Application and Comparison of International Pedotransfer Functions for Mazandaran and East Azarbaijan Soils

In this study, the applicability of 16 series of the developed pedotransfer functions for estimating soil water characteristic curve (SWCC) of 57 soil samples from Mazandaran and East Azarbaijan provinces were examined. Clay, sand and silt percentages, bulk density, soil particle density, organic carbon percentage and depth of sampling were used as readily available soil parameters to estimate the water contents at different matric suctions, while parameters of Brooks and Corey and van Genuchten models were considered as difficult to measure soil parameters. The measured and estimated water contents at the different matric suctions were compared with each other and the pedotransfer functions were evaluated by statistical criteria. The results showed that clay and organic carbon percentages and bulk density had significant correlations with the most of the coefficients of the Brooks and Corey and van Genuchten models. The Campbell and Shiosawa parametric pedotransfer functions with the inputs of clay and sand percentages and bulk density had the amounts of IRMSE=0.0676 cm3cm-3 and AIC= -3600 (the best model) and Mayr and Jarvis parametric pedotransfer functions with the inputs of clay, silt, sand and organic matter percentages and bulk density had the amounts of IRMSE= 0.2452 cm3cm-3 and AIC= -1900 (worst model), for the 0 to 15000 cm matric suctions. The results showed that some of international pedotransfer functions could be used to estimate the water content of Iranian soils.