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REGIONAL SOIL WATER RETENTION IN THE CONTIGUOUS US: SOURCES OF VARIABILITY AND VOLCANIC SOIL EFFECTS
Citation:
Kern, J. S., M G. Johnson, AND R B. McKane. REGIONAL SOIL WATER RETENTION IN THE CONTIGUOUS US: SOURCES OF VARIABILITY AND VOLCANIC SOIL EFFECTS. Presented at Soil Science Society of America annual meeting, Denver, CO, November 2-6, 2003.
Description:
Water retention of mineral soil is often well predicted using algorithms (pedotransfer functions) with basic soil properties but the spatial variability of these properties has not been well characterized. A further source of uncertainty is that water retention by volcanic soils has received less study although they occur in large areas in the western contiguous US. These topics are being explored by constructing a spatial dataset based on USDA Natural Resource Conservation Service (NRCS) STATSGO geographic data and the NRCS National Soil Characterization dataset (NSCD) for the contiguous US. Basic soil properties were derived from STATSGO but organic matter as soil organic C was based on the NSCD because of missing data. In areas where soil property variability was greatest, we used more detailed soil geographic information (SSURGO) to examine the magnitude and spatial scale of the variability. We are examining water retention at even finer scales by combining data from the NSCD and our own studies in the South Santiam watershed in the Western Oregon Cascades, an area dominated by tuffs, breccias, and wind deposited volcanic ash. The feasibility of developing pedotransfer functions to predict soil water retention for volcanic soils is being explored.