Spatial Distribution Maps of Soil Chemical Properties Using Kriging Model and ArcGIS in Kirkuk City, Iraq

This study specifically investigates the chemical properties of soils and their distribution across various geographical areas. The Kriging approach together with Geographic Information Systems (GIS) are utilized to forecast the chemical properties of the soil. A total of twenty-five sampling points were selected among various parts of Kirkuk City. Five soil properties are examined: soil reaction degree or potential hydrogen (pH), total dissolved salts (TDS), gypsum content, sulfate trioxide (SO3), and organic matter (OM). The chemical analysis indicates that the soil pH is of low alkalinity. This study reveals a limited presence of total dissolved salts between (1.02 - 13.541) %. Moreover, a positive correlation is detected between the gypsum and sulfate concentrations. Conversely, organic matter displays a negative association but it is most pronounced in the southwestern region. The Kriging technique successfully depicts the spatial distribution of various soil properties in Kirkuk City showcasing a range of accuracy from satisfactory to exceptional. In addition, a cross-validation method is used to evaluate the relationship between the fundamental and explored chemical properties. The Kriging maps show varying degrees of model fit, with lower root mean square error (RMSE) and higher coefficient of determination (R) values of 0.9583, where the higher property is the organic matter. The evaluation of the interpolation methods confirms the dependability of the projected values, so augmenting our comprehension of the soil properties in the region.