10.2190/ECE7-2PY3-N3LH-VVKA ECE72PY3N3LHVVKA 5 Dependence of Variability in Hydraulic Properties on Physical Properties of Field Soil 171 189 20020509 20020509 20020509 20020509 ECE72PY3N3LHVVKA.pdf http://baywood.metapress.com/link.asp?target=contribution&id=ECE72PY3N3LHVVKA 2 J. Y. Diiwu R. P. Rudra W. T. Dickinson G. J. Wall University of Guelph, Ontario, Canada Land Resource Research Centre, Ontario, Canada A method based on the spatial distribution of texture and bulk density has been proposed for characterizing spatial variations in the hydraulic properties of soils. Soil samples collected from the A and B horizons of the study field were analyzed for texture, bulk density, soil water retention, and saturated hydraulic conductivity. Analysis of the data showed that these soil properties are spatially variable between the A and B horizons and between zero tillage and conventional tillage treatments. A multiple linear regression relation was developed to relate the spatial variability of soil water characteristics to the variability of texture and bulk density. the coefficients of the derived relation reveal that the influence of physical properties on variability in hydraulic characteristics of soil does not only depend on the degree of saturation of the soil, but also on horizon and tillage treatment. Soil water content predicted with the derived relation compared fairly well with observed soil water content. D. R. Nielsen, J. W. Bigger, and K. T. Erh, Spatial Variability of Field-Measured Soilwater Properties, <i>Hilgardia, 42</i>, pp. 215-259, 1973 A. J. Peck, R. J. Luxmore and J. L. Stolzy, Effects of Spatial Variability of Soil Hydraulic Properties in Water Budget Modelling, <i>Water Resources Research, 13</i>, pp. 348-354, 1977. L. R. Ahuja, J. D. Ross, R. R. Bruce, and D. K. Cassel, Determining Unsaturated Hydraulic Conductivity from Tensiometric Data Alone, <i>Soil Science Society of America Journal, 52</i>, pp. 27-34, 1988. J. Y. Diiwu, <i>Transfer Function Modelling of Drainage and Solute Transport through Layered Macroporous Soil</i>, Ph.D. thesis, School of Engineering, University of Guelph, Guelph, Ontario, 1997. G. Dagan and E. Bresler, Solute Dispersion in Unsaturated Heterogeneous Soil at Field Scale. 1. Theory. <i>Soil Science Society of America Journal, 43</i>, pp. 461-467, 1979. C. S. Simmons, A Stochastic Convective Transport Representation of Dispersion in One-Dimensional Porous Media Systems, <i>Water Resources Research, 18</i>, pp. 1193-1214, 1982. W. A. Jury, Simulation of Solute Transport with a Transfer Function Model, <i>Water Resources Research, 18</i>, pp. 363-368, 1982. E. Bresler, G. Dagan, R. J. Wagenet, and A. Laufer, Statistical Analysis of Salinity and Texture Effects on Spatial Variability of Soil Hydraulic Conductivity, <i>Soil Science Society of America Journal, 48</i>, pp. 16-25, 1984. J. L. Hutson and A. Cass, A Retentivity Function for Use in Soil Water Simulation Models, <i>Journal of Soil Science, 38</i>, pp. 105-113, 1987. D. Hillel, <i>Fundamentals of Soil Physics</i>, Academic Press, Inc., San Diego, California, 413 pp., 1980. A. Mantoglou and L. W. Gelhar, Stochastic Modelling of Large Transient Unsaturated Flow Systems, <i>Water Resources Research, 23</i>, pp. 57-67, 1987. O. Tietje and V. Hennings, Accuracy of Saturated Hydraulic Conductivity Prediction of Pedo-Transfer Functions Compared to the Variability within FAO Textural Classes, <i>Geoderma, 69</i>, pp. 71-84, 1996. G. S. Campbell, A Simple Method for Determining Unsaturated Conductivity from Moisture Retention Data, <i>Journal of Soil Science, 117</i>:6, pp. 311-314, 1974. K. E. Saxton, W. J. Rawls, J. S. Romberger, and R. I. Papendick, Estimating Generalized Soil Water Characteristics from Texture, <i>Soil Science Society of America Journal, 50</i>, pp. 1031-1036, 1986. J. S. C. Mbagwu, Saturated Hydraulic Conductivity in Relation to Physical Properties of Soils in the Nsuka Plains, Southeastern Nigeria, <i>Geoderma, 68</i>, pp. 51-66, 1996. L. Wilkinson, M. A. Hill, J. P. Welna, and G. K. Birkenbeuel, <i>SYSTAT for Windows: Statistics</i>, Version 5.2 Edition, Evanston, Illinois, SYSTAT, Inc., 724 pp., 1992. A. Klute, Laboratory Measurement of Hydraulic Conductivity of Saturated Soil, in <i>Methods of Soil Analysis, Part 1</i>, American Society of Agronomy No. 9 in Agronomy Series, C. A. Black (ed.), pp. 210-221, 1965.