Soil water retention curve is a key function that expresses soil vadose zone characteristics quantitatively. The direct measurement of this curve is time- consuming, laborious and costly. Therefore, many attempts have been made to predict water retention curve from other soil characteristics indirectly. Pedotransfer functions (PTFS) is one of the indirect methods. The objective of this research was to study the effect of geometric mean diameter (dg) and geometric standard deviation (σg) calculated the basis of three and nine soil particle size classes in the prediction of soil water retention curve and Van Genuchten equations parameters applying pedotransfer functions. Consequently, 40 loamy soil samples, including 35 samples for prediction and 5 samples for validation, were randomly collected from Karaj area. Particle size distribution, bulk density, calcium carbonate and organic carbon precentages were determined with the hydrometery, cold, acid neutralization and Walkly and Blacks methods, respectively. Soil water retention curve was obtained using pressure plates. The best subset of independent variables for estimation of soil water retention curve and Van Genuchten equations parameters were selected by best subset regression command. Regression equations were obtained using multiple linear regressions. The results indicate that there is no significant difference in calculations in predicting point estimation PTFS by using dg or σg obtained from the data of threee soil particle size classes or nine soil particle size classes. However, in the case of parametric estimation of water retention at tensions of 10, 33, and 100 kPa, using dg and σ g obtained from the data of nine soil particle size classes and at tensions of 300, 500, 1500 kPa than using dg andσ g obtained from the data based on three soil particle size classes made more valid predictions. Statistical analysis indicated high validity of derived PTFs.
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Mirkhani, R., & Khodaverdiloo, H. (2006). Effect of Geometric Mean Diameter and Standard Deviation of Soil Texture to Predicting Soil Moisture Coefficients. Iranian Journal of Soil Research, 20(1), 51-59. doi: 10.22092/ijsr.2006.127173
MLA
R. Mirkhani; H. Khodaverdiloo. "Effect of Geometric Mean Diameter and Standard Deviation of Soil Texture to Predicting Soil Moisture Coefficients". Iranian Journal of Soil Research, 20, 1, 2006, 51-59. doi: 10.22092/ijsr.2006.127173
HARVARD
Mirkhani, R., Khodaverdiloo, H. (2006). 'Effect of Geometric Mean Diameter and Standard Deviation of Soil Texture to Predicting Soil Moisture Coefficients', Iranian Journal of Soil Research, 20(1), pp. 51-59. doi: 10.22092/ijsr.2006.127173
VANCOUVER
Mirkhani, R., Khodaverdiloo, H. Effect of Geometric Mean Diameter and Standard Deviation of Soil Texture to Predicting Soil Moisture Coefficients. Iranian Journal of Soil Research, 2006; 20(1): 51-59. doi: 10.22092/ijsr.2006.127173
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