Zone Classification of Soil Salinity in Maize Root Zone Under Different Irrigation Treatments Using Geostatistical Methods

This study was carried out as a complete block design with three treatments including, full irrigation, partial root-zone drying in two levels at 75% and 55% of full irrigation to evaluate three Geostatistical methods including Kriging, CoKriging and Weighting Moving Average for interpolating the values of soil electrical conductivity, as the best index for soil salinity. Soil electrical conductivity (EC) was measured using Decagon 5TE TDR sensors. Then zone classification maps of the EC were prepared using a linear relation between EC and soil water content values measured by IDRG SMS T2 sensors. Results of the variograms analysis showed that the effective range of variograms was higher than the maximum space between observed points in the all treatments. Comparing the observed and Geostatistical estimated values of EC based on the evaluation criteria including root mean square error (RMSE), mean bias error (MBE), mean absolute error (MAE) and index of agreement (d) showed that there was a good agreement between observed and estimated EC values. Duncan test at 5% probability level showed that values of the evaluation criteria for the Kriging method were significantly lower than those for the other methods at the all treatments, and CoKriging method ranked as the second method (p≤0.05). Also there was no significant difference between the Cokriging methods by simultaneous consideration of the electricul conductivity with one of the temperature or soil moisture covariates as the model input.