Evaluation methods to verify the improvements in measuring soil physical properties by new fusion device using geostatistical analysis

In our previous study, a new device for measuring soil cone index (CI) was developed in order to replace the conventional devices. Although basic experiments at various field conditions had proved that the device was suitable to replace the conventional device, the improvements in measuring soil CI by new device were not sufficiently evaluated. One of the most major difficulty could be the absence of promising datasets to be referenced due to both spatial variations and the limitation of spatial frequency of measurement. In this study, evaluation methods based on geostatistical analysis were investigated and compared to verify the improvements and effectiveness by new device. Basically,spatial interpolation method using various algorithms and nugget estimation from semi-variogram method were investigated. Additionally, phase correlation method was investigated to compare relative consistency between spatial variations from different measuring depths. As a result, estimated nugget was some or less than 5% and phase correlation index was some or higher than 3% in every case with comparison analysis between the conventional and new device. The improvement and effectiveness in the developed measuring device could be proved by results from both of methods. Based on the results, the proposed methodology could be useful to evaluate the performance of a similar kind of measuring device that has to process spatial variations, e.g., soil water content and chemical properties in field.