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Title: SOIL WATER RETENTION AS RELATED TO THE TOPOGRAPHIC VARIABLES

Author
item Pachepsky, Yakov
item Timlin, Dennis
item Rawls, Walter

Submitted to: Abstract of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/2000
Publication Date: 8/5/2000
Citation: N/A

Interpretive Summary:

Technical Abstract: Digital elevation models were proposed and used as a data source to estimate soil properties. Our objective was to determine and describe any correlations of soil water retention with soil texture and parameters of surface topography across the hillslope. The study was done for a gently sloping 3.7 ha field located in Beltsville, MD. Soil was sampled along four r30 m transects and on a 30 m grid. Textural fraction contents, bulk density, and water retention at tensions of 2.5, 5.0, 10, 33, 100, 500, and 1500 kPa were measured in samples taken from 4-10 cm depth. A 30 m digital elevation model was constructed from aerial photography data. Slopes, profile curvatures, and tangential curvatures were computed in the DEM grid nodes and interpolated to the sampling locations. Sand, silt, and clay contents showed dependencies on slope and curvatures. Soil water retention at 10 and 33 kPa correlated well with sand and silt contents. The regression model relating water retention to the topographic variables explained about 79% of variation in soil water content, and was as accurate with the validation data as with the development data used for cross-validation. Results show a potential for the topographic variables to be used in interpretation of the field-scale variability of soil properties and, possibly, yield maps in precision agriculture.