A Sampling Strategy in Mapping of Soil Parameters of Paddy Field

Abstract

The study to evaluate the sampling design were conducted in a 100m×50m of paddy field located in Kyoto, and in a 156m×77m of paddy field located in Ishikawa prefecture, Japan. The variability of five soil parameters: moisture, SOM, NO₃-N content, pH and EC was described by collecting the soil reflectance at interval of 1m×5m and 1m×10m for Kyoto and Ishikawa field, respectively. The Kriged standard errors of seven subsets for Kyoto data, and eight subsets for Ishikawa data resulted from different scanning intervals, were calculated. As a result, the cumulative Kriged standard error decreased with an increment in sampling size, followed by slightly increase after a minimum value was achieved. The optimal sampling sizes for mapping of each soil parameters are presented.