Evaluation of Geostatistical With Soil Texture as Covariate and Pedotransfer Functutions Methods for Estimating Soil Saturated Hydraulic Conductivity

In this study, Pedotransver Functions and geostatistical methods are compared for estimating soil saturated hydraulic conductivity by soils texture. Data collected from 196 soil profiles related to soil and land reform Agricultural Organization of Ardebil. Results showed that among the geostatistical and Pedotransver Functions methods,ordinary cokriging with soil texture as Covariate has the best estimation in the region with Coefficient of Determination equal to 0.93 and Root Mean Square Error equal to 3.21(Centimeters per day) and other goestatistical methods without covariate have lower accuracy estimations. The best fitted variogram in ordinary cokriging, was determined as exponential model with zero nugget effect and 156 of sill range that showed the strength of the spatial structure of the region and the full impact of the spatial structure on region variogram. Accuracy of Pedotransver Functions methods respectively decreased from Ferrer-Julià et al (2004), Roseta, Dane and Puckett (1994), Cosby et al (1984), Puckett et al (1985), Campbell and Shiozawa (1994).Among Pedotransver Functions methods Ferrer-Julià (2004) has more accuracy with coefficient of determination equal to 0.89 and Root Mean Square Error equal to 2.1 (Millimeters per hour)for estimating soil saturated hydraulic conductivity by soils texture.