مقايسه كريجينگ و كوكريجينگ در برآورد غلظت كلر محلول در خاك

A Comparison of Kriging and Cokriging Techniques in Estimating Cl- Concentration in Soil

Estimation of spatial variables using data of the property under estimation (kriging technique) or by employing data of supplementary variable(s) (cokriging theory) has been of prime interest to soil scientists in the last few decades. Chlorine is both an essential and a toxic element for plant growth and its measurement is not only costly but also time consuming. The objective of this study was to evaluate the ability of kriging and cokriging techniques to predict the chloride concentration in selected surface soils from Rudasht area. Six hundred surface soil samples (0-30 cm) were taken from the, nodes of a 100* 100 m regularly spaced grid scheme. ECe was measured in all the samples whereas, the Cr concentration was measured in half of them. Both parameters were highly variable and showed strong spatial correlation. Both kriging and cokriging provided reasonable estimates for Cl^- concentration However, using soil salinity data (ECe) for the estimation of Cl^- concentration by cokriging could reduce the MSEE by 38% and, as a result, the correlation coefficient between the estimated and measured concentration of Cl^- improved from 0.76 to 0.90. Therefore, if higher accuracy is needed, cokriging is preferred to kriging particularly when soil salinity data have been collected for other purposes.