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United States Department of Agriculture

Agricultural Research Service

Title: Water Retention Pedotransfer Function for a Horizon

Authors
item Rawls, Walter
item Nemes, A - USDA ARS CONTRACTOR
item Pachepsky, Yakov

Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: September 2, 2003
Publication Date: November 2, 2003
Citation: Rawls, W.J., Nemes, A., Pachepsky, Y.A. 2003. Water retention pedotransfer function for a horizon [abstract]. Soil Science Society Of America Annual Meeting.

Technical Abstract: Reports about the relationship between soil water retention and organic carbon content are contradictory. We hypothesized that this relationship is affected by both proportions of textural components and amount of organic carbon. We examined the relationship between total clay, sand and silt, texture class, taxonomic order and organic matter to the water retention of topsoil, measured at -33 kPa and -1500 kPa matric potentials. To test the hypothesis, we used National Soil Characterization data base from which 2149 soil horizons were selected according to the following criteria: Mineral soil horizons were selected from the contiguous United States having horizon notation 'A', 'A1' and 'Ap' (and their derivatives), with the condition that the top of the horizon was at the soil surface. Regression trees and Group Method of Data Handling were used to analyze the complex joint effect of total clay, sand and silt, texture class, taxonomic order and organic matter on water retention at -33 kPa. and '1500 kPa.. Organic matter was important in predicting water retention at -33 kPa from total clay, sand, silt and organic matter except for the soils with greater than 66% sand. While organic matter was only important in predicting water retention at -1500 kPa from total clay, sand, silt and organic matter for the soils with less than 15% clay. Organic matter was important in predicting water retention at -33 kPa. and '1500 kPa. when combined with taxonomic order only; however, when combined with soil texture classes and taxonomic order it was less important. Developing pedotransfer functions for predicting water retention at -33 kPa. and '1500 kPa. using total clay, sand, silt and organic matter for each taxonomic group indicated that organic matter had the most influence for the Mollisols, Alfisols, Ultisols, and Inceptisols. Developing pedotransfer functions for predicting water retention at -33 kPa.. using total clay, sand, silt and organic matter for each soil texture class indicated that organic matter had the most influence for the silty clay loams clay loams and silt classes, while for -1500 kPa. water retention organic matter had the most influence for the loam, sand, silt and loamy sand classes. Results are expressed as equations that can be used to evaluate effect of the carbon sequestration and management practices on soil hydraulic properties.

Last Modified: 10/25/2014
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