Wednesday, 8 October 2008

George R. Brown Convention Center, Exhibit Hall E

Michael Young, Div. of Hydrologic Sciences, Desert Research Institute, 755 E. Flamingo Rd., Las Vegas, NV 89119, Todd Caldwell, Div. of Earth and Ecosystem Sciences, Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, Jianting Zhu, Div. of Hydrologic Sciences, Desert Research Institute, 755 E Flamingo Road, Las Vegas, NV 89119, Lynn Fenstermaker, Desert Research Institute, 755 East Flamingo Road, Las Vegas, NV 89119 and Eric V. McDonald, Division of Earth and Ecosystem Sciences, Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512

The Mojave Global Change Facility (MGCF), located in the Mojave Desert in Nevada, extends for several hundred meters across a north-facing alluvial fan complex. The specific objectives are to evaluate the spatial structure (correlation and variability) present in soil texture, bulk density, and soil hydraulic properties; determine the impact of soil texture on depth of wetting at the meso-scale; and, determine whether a relationship exists between plant response and texturally induced differences in the water balance. Soil properties were obtained at two scales. First, soil was collected at two depths (0 to 5 cm and 5 to 10 cm) at each of 96 test plots, analyzed for texture and bulk density, and used to obtain soil hydraulic (van Genuchten) properties using the pedotransfer function method. Second, hydraulic properties were obtained at ~20cm increments from undercanopy to interspace microsites using a tension infiltrometer. Data were examined for spatial structure using semi-variograms. We then simulated soil water balance at both scales using a Richards-equation based computer model, field collected (eddy covariance) evapotranspiration estimates for a one-year period, and shrub coverage at the site. The results show a distinct fining of texture at both depths in the northeast quadrant of the site (p<0.05). The textural patterns led increasing saturated water content and increasing air entry pressure from the southwest to the northeast of the facility. Subshrub-scale variability in hydraulic properties was also significant, showing that soil structure does exert an important influence on soil properties, and the overall water balance at small scale.

See more of: Environmental Soil Physics: Bridging the Critical Zone to Crops, Climate, and Remediation: II (Posters)
See more of: S01 Soil Physics

2008 Joint Annual Meeting (5-9 Oct. 2008): Multi-Scale Variability of Soil and Hydraulic Properties and Impacts to Arid Water Balance.

740-10 Multi-Scale Variability of Soil and Hydraulic Properties and Impacts to Arid Water Balance.