Grid-based Correlation Analysis of Surface Elevation and Topsoil Depth in a Rice Paddy Field Using a UAV and a Smart Rice Transplanter

Abstract

　This study conducted a grid-based correlation analysis of surface elevation and topsoil depth (TD) in a 1.4 ha rice paddy field using a 2 meter grid. A UAV collected 34,080,826 surface elevation data points, while a smart rice transplanter measured 8,021 TD points. Offset correction minimized missing TD data to 2.2 % within the grid. A weighted RMSE optimized the grid size, balancing spatial homogeneity and local variability. Analysis revealed a negative correlation between surface elevation and TD (r＝−0.53), indicating that lower elevations generally correspond to deeper topsoil.