was derived from basalt and Rhyolitic welded tuff at all sites except Johnston Draw, which was derived from granitic parent material. Soils were collected from profiles by genetic horizons down to ~1 m or bedrock. Soil hydraulic properties were determined in the lab using a dew point potentiometer to determine the drier end of the soil water characteristic curves. Estimates of soil water retention and hydraulic conductivity near saturation were determined using a multistep-outflow and evaporation method. Soil bulk densities were also determined, and soil particle size distributions were previously determined (Patton et al. 2017). Using Marquardt-Levenberg type parameter optimization, soil hydraulic parameters for the standard van Genuchten-Mualem water retention and hydraulic conductivity functions were inversely fit. For several rocky subsoils where intact soil cores could not be collected, hydraulic parameters were estimated using a pedotransfer function (RosettaLite v1.1), bracketed using measurements from the nearest soil horizons. Results display subtle increases in soil water storage capacity (1.06%) and effective saturated hydraulic conductivity (~10%) moving from low to high elevations in the watershed. Both alpha (1.9%) and n (1.1%) parameters increased with increasing elevation and rainfall, typical of coarsening soils. In contrast, however, soil particle size distributions had more silt+clay fraction at the highest elevation site. Soil Bulk density was lowest at the high elevation site. Plant available water, determined from weighted average values of field saturated volumentric water content and the water content at the permanent wilting point displayed no trend with elevation or precipitation, suggesting potential tradeoffs in controls on ecohydrological processes with elevation. Not surprising, plant available water was highest in under-shrub soils vs. bare inter-plant patch spaces. In addition, the saturated water holding capacity was greater in surface soils at the low elevation site, with low precipitation, but greater in subsoil horizons at higher elevations with greater precipitation, presumably due to greater eluviation with greater precipitation totals