Effect of texture on the performance of soil particle-size distribution models

The best mathematical models describing particle size distribution of soils

“…After these models, Fredlund model had the best accuracy than the others, but, hadn't significant differences (p B 0.05) with van Genukhten and power-exponential models. This was in contrast with Hwang (2004) results, which stated Fredlund had better accuracy than Van genukhten model. But Hwang (2004), emphasized that WeibulL and van Genukhten had reasonable fitting accuracy.…”

“…This was in contrast with Hwang (2004) results, which stated Fredlund had better accuracy than Van genukhten model. But Hwang (2004), emphasized that WeibulL and van Genukhten had reasonable fitting accuracy. In our study, these two later models had good fitting accuracy, too.…”

“…Thus, it is concluded that accuracy of a model, doesn't always increase with over-parameterization. This result was different from Hwang (2004) one as well as Fredlund et al (2000), who reported that the performance of the Fredlund model would be All small letters are signs for significant difference at level 5 %. SD standard deviation, Ave average Fig.…”

“…Tested five log-normal models for 71 soils from New Zealand Hwang et al (2002) Evaluated fitting ability at 7 models on 1387 Korean soil samples Hwang (2004) Studied the effect of soil texture of 1387 Korean soil samples on the performance of nine different PSD models Lima and Silva (2007) Conducted a study on PSD of suspended sediments in river water Bah et al (2009) Compared the fitting ability of seven PSD models to data of 55 fine-textured soil samples from New South Wales in Australia Bagarello et al (2009) Evaluated the ability of the hyperbolic and Fredlund models to fit 243 soils Shangguan (2012) Investigated ten PSD models for the conversion of soil texture classification from ISSS and Katschineski to FAO/USDA system for soils from china Botula et al (2013) Evaluated the performance of 18 PSD models for 1412 soils from Central Africa which had humid tropics Weipeng et al (2015) Studied critical evaluation of PSD models of 1013 soil samples from different regions of china Bayat et al (2015) Investigated fitting capability of PSD models on the 713 PSD experimental data of the UNSODA database…”

“…This result may be due to the penalties imposed by the AIC (Burnham and Anderson 2002) for additional fitting parameters of multiparameter models comparing with the one-parameteric models (Bayat et al 2015). Hwang (2004) deduced that van Genukhten model wasn't suitable for soils with high clay content. In clay texture group, AIC indicator, demonstrated difference between all models in the best manner while R 2 adj criterion, didn't show a good separation capability.…”