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Title: THE BALANCED ENTROPY INDEX TO CHARACTERIZE SOIL TEXTURE FOR SOIL WATER RETENTION ESTIMATION

Author
item MARTIN, M - U.POLITECNICA,SPAIN
item Pachepsky, Yakov
item REY, J - U. COMPLUTENSE,SPAIN
item TAGUAS, J - U. POLITECNICA,SPAIN
item Rawls, Walter

Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/23/2005
Publication Date: 9/1/2005
Citation: Martin, M.A., Pachepsky, Y.A., Rey, J.M., Taguas, J., Rawls, W.J. 2005. The balanced entropy index to characterize soil texture for soil water retention estimation. Soil Science. 170(9):759-766.

Interpretive Summary: Ability of soils to retain water needs to be characterized in models of agronomy, hydrology, environmental engineering and many other fields. Such characterization most often consists in relating soil water content to the level of applied suction. Soil particle size distribution is generally known to be a dominant factor of water retention. Several ways to condense information about soil particle size distribution into small number of parameters have been suggested to facilitate searches of relationships between this distribution and soil water retention. A single index, called balanced entropy, has been recently proposed that reflects a relative heterogeneity in soil textural composition and therefore has a potential to reflect not only texture but, to some, extent structure or at least probable particle packing. The objective of this work was to test the predictive ability of this index with respect to soil water retention using the massive US National Soil Characterization database. We computed the balanced entropy for 9700 soil samples, and applied data mining tools to estimate water retention from soil textural composition, organic carbon content, and bulk density. The balanced entropy was the best single predictor and the most important predictor of volumetric water contents at '33 kPa which are notoriously difficult to estimate. Using the balanced entropy is a promising approach to improve the accuracy of estimated soil hydraulic properties.

Technical Abstract: Pedotransfer procedures are often used to estimate soil hydraulic properties from soil basic data available from soil surveys. Soil particle size distribution, or texture, is known to be a leading soil property affecting soils' ability to retain and transmit water and solutes. A substantial effort has been put in searching for small number of parameters to characterize soil texture for estimating soil hydraulic properties. We have developed a new, entropy-based index that, when applied to soil texture, shows presence of particle sizes dominating in particle size distributions. This index called balanced entropy has a potential to reflect probable packing of soil particles. Our objective was to see whether the balanced entropy can serve along with other soil basic properties as one of variables-predictors of soil water retention. We computed the balanced entropy for 9700 soil samples in the NRCS soil characterization database, and applied the data mining tools to estimate water retention from soil textural composition, organic carbon content, and bulk density. The balanced entropy was the best single predictor and the most important predictor of volumetric water contents at '33 kPa which are notoriously difficult to estimate. Using the balanced entropy is a promising approach to improve the accuracy of estimated soil hydraulic properties.