Evaluation of Interpolation Accuracy of Soil Properties in Paddy Fields According to Variogram Models

Precise management that considers the spatial heterogeneity of soil properties within the paddy field is essential for stable crop production and sustainable agriculture. However, analyzing soil properties across the entire paddy field at high resolution is inefficient in terms of time and cost. This study compared and evaluated the accuracy of three Variogram models(Spherical, Exponential, and Gaussian) for predicting soil properties across the entire paddy field using a limited number of soil samples. To this end, Total Nitrogen (TN) and Available Phosphate (Av-P₂O₅) were analyzed from a paddy field located in Iksan, Jeonbuk-do, Republic of Korea. Ordinary Kriging was conducted using each Variogram model, and model performance was evaluated based on Mean Absolute Error (MAE) and Root Mean Square Error (RMSE). The analysis revealed that the Spherical model yielded the most accurate prediction for TN(MAE = 0.013, RMSE = 0.017), while the Exponential model exhibited the best performance for Av-P₂O₅₍MAE = 18.988). The Gaussian model exhibited relatively higher error. However, the overall differences in performance among the models were marginal, which is likely attributed to the limited number of samples and the spatial characteristics of the paddy field. The findings of this study are expected to serve as a valuable reference for selecting appropriate spatial interpolation methods in the implementation of variable-rate fertilization technologies.