Spatial Variability of Soil Air Permeability and Hydraulic Properties in Desert Soils.

Air permeability (ka) is a viable alternative to water- and textured-based methods to rapidly map saturated hydraulic conductivity (Ksat) and provides information about the hydraulic properties and structure of the soil. The ability to measure this important hydraulic property without the use of more cumbersome and time-consuming direct methods may provide a practical approach to generate more complete data to describe hydrologic conditions. In particular, air permeability provides the opportunity to understand desert environments and changes in soil hydraulic properties due to soil development, land use, and climate. The purpose of this study is to characterize the spatial and temporal variability of soil air permeability and hydraulic properties of arid soils to improve our understanding of the dynamic processes that control the movement of water (downward recharge and upward evaporation), air, CO2, and contaminants in soils. Characterization of air permeability provides critical information for improving predictive models that allows us to minimize environmental degradation and improve environmental management in such a critical environment such as the arid state of Nevada. The protection of fragile desert ecosystems requires the understanding of water movement through soil, soil physical and textural characteristics, and percent organic matter. However, because of the complexity of desert soil systems and the link to water movement, our understanding of how soil structure affects air and water movement in soils and the dynamic relationships between physical and hydraulic properties in semi-arid and arid soils is limited. Availability of field-based data will improve the understanding of these fragile ecosystems while providing critical information needed by land managers for making decisions in a fast growing urban center.