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United States Department of Agriculture

Agricultural Research Service

Title: Evaluation of Methods to Estimate Macropore Characteristics in Montmorillonitic Clay Soils

item Rawls, Walter
item Pachepsky, Yakov

Submitted to: International Symposium on Preferential Flow
Publication Type: Proceedings
Publication Acceptance Date: November 29, 2001
Publication Date: December 20, 2001

Technical Abstract: Macropores contribute to the rapid movement of water and solutes through the soil. Rawls et. al. (1993) developed methods based on fractal geometry for estimating the macropore saturated hydraulic conductivity for no-till soils. These procedures required a measured areal macroporosity, or a measured areal macroporosity and a measured radius of the largest macropore. The objective of this study was to test these procedures on montmorillonitic clay soils. The soil survey macroporosity classes were highly correlated with the measured macroporosity. The equation for predicting macroporosity based on the largest macropore radius gave poor results. The macropore saturated hydraulic conductivity prediction equations based on a measured macroporosity and the radius of the largest macropore gave good results; however, the constant had to be reduced by about a factor of 10.

Last Modified: 4/19/2015