Spatial Variation of Soil Clay and Organic Carbon by Kriging and Geographical Information system (GIS) in Ardabil Plain

Soil management and planning is necessary for proper utilization of the soil and in this relation, the spatial distribution of soil properties is very important. Thus management and various uses plays a key role in organic carbon content and aggregate stability and subsequently degree of soil erosion .This research was carried out with the aim of investigating the spatial variations of soil organic carbon and clay percentage by different methods of interpolation and then choosing the most appropriate method in Ardabil plain. 77 composite samples of soil were taken from 0-30 cm depth and soil properties including organic carbon and soil clay percentage were measured. After normalizing the data, geostatistical analysis done to show spatial dependency of these properties. Then soil clay and organic carbon map produced in the ArcMap. Interpolated map of clay and organic carbon shows that soil organic carbon content increased by increasing of clay percentage that 77.23% of the area has organic carbon content higher than 1% and the exponential model selected for both variograms according to model correlation coefficient (R2) and measurement error (ME). Geostatistic analysis results also showed that clay and organic carbon have a moderate spatial structure (nugget to sill ratio) in the study area. Keywords: Spatial distribution, Interpolation, Geostatistical analysis, Organic carbon